Suspension Disaster - The C4 Suspension won't fit!

[@FredricLindberg]

Please stop thinking that you're wasting ppls time! This episode is more interesting to watch than most videos on the web. We who follow you are doing so because of your tendancy to do things "right" and explaining it well while you do. Keep the good work up! :)

[@ThrottleStopGarage]

Thanks, I'm really grateful that people do watch and support this adventure.

[@takhini]

Something something "fall down" something "get back up" ... You're a shining inspiration Craig. Take your time, regroup, and carry on. Well done!

[@ThrottleStopGarage]

Thanks - much appreciated.

[@bewernia]

Your videos are never a waste of time.

[@ThrottleStopGarage]

Thanks - I wasn't sure with this one, but it felt good to just share the problem.

[@Neilywop]

Thanks for not ending the channel 😮😊. I always enjoy your videos

[@ThrottleStopGarage]

I was just kidding! I'll sort this mess out.

[@mopedmarathon]

Oh man that sucks. I’m gutted for you dude. However you’re more than qualified to solve this problem. Glad you didn’t end the channel. Can’t wait to see the results of this next challenge. Keep on keeping on!

[@ThrottleStopGarage]

Thanks - it's been a roller coaster for the past few weeks.

[@colbyscott9822]

Don't end the channel! I just found this video. I'm very interested to see how you engineer this!

[@ThrottleStopGarage]

I was joking - I'm far too deep to give up now!

[@glencoad737]

This is going to be awesome to watch you sort this all out, really appreciate you taking the time to share. I may waste a lot of time watching youtube videos but would never consider watching yours a waste of time.

[@ThrottleStopGarage]

Thanks, I'll do my best to solve this challenge.

[@ronkluwe4875]

Craig - I have watched your videos from the beginning and I know you will overcome this hurdle with a great bit of engineering and fabrication, just as you have with all the other parts of the car. "Trust but verify" is a mantra I lived by when managing engineering projects and more than once it ended up in huge saves when it turned out what was being said would not work. Waiting a month to see the outcome of this fix is worth the wait.

[@ThrottleStopGarage]

Much appreciated Ron. The ultimate irony is that I would never normally accept any part without validation. The one time that I do this, it comes back over and over again as a bad decision. Learning the hard way sucks.

[@GrayRaceCat]

@@ThrottleStopGarage, Craig, it's not called "The School of Hard Knocks" for nothing! You will prevail, and as long as you continue to post, I will be here too. Thank you.

[@prestonengebretson2920]

You found out exactly what we did when trying to use another Front Suspension on our design...we also ended up Starting with a Clean Sheet and having to Fabricate the Spindle Brackets to hold the upper and lower Ball joints...additionally, when you change the Dimensions of the Distance between the Pickup Points...you change the Roll Center...we finally got our Front Suspension for our Stylized 1929 Type 32 Bugatti Tank finished with minimal Bum Steer and the desired Roll Center...Excellent Video...Keep it up please!!!

[@ThrottleStopGarage]

Thanks - lessons learned.

[@Syscrush]

Man, i relate to do much in this update. Good on you for deciding to set up and work from first principles. It's funny that you think a video like this is wasting viewers' time -we're not here to see a built car, we're here to see a car built! The ups and downs, the success and failures, the mistakes and the good luck. Seeing how you identify and solve problems is exactly what we want. This is what we're here for. If someone wants to watch someone bolt crap together with no regard for how well it works, there are plenty of other channels for that. However long it takes, I'm looking forward to your next update and seeing how you've sorted all of this out. Keep up the great work!

[@ThrottleStopGarage]

Thanks - I really appreciate this comment.

[@jaybauer6978]

Filled with admiration for your work. I have a much less sophisticated project 122s languishing in a tent garage in the side yard. Really enjoy your channel, and looking forward to the day when we can both say “it’s done!”

[@ThrottleStopGarage]

That will be a great day! Just hoping to have this thing be able to roll in a few months. Famous last words.

[@HomeBuiltByJeff]

These things are really frustrating but it is worth doing it right. I spent so much time playing around making sure my bump steer was good, but didn't realise until I drove the car that the steering was dangerously slow. If it is worth doing, it's worth doing twice ;)

[@ThrottleStopGarage]

You've got the same issues - no space to pack modern stuff. The narrow rack I found is 2.8 turns lock to lock and is an off the shelf part.

[@earlhorton1092]

Always look forward to any updates. Your carbon fiber videos have taught me quite a bit and have been so useful in my carbon fiber projects.

[@ThrottleStopGarage]

That's great to hear. Thanks.

[@philsommerard203]

Hi I have also been fallowing along for years , I am going through the ringer on my build at the moment , so I totally understand . We all appreciate you content , from composites to metal work . Thanks for sharing your aggravation , it helps to know we're not alone in the world of building dreams that seem to be all up hill most of the time , hang in there !!!!!

[@ThrottleStopGarage]

Thanks - this is a two-way street. Knowing that I'm not alone is important for keeping going.

[@eeblatter]

I've worked with several "professional" suspension engineers before on new vehicle projects only to have huge problems that they would shrug off. It's good to have a healthy skepticism when working with one. Sorry to see this happened to you but you sound like you are ready to do what it takes to get it resolved. More power to you!

[@ThrottleStopGarage]

Hard lessons stick. Engineers that don't work details should stop.

