How to Rebuild a Corvette 4+3 Doug Nash DNE Overdrive

Learn how to disassemble and rebuild the Corvette Doug Nash 4+3 Overdrive used in 1984 to 1988 Corvettes. In part one of this series Paul Cangialosi shows the proper way to dismantle it.
My Books: amzn.to/2vnZPWc & amzn.to/2voHesW
Contact:[e-mail]
Website:www.5speeds.com

[@chrischristenson]

Having been a regular visitor to Paul's shop in the 80's, I can attest to the fact that he built and updated 1000's of these over-drive units... They were everywhere! The Overdrive Automatic THM700R4 first appeared in 1982 and the C.A.F.E. - Corporate Average Fuel Economy - was the real driving force in getting Overdrives and Fuel-Injection into production runs, especially in the Corvette. Another interesting note is that a Chevy Chevette with a diesel motor getting 50mpg could skew the Corporate Average to give Corvettes a little more "breathing room" with the Corvettes getting less MPG then the rest of the Production Line. The C.A.F.E. Standard was actually the real reason for the Electric EV-1... GM wasn't going Green... they were skewing the Corporate Average to save money... Great Video Paul!

[@GearBoxVideo]

Chris Christenson thanks Chris, those were fun times.

[@insertgoodname4809]

I have no legitimate interest in transmissions but find your videos utterly fascinating and thoroughly enjoyable. Your keen and specialized insight into the this aspect of cars is presented in such a clear and coherent manner that I think even people mildly interested in cars would find your vids entertaining.

[@GearBoxVideo]

Appreciate the comment.

[@Michael_Lorenson]

Thanks! I just bought a 1988 4+3 Corvette with inoperable OD, and I'm a gearhead, and I wanted to really understand it before deciding what to do with it. The thing is weird, but also kinda cool. I might want to keep it for that reason, as long as I can fully lock-out the OD, anyway. I'll watch this whole series with great interest. Also, I appreciate the no nonsense, 'let's get to it' presentation.

[@Matthew-wn8oq]

You would be an outstanding teacher at an ase mechanic school. Have a great way of explaining things without complicating the repair.

[@hugieflhr03]

Great detailed video and you weren’t kidding when you said that plate was under 1300lbs of pressure! I wish they made this unit for the old Chevy trucks with the NP465 4speed

[@jimjohnson1041]

Great video as usual Paul. Thanks for doing it, I look forward to part two.

[@GearBoxVideo]

Thanks for watching

[@unclequack5445]

Paul, You make this look fun instead of work. Great video very informative.

[@JahanZeb1976]

Great tips you have given on such units. Part 2 will be sure same way interesting as this part was. Great work uploaded.

[@bolawdean]

very interesting, i have always wondered how one of these transmissions functioned. Very impressive that you were that closely involved with GM during design and warranty, although not surprising considering all the knowledge you drop frequently.

[@GearBoxVideo]

The next video will detail how it functions. Thanks for watching. My company manufactured parts and sold them to GM .

[@ramiram84]

@@GearBoxVideo wow you must have been super young at the time 👍👍✌️

[@danb2122]

Thank you sir for your outstanding videos and extensive knowledge you pass on. I can't begin to tell you how much money I saved doing transmissions myself. I also been doing gm auto overdrive transmissions, if you can make videos doing more autos that would be great! 👍🏻

[@unclequack5445]

First time Ive ever seen a transmission like this Paul, you really make it look easy, another awesome video Paul. Rhonda Wow..........

[@Roy_Godiksen]

Another awesome video! Really cool scene change at 4:14! It's the details that makes the difference:-)

[@hash46176]

Doug, I want to thank you so much for your videos as im looking for a 84 c4 with the 4+3 transmission

[@jasongrady4964]

Awesome video. I really appreciate the socket size call outs. What a nice touch!

[@GearBoxVideo]

I try to get detailed if edit time permits..

[@Squirrel2069]

When I rebuild mine, I used a threaded rod and bolt set up to hold back piston and released slowly doing 1/2 to 3/4 turn on tension nuts in a clockwise direction when a hydraulic press wasn't available. This video would have been so helpful to me 13yrs ago. but glad it's out now,. you can only imagine how hard it was to align those planetary gears without disassembly of the unit.

[@GearBoxVideo]

The rod or bolts are just to hold the piston in place. Whether you release the plate or pull it down risks breaking the Piston. GM actually ran out of pistons because they didn't account for people breaking them. Reality was, it really has no reason to break . Most of the sales of that part we're due to people removing and installing them wrong.

[@gneric85]

Great video. I became the owner of one of these setups back in 1994 when the Corvette owner ran over something and ruptured the cooler line and lost all the fluid. He wound up paying me to convert his car to 700R4 and I got to keep everything except the shifter and ecu. Going to build it and possibly install this into my 1977 Monza Spyder.

