Matching stall speed and gear ratio for street.

Getting the torque converter and rear gear matched properly for street use is very important for transmission reliability. If converter slippage is too high, it can cause too much heat build up in the transmission fluid, and hurt the transmission itself. So how do you match these up? I explain this in the video, using wallaceracing.com and their Gear, MPH, RPM, tire diameter calculator.
At about 6:15 into the video I give an example with 3.54 gear, and 26" tall tire resulting in a cruise RPM of 2883. With this information a guy can decide if he wants to go 3000 stall, with a transmission cooler added, or lower stalls like 2500 or 2800 which may run a bit cooler. The choice depends on what you personally want, but this provides information to more easily decide which to choose.

[@whitewolf30f]

I've tried a few aftermarket torque converters, with varying results, but the one I feel to share is when I put a B&M 2400 in a pure stock '95 Z28 convertible with the lame 2.73:1 axle. Best single mod I ever did in my 47 years. It instantly became a tire shredder. Absolutely would do all over again.

[@mean70632]

Guys, first off, I do tens of thousands of dollars of business with summit business every year, but I have to tell you that their tech videos are very general and very generic. So if you're taking advice on torque converter stall speed rpm choices from their videos, then good luck with that. Secondly, I had a street/strip car that i bought brand new off the showroom floor which was also my daily driver for well over three years for 12 months out of the year. In that three years, I put 55,000 miles on the car, and I raced it at two different drag strips. It was a low 12 second car. I installed an aftermarket torque converter which had a 3,000 rpm stall speed and my cruise RPM@70mph was 2,700 rpm and I NEVER had any problems with neither the engine nor the transmission overheating and I only had a plain factory radiator and cooler. It wasn't a super cheap torque converter, (you only get what you pay for so avoid those crappy B&M models or the like for $400) but it wasn't any top dog super expensive one either, I paid $700 for it. Furthermore, those cheap sub-$500 torque converters will give you a whole lot more slippage than 5%. And I'm not talking about stall speed, I'm talking about slippage percentage which is measured at full throttle ABOVE the stall speed RPM. Some of the cheap ones slip as much as 17% and that's what will create a whole lot of heat and kill your transmission over time, even if you have a real low 1,800 rpm stall speed. I'm definitely done here trying to warn you guys. Good luck

[@Ecosse57]

this was helpful to me as i seem to get confused by other explainations that i think maybe throw too much at me at once. thanks.

[@rickynelson3222]

Great video. I'm just at the point of my build I have to pick a gear I have a 3000 stall already I chose a 350 gear on a 26 in tire that was before I seen your video, it looks like it will work fine 👍

[@timsprojectcar1875]

Absolutely will! Thanks for the feedback.🎯

[@goodsirtwiztid3101]

Jess and summit both recommend choosing stall speed below cruise RPM

[@michaelgallopo5879]

I have 700r4 with 29 tire with 28 stall looking some fun at the track but still drive on the street I was looking at 373 or 410 ???

[@timsprojectcar1875]

I think either gear will work fine. I put 3.73 in mine though, because the low gear in a 700r4 is 3.06 and I didn't want to have 1st to be too low.

[@michaelgallopo5879]

Thank you

[@timsprojectcar1875]

I had a stroke so I be doing this for a while

[@heshtesh]

My 1st gen sbc stroker is a little soft on the lower end so I went with a 3500 stall in my 94 Sonoma with 28" tires, 3.55 gear and th400. As my truck is 95% city/street I leaned towards my dyno sheet while choosing my torque converter, 400ft lbs@3500.......513ft lbs@4500, I also run a trans cooler with a fan. Does my setup seem reasonably close?

[@timsprojectcar1875]

It does. I would add a good transmission cooler if you haven't already. A temperature gauge for the transmission is also a good idea. Heat is the main thing to watch for.

[@timsprojectcar1875]

That sounds pretty stout. It must just vaporize tires! I see you already have a trans cooler with a fan. That should work great.

[@heshtesh]

@@timsprojectcar1875 My set up runs a steady 160-170 degrees.

[@williamsimpson8465]

I have 391 gears 29 inch tall tire with circle d 3000-3200 converter is that good

[@williamsimpson8465]

Plus mark82 cam

[@williamsimpson8465]

Plus mark82 camshaft

[@michaelgarrow3239]

So,,, basically get a converter that will lock up at cruising rpm?

[@timsprojectcar1875]

That's the premise I was working with. This will make a good compromise between driveability, performance and heat build up. It can work running higher stall speeds, but very good cooling would be needed. A good transmission cooler with a dedicated fan would be advised for higher stall speeds.