[@lasskinn474]

well often you wont have the right details before you actually try. clients at first don't like the "I don't know, we can't know without testing/extensive checking/etc" answers. some clients will just straight up think that you don't know your stuff because you know what you can't trust as correct without checking. either virtually or in practice. practice is the more expensive. that's how internet and community info and vids/pics/journals of actually checking stuff is so valuable for hobbies. stuff like this really :) where it gets really frustrating is when you're dealing with a billion dollar company with dedicated developer PR personnel who will say that such and such works because it's implied in the documentation, while in reality you can't trust it if you don't check on a shipped device, so the only thing those people are good for is getting free lunches.

[@robertkonchan197]

I enjoy all your videos and appreciate you making them. Thank you!

[@ThrottleStopGarage]

Glad you like them!

[@nobodynoone2500]

This happens so much. Most people just give up or bubba it together. Suspension is big boy stuff. Don't sweat, just work through it and check in sim and IRL for binding issues. Great work. Love the episode, and it really is one. Don't sell it short.

[@ThrottleStopGarage]

Thanks. I'm hard at it on the computer. I'd rather not be doing it but there is no other way.

[@mark63366]

What a nightmare. Good luck moving forward. I'm really interested to see how you solve your problems.

[@ThrottleStopGarage]

Thanks. Burning the midnight oil getting all the parts drawn, and a new design working.

[@patrickorr813]

I find watching your episodes inspiration and informative well worth the wait.

[@ThrottleStopGarage]

Thanks - I appreciate everyone that watches. I get a boost out of knowing I'm not alone.

[@kentmckean6795]

Sorry for your loss... I have no doubt that you will overcome and succeed with whatever you end up using or building!

[@ThrottleStopGarage]

I'll do my best to get it right.

[@garygardner9677]

I just discovered your channel. I thoroughly enjoy this stuff. You're playing with a 3 dimensional dynamic puzzle. Most people would through in the towel before even starting a project like this. I applaud You're persistence to make this happen. Suspension dynamics is a black art to almost everyone. You'll get this. I know it.

[@ThrottleStopGarage]

Thanks - I appreciate the vote of confidence. I'll give it my best and if it doesn't work - will learn something and try again.

[@chadm3704]

Oh man, what a debacle! I have to say, the "totally bespoke" front suspension is what I always imagined you'd end up. I'm excited to see you move through this. Hope everything else is good down there, I still miss it every day 🙂

[@ThrottleStopGarage]

Thanks Chad. It's been a bit of a rodeo. I'll get this garbage sorted out. Stay safe.

[@russellfreeburn6284]

I appreciate the level of technical detail and knowledge you provide. Fortunately as a mechanic I understand what you’re saying, it’s a consistent problem of people interchanging names of parts when in fact they are wrong. Myself included. Good job mate

[@ThrottleStopGarage]

Thanks - I still can't work out why all this is wrong or where the one wrong number comes from - but everything was shrunk based on the notion that the wheel mount to wheel mount was narrower than it is.

[@jp.lagrange]

The amount of info and verification that you provided it's priceless. Thanks for going over everything. Good luck with the next iteration. I was considering the C4 IFS for my '54 Pontiac, ended up with a disk brake conversion and cut springs haha. Maybe down the road. I may consider buying your C4 parts👍

[@ThrottleStopGarage]

Thanks - when this is all done, they will be for sale.

[@forthwithtx5852]

It’s an episode. Enjoyed the tech talk!

[@ThrottleStopGarage]

Thanks - hard video to make. Glad I did it.

[@joell439]

Well….. that all makes sense now. This was very helpful information. The result is going to be epic. Please don’t spare us from the details 😉. That’s why we’re all here 👍👍😎👍👍. We’ll be here when you’re ready

[@ThrottleStopGarage]

Thanks - much appreciated. It was like getting hit with a 2 X 4 a few weeks ago when I came to this realization. It took me this long to recover, reset and start again.

[@stephenridley6252]

I feel your pain! It is, however, comforting to know that even pros like you can screw up from time to time! I’m sure your final solution will be elegant! Can’t wait to what you design.

[@ThrottleStopGarage]

We all make mistakes...this one is pretty massive. I'll do my best to find a decent solution.

[@zerodrift1]

That is a tough spot to be in, but you are on the right path. Start with a clean sheet and work your way back into a good solution. Hang in there and keep up the good work!

[@ThrottleStopGarage]

Thanks - working on it now and it is possible.

[@kennethdong8490]

It is great watching your mistakes from across the alley since I'm making similar ones here but mine don't cost as much money.

[@ThrottleStopGarage]

LOL - do you want a C4 cross member?

[@gergobodnar7970]

On one hand I am sorry for your loss, on the other I love suspension math so looking forward to the new videos! Mixed feelings 😢😊

[@ThrottleStopGarage]

This is going to be a fun ride. I can't think of anything I've done that has been more challenging.

[@brianbuckle2635]

Love these videos. Everyone has setbacks when building cars. Most of us would have had this thing mounted before we found the issue...😅

[@ThrottleStopGarage]

Thanks. I did weld the old version in before finding the problem.

[@declanburke4146]

Good man Craig, suspension engineering is a science, but you got this 😎👍

[@ThrottleStopGarage]

I'll give it my best. Thanks.

