Weird transmission swap options

[oldopelguy]

Some weird tranny swap options, stuff other than the usual Getrag 240 or 265 even.

Start out with some reference shots, the Opel 4-speed and auto trans mounted to the back of an engine block. In all the shots the tape measure was set with 30" at the front of the transmission.

[oldopelguy]

First swap to consider is the Chevette T-5, which gets talked about a lot but seems to be sort of unobtainium. It has close gear ratios and shares alignment pins and 4/6 of the bolts between the bell housing and the engine with the Opel. The shifter is also set further back than the Opel one and the transmission body is set back with respect to teh engine due to the much deeper bell housing.

[oldopelguy]

Next is the Opel R25, a 5-speed used for a few years in Europe and hardly ever seen in the US. It's shorter overall than the Opel auto trans, but very tall and wide. It also requires the remote shifter like the Getrag and uses a Guibo instead of a front u-joint. Source the driveshaft to mate to it with the trans or get one from a BMW or Caddy Catera here in the US.

[oldopelguy]

While not adding another gear, the sport-shift Chevette 4-speed might be an option for some folks. It is remarkably narrow, which would allow for exhaust or maybe swapping into a 1.1L floor Kadett. Not sure on the ratios yet, but odds are they are closer than the Opel 4-speed. Shifter is set back a bit, and same 4/6 of the bolts issue as the Chevette t-5.

[oldopelguy]

More details on this one in the "T5 interest" thread. Some comparisons pics between the S10 and Chevette as set up for the Opel.

[oldopelguy]

The adapter for the S10 T5 can also be used to bolt up several of the GM transmissions from the 60s-80s. Monza T-50 pictured below.

[Barrmust]

How about some info on swaping in a late model automatic? Any swaps that work? how about a adaptor plate to swap in a 700r4? one question, do you know the diameter of a auto flex plate for the 1.9? something like this:

TCI 230000 - TCI GM Bellhousing Adapters - summitracing.com

TCI 149260 - TCI GM Bellhousing Adapters - summitracing.com

Russ

[wrench459]

Originally Posted by Barrmust How about some info on swaping in a late model automatic? Any swaps that work? how about a adaptor plate to swap in a 700r4? one question, do you know the diameter of a auto flex plate for the 1.9? something like this: TCI 230000 - TCI GM Bellhousing Adapters - summitracing.com TCI 149260 - TCI GM Bellhousing Adapters - summitracing.com Russ

Russ
I know what you're after but the driveline loss will be hard to makeup.
The 700R4 has a killer first gear, we've been swapping out AOD's for the 700R4 for years. The 1.9,2.0,2.2 or the 2.4 wont make the power to make it work.
Just my opinion for sure.

[neuropel]

I have a bellhousing from a T-5 chevette if anyone is interested. As Stephen says, 4 of 6 bolts fit the CIH block, and it appears you could either elongate the holes or make a Z bracket for the remaining two. Not 100% sure, but I believe the bolt pattern for the Chevette T-5 is the same as the Ford T-5?

Todd

[oldopelguy]

Originally Posted by neuropel I have a bellhousing from a T-5 chevette if anyone is interested. As Stephen says, 4 of 6 bolts fit the CIH block, and it appears you could either elongate the holes or make a Z bracket for the remaining two. Not 100% sure, but I believe the bolt pattern for the Chevette T-5 is the same as the Ford T-5? Todd

I'd love to have it Todd, I call dibs!

[wrench459]

Originally Posted by neuropel I have a bellhousing from a T-5 chevette if anyone is interested. As Stephen says, 4 of 6 bolts fit the CIH block, and it appears you could either elongate the holes or make a Z bracket for the remaining two. Not 100% sure, but I believe the bolt pattern for the Chevette T-5 is the same as the Ford T-5? Todd

The Chevette has the GM mounting flange. The Ford T-5 has a different mounting flange. The Ford blue print is easy to find on the net. I've yet to find GM's.
So no there not interchangeable.
Dang can I have second dibs? Like Mr. S beat me by seconds.

[oldopelguy]

Originally Posted by wrench459 The Chevette has the GM mounting flange. The Ford T-5 has a different mounting flange. The Ford blue print is easy to find on the net. I've yet to find GM's. So no there not interchangeable.

Actually, that's completely wrong. The Chevette trans uses the Ford/ V8 bolt pattern and not the regular GM one like the S10.