[@GearBoxVideo]

Not a good idea. Sell it and get a conventional 5 speed

[@customdesignperformance6641]

Hi Paul, I recently purchased a 1988 corvette with 4+3, and of course the OD doesn't work, your illustrations and explanations are awesome and well presented. I work on lot of classic cars and the transmission are always a voodoo box for me. I'm starting to diagnose the issue(s) with my overdrive unit and video's will be my bible- thanks for all the videos, I also have couple of muscle cars with Muncies will be watching all the videos Thx! 👍 perry

[@GearBoxVideo]

Put the car in diagnostic mode and check that the OD light is on and you have power to the lead at the OD unit. That's your first step.

[@kurtschwaninger1950]

Thank you so much for the video! Very well done, easy to understand. The tips for identifying a bad unit from the outside is a real bonus! I rebuilt one of these overdrive units last winter based on what I believe was information posted by you throughout the internet. Installed it on my 1985 Corvette and it works! so much fun I'm doing another. Just viewed your part 2 video on the pump. Great also! Can't wait for the next video(s) on reassembling a 4+3 (overdrive unit) and especially any tips from your experience rebuilding these, Please hurry ; )

[@mikes9939]

Thanks again for another great video. Looking forward for part 2.

[@aroundlinemen]

Nice job , thanks for sharing 🇺🇸

[@wysetech2000]

Of course we'll be back. You're the best.

[@billyjoejimbob56]

The simplicity of an automatic, with the convenience of driving a manual. Took GM 25 more years to end up in bankruptcy, but it was engineering decisions like this that got them there! How you figured out all the work arounds to get this POS to function correctly... half genius, half persistence. Great vids!

[@GearBoxVideo]

I actually sold my upgrades to GM

[@billyjoejimbob56]

@@GearBoxVideo Good for you! I worked as a contractor for 7 1/2 years at GM in market research and competitor intel... Sometimes they need help getting out of their own way.

[@GearBoxVideo]

How true. The paperwork alone is staggering

[@Ernswrld55]

Great Video. I own 1986 with 33k. So far everything works Great but wondered who to ask if I had problems ……. I found my Guy ! Thx Man !

[@fatboys124]

Paul, If you’re looking to give a gift for Christmas I would love an assembly video, Dave

[@ricksgarage8069]

GREAT presentation. Thank you, Paul! -Richard Curtis

[@joseugaz6338]

Love this video, all the information is here

[@eformance]

"This is in very good shape, this piston" is like when you go to the Dentist and get a checkup and they say "Your gums look excellent and I don't see any cavities".

[@R.E.HILL_]

You are very entertaining to watch and the subject matter is very interesting. And it's easy to see that you put a lot of time and effort in making the videos. And the bit you do with your office manager is just hilarious. So this means that I want more, much more. So please keep on making them. Do ever do automatic transmission or are they banned in your shop? Are they forbidden? ☺

[@GearBoxVideo]

R. E. Hill I've done quite a few automatics but there are probably alot more builders that have done more than I ever have. They by no means are banned and Im working on some auto trans projects in the future

[@R.E.HILL_]

GearBoxVideo Cool. Looking forward to seeing that.

[@jahbriz2483]

The best Transmission I have ever came across was A T56 from a V6 3.4 Camaro 1994 never failed ever you could drive it 3000 miles with minimal bullshit.

[@therealjayseh]

This is some bad ass s*** man!!! Bravo 🥂 thanks for showing us

[@Maxreverse]

Thanks for this video Paul. Great explanation on why this transmission was developed and how it works. What transmission fluid do you recommend for the OD and what do you recommend for the manual portion of the transmission? I own an 87 C4 with the 4+3.

[@stevenhaffley9852]

Hi, I saw a comment you posted on a website forum where you said parts for these were readily available. I've looked for the 4+3 solenoid for 3 years and can't find one new or used. I think that's what I need, I have an 85 with 86k miles on it, sometimes when I'm driving it on the highway the overdrive will keep engaging and disengaging quickly, I have to turn it off, slow down for a few minutes, and then I can re-engage it and it'll work. I think I need a solenoid but I haven't been able to find one.

[@GearBoxVideo]

sk trans 631-957-9427 for the solinoid.

[@stevenhaffley9852]

@@GearBoxVideothank you, with only 80k miles on the entire car it's too early to give up on it over a small part like that, I'll give them a call tomorrow.