[@1HotRodHudson]

It’s always an uphill battle with old cars, when going down a road less traveled it gets exponentially more difficult. I have loved my 89 Corvette for almost 25 years now & some day will put a C4 suspension under my 30’s coupe…. Buy a C4, drive it, race it & have fun with it as you work on your build it will help the ups & downs of the build!

[@ThrottleStopGarage]

Completely agree. I've got another car that I race and it does even out the ups and downs.

[@tho4747]

Looking forward to the next episode. Hope that you get it right. This is such a great channel.

[@ThrottleStopGarage]

If I don't get it right...we'll do it again!

[@MaddMattsGarage]

Crappollia, totally!!! Well respect what you done, and about to do. You will never waste my time you always put up excellent content, keep it going and we'll support you. Cheers Mate from NZ.

[@ThrottleStopGarage]

Thanks, much appreciated. It's been a roller-coaster for a few weeks. I'm hard at the design work.

[@alanmony1582]

Professor, so sorry to hear you got caught up in the "others" mistakes. I know you'll figure this out and it will be spectacular!

[@ThrottleStopGarage]

Thanks Alan - good thing I've got a little mule stubbornness built in to my DNA. I'll get it solved.

[@TylerLinner]

I clicked like before the video even started. Good to see you again!

[@ThrottleStopGarage]

Thanks. Appreciate the positive energy.

[@criticalmass181]

Love your work. Don't let this hurdle bring you down. (Some inspiration...About 30 years ago, I rebuilt a 37.4 litre V10, twin supercharged engine, on the ground, in the dirt. Big job? Yes. Difficult?. Of course. Rewarding? Shit yeah! Nothing rewarding is easily won.)

[@ThrottleStopGarage]

Thanks - as they say - it's not how many times you get knocked down, but how many times you get up.

[@gofastwclass]

Sorry about the stress but you have the skill to conquer this. Life in the custom car world - nothing fits like you think it will. From being burned on similar stuff, I've found the only measurements I can trust come from my own tools or the OEM supplier's drawings when you can get them.

[@ThrottleStopGarage]

This has been a hard lesson that I won't forget. Google is not my tape measure!

[@VacFink]

It’s been an invaluable journey. I’m certain what you learned in the process is what will make your own design possible. No small feat. It’s not a disaster, it’s an education from which you will graduate to new mastery. It’s your fun have it your way. Thanks for bringing us along.

[@ThrottleStopGarage]

Thanks - much appreciated. Hard lessons are often the best.

[@abitoffcenter383]

Wow!! This is a cluster ***k!! As I am NOT an engineer, I'm a mechanic. I have nothing to offer you but words of encouragement. It's not always the destination that's important. More often than not, it's the journey that's the most important thing to learn from and remember. It's also, more often than not, what defines us. I don't need to say these things. You know them already. I'm also pretty sure, that if you read this, what I'm saying sounds stupid and/or absurdly obvious. But every now and again it's the stupid and/or absurdly obvious things we forget. I know I have on many occasions. 😉 You got this!! I have faith!

[@ThrottleStopGarage]

It's kind of you to take the time to provide encouragement. I know it's true, but having to take the road you don't want to travel to get where you want to go is usually the way I learn.

[@fredygump5578]

I relate to this struggle! Good luck. And when it is done, everyone who sees the car is going to ask, "But why didn't you use a Corvette suspension? It bolts right in!

[@ThrottleStopGarage]

That's so true. I will just nod and smile 😃.

[@korosuchimu1479]

1986 toyota corolla track width is just under 54 inches. With lots of aftermarket support. aftermarket cross members, arms Knuckles, brakes, hubs with lug pattern options. Manual and power racks

[@ThrottleStopGarage]

It's a strut suspension. Not what I'm looking for.

[@evotoadracekartscars.6738]

Thanks, I've got all this to come.

[@ThrottleStopGarage]

I hope the videos help in some way.

[@chrisshorman522]

I've been there many times Craig. It blows chunks. You'll figure it out. As you have no doubt found out its usually 3 attempts at building what you want. This front suspension has haunted you for awhile. I'm glad you are binning it and moving on.

[@ThrottleStopGarage]

Great point Chris...I did have to do the rear 3 times to get it right. At least eBay will benefit from the sale.

[@Syscrush]

When someone asks me how long something takes me, I always break it into 3 phases: 1. The time to do it wrong. 2. The time to figure out what's wrong. 3. The time to do it right.

[@michaelfust9520]

Sorry to see this go south again. However we are all learning vicariously thru you on how to adapt the Corvette components into the more average smaller footprint cars. This will be on B..A... car when you get it on the road.

[@ThrottleStopGarage]

I think it's been heading south for around two years...it sort of oscillated for a while and then finally crashed.

[@ODGColornChrome]

Good work keep it up and well done!

[@ThrottleStopGarage]

Thanks

[@Agroeureka]

Keep going the only way to get what you want is to build it yourself. Suspension is an art in its self most people don’t consider the effects of what their modifications do and how they effect the ride and handling. And do I even have to mention tyre wear. Also good work as usual I would appreciate any design info as i may be thinking of falling down a similar black hole.

[@ThrottleStopGarage]

Thanks - I'll do what I can to explain (at least) why I will make the decisions I make. I can't say they're all going to be correct. I will try.