[neuropel]

Stephen, are you coming to Carlisle? If so I could bring it. I have $60 in it - sound ok?

Todd

[wrench459]

Oh I learned some thing then. Cool
What about the driveshaft length? Would it be better to go with a coupler? Or a very short shaft of around 6 inches c-c.

[oldopelguy]

Originally Posted by wrench459 Oh I learned some thing then. Cool What about the driveshaft length? Would it be better to go with a coupler? Or a very short shaft of around 6 inches c-c.

You can look at the pictures, the Chevette T5 is about 2" longer than an Opel auto and the S10 is about 5". In anything other than a GT that's fine, in fact I'd bet a GT 4-speed driveshaft might just work in a Kadett with the S10 after the yoke was swapped. In a GT you're going to have a short driveshaft unless you go with a different rear end and use a torque arm instead of a torque tube.

[Barrmust]

so when you say that the 1.9 ect wont have the power to run the trans, what exactly o you mean? That the car will be underpowered becuse of the parasitic loss through the trans? so what condition would that cause? Slower than stock? If you were just looking for a auto overdrive in a daily driver and not power what would happen? They ofered the 700 with a 2.2 in the s-10. not fast but very drivable as a daily driver.

also any measurements for a auto flywheel?

Russ

[oldopelguy]

The flywheel dimension really doesn't matter, since with the way the starter is mounted on the Opel you really only have the option of running the stock Opel flexplate and having it engage correctly.

If you really wanted to bolt up a 700R4 trans to an Opel engine you would need to build a custom adapter plate to go between the engine and the trans, then some spacers to go between the flex plate and the torque converter. So far as I know no one has built such and adapter plate, so you would have to do all the measuring and such yourself and be good enough to get it all aligned correctly. And if you're going to go through all that work, why stick with a GM automatic and not swap in a smaller Miata or 240SX one?

The stock Opel trans was transformed into an overdrive unit later in life, and the overdrive portion of the trans is a small extension that bolts in between the bell housing and the main body of the trans. I have been working off and on for a while now to get the unit installed into an Opel trans but haven't been able to find the time to get it much past the taking everything all apart stage. Keeping in mind that the new longer transmission wouldn't line up with any of the mounting ears and probably won't fit under the tunnel, there's not a lot of good reasons to pursue it.

If you're driving a Manta of GT with an auto and it's just bumming you out at highway speeds, you might want to consider the 3.18 Kadett auto rear end gears. The torque converter allows for enough multiplication to let it take off reasonably well but you can keep your rpms down a bit on the highway.

[RallyBob]

Originally Posted by Barrmust so when you say that the 1.9 ect wont have the power to run the trans, what exactly o you mean? That the car will be underpowered becuse of the parasitic loss through the trans?

I think the speculation is that a stock (or even warmed over) 1.9 Opel engine couldn't pull the gearing. While first gear is lower with the 700R4 (3.06 as I recall, compared to 2.45 for a Trimatic), the overdrive 4th is .70, giving an effective final drive of 2.408 in 4th gear (with stock 3.44 rear axle). 67 mph would be 2200 rpms....fine for a V6 or V8 or maybe a breathed-on 2.4, but a 1.9 would struggle.

I don't think the driveline losses would be too bad, the 700R4 is fairly efficient, and if you use the Opel converter you won't have as much fluid inertia to spin up.

But I'd want to put 4.22 gears or something similar into any car running that much of an overdrive.

[Barrmust]

I have a 70 gt 4 speed. it has a 73 engine in it so lower compression/lower HP. I was wondering about the diameter of the flywheel so it would give me some idea on converter diameters. I realize that i would need to use a stock flex plate.

My wife would really like for the car to have a auto instead of the 4 speed. I think that if i am going to go to the trouble to convert it i would like to put a 4 speed OD trans in it.

Fabing up an adapter is quite doable for me. I was wondering about a 700 becuse i have a few and was a gm trans tech so putting one together is not a problem.

If i am correct does the 70 gt 4 speed have a stiffer gear than 3.44? this would put the rpm higher than with the 3.4 ratio and MAY help withthe .70 OD.

Am i correct in assuming that there is not enough room in the GT trans tunnel for the size of the 700? So something smaller in size with a OD would be a better choice? any GM / non computer controled suggestions?