[@kennethmarston8687]

Here is a complicated one. 90 Mercury wagon. 5.0 HO Mustang block and cam. GT 40 heads and intake, headers and 65mm throttle body. 70 mm mass air. It has a stock AOD and 3.55 posi. Body weight is 4000-4200 lbs. 27.4 inch 225 70 15 Cooper Cobra tires. Current converter is a dirty dog 2000 stall. It does have the HO governor in the trans. It chirps 2nd gear at 3800. It will not shift at higher rpms at WOT. Should it have a higher stallTC? Thank you

[@timsprojectcar1875]

I hate to admit this, but I don't know the cause for it not up-shifting at full throttle. I have never worked on Fords. It doesn't sound like torque converter to me though. I have messed with the governor on my 700r4, which can affect shift points, but I don't know if a stuck governor can stop it from shifting altogether. The place I would look before taking it to a transmission shop is the throttle valve and/or TV cable, to see if it is stuck or damaged. Lastly, I don't think overdrives will go into overdrive at WOT anyway, but 1,2,and 3 should work. Sorry I can't be more help.

[@timsprojectcar1875]

I just watched a video by monster transmission on how to clean the governor on an AOD transmission. That may be of interest. I don't know if it's the solution, but it is worth a try.

[@kennethmarston8687]

Thank you

[@kennethmarston8687]

Thank you

[@kennethmarston8687]

I'm sorry it will up shift but 3800 is the max shift points. I thank you again. It probably is a dirty governor limiting the rpms.

[@1hunda100]

I have 3.42 gears in my 1996 Chevy caprice lt1 5.7 I believe the stall converter is 2000 or 2200 By these calculations and your experience is that stall converter to low ?

[@timsprojectcar1875]

Good afternoon. The stall is fine if the engine is stock. I did the calculation with your gear ratio for a high performance street application. I assumed a cruising speed of 60mph, a tire diameter of 26", a typical converter slip of 5%, and the result was 2785rpm at 60mph in 3rd gear. If your engine has a different cam, and so on, a 2800 stall would be good. Depends how big the cam is of course. If you have an overdrive transmission, I believe you can get a converter with that stall speed and retain the lock up feature.

[@1hunda100]

@@timsprojectcar1875 yes my transmission has over Drive

[@tojones1967tj]

How would you figure out a powerglide transmission 3800 stall

[@timsprojectcar1875]

The stall speed depends on the power curve of the engine. That may be the right stall, I don't know. However powerglides are used in drag racing, but I believe they tend to need frequent rebuilds. My Cutlass came with a powerglide, or "jet away" as Oldsmobile called it. I asked a transmission shop about building it to bracket race. He told me don't use it, as it won't last. My car also weighs 3500 pounds. With enough cooling, you can keep the temperature down, but longevity of the powerglide, I have to defer to the transmission shop.

[@timsprojectcar1875]

If you are making much more than 450 foot pounds, and it sounds like you probably are, you would need to call a vendor and spec a converter to hold the torque you make at the RPM you want. A off the shelf converter may not be strong enough to live behind that engine. It may also stall higher than rated. Thats all I have. Good luck with it.

[@tojones1967tj]

Thanks for your response. I had PTC to build the converter for me,it wasn't off the shelf thanks

[@patrickschumacher5968]

What should I use if I ran a 411 gear with a 29 in tire what size stall do I need

[@timsprojectcar1875]

Using the wallace racing RPM calculator I plugged in a gear ratio of 4.11, a tire diameter of 29, and a converter slip of 5%, which is fairly typical. And a cruise speed of 60 MPH. The result was 3001 rpm at that speed. 3000 stall would work well in this case. 2800 would also be good, if you have a high torque engine.

[@michaelgallopo5879]

@@timsprojectcar1875 thank you

[@Steve69SS396]

Incorrect information on stall and cruise RPM. The rated stall speed is at full throttle. Do you cruise at full throttle? No. The slippage is minimal when cruising at part throttle. I've been running 5,000-6,000 converters on the street for more that 20 years. In fact I'm still running the same Redline synthetic fluid since 2005. Fluid still looks fresh.

[@timsprojectcar1875]

I understand it's possible to make that work, but my approach is more conservative. I'm sharing what I believe will work good and be reliable. I stated in my video you can run higher stall with enough cooling, so I really didn't say you can't do that. Just tthat I wouldn't recommend it. It's all good. Enjoy!

[@musclebone7875]

High stall converters suck on the street. They build up too much heat quickly especially climbing hills.

[@Steve69SS396]

@@musclebone7875 A good converter will drive almost like a stock one at part throttle but flash to high RPM when you go full throttle. Should not generate any additional heat at part throttle. If it does you need a better converter.

[@musclebone7875]

@@Steve69SS396 I don't believe that one bit. It's too many variables that go with that. Only way that a high stall converter would work well on the street if it was a lockup converter. I had a 4,000 stall 3,500 stall, and a 2,500 stall in my car. The 2,500 is way better. High stall is only good for launching from a dig. The 2,500 stall launches hard from a dig, a roll, and cruisers down the highway for long trips great.