[@SpankysHotRodsandCustoms]

Thanks for sharing.

[@ThrottleStopGarage]

Cheers.

[@arthagner4235]

During all of this I hope you add the thickness of the brake rotors to your overall width Great job !!

[@ThrottleStopGarage]

The mounts are the same as my rotor thickness...I forgot to mention it. Sorry.

[@josephjones4293]

Good luck man. I’m building my own car from scratch, I know the pain of getting parts online just to find out x or y spec was off and now you need to pivot. Luckily I am designing it all so I am the only one to blame if the subframe doesn't fit later.

[@ThrottleStopGarage]

Thanks - I'm now joining you on that journey.

[@stephengent9974]

I am somewhat surprised that you did not do this from the get go, makes sense to me.

[@ThrottleStopGarage]

I thought I was fine with the pre-engineered part. It looked easier than doing this and when I made the decision, I could not do CAD or get parts cut easily. I've learned a few tricks since then.

[@silverburrito]

In your track measurement/calculation, a couple things I noticed: 1) you need to included brake rotor thickness on the mount flange. Its not the total difference, but it does take up some of it. 2) any differences in aftermarket wheel bearing options 3) not to undermine all the measurements you have done, but some things could be slightly tweaked from where there supposed to be (i.e. LCA angle and mount height, UCA mount height, etc.) But that could also be due to inaccuracies by 80s GM or if the car it came from had any damage. Again, not 1 thing could make up the difference, but being slightly off or assymetrical, sprinkled everywhere, does add up. 4) any camber is going to alter the measurement, and it's likely the factory measurement was taken from the tire centerline on the ground. Going forward, glad you're working to a custom setup rather than narrowing an existing system (which brings a lot of steering issues).

[@ThrottleStopGarage]

I was measuring from the brake face (my mounts are the same thickness as the rotor) - I should have changed that from hub mount face to wheel mount face. I've got a set of new Delco bearings for the C4 - same dimensions. The suspension was set to the mid range of the stock settings for caster and camber. The measurements are as correct as I can get them. The cross member is used (all the parts are) but there is no sign of any significant issues. There was a little twist - but the jig nails it down (it's about 5 mm). I spent weeks looking at this before I decided that it just stopped making sense to try to put this suspension in the car.

[@GrayRaceCat]

I was an ASE-certified master mechanic for 38+ years. I understood the "how" but not the "why" of things. I never got into Engineering and Design until recently. Your explanations are more helpful than the tech books and websites I've seen. Thank you! I have been wondering why you chose the C4 suspension. Would you mind telling us what features of the early C4 suspension caused you to choose it over designing and making your own?

[@ThrottleStopGarage]

Thanks, much appreciated. I'll cover it in more detail in one of the upcoming episodes when I start to tackle the problem. The main advantage to using a "modern" geometric design is that there are a number of "tricks" that are used to improve both handling and ride quality. The original suspension had none of these features (specifically anti dive and it had very little caster). Having anti dive effectively transmits force from the sprung mass through the suspension linkage instead of just through the spring. So the geometry is resisting the tendency of the car to dive under braking force. This is a dominant property of the C4 as is the caster (and how the caster and camber interact when turning). This is a start of why the suspensions from the 1950's are not really a great place to start for modification - they lack these features.

[@seancollins9745]

Just build 2 knuckles, the deal with bumpstop, basically, make sure the pivot length is the same as r the lower arm, while your building knuckles, drop the steering arm down. The Nissan hubs could definitely fit. If you need CNC parts, shout, I've got a idle CNC machines

[@ThrottleStopGarage]

Thanks Sean. I'm working on the design. I'm not sure if it will be an aluminum upright or if I'll go sheet metal. I've seen some nice CNC uprights.

[@donsmanufactory]

I feel ya, I spent a bunch of time redesigning front suspension on my 66 mustang only to have disappointments along the way. The worst was finally figuring out every conclusion drawn from the road testing was wrong. The handling issues were actually caused by bad ball joints not geometry errors. Been chasing my tail for months…

[@ThrottleStopGarage]

That always hurts. In the end, that's one of my greatest concerns - why would I think I can do this? What if I get it wrong? I'm going to try, but I can't say it will work.

[@donsmanufactory]

@@ThrottleStopGarage my thought has always been, if they did it why can’t I? How tough can it be? Of course, I was younger then… Watching your videos helped me figure out my own folly, thanks.

[@dalespencer3565]

Love your show !

[@ThrottleStopGarage]

Thanks for watching.

[@insAneTunA]

I do not blame you one bit that you do not want to put those fender flares on the car. I can see why people do it because it is the easiest and cheapest way to get a decent suspension. And not all the people have the money or the skills or the facilities or the time to redesign and construct an entire new suspension. But you are taking the extra mile, and at the end of the day that will show in the end result. If you are doing a once in a lifetime build you might as well do it right without any compromises. Especially such a major component from the car. Which is not only technically important, but it also has a big visual impact on the car. And the extra time that you spend to get it as desired is negligible on the entire project. I think that you are on the right track 😁Big 👍

[@ThrottleStopGarage]

Thanks. I own the mistake. I should have had more patience and done more work on this from the start. I thought it would be easier this way and I stubbornly held on too long.

[@Looptydude]

I commend you for just taking for control of this and building it from scratch, I would have taken the easy way out and gone with something from Art Morrison.