Russ

[RallyBob]

Originally Posted by Barrmust If i am correct does the 70 gt 4 speed have a stiffer gear than 3.44? this would put the rpm higher than with the 3.4 ratio and MAY help with the .70 OD.

Hi Russ. All the GT's had the same ratio in the US...3.44.

Some Kadett's had 3.18's, some had 3.67's.

Some Manta's could be had with the 3.67's.

But for the most part, probably 90-95% of all the US Opels (with 1.9) had 3.44's.

Just as an example, a stock 1.9 engine has trouble pulling a 3.44 rear axle ratio up hillls with a Getrag 5-speed and .805 5th gear ratio. And of course that application has less driveline loss since it's a manual trans.

Opel converters are 9", BTW. I have one in my car I'm dropping off to get reworked tomorrow (higher stall speed), so it was easy to take a tape measure to it!

[bello]

Originally Posted by oldopelguy Next is the Opel R25, a 5-speed used for a few years in Europe and hardly ever seen in the US. It's shorter overall than the Opel auto trans, but very tall and wide. It also requires the remote shifter like the Getrag and uses a Guibo instead of a front u-joint. Source the driveshaft to mate to it with the trans or get one from a BMW or Caddy Catera here in the US.

Hello Old Opel Guy- This is Ernie- Another old Opel guy! I have been trying for 2 years to figure out what brand/who makes the R25 transmission. Could you kindly tell me the brand of that gearbox? Getrag? ZF? Aisin? Is it US made?Who the hell makes it? It looks like a Getrag from a BMW minus the obvious difference in the bellhousing architecture. The guys in the OpelTuners forum speak badly of the R25/R27/R28 line of trannies, but no one coul tell me what brand it is! Also, since I am asking nice, how about any numbers, codes, model numbers, anything written/printed/cast on the gearbox would be appreciated! Some of the ZF gearboxes on BMW's have the gear ratios lightly printed (like a VIN)on the driver's side of the body. Thanks for your help! Ernie Bello

[tekenaar]

. . . . assuming the 4 "side bolts", right?

On the AOD auto question, what about the 200-4R with Chevy/BOP bolt pattern, 2.78 first/0.67 OD and lock-up converter?

[oldopelguy]

Originally Posted by tekenaar . . . . assuming the 4 "side bolts", right? On the AOD auto question, what about the 200-4R with Chevy/BOP bolt pattern, 2.78 first/0.67 OD and lock-up converter?

Correct, the top two center bolts on the Chevette engine are 1/2" or so lower than the ones on the Opel.

The 200R4 is shorter than the 700R4, and it's main body is overall smaller, but the width of the bell-housing on any of the v-8 transmissions is wide enough to preclude fitting in the tunnel of any Opel. I assumed the 700R4 used would be the 2.8L v-6/ 4-cylinder one with the much narrower bell-housing.

[tekenaar]

Originally Posted by RallyBob . . . Some Kadett's had 3.18's, some had 3.67's. Opel converters are 9", BTW. I have one in my car I'm dropping off to get reworked tomorrow (higher stall speed), so it was easy to take a tape measure to it!

Hmmm, interesting . . . ever looked into having the Opel converter reworked with a "mechanical lockup", Bob? Would you perhaps ask them if that's possible?

Just the "lockup" function with standard everything else should give 5-10% better mileage, currently a bit over 22MPG, by eliminating "slip" entirely, I would think. It would definitely be worth it in my sprint Kadett, methinks!

[RallyBob]

Originally Posted by oldopelguy Correct, the top two center bolts on the Chevette engine are 1/2" or so lower than the ones on the Opel. The 200R4 is shorter than the 700R4, and it's main body is overall smaller, but the width of the bell-housing on any of the v-8 transmissions is wide enough to preclude fitting in the tunnel of any Opel. I assumed the 700R4 used would be the 2.8L v-6/ 4-cylinder one with the much narrower bell-housing.

I have one of these 700R4's from a 2.8 Chevy. The bellhousing flange is within 1/4" of the diameter of the Opel's. I was going to mill 3/4" off the 700's bellhousing flange, then cut the same amount from an Opel 4-speed bellhousing ( I have lots of spares), then weld them together, keeping the input shaft in the same relative location. I already test fitted the Opel converter into the 700R4's pump....it fits. The 700R4 from an S-10 2.8 is almost exactly 4" longer than the TH-180. Dimensionally, it'll fit a Manta/Ascona no problem. Never checked a GT however.