[@Steve69SS396]

@@musclebone7875 Here's a video of me driving around town in my car. Most of the time I'm shifting it at 3,000rpm and driving between 2-3K. At about 5:20 in the video I go full throttle and short shift the car and you will see that the RPM's don't drop below 6K. I'm not saying that every car needs a 4-5K converter. I'm saying that it ridiculous to worry about your stall speed being higher than your cruise RPM. I've been running converters like this in my car for 20years. kzbin.info/www/bejne/d2PUmX1_fqusr6ssi=SV_ieuqNnGzVhTk1

[@mean70632]

You're instructing others here to go with and adhere to one of the biggest misconceptions people have about torque converters. Cruising speed RPM has NOTHING TO DO WITH stall speed rpm. the reason being that your torque converter will NEVER reach anything close to the stall speed RPM at part throttle. the stall speed RPM occurs only at FULL throttle. When you're cruising you're not using full throttle. Not even close. So your math in this video is ALL WRONG. I mean no offense but I had to point this out to you and to your viewers

[@timsprojectcar1875]

I respectfully disagree. The stall speed does vary with torque input, which is why converters are often listed as a range, like 2400-2800 and so on. However said converter cruising at 2800 at part throttle is locked, because it is centrifugal force that is aiding in that happening. The math in my video is not related to the torque converter itself. It's just a means to calculate cruising RPM for people in the planning stage, who don't have their cars assembled yet. My only premise in the video is to choose a stall rating close to cruise RPM to control heat build up in street driving. It's a conservative recommendation leaning more toward street than drag racing, as in my opinion thats where most cars spend most of their time. There's nothing wrong with running more stall speed if you want to. The object of having a hot rod is to have fun after all. Just depends how you want your car to behave. Anyway, best of luck with everything. Take care, Tim.

[@mean70632]

@@timsprojectcar1875 Tim, thanks for being polite about this, but I have to tell you that again you're wrong in what you said in your reply. You mentioned "which is why converters are often listed in a range like 2,400-2800, (RPM)" but what many novice guys don't know is that off-the -shelf crappy converters are the only ones where the retailers/manufactures list an rpm range. Because most experienced amateur drag racers who also drive their street/strip cars on that street know that any purchase of decent, well made, quality torque converter requires the customer to fill out a "vehicle spec sheet" or at least call the sales person on the phone so that they can fill it out for him after asking several questions such as vehicle weight, tire height, engine horsepower, camshaft specs, first gear transmission ratio, and rear gear ratio. Without that information there is no way the manufacture can ever get the stall speed RPM correct for your vehicle combo since there are just too many variables which will effect stall speed RPM. Furthermore, it is NOT centrifugal force alone which controls and dictates stall speed RPM as you've claimed. It's the fin count and angle of the fins welded in the stator of the torque converter which does as well as the converter diameter. And that is why when owners of hi-performance cars as well as drag race cars want a stall speed RPM change, they have to send the converter back to the manufacture, so they can replace the stator in the torque converter with one that has a different number of fins welded into it, and/or a different angle on those fins. So again, your torque converter regardless of brand and size will never come close to the stall speed, (known as "flash" rpm) during cruising when you're using part throttle input. The stall speed rpm rating is always at full throttle ONLY. So although I'm sure your intent is well, I have to tell you that you've been misleading your audience BIG TIME. If you don't believe me, then call any of the well known torque converter manufacturers which have a good reputation, (ie. Coan, Neal Chance, Hughs, etc., etc.) and ask them about what I'm telling you here, and they will confirm my claims. Also what many people don't understand is the reason why you should never buy a torque converter without you or the sales person filling out a vehicle spec sheet is due to the fact that any given torque converter will exhibit a different stall speed RPM in any given vehicle it's installed in. FOR EXAMPLE: If you have a converter in your car that weighs 3,500 lbs and it creates a 3,000 rpm stall speed, and you remove it and sell it to me and I put it in my 4,000 lb car, that same converter that created a 3,000 rpm stall speed in your car will now create a much higher rpm stall speed in my car since it's 500 lbs heavier than your car is. And vehicle weight is just one of the many contributing factors that determine stall speed RPM. And if the reailer and/ manufacture doesn't know and inquire about your vehicle weight, as well as many other factors, then their stall speed rpm "range" claim is non-sense and their converter is a cheap piece of garbage. Here's another example: When you're driving your car with only you behind the wheel, your stall speed RPM will be lower than it would be when you have 4 people in the car, (three adult passengers I mean) since the vehicle weight is increased by about 500 to 600 lbs. But again that's during FULL wide open throttle input. OK I've done all I can do here. If you don't care to listen then you'll continue to spread misinformation about torque converter choices and stall speed RPM. I'm merely trying to educate you Tim, as well as your readers. What you've said and claimed is simply NOT true regardless of how much you want to believe it.

[@timsprojectcar1875]

@@mean70632 Hughes performance "EP. 5 Torque converters 101: What is stall speed?" is a good video to watch. I didn't think I contradicted anything I heard in their videos, but maybe I did. I know for sure I heard either them or Monster say to use a stall speed close to cruise RPM in a street application. I'm going to start looking for that video, so I can name it specifically if I can find it. I didn't conjure that up on my own I promise.

[@goodsirtwiztid3101]

Summit racing has an article recommending that stall speed should be kept lower than cruise RPM

[@judedooley6971]

What stall should I use I have 4.56 gears with 33 inch tires

[@timsprojectcar1875]

With 4.56 gear, 33 inch tire, and 1:1 top gear, it works out to 2926rpm at 60 mph. 3000 stall would be good for street use.

[@judedooley6971]

Do you think it would be alright during highway use during long distance drives