[@arthurrodesiler3109]

Paul you do a great job and really appreciate your videos. My point I guess you buy something like them year Corvette and GM threw a junk overdrive in there. Then the Bean Counters figure it will fix them under warranty. Which the bean counters know they will have to fix a few. They know most Vette owners won't putt enough mileage on them and when the owner warranty runs out there stuck with a high dollar fix down the road. At the beginning of the video I could tell by your words and actions that GM should have had a recall rather than stick it to the owner after warranty is over. You fixed a few under warranty but all the other ones that went out after warranty could be in the thousands of those cars. GM should have been sued over this screw up. Am sure they do this with a lot of there screw ups. I don't think GM did right but the owner in the ones that gets screwed. Would you be happy with this Paul if you bought one of these vette with your hard earned money and have to pay out of pocket that GM messed it up. I see these cars sell cheap because of all that electronic stuff that cost big bucks and most are outdated electronics that you can't probably even get from GM anymore. Really most of the car manufacturers make a lot of this junk. I have a friend that works as a technician for GM. We have pizza every Saturday night as we fly our drone and he is so tired of all the junk being made today. I asked him what is a good car or truck today. His answer there all junk. Why a lot of people lease today or buy the extended warranty. He lease his vehicle for this same issue. I hope at the beginning of your video your secretary don't treat your customers like she does you. A bear first thing in the morning and cussing at you first thing in the morning is not good start to the morning imo. Hope this is a joke. If I did this at my work I be fired on the spot. Seems like so much anger in people these days. You make it up by your excellent videos and work ethics for sure. And I really learn a lot and what vehicles to stay far away from them. Keep up the great videos though Paul.thanks

[@GearBoxVideo]

Rhonda is actually amazing with my customers. The issue of companies avoiding the dreaded "recall" by issuing service bulletins still happens with every auto manufacturer. Investing in a new Vette today is financial suicide because parts typically can become unavailable in 10 years. The newer better models with those 6 speed T56 transmissions already have parts shortages. This is what fuels the aftermarket and keeps people like me in business. Thanks for the great feedback and watching the vids.

[@joshuabenson9279]

awesome video. makes me confident this is something I can tackle myself. would like some input from you though. mine locked down to the point the car would barely move. it was like it was holding direct and od.

[@GearBoxVideo]

Joshua Benson in the video I talk about the direct clutch thrust washer. If it breaks the washer can get the OD unit stuck in both modes. What year do tou have?

[@joshuabenson9279]

GearBoxVideo it is an early 87 car. I was driving the car and it started making a popping noise and came to a stop. it was like trying to take off with the parking brake on.

[@leopestano4877]

what great video Paul you make it look so easy. Sir! I have a 84 corvette manual transmission as a project car the reverse suddenly stop working but the forward gear is ok! I went to corvette forum some member saying that my overdrive is shut I know you also mention that in this video I'm just wondering that you have advice for me to check first before I rebuild my overdrive I watch this video part 1 and 2 over 5 times each not kidding to learn as much as I can thank you again and have a great day.

[@GearBoxVideo]

Thanks. Typically the forward clutch pak is smoked

[@leopestano4877]

@@GearBoxVideo Mr. Paul thank you for the fast response one more question. With your professional should I rebuild it or should i get a re build 700r4 thank you

[@RobertKohut]

Great video, very interesting!

[@jacobcox198]

u bet thank u for sharing your great years of knolage and awsome tips ty your pal boostbuick

[@f22bsd]

Exist any configuration on ECU about rpm, temperature, etc of OD? Should it be adjusted? When you say to put car in diagnostic mode, how do that?

[@f22bsd]

Paul??

[@aussiebloke609]

"...and so begins another day..." - and I spat coffee all over my keyboard. Nice one! Btw, that system of piggybacking the overdrive onto a 4-speed...reminds me of the Triumph overdrive setup for the TR6. I believe it basically used an auto trans on the back of the regular gearbox, that could be used with 2nd, 3rd and 4th gears (I guess giving a total of 7 gears - unless some of them overlapped in the effective combined ratio.) Ever work on one of those?

[@GearBoxVideo]

Those were Laycock overdrives. They were coupled to Moss 4 speeds, especially on Jaguar sedans. Yes I have worked on those. Pretty much a company called Gearvendors makes a modern day version of that.

[@aussiebloke609]

Thanks, mate. I thought the basic concept sounded familiar. And thanks for the breakdown of the teardown. It's nice to find the pitfalls and potential problems before learning the hard way. :-)

[@jordanmccauley4880]

great video paul. I was wondering where you get your rebuild kits or parts for the DNE overdrive? Thanks in advance!

[@GearBoxVideo]

I make my own kits. They are available on my website www.5speeds.com

[@TopNotch50]

Another great video. How about doing an MT-82 rebuild?

[@GearBoxVideo]

Send me a unit!

[@dennypassialis5376]

Really Kool Your the Best Man Love all ur Videos

[@GearBoxVideo]

Glad you like them!

[@oklahomacrabber]

Nice! Thanks

[@junkyardhemi]

Great video. Very informative. I plan to rebuild my OD unit in the spring. Are there any ways to help it handle more HP? I intend to twin turbo my car next year.

