1980 Malibu Auto to Manual conversion w/ '92 S15 donor?

[Shackleford]

I want to convert my 1980 Malibu project to a manual transmission. The car currently has the original TH200 and a swapped 305 SBC. I found a 1992 GMC S15 Sonoma with a factory 5-speed V6 but it's far away and I'd like to know if it's a feasible swap before I look at it.

I don't know the specific brand of transmission. That generation was produced with Borg Warner T5s, Getrag 290s, 5LM60s, and NV3500s. I am only familiar with the Borg Warner T5. Will all of the models work and does anyone know which trans the '92 S15 likely came with.

Next question, I don't know if the V6 in the truck is the 4.3L or the 2.8L. I believe the bolt pattern on the 4.3 is the same as a small block V8 as is any 90 degree V6, but what about the 2.8L? Will I have to get another bellhousing if it's the 2.8L?

There's also a question of durability with mating a trans designed for a V6 to a V8. I know it's possible, but is it worth my effort/money? A brand new trans is out of budget and I haven't had any luck finding a suitable V8 based donor.

 

[pontiacgp]

You should try to find a T5 WC from an 1988 to 1992 F body, the shifter on the S15 will be too far forward

 

[Michaelweez]

If it's a 2.8L v6, that is a 60 degree engine and the trans will not bolt up without an expensive adapter, I wouldn't bother with this trans at all. If it is a 4.3L it is likely a Getrag NV3500, this trans could live behind a v8 as it was also used in v8 1500 full size trucks.

 

[pontiacgp]

If it's a 2.8L v6, that is a 60 degree engine and the trans will not bolt up without an expensive adapter, I wouldn't bother with this trans at all. If it is a 4.3L it is likely a Getrag NV3500, this trans could live behind a v8 as it was also used in v8 1500 full size trucks.

the Getrag and NV43500 are two different transmissions

 

[Michaelweez]

the Getrag and NV43500 are two different transmissions

Yes my bad thanks for correcting me.

 

[pontiacgp]

Yes my bad thanks for correcting me.

your welcome, the Getrag is a very expensive transmission to repair because of the parts...the NV3500 is in the trucks 93 and up. The T5 WC that I use are getting very rare so I was researching options

 

[Michaelweez]

your welcome, the Getrag is a very expensive transmission to repair because of the parts...the NV3500 is in the trucks 93 and up

I thought the NV3500, or at least the GM interation of it

your welcome, the Getrag is a very expensive transmission to repair because of the parts...the NV3500 is in the trucks 93 and up. The T5 WC that I use are getting very rare so I was researching options

Agreed on the T5 WC, I looked around for this setup for my el camino before I decided to just stick with an automatic.

 

[marcar1993]

Can it be done, yes. My friend had an s10 nv3500 in his malibu. It worked, but it was not optimal due to gear ratios. He now has a t56 in it. Also, nothing else will really work on the car from the s10.

 

[ssn696]

The S10 T5 has a granny 1st gear, on the order of 4:1. In order to make that work, some tradeoffs in strength had to be made and they can get ripped apart with too much torque, plus you might just start in second all the time unless you have a 2:14 or 2:29 rear axle. You have several options, with the World Class T5 from a Camaro being the lowest cost, if you are lucky. Many of the F-body T5s had a mechanical speedo sender which solves one problem most don't discover until later. I will echo PontiacGPs comment that shifter position is another big issue. When I did this swap 20 years ago, the shifter came up right square in the middle of the factory console floor shifter location. The major problem (other than finding one) with the F-body T5 is that GM tilted them towards the driver, so when you put one behind a G-body bellhousing, the mount on the tailhousing is at an angle and requires some creative welding to make a tilted mount. I looked into it and there isn't enough meat to try to machine and weld a new pad onto the aluminum. A solution is to use the F-body bellhousing, and this may be a benefit because it uses a hydraulic clutch mechanism, although I don't know it it hits the floorboard on a G-body. I have seen early 80's Corvette bellhousings used (with the 4+3 transmission) work. One option that may work out is to use a Ford T5 WC transmission - need to use a Mustang clutch disc, and a Lakewood-like bellhousing that is drilled for multiple brands, then you have to figure out a clutch linkage, hydraulic or mechanical. I explored this swap a while back - the shifter is 1-1/2" forward from the F-body location.

If you are on a budget, and your engine won't make more than 300 ft-lbs of torque, the F-body T-5 is probably the best solution. The G-body aluminum bellhousing is not impossible to find, although you need to also obtain the particular G-body clutch fork to make it work, plus all the mechanical linkage parts and pedals. General G-body manual transmission facts can be found here: http://www.garage-scene.com/

Expensive parts can be found here: http://www.4speedconversions.com/g_linkage.html

Better options, except for the huge cost, are aftermarket manuals, although there are tradeoffs there, too. The T56 requires some work on the floorpan to fit. I used a Tremec TKO600, and had to rework the tunnel some as well, although it has a normal transmssion mount, and the GM versions bolt up to the G-body bellhousing no problem. One option that mat be the least amount of re-engineering is the new McLeod product, which looks remarkably like a shaved Ford T5 version. Supposed to have better strength, and is very compact. https://www.summitracing.com/parts/mcl-512957/overview/

If I was committed to spending the money, the T-56 is probably the best option for driveablity. The T-5 can be had with a 0.63 overdrive, good for 3.23-3.73 rear axles, but there is a long shift between the 1:1 4th and this 5th gear. The T-56 puts one more gear in between, around 0.80:1. The LS1-style used in the 1998-2002 Camaro and 2004-2006 Pontiac GTO is an ideal choice - it uses a hydraulic throwout bearing that may be the simplest way to adapt a manual to the G-body. Read up of how to make one of these work here: https://gbodyforum.com/threads/t56-6spd-manual-transmisson-install-into-a-gbody.60659/

 

[Mike buttafuoco]

Also want to point out that the mustangs from 87-93 used the same trans and does not have the tilt built into the casting. They also(I'm not 100% sure) have the larger countershaft bearing which would make it a world class. And yea the bolt pattern is the same from the trans to the bell housing. I can't remember if you have to change the input shaft or use a ford clutch. You can call G Force transmission in Lebanon Pennsylvania and ask because these guys build that exact trans for racing. I agree with the s10 transmission comment. Also, These transmissions weren't very stout, as I installed one in my 76' cutlass and it lasted about 9wks. I went to a super t10 and it took all the abuse u could give it at the time. Another resource is Hawks 3rd gen. They can help too. Good luck and keep us posted.