[@ThrottleStopGarage]

The hard part is, I called them years ago and they made the rails. I should have sucked it up and bought the suspension. The issue was they wouldn't give me details on what the suspension they were selling worked...I needed the numbers.

[@Looptydude]

@@ThrottleStopGarage I see. At least you doing it yourself is more content for us.

[@konjiki240sx]

Think of it as a blessing in disguise the c4 subframe is heavy and a flimsy mess. We watched this thing flex and bend into different location on our C4 track car. We ended up building jig and chromoly tube frame since the factory frame was trash. (we had the 89 version w/ reinforcements. I can only imagine the horrors that were the earlier years )

[@ThrottleStopGarage]

They really are not very nice...the mock up one I have is a welding nightmare with porosity, left over wire, spatter everywhere and I get cut every time I touch the thing. There are cracks on the LCA bushing areas to boot.

[@krusher74]

You are right, fender flairs do look horrible and are used by people who don't want to do the hard work to make things fit. Then they tell themselves it looks good. Take your time there is easily a month's worth of funny cats to watch.

[@ThrottleStopGarage]

Thanks - I also notice that these "built" cars tend to be sold after the magazines have featured them.

[@codysmithmotorsports736]

Speaking from experience on scrub radius....(assuming you'll have power steering) don't worry about it. I have 3" on my car and it's kinda an unnoticeable thing as far as the driving experience. I can see it being way more of an issue for your car with the size of the swing arc the wheel and tire will use. I've gone through designing and building improvements to my G body suspension over 5 years of road course and autocross. Just looking at where you have the pivot points layed out I would trying to move the lower arm pivot higher (downward angle to the wheel) in order to raise the roll center and mechanically reduce roll. The upper pivot needs to come down to increase camber gain during body roll/cornering/weight transfer. Similar results can be had with taller ball joints (incresed lower BJ will also lower the car) or since you're looking at custom upright, a taller spindle. The way it looked in the video the suspension would have very little camber gain and lots of body roll...so typical 80's suspension. You have a wide open number of ways to accomplish getting good geometry. All have different pros and cons. Personally I went with a lot of circle track parts due to availability, low cost, and lots of options

[@ThrottleStopGarage]

It's good to hear from people with actual experience on this. All the stuff in the video (except for the static images) is the C4 stuff that's not going in the car. The diagram I was using, is actually my roughed in suspension model in 2D. I've got targets for camber gain and caster angle as well as the rest.

[@HsPerformanceWi]

I just jumped back and re-watched all of the suspension series, I have the same manufacturer's x-member that shall not be named. It appears I can cut the top mount off and rotate/lower it to correct the issues, but like you in the beginning I have nothing to reference. Am I correct here? Also, once you got the factory x-member how far were your optimized pickup points deviated from the factory piece? Just a little more clarity would help me out a ton, and thanks for bringing us along through your trials and tribulations.

[@ThrottleStopGarage]

Happy to help where I can. I'd first set your cross member up and install the arms and make a few measurements of what you have. I'm happy to share the dimensions, but I'd do them and not take my word for it. I struggled with how to start this part - but start with the original tire the car was designed around (that radius is needed). Then set the upper flat part of the LCA level. This sets the LCA height (they are level). Next the UCA has to get placed. The C4 has a lot of anti dive, but the rest is pretty normal. 5 - 6 degrees of caster, -0.5 degrees camber. If you then find that it is doing weird things (which mine was - partially because of not knowing where that LCA was supposed to go - that's not really "engineer" dude's fault - but it's not like this dimension was in the instructions and I asked. Measure it all - especially the roll centre. You can put the basic dimension in a suspension analysis package (racing aspirations works) and find out how much the RC moves and what happens with camber curves. These can also just be measured as I show in the other videos. Correcting it is a matter of moving the cross member to get these values to be reasonable or moving the pick up points entirely.

[@tababobi]

If you have enough vertical space for a taller upright, have you measured if the aluminum 2002 Thunderbird control arms are any shorter than the C4's? You would not be able to use the Tbird spring but modified mounts on the lower arm might still allow coilovers. Would swapping left and right uprights allow the rack to be placed ahead of the engine? Great series.

[@ThrottleStopGarage]

I've not thought of that car...not sure how common parts are for them. I think going the complete custom route will be about the same effort as trying to find something that may fit.

[@davehowland5270]

Have you looked at the gm metric spindles they are sold in many shapes and sizes for econo mod stock cars and an infinate number of control arms as well

[@ThrottleStopGarage]

I've looked and I didn't see the advantage. I really did try to search around and find a good start point. There is a C5/C6 welded upright that is nice, but then you're into that entire part ecosystem and I'm not sure that it's getting me out of trouble or getting me into trouble. I wanted to have the freedom to move the upright pick up points to where they need to be, rather than working from there back to the chassis and dealing with things there.

[@Oli-jw2hh]

Keep it up!

[@ThrottleStopGarage]

Thanks!

[@Metal2Mesh]

Changing the HUB, will brakes fit? rotors and caliper will need to change due to the shorter distance.

[@ThrottleStopGarage]

Sorry for the confusion. None of the C4 parts will remain. Redesigned everything.