[@GearBoxVideo]

The OD will last. You might break the 4 speed

[@chrissmith7669]

After watching I’m going to find someone who has done a bunch and let them do it first time right.

[@andrewlewandowski868]

Great video, thank you!

[@fatch76]

could this unit potentially bolt up to a muncie m21 wide ratio? or is there any type of OD that can bolt upto a m21?

[@GearBoxVideo]

Flavio Borbon No. It already ia designed and part of sn ST10. In part II of this series I discuss the pros and cons of using these in a non Corvette application.

[@Marco_diaz928]

Hey, thanks for all the information but I have one question about the transmission. What would be the cause of the reverse gear not working ?

[@GearBoxVideo]

Remember everything goes thru the OD unit. It doesn't vanish when you are not using it. Reverse is another mode. The OD direct clutch pack is burned up. A common problem

[@Goatkid76]

Hi, great video. My 88 vette has an issue with the od unit . If I don't disengage the od before parking it, it acts as if I lose reverse, or sometimes bangs into gear. If I disengage the od switch and drive it a little before parking , everything seems fine. Your thoughts on what to look for when I disassemble it this winter? Otherwise the od and transmission work fine. Thx for any input.

[@rafelinasn8446]

Hi Paul. I'm in the middle of rebuilding my nash unit. You mentioned that those 5mm flat bolds are sealed with silicone. Do I need to apply it again when re-assembling the unit? If so which type of silcone should i use? As always thanks for your help.

[@beetragg]

great video! Thank you!

[@GearBoxVideo]

Thank you

[@JSchrumm]

Did you see any sign's of unusual wear or damage during disassembly or was I spacing out?

[@GearBoxVideo]

James Schrumm No. Minor clutch wear and a worn sprag.

[@russellschipkie1112]

fantastic video pual any idea when the rebuild video is coming out mate . and would you have acost for a full rebuild kit with bearings cheers mate .

[@GearBoxVideo]

The kit for the OD is on my website's shopping cart www.5speeds.com/cart . I working on 2 more videos on this transmission.

[@Gr8thxAlot]

You are the transmission god! Were you in The Sopranos too?

[@GearBoxVideo]

Gr8thxAlot The very last scene of the very last episode. When Tony looked up, it was at me.

[@Gr8thxAlot]

Members Only

[@Heavy_metal_rulez]

Very in-depth information Paul!! Have you ever messed with a gear vendors overdrive?

[@GearBoxVideo]

Desert88 Z28 Yes. I'm not a big fan of those.

[@josephforcino6399]

Hey paul, I have 1986 4+3 , starting to have an issue . The Manuel part of the transmission works fine but when I drive it now the overdrive is slipping and motor is revving up when I it the gas. Overdrive light stays on . I can drive the car normally without the overdrive. There isn't any transmission shops that know jack about these transmissions in my area. Why is overdrive slipping.

[@GearBoxVideo]

OD clutches are burnt. Call SK at 631-957-9527 for an exchange unit

[@jazbuh1794]

Wow it's like a small Automatic trans bolted to the manual.

[@tjhamer3]

good one

[@GearBoxVideo]

Thanks!

[@MrSanjacjewels]

I am Looking for a console switch for an 1985 doug nash 4+3. Any idea where I might locate one? Thanks for your video on this transmission

[@GearBoxVideo]

If you look at the switch it is an ALCO switch. Part # is on the switch.Digikey use to sell them

[@TheEZGZ]

I enjoyed watching this excellent presentation but it was way over my head. I can't imagine with todays technology why someone would want to put that back in instead of upgrading to a modern overdrive unit. I know $$$$$ would be a stumbling block but I'm asuming these owners have $$$$

[@GearBoxVideo]

TheEZGZ This was 1980's technology. These cars can be upgraded but the cost would exceed the value of the car.

[@chrissmith7669]

I’m putting one back into car that it removed for some reason. I want my car to have all the quirks the 80’s had on offer. I’ve heard many were used hard, abused then dumped off when they failed from neglect. I only wish the over ride button was three position; OD, auto, no OD

[@GearBoxVideo]

A simple chip change can do that

[@user-xc6ux2nu2e]

Hi I have a 1985 C4 with this Transmission. My question is to do with a comment you made in this video around the 6 minute mark I think the problem is to do with the bearing pushing the seal out of the housing causing the trans stuck in reverse gear (I haven't been able to get the car out of reverse the last time I had the car out for a drive) Do I have to drop the overdrive unit to get the shifter to get into neutral?. or do I need to drop the whole transmission to get the overdrive out for repair. Thank you and look forward to your reply. Cheers

[@GearBoxVideo]

First, see if you can get underneath the car and manually move the reverse shifter shaft back into neutral. If that doesn't work then you will have to drop the whole transmission you cannot slide the overdrive unit off of the back. Once the overdrive is off you can usually push in the roller bearing, stake it in place and install a new seal

[@user-xc6ux2nu2e]

Thanks Paul I will try that. I have another question ? Do you know what other transmission will bolt up to this car in place of the 4+3 , preferably something out of another car 5 sp with an overdrive. ?

