88 gt 5 speed swap

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Rettax3
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Joined: Mon Oct 22, 2012 3:34 pm

Re: 88 gt 5 speed swap

Postby Rettax3 » Thu Nov 07, 2013 4:05 am

:deadhorse:

Rough list of parts:

-Transaxle. Preferably a Muncie/Getrag 282 or the NVG~whatever it was later called. Make sure it has the 'GM Metric', i.e. V-6, bell-housing, and NOT a Quad bell-housing.
-Flywheel, and clutch assembly.
-CV joint axles, left and right. Make sure you have the bracket on the end of the passenger-side CV (or jack-shaft, depending on which version you get).
-Shift assembly, from inside the console.
-Shift cables (2). These are hard to replace, and wear out over time, so you need some luck finding them. Also get the rubber weather-plug in the fire-wall and the metal piece that holds it in place.
-Clutch pedal assembly, also grab the manual brake-pedal, or you will have to cut-down your original as the autos use a wider brake pedal.
-Clutch master and slave cylinders, and hydraulic line. You will have to drill three holes into the fire-wall, one large and two small, I used a template on my GTU, but you can also drill from the inside by pulling the carpet and jute-backing away from the fire-wall under the dash.
-You might have idle issues if you do not also replace the ECM or at least the PROM chip with one from a manual tranny car, but it will still probably be driveable.
-A five-speed shift-plate for the center console would be nice, but you can modify yours if you have to.

If you can swap a clutch on one of these cars, you should be able to pull off the swap. Good luck...


1989 Super Charged 3800 Series II (First)Six-Speed Conversion GTU
1990 Turbo 3.4 Five-Speed T-Type
1990 4.0L 4-Cam 32-Valve V-8 Five-Speed Indy GTi (Rebuild Project)
1990 Stock(!) 3.1 MPFI Auto Indy
1995 3400 Top-End Auto OD Z-26

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Rettax3
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Re: 88 gt 5 speed swap

Postby Rettax3 » Fri Nov 08, 2013 1:51 pm

Well, as I said, if you are comfortable pulling the tranny for a clutch-swap, you should be good. The rest of the swap is a pain and takes time, but it isn't any more technical. Drilling the holes for the clutch master can be a challenge, if you don't have a decent hole-saw set, but even a cheapy kit from Harbor Freight Tools or the like will probably get the job done. So far as swapping the PROM in the computer, if you need some guidance on that, the people here can help you through that once you get to that point. You will need a decent jack, jack-stands, basic wrenches and sockets (including deep-well) up to 18mm, and a deep-well 30mm socket for the wheel-hub nuts, and you really should invest in a torque-wrench if you don't already have on.

Is it hard? That depends on your experience level, whether or not you have a decent place to work on the car, if you have anyone available to give you a hand with the harder parts, and what kind of tools you have to work with -having just a cheapy 3/8 ratchet set will make it a real challenge. :wink: Before you go any further on it, I would highly recommend you pick up a service manual for the car, just a Haynes or a Chilton will do it for you, and go through the entire procedure on replacing the clutch. If it looks like something you want to tackle, you should be able to do this swap.

Cost, well that is tough, I have all the tools already, and I used to have connections at the salvage-yard, so the last time I did one of these conversions, it cost me a little over $100 for all the parts. If you can't find a donor vehicle in the yard or if the yards near you all think their parts are made of gold, it could cost five times that much, or more. I am also not ashamed of using old CV axles, if they look and move okay -if you want all new parts to go into your build, you are looking at maybe $125 for a new clutch, I would guess about $40 each for the CVs, and now would be a great time to install all new seals on the transmission -input shaft, shift-shaft, and two output shaft seals, you are looking at maybe another $20 for those, and fresh synchromesh transmission fluid would add to your bill (the last stuff I had to buy was a fully synthetic fluid that cost $20 per quart, and that was a bargain :roll:, but it was for the six-speed I put into my GTU). Search the classifieds here for the parts you need, shift cables almost certainly won't be found here, but there are a five-speed or two for sale. If you do find a donor, what you want to look for on that five-speed to be sure it is good is to push up, down, forward and backward on one CV joint and watch to see if the opposite CV wiggles around -the differential carrier/bearings can wear out on these- and the second test is to make sure the CVs turn when you turn the input shaft through all five forward gears, and reverse. Synchronizers can still be worn, but if the tranny passes the first two tests, it is almost certainly serviceable. For syncromesh fluid, a new clutch, seals, and CVs (if you go that route), check Rock Auto, e-bay, and Amazon, as well as local parts stores to get the best price.

It is definitely a good bit of work to do, but it is a good feeling at the end to say 'I did this, myself'. And you will have a much better understanding of your car, too.
Good luck.


1989 Super Charged 3800 Series II (First)Six-Speed Conversion GTU
1990 Turbo 3.4 Five-Speed T-Type
1990 4.0L 4-Cam 32-Valve V-8 Five-Speed Indy GTi (Rebuild Project)
1990 Stock(!) 3.1 MPFI Auto Indy
1995 3400 Top-End Auto OD Z-26

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jking18
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Joined: Sat Jul 16, 2011 10:18 pm
Location: South Haven, MI

Re: 88 gt 5 speed swap

Postby jking18 » Mon Nov 11, 2013 4:09 pm

http://www.v6z24.com/howto/5spdswap
This site also has good info. I believe the L body and J body are the same from the windshield forward. At least in the engine bay should be.


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1989 Beretta Base 2.8


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