[@travisfabel8040]

I don't know if the whole front suspension needs to be bespoke. From what it looks like, you just need a custom front upright. I say just like that's minor but... You could use the regular a arms, and then use your new chosen hub and move the steering arm and just have a custom upright.

[@ThrottleStopGarage]

I hear what you're saying - not sure where this will end up. Custom upright is for sure a thing and the arms are going to be designed to optimize kinematics and packaging. I need the engine bay room. It's a pretty wide open space right now.

[@ericdolan2130]

16:09, Unless I missed something, you have the C4 rear suspension. Those hubs are 5 on 4.75". I have the same setup in my LoCost 7.

[@ThrottleStopGarage]

I have a Toyota Supra MK3 IRS in the car not a C4 part. The hubs are 5 X 4.5".

[@ericdolan2130]

@@ThrottleStopGarage My bad, thought you said it had the C4 setup.

[@leemuscarella2728]

Found this episode very worthwhile. I’m really curious about how you’re going to redesign it. Do you still plan to use the C4 control arms and uprights? If so would the 350z hub cause issue with the disk brake and calipers? Thanks and keep the knowledge flowing.

[@ThrottleStopGarage]

Thanks - the C4 parts are going to all be sold. I'm just going to reuse the 3 part bushings that I designed as I don't want to pay to do them again. I had not bought brakes - thankfully!

[@thunderbirdizations]

15:00 a different geometry might help. Longer upper arms with a steeper angle might help replicate what you currently have

[@ThrottleStopGarage]

There is going to be different geometry for sure. I'm working on it when I can and I need to pack it all inside the frame rails that are currently in the car. This would be enough room without a doubt.

[@mgbrv8]

I’m gonna be honest you need to make some sheet metal spindles

[@ThrottleStopGarage]

That's the plan...unless it's carved from aluminum.

[@moptop85]

Have you ever looked at the (08+) 5 lug miata suspension? The subframe almost looks parallel to the ground and both a arms bolt on to it. Not sure if its narrow enough

[@ThrottleStopGarage]

I've looked at every generation of Miata. The ND has a front track of 58.7" so we're back to doing all this work either way. It is a very nice, compact design and I will borrow a few of their ideas.

[@peterraffin2227]

Just caught your channel and watched this video. Out of interest which suspension analyser are you using. I've been looking at Performance Trends and susprog3d for a front suspension upgrade I'm planning but not sure which will be best. Goodluck with your project.

[@ThrottleStopGarage]

Thanks - Racing Aspirations is doing the light lifting on the 2D model to get me going. It's web based and actually decent (unlocking it cost a few bucks - but like coffee money not real money). I'm using Lotus SHARK for the final 3D modelling. It's old but it does just about everything and I'm learning how to use it.

[@michaelevans7013]

Look at Toyota Supra front suspension. Think the wheel base should be close and lots of aftermarket options available. Alternatively BMW 3 series front suspension on full cradle with low mount steering rack

[@ThrottleStopGarage]

The Supra is a McPherson Strut - so not what I'm looking for. The steering rack that I'm planning on using is from a BMW Z3.

[@mchristr]

Can I assume that you know abut Rick Dobbertin's adapters to mate a C5/C6 suspension to various frame rail setups?

[@ThrottleStopGarage]

I didn't know about this - just had a look. The challenge would be that the narrowest front they have is still a little too wide and will be leaving me a very narrow engine bay. The C5/C6 still steers from just below the CL of the hub.

[@k.bellingham8335]

So glad you're stubborn and still posting. Always interesting to hear about the difficulties, these are as valuable as or more than the successes. I want to throw more shit on your engineering table, you can ignore me, I won't be offended. You have enough going on right now. "Front anti-dive, rear anti-squat. From what I've found in my search regarding same.. nothing. Ok I exaggerate for effect haha, really very little. The upper A-arm pitch or angle is "said" to control anti-dive, since you are concentrating on the front at the moment. But I disagree, partially. The lower A-arm should or would have a more significant effect. Since you have a factory Vette cross member sitting on your bench, I'd be very very.. very interested to find out what the angles are, front to rear, for both upper and lower, A-arm to frame mounting/pivot locations. If you find the time to comment or respond with your opinion/ findings I'd appreciate. Thanks for the updates and episodes. Your car will be amazing with all the great details you've incorporated. E.g. shifter stock and handle, I think exquisite is a decent description.

[@ThrottleStopGarage]

I hope I never get to the point where ignoring people is cool. I can comment on the suspension and I'm going to try in explain the "anti's" when I get to the design phase. I find it easier to learn these things by hand - I can then make the lines in the diagrams make sense. Many people learn the other way (or they "see" it better than I do). My problem with any simple representation of complex geometric things is that it gets a little too simple. The C4's LCA sits level at the chassis mount and the ball joint is below this level. I see this constructing a plane with the ball joint controlling the attitude of the surface. We can add in the tire's contact patch as the place where these geometric things apply. UCA's sit 12 degrees down in a pretty aggressive anti-dive orientation. Even when I did the first round of optimization of this design, I took to dialing out the amount as it seemed like a lot. Same visualization - a plane - but this time with the ball joint higher than the pivots. Their intersection defines both the anti dive percent and the static position of the roll centre (again with the tire being the receptor). These are actually similar concepts. All of the points on the planes have equal importance but different effects. Moving any of them changes the orientation of the plane. LCA points create the "ground" plane and therefore the limit to the vertical (so long as the points are within reasonable limits of location). Anyway, the LCA play a role in the side view anti as it sets the stage - the UCA then sets the distance - and I think sets the dynamics (I'd have to think about this and model it).