[@GearBoxVideo]

Nothing, other than a later ZF 6 speed. Which has zero service parts

[@dalekennedy3593]

Paul super videos are there more than 2 one on the build? Paul where can I get parts. looking for Thrust Bearing, pump seal and the improved thrust washer. This unit got noisy at 50000 miles and did not fail totally. I watched a video of yours that made a special point about a seal installation. Thanks for a great great video..Dale K

[@GearBoxVideo]

My website has some parts video does have the info

[@arthurfiorillo8591]

Back in 87or88, we did the first one I did not have a book. I told the rebuilder don't touch until I come back with the book from my chevy dealer. But any one that owns a shop the help does not sometimes listen when I came back with the book and talking to the mechanic about rear piston danger under pressure. Alex was at the hospital he was very lucky left eye and head if he did not have his coca bottle glass on he would have lost his left eye I had the glasses in the rebuilding room for 30 years. Read the book or use all data none of us are above knowledge.

[@GearBoxVideo]

I've seen a few accidents like that.

[@Watcher3223]

Well, you can be sure the help learned his lessons. 1. Listen to directions from those who know what they're doing. 2. Heed any and all dangers, warnings, cautions, and notices in the service literature and/or on the component being serviced. At the very least, it will save you from frustration. At the very most, it could save your life.

[@stevedishmon1599]

good morning, I see you know what you are talking about on these transmissions. I would like one rebuilt. Can you help me? .

[@GearBoxVideo]

Contact SK at 631-957-9427

[@Domobomb]

Thanks for the great video Paul! The carrier bearing in my '85 is starting to make noise when OD is not engaged and needs to be replaced. The OD works perfectly fine otherwise as far as I can tell. Is it possible to replace the carrier bearing without tearing down the whole unit since it is right at the front? I am not confident in reassembling the unit (timing the planetary gears, and I assume other necessary steps I don't know). Just looking to fix at least the bearing before real damage occurs. Thanks, Dom

[@GearBoxVideo]

Don't drive it like that at all. The unit has to come apart.

[@stevencarter2900]

Great Video very informative but in the future could you touch on the Early DN 4+3 with Detente Cable

[@GearBoxVideo]

Thats coming soon

[@stevencarter2900]

@@GearBoxVideo thanks, I too did rebuild many of these O/D units probably 2 a week from 84 to mid 86 then it dropped off

[@rainingacid91]

Intros are hilarious!

[@rudytoews941]

Great video. I just took mine out of my 86. No symptoms except overdrive didn’t work. I checked the fluid level and it smelled burnt. So I pulled it out to replace clutches and seals and found the direct clutch thrust washer broken and it had damaged the overdrive direct clutch piston. Do you have any idea where I could get a new direct clutch thrust washer and a new direct clutch piston? Tried my corvette guys here in Canada.

[@GearBoxVideo]

My contact info is in the video and video description.. Use it

[@hairymongrell]

currently have mine out on the bench and cant find anyone in Sydney that will touch it. I have been tossing up trying it myself. I think mine only needs plates, do I have to strip the rest or can I just change the plates ? keen to see part 2 ! great video !

[@GearBoxVideo]

Hairy mongrel you can leave the pressure plate anchored if you think those spribgs are OK

[@rd4in37]

Hi..ive got an 84 4+3 and it has a weird fault.....once a year or so it leaks a patch of dexron fluid out after I push the car backwards out of the garage...sometimes over the years when I check the O/D fluid level it is overfull...is it possible for the T10 to be leaking into the O/D unit causing an overfill situation ? The O/D unit works no problem and the T10 shifts fine...Thanks.

[@GearBoxVideo]

Check the 4 speed oil level. A common problem

[@rd4in37]

@@GearBoxVideo Thanks....is it the front seal in the O/D..?

[@christieturner202]

How does the automatic transmission adapt to the standard?

[@GearBoxVideo]

The output of the 4 speed drives the pump. Electronics keep it from shifting prematurely until proper line pressure is achieved

[@evansisco]

Hi, I was just wondering how many plates and clutches are used in this unit I’m pretty sure the outer is 11 and the inner is 13 am I right?

[@GearBoxVideo]

Ods are either 4 or 5 OD and 5 or 6 direct

[@evansisco]

Thank you so much frfr

[@Goatkid76]

Would you know what colour wire I tap into off the overdrive to adjust the Speedo? I see two wires for the speed sensor

[@GearBoxVideo]

It's a pulse generator. No positive or negative

[@Goatkid76]

@@GearBoxVideo right, what I mean is I have the Abbott control box to correct my rear gear change.

[@myjunkisstuffgarage967]

Paul, were you involved at all in the early C4 SCCA and Corvette Challenge years when they used the 4+3? If so, did you do anything special to the OD or was it strong enough to last as it was with the rad oil cooler?

[@GearBoxVideo]

I did most of them. They had a special .80 OD set. I set them up with boosted line pressure as well as solid clutches. No waffled styles. This added to the holding power. The .80 OD also meant less load on the clutch system. The gears are long gone. Also the cars had a different chip in them. My numbers are stamped on the back end of the OD case where the beam attaches.

[@tipetu]

Quick question, Does double clutching in an standard manual box reduce wear on synchro-rings?

[@GearBoxVideo]

tipetu I dont think you are going to see a major savings doing the double clutch work. Yes you xould cut down on wear.

[@troydiomartich1211]

Paul, do you have a video on dismantling the front 4 speed part of the 4+3 Doug Nash transmission on a 86 Corvette?

[@GearBoxVideo]

It's the same as my super T-10 videos on my channel

[@troydiomartich1211]

@@GearBoxVideo Does the pin that holds the reverse shift shaft in place in the rear bearing retainer housing get removed by tapping it from the inside out or from outside in? It looks like a tapered pin.

[@GearBoxVideo]

Watch the video. It is tapered.

[@eformance]

Have you rebuilt the Laycock overdrives on Volvo transmissions too? Those are the units that Gear Vendors adapted for the aftermarket, I've always been interested in the Volvo units because they aren't $2000 :-)

[@GearBoxVideo]

Yes I have, they are quite simple.

[@jamest.5001]

Is this similar to the gear vendor units? It looks Alot more complex!! From what little I have seen anyway..

[@GearBoxVideo]

GV have no valve body. Totally different

[@JosePerez-fw4nz]

Where can I get a pressure switch haven’t been able to find one

[@GearBoxVideo]

email [e-mail].

[@f22bsd]

I have a corvette c4 1985 with doug nash without kickdown cable, all is work correct until we open the OD to repair leaks, after reassembly and put on car, when i tested on highway, the OD engaged only when i stop gas the pedal, if i gas the pedal, even though only 5%, the rpm increases. We open the OD because my friend open the first plate without lock the mechanism and the springs push mechanism out, we watched your video and lock the mechanism to reassembly again. My friend think had two most springs, then reassemly without two springs. Question: the lack of these two springs may be the cause of the problem?

[@GearBoxVideo]

It's just assembled wrong and most likely damaged. This happens often.

[@f22bsd]

Any suggestions for where to look?

[@GearBoxVideo]

You are saying ENGAGED when stomping gas pedal and it should disengage. Something is screwed up and it's hard for me to diagnose it with messages

[@f22bsd]

@@GearBoxVideo can you send your private contact, i'll pay for remote assitance.

[@f22bsd]

@@GearBoxVideo i took many, photos of OD open.

[@markd4524]

Paul, I have an 86 with the 4+3. Relays are working, power is going to the unit. Both od light go on when you mash the button. What else should I be looking for? How do you fill the unit and what do you fill it with? Any help would be greatly appreciated.

[@GearBoxVideo]

You fill it to the level of the fill plug. Drop the pan, put the car in diagnostic mode and check your connections and bypass the pressure switch to check if the solinoid works. Could be a stuck or clogged shift valve.

[@markd4524]

Thank you Paul. I will look into that after Turkey day.

[@markd4524]

Good day Paul, I am in the process of getting all the parts to rebuild the overdrive unit, I can find everything to rebuild it except the solenoids. Do you have a source that I can purchase these? Your help would be greatly appreciated.

[@TargaWheels]

Is the Super T-10 output shaft unique in the 4+3, or can you use a typical output shaft with the same length and spline count? Is it possible to mount this OD unit on the back of a Muncie or Saginaw?

[@GearBoxVideo]

TargaWheels it's a shorter special output , housing, and reverse setup. I do not recommend using these in applications they were not intended for.

[@realhorsegarage5359]

Can you use 85 4+3 in 84 . Curious if I can just swap side cover plate with 1st 2nd 4th switch from 84 looks like the 85 only has plug on shift bracket plate on driver side of 4 speed thanks

[@GearBoxVideo]

Yes you can! Just use the same side cover since the 84 has more switches

[@realhorsegarage5359]

@@GearBoxVideo Also the car is carb swamped . Basically does the 4+3 work with carbureted engine for overdrive ? meaning all throttle position stuff is out of equation. Only thing I can use is cooling temp sensor in front of intake for ECM

[@GearBoxVideo]

Grab a wiring diagram for your car and think it thru.