[@k.bellingham8335]

Wow! Thank you for responding. I'm going to have to do some research to be able to respond in kind. All these intersecting planes has my head spinning. I hope to offer something useful to this topic. Now get back to work, that's my advice to me. Have a great day@@ThrottleStopGarage

[@hoffbug]

It isn’t the mountains ahead to climb that wear you out, it’s the pebble in your shoe.

[@ThrottleStopGarage]

LOL - truth.

[@declanburke4146]

Thanks

[@ThrottleStopGarage]

Next rounds on me! Cheers.

[@ryanlove5332]

Did you account for the brake disc thickness at the mounting face when calculating the track width? Only 5mm ish per side. Still sounds like you are way off where you need it. Good luck with it.

[@ThrottleStopGarage]

Yes - I forgot to mention that the mounts are the same as the rotor thickness - so the measurement that I gave you was wheel mount to wheel mount and I said hub...sorry about that. the math is correct.

[@ryanlove5332]

@@ThrottleStopGarage I have no doubt, you seemed to have the important parts covered, and like I was trying to say, it sounded like the 5mm of space from the brake rotor face was still going to leave you well short of your desired design objective. I look forward to seeing what you come up with. I will have to do the same for my GT40 project at some point. I did have some live hub Toyota supra knuckles, but they have the hub axle behind the kingpin axis which increases the mechanical and pneumatic trail even more. I am not a fan of the feeling that these cars provide through the steering wheel. I much prefer what a Lotus/MX5/RX8/BMW does. All of these seem to have a reduced pneumatic trail, thanks to the axle being in line or forward of the kingpin axis. So this is likely what I will be doing. Cheers. Ryan

[@ThrottleStopGarage]

@@ryanlove5332 I've not got that far in the design yet. I'm not sure that mechanical and pneumatic trail are connected as directly as how I'm reading it - but I need to study it more. How much to design in is a sticking point. Reverse engineering what other cars do well is also a challenge (mostly availability and sifting through low signal/noise ratio forum posts). I'll get to this once the front view is complete.

[@ryanlove5332]

Just pick some cars that you enjoy the driving experience and feedback from and reverse engineer from those.

[@stigwelder6142]

have you thought about talking to the guys at fdf ? He's a suspension wizz and a fellow Canadian

[@ThrottleStopGarage]

Just looked him up! Thanks!

[@travisfabel8040]

This is still an episode. Just because something isn't complete or problems are discovered, doesn't mean its not part of the build. It can't always be a "everything is going great" because that's just not how projects work.

[@ThrottleStopGarage]

Fair - probably the most important learning happens when we fail.

[@Bill_N_ATX]

I guess this is why so many folks us the parts out of the mustang 2? There has to be some reason it’s so ubiquitous.

[@ThrottleStopGarage]

Yes - that and they were everywhere and cheap. They're narrow and have great support. I don't know why people haven't developed them to be more modern.

[@kathysarmcandy1992]

The most important measurement to this whole mess, is a balanced L-R mustache bar thrust vector . Some serious toe-out on the right side..., best align that by the next vid as it's distracting from the main message. winkwink

[@ThrottleStopGarage]

LOL - I noticed that after. Probably from sitting with my head in my hands staring at this mess for too long.

[@heathsmetalwerx]

So your cross member is at the right height? If u raise it the hub faces go in.... These are off factory height so if its not right height (cross member) the hubs wont be either. If everything is at factory height than its on them if not its user error.

[@ThrottleStopGarage]

Yes - the set up on the jig is as per the drawings from GM.

[@103erik]

Quite a problem! No offense, but what's wrong with the suspension Volvo put under the Amazon? Why redesign the wheel?

[@ThrottleStopGarage]

Good question. I had restored this car before the current effort and the suspension is very much of it's time. There is almost no camber gain or caster build in. They way most make them work is to basically add a very large antiroll bar and lower them a little. I found that there just wasn't much development room to improve on this method (it's been done for 60 years...it works) - it's just not very good by modern standards. I wanted to try something different.

[@djremotion2]

Like you said those over fenders ruin everything and they are lazyness and lack of desing skill manifested. Just screw the whole idea of using any car’s existing suspension and make your own. Like you said, now you are going to somewhere really. But at the same time be cautious of what kind of driving behaviour different choices will put you into. And in that reading magazines from different cars that have different suspension can be helpful.

[@ThrottleStopGarage]

Agreed - there is a segment that likes that stuff and that's not me. I've looked up a bunch of different modern cars static measurements and there is convergence over the years on what a "good" start point would be for KPI and Caster - the rest is dependent on too many variables to be much use without a complete model. I am reading everything I can get my hands on.

[@honorharrington4546]

Before you go re-inventing the wheel, see if a Mustang II suspension will do what you need. Common as dirt and lots of aftermarket parts as well. What do you need? Are you building a race car that pulls 5-6 G's? Are you building a street car? Off-road? KISS

[@ThrottleStopGarage]

I know - the stock suspension would be about as good as the MII. The point has always been to push what I can do and to learn. This was one of those lessons that I hope will end well, but along the way has been difficult. The best lessons are often that way.