[@realhorsegarage5359]

@@GearBoxVideo thought it thru. Overdrive works and has engine brake. When overdrive is not on I have no engine brake. Reverse works with light throttle but still makes noise if given too much. Also replacement tranny (not yet installed) shift plate cover is same as original but has no holes for switches. What year would this be from, is this normal? Thanks

[@victoriano7507]

Damn that was a cool video. Would you mind please helping me out if you can? I found your video cause my car appears to be stuck in gear it’s an 84. I was driving when suddenly I couldnt shift gears. I forced it into neutral position but it stayed in gear I got home and it stalled where I parked it. I checked under the car and one of the linkage things from the shifter was disconnected, so I connected it and now it seems the shifter is even harder to move than before. It’s supposedly in neutral but it’s in gear cause the car will start and try to take off. Do you know what i could try or what it could be? Thanks an Advance for any info you’re the man!

[@GearBoxVideo]

Sometimes the 1-2 shifter shaft breaks and it stays in 1st gear

[@victoriano7507]

@@GearBoxVideo i will check that out, appreciate it thank you!!

[@rafelinasn8446]

Hi Paul great video I just purchased an 87 vette. Got a great deal on one as it has transmission issues. Shift through the gears fine but won't go into reverse. Would this also be caused by the Nash bearing obstructing it? Would appreciate your input on this.

[@GearBoxVideo]

The carrier bearing fails causing the Rev direct clutch pack to burn up. You would loose reverse and also engine breaking when you let off the gas.

[@rafelinasn8446]

@@GearBoxVideo thanks Paul

[@MrJmoreno19]

If scoring Is found in thr body , piston and pressure plate Is replacement needed .

[@GearBoxVideo]

If it affects the sealing areas...yes

[@MrJmoreno19]

@@GearBoxVideo thanks for your reply. It would seem the scoring is mostly were the friction rings ride. Also I checked your website but it would seem I can't find a direct friction plate washer.

[@37hicks37]

Paul! Hoping you could help... I have read that you can pull the overdrive and convert it to a non overdrive super t10. Do you know if that is true? The transmission would be going in a older truck with front and rear c4 suspension.

[@GearBoxVideo]

Just get a standard St10 Mainshaft tail and Rev gears

[@37hicks37]

@@GearBoxVideo awesome thank you. Would you be interested in the overdrive unit?

[@joseugaz6338]

What's the going price for a clutch job on 87.

[@GearBoxVideo]

No clue. I'm not a shop. Labor prices vary.

[@roberthunt7491]

Ok, so here's a question: in an 87 C4 Vette, with the 4+3 overdrive, this car is engaging and disengaging the overdrive unit at will, even in first gear. It will do this all by itself, or it will decide on its own as to whether or not it want to be in overdrive even if you press the overdrive switch. What could cause this? I'm suspecting a bad relay, but I'm really not sure.

[@GearBoxVideo]

Robert Hunt if it's the relay both the light and OD will go on and off at the same time. It may also be a bad shifter switch

[@roberthunt7491]

Yessir, my OD and my dash light go in and out at the same time. Guess I'll look for both the relay and the shifter switch at the same time and fix it for sure! Thanks for your help and keep the great videos coming!

[@johnbrooks4899]

What can be done about repairing or replacing the slave cylinder dust boot cover.

[@GearBoxVideo]

You buy a new one. They are still available

[@bernardox]

Hello In the 28:16 min you talk about bearing, I have a problem with it, it totally destroyed and I need to buy it, in the piece comes a name MRC 1912R, the only one I found in Amazon is worth more than 800 dollars, it really is so Face is bearing Thank you very much for your help. I am in Honduras Central America. There are not many corvettes here or spare parts for these cars.

[@GearBoxVideo]

bernardox parts are available on our website's store. See the description

[@bernardox]

Can you send me the link To buy it, my email is [e-mail]

[@GearBoxVideo]

www.5speeds.com/cart/index.php?route=product/product&path=75_84&product_id=180

[@bernardox]

Hi good day I'm seeing the bearing you sent me, I can see that it is (1912 "S") The one I get out of my transmission is a (1912 R) no problem? Can any of the two bearings be used?

[@GearBoxVideo]

bernardox yes this replacement works fine. You must still set endplay before installing. Wait for the assembly video if you can

[@dannymartin032992]

Is there a way to gut this unit out our weld the gears or plates shut and just have a normal 4speed. Or a way to put a normal t10 tail on it and still use in a c4.

[@GearBoxVideo]

There are long Ford ST10 mainshafts that you can put into the trans and seal off the bottom. Call SK at 631-957-9427

[@randallfox4265]

Can you tell me which switch is the 2nd gear switch on an 87 DN4+3? There is only 2 on the side one with a Green and black/white wire and the second one, Green/blue wire. Can't find anything in the FSM or internet. I want to bypass it and see if it is the reason why my OD doesn't engage . If not tit has to be pressure switch or solenoid. Everything else checks out...

[@GearBoxVideo]

Learn how to put your car in diagnostic mode and check your circuits. I would advise you to invest in a shop manual for your car if you plan on working on it. They are available on eBay. All circuit info is available on my website at www.5speeds.com

[@randallfox4265]

@@GearBoxVideo Yes I have one. I overlooked the schematic. It appears mine only has an a 1st gear switch and an overdrive switch. when driving car OD light comes on between shifts and shifter button has on off function I'm trying to diagnose if I have a failed Pressure switch, solenoid, OD switch or a burned up OD unit. Didn't notice any metal shavings or anything odd when I dropped the pan. If it's toast I may have to send the OD unit to you.

[@GearBoxVideo]

It's electrical. The ECU flips the light on, not the OD unit. It can be fried and the light would still stay on.

[@randallfox4265]

@@GearBoxVideo Was it common for the pressure switch or solenoid to fail in these? I assume if one of these fail no OD engagement?

[@randallfox4265]

@@GearBoxVideo If the OD unit is toast wouldn't it be hard to get car in reverse? I read this is a common symptom of a fried OD unit. My reverse is fine along with the rest of the gears in the 4 speed.

[@skutahuniai697]

Can I assume that after 1 year, there will be no part 2 of the assembly?

[@GearBoxVideo]

Skutahuniai Sooner. I'm pretty busy right now with a backlog of work. So in the next month that will get into edits.

[@JBAutomotive794]

was this unit still operating? what Symptoms did that broken sprag cause?

[@GearBoxVideo]

James Bradley the sprag will work fine, it's just worn. It would start slipping in direct. Function will be explained in the next part

[@brandondavis9270]

Old video, but any way I could reach out to you with some issues I have been having with my Corvette? Its an ‘87 4+3. Had a shop in Connecticut rebuild my overdrive box, and it has now failed twice within 100 miles. Just looking for some troubleshooting advice as they have not been helpful and it may be up to me. Thank you.

[@GearBoxVideo]

Contact and website info is in the video. Use it! I'm still around.

[@myattsgarage]

What is the part number on the tail shaft seal on the over drive were the drive shaft goes i to?

[@GearBoxVideo]

Its here: www.5speeds.com/cart/index.php?route=product/product&path=66_74&product_id=110

[@myattsgarage]

GearBoxVideo thank you

[@randallfox4265]

I dumped the Doug Nash for a Borg Warner - T56 out of a 1997 Camaro. I was to much of a headache trying to get the DN 4+3 right.

[@GearBoxVideo]

How did you attach the beam. Does someone make an adapter? Could be a good conversion option

[@randallfox4265]

This company makes a C beam adapter for LS conversion but worked on my application as well. They sell it separately by itself. C Beam has to be trimmed on the trans end a couple inches and new holes drilled. It was a snap. It was pricey at $300 but great for me since I don't have a welder at the moment but a bracket could be fabricated easily as many have done.

[@GearBoxVideo]

How about sharing the company name?

[@randallfox4265]

For the swap i needed the 1) c-beam adapter, 2) a new drive shaft made that was exactly one inch shorter . 3) An adjustable clutch pedal stop when going from push type to pull master slave and I spliced in a braided line to the factory hydraulic line to connect to the LT1 master slave. Without the pedal stop the fork extends to far and rubs the flywheel. 4) Also for the speedo to work an SGI-100 BT from Dakota Digital is needed. Summit Racing sells them for $100. 5) a patch panel to cover the trans tunnel where the 4+3 shifter placement has to be cut out since it angles in and will interfere with the new trans. You can make your own or Holley sells one for c4 for around $50

[@randallfox4265]

This car is so much better now with the Lt1 6 speed. 93-97 camaro/ firebird is what is needed.

[@brodyolson6]

I'm planning to put an overdrive unit from an 86 onto my 84. Can I still utilize the factory overdrive switch or do I need to switch the shifter out?

[@GearBoxVideo]

No, you would still use the factory switch. You would just be eliminating the cable. I have all the gaskets in stock if you need them.

[@brodyolson6]

GearBoxVideo Thanks! Great video. The o.d. unit that I'm buying is supposed to work so I just plan to pull mine off and throw that one one. I'll replace the fluid and filter before I do so. Will I need any gaskets other than a pan gasket to do that?

[@torreydonnell769]

How can my buddy get the solenoid to activate the splitter? His 4 speed 88 c4 built in oct 87 has a 8ball shifter :/ I'm starting to worry if the previous genius that built this car ground wired the amp to the transmission idk what to do next.

[@GearBoxVideo]

Rewound solonoids are available from SK Trans at 631-957-9427

[@torreydonnell769]

@@GearBoxVideo the car doesn't have a button on the shifter for the splitter/solenoid

[@GearBoxVideo]

The wiring is under the shifter in the console. It's a momentary push button switch you need. Learn about putting the car in diagnostic mode and check your circuits