[@willisxj]

What is the radius from the hub center plane on a C4 front suspension to the point where the KPI meets the tire center contact giving zero scrub radius with stock wheels?

[@ThrottleStopGarage]

The scrub radius is around 3" (75 mm) with stock 38 mm offset wheels. So to move the wheels in to where I'd need them would yield around 70 mm offset wheels. Now I only need a few inches, but I'd still need 55 mm offset wheels. I'm hammering away on the new design and will try to get a video out of the progress in the next week.

[@willisxj]

@@ThrottleStopGarage there is a point in space where the KPI and wheel canter line meet and if one were to run tall enough tires could achieve a zero scrub radius with stock wheels. Have you calculated how far from hub centerline that is? (How tall the tires need to be?) I’m asking for my curiosity on a potential project. Sounds like you can’t run tall enough tires to accomplish this on your setup.

[@ThrottleStopGarage]

@@willisxj This is with a standard tire height. To get the two to intersect, you'd be 4" taller in radius) using a little trig. So 33" tall tires.

[@willisxj]

@@ThrottleStopGarage wow. That’s nuts! I wonder what the GM engineers were thinking where a 3” scrub radius was a good idea.

[@ezacher4634]

Acura Integra double wishbone setup?

[@ThrottleStopGarage]

Those are cool - I'm happy with just doing this myself and getting it right.

[@stefantroedsson5483]

to win space is one ide is to put upper dog bones inside the cross member like the original Amazon front suspension

[@ThrottleStopGarage]

That's how they are on the suspension that I put in the car a few years ago. I can't shrink it in any more or I hit the manifold and won't be able to get an AC compressor changed without raising the engine!

[@markstearns2980]

Why not just go with a mustang II front end?

[@ThrottleStopGarage]

It's not a lot better than what was there. There is no anti dive and it's still a very 70's design. No other real reason.

[@MrHandyDad]

This gave me a headache, I cant even guess what it did to you. Also never trust Car People... LOL

[@ThrottleStopGarage]

Thanks - I think the aftermarket suspension industry has come a long way and is much better than it was.

[@thunderbirdizations]

5:00 What about brake discs??

[@ThrottleStopGarage]

My brain was not really 100% with me on the weekend. The measurement given includes the brake rotor thickness (the mount is the same thickness as the rotor). It is, therefore, not hub face to hub face, but wheel mount face to wheel mount face. Either way - 59.6" falls out of nothing that I can measure.

[@manuelceballos389]

link to the new hub please

[@ThrottleStopGarage]

Nissan 350Z - available anywhere. Models up to 2009 are what I'm using.

[@iliketorockrock]

Huge bummer, if you whant to do it right- do it yourself

[@ThrottleStopGarage]

Let's see if this is possible. Determination I have in excess - knowledge...not enough.

[@SylvesterOziomek]

First, there are few definitions of track width: a) hub to hub, b) centre of tire to centre of tire, c) centre of contact patch to centre of contact patch. Answer a) is stupid and shouldn't exist. Answer b) it depend where you measure, and that's because many cars use a bit of camber so your measurements at the hub, at the top and at the bottom will be different. I'd never measure hub to hub, but at the bottom. Second, that suspension geometry look weird, like there will be positive camber gain. But this is american car so I am not surprised. That lead me to point three. Who would copy suspension geometry of american car? I understand using suspension parts but geometry, never. If you want to save that, turn upper wishbone upside down and lower it, than you have chance. Forth, unless you sure you are dealing with expert, double and triple check everything you learn on the internet.

[@ThrottleStopGarage]

There's nothing inherently wrong with what sits under Corvettes from the C4 forward. Modern design and kinematics are excellent. It behaves properly and as I am in Canada...it's common enough. I was going to optimize the geometry - you can't shorten it and think it will be OK. I'm checking everything - no worries there.

[@SylvesterOziomek]

@@ThrottleStopGarage Before I made my comment I checked your geometry in CAD design, because after one glance at it I suspected there will be camber loss in the corner. You got CAD, check it yourself. After your claim about C4 greatness I checked how it behave in the corner. (In this video "1992 Chevrolet Corvette LT1 | Retro Review".) And I was right about the geometry, probably the only reason it's not crushing every time it's cornering is it's heavy front. So I sustain my opinion C4 suspension geometry is absolutely rubbish. But hey, that's your car build it the way you like.

[@ThrottleStopGarage]

​@@SylvesterOziomek I'm not using this suspension. When I measured it, the camber gain was around 0.7º per inch of travel. It does gain camber in extension and loose it in compression.

[@SylvesterOziomek]

@@ThrottleStopGarage That's a good start. "It does gain camber in extension and loose it in compression." Sounds abut right, and by that I mean wrong. Pause the video I mentioned in 1:04 you'll see the wheel has positive camber. It's tilted the wrong way, and that's due it's rubbish geometry. Btw. I'm not american, I don't speak inches.

[@filepz629]

👀

[@mlrable]

You should not protect people giving dangerous products

[@ThrottleStopGarage]

True - but custom parts like the cross member I bought are never sold without the understanding that the person doing the installation is responsible for the ultimate safety.

[@martinsteele3259]

I am willing to bet everyone else on the internet is stupid.

[@ThrottleStopGarage]

Occasionally there are signs. LOL.