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Just Some Dude in Jersey
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Discussion Starter · #1 · (Edited)
Here begins my renewed effort to get a commonly available 4 speed automatic transmission to work in my Opel GT.

Most of you may recall my previous effort at this mod, in which I acquired an AW-71 from an Opel Monza(?). This transmission had an extension(-housing) added to the end of the tranny that provided the 4th gear, but that extra length would have caused me to have to shorten my driveshaft to about 4" long or mod the car body and torque tube or replace the whole rear drivetrain........uhhhh.........NO! I decided the challenge was too great for me to tackle at the time and I sold the tranny to Gary, who's car the tranny was a perfect fit for. Documentation of this first attempt here:

http://www.opelgt.com/forums/7b-transmission/42450-4sp-auto-tranny-older-opels.html

Much more discussion and information on the subject of alternate automatic transmissions for our Opels can be found in this thread:

http://www.opelgt.com/forums/clutch...57-4-speed-catera-automatic-transmission.html


Okay, so, this time around I'm going to pursue the idea of installing a commonly available Chevy TH700R-4 transmission. RallyBob had mentioned his interest in modding one to work in previous threads, so I asked him to give me some details to get my ball rolling:

RallyBob said:
The Scifi Guy said:
Hey Bob, could you give me the specifics about the 4sp auto tranny that you were contemplating modding to work on an Opel? Maybe I could get one and work with machine shops or other Opelers to get the mod accomplished.

I need to know the type and maybe the model years that would work and maybe what cars had them.
I got my TH700R-4 from a Chevy S10 with the 2.8 V6. Other V6's or V8's are totally different.

You will need to machine the bellhousing and weld on an Opel bellhousing flange. You will need to have a custom torque converter made that fits the Opel flexplate and mates to the TH700R4 pump spline. You will need an aftermarket electronic converter lockup switch. You will need a custom driveshaft and tranny mount. You will need an aftermarket cable type 4 speed shifter.

I have NO idea if it fits into a GT transmission tunnel. I haven't checked.

Soooo.....Step One: Will it fit?

The length was the deal breaker on the AW71. Plus, it needed some external electronic control. I have not seen mentioned that the TH700, does. Here's some tranny lengths:

Automatic Trans Dimensions

The TH700 is 23.75" long. The Opel TH180 isn't listed. This is another problem with the darn 180's. There's very little mention of them, very little tech/mod support, or info in general. They don't seem to be part of the discussion these days and mods are seldom mentioned. So I fetched a tape measure and roughly measured the length of a spare TH180 in my basement. About 27.5"! Roughly the same as the TH700's!

HOORAY!

THAT, my friends, is HUGE in my regard. It's likely that the only mod to the car itself would involve the likely expansion of part of the tunnel. I have a custom dash that I can modify at will. Not only do I no longer have the headlight flip handle assembly on the tunnel, but I also don't have the parking brake handle. It's just a sheet metal half-pipe that I can mod as needed. I haven't found any width measurements yet, but there's some local tranny and repair shops that might have a TH700 for me to borrow or measure, then compare with my trannies and car. I guess the smallest bellhousing they came with was on 6-cyl applications?

The next biggee is investigating the flange and torque converter mods.


I'm open to other ideas, I'm not locked in to this one tranny choice. It does seem to be a good candidate though, there's lots of support and products and performance builds of them offered. Some write-ups have a high regard for these trannies. I may even get lucky and find a place that will do the flange/TC modding.


Comments and corrections welcome.......
 

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Here begins my renewed effort to get a commonly available 4 speed automatic transmission to work in my Opel GT.



The length was the deal breaker on the AW71. Plus, it needed some external electronic control. I have not seen mentioned that the TH700, does. Here's some tranny lengths:

The next biggee is investigating the flange and torque converter mods.


I'm open to other ideas, I'm not locked in to this one tranny choice. It does seem to be a good candidate though, there's lots of support and products and performance builds of them offered. Some write-ups have a high regard for these trannies. I may even get lucky and find a place that will do the flange/TC modding.


Comments and corrections welcome.......
Gordo, I have used the B&M lockup controller as well as a complete B&M performance Th700 before with great results behind SBCs in a 63 Vette and 67 Impala. While I can't say how it compares to a TH180, IIRC the TH700 is significantly wider at the pan than a Powerglide and required some very tight bends in the exhaust to get them to line up with holes in the frame of the Vette.

Category List - B&M Transmissions, Shifters, Torque Converters, Diff Covers, Coolers
 

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Opel Tinkerer and Rescuer
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Not sure if anyone has tried.. BUT its POSSIBLE the TH180 and the 700R4 share the same spline and thus the Torque Converter from the TH180 MAY work.

The reason I mention this is the TH350 and the TH180 share splnes.. to the point racers used out Torque Convertor on their drag 350 transmissions.

Best bet is to get one and find out :

https://www.ebay.com/itm/88-93-700R...ash=item43eeca120b:g:-xkAAOSwEOxXPx4V&vxp=mtr
 

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This shaft will not work because there is an o-ring on the end of the shaft and the shaft is hollow for the converter clutch apply signal. If you did not want the converter lock-up ( 10 to maybe 20% fuel improvement) and just take advantage of the overdrive gearing, you could just not use the lockup. You will also have the advantage of the variable displacement transmission oil pump (saves HP draw and fuel). HTH
John
 
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Gordo, the TH700 is 4" longer than the TH180. I've lined them up side by side.









 

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Just Some Dude in Jersey
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Discussion Starter · #6 ·
Thanks for the input guys.

I can work with a 4" length difference.

I went to the tranny shop and they had an older 700 on the shelf with the small bell housing. The width measurement is what I was after and both the 180 and the 700 have 13" wide pans, but as Bob's pics show, the 700 has a longer (front to rear), more rectangular, pan that extends back farther.

I spent a while talking to the owner and another guy who worked there and also used to have his own shop for many decades about possible other tranny's that might work. The 4L30 and the Ford A4LD. The Ford was very narrow and supposedly the bell housings are not integrated into the oil passageways and are removable/swapable without affecting the function of the tranny in any way. This would make modifying or acquiring bell housings that would be a close match for Opel engines a lot easier. I notice from Bob's pics that the 700's bell housing is an all one-piece casting with the body of the tranny. This would make the machining more cumbersome.

The former owner guy suggested a top tranny mod company called Advanced Adapters as a go-to place to maybe get some of the adapting done. Another suggestion was a company called Rockland Standard Gear.


That's what I've got so far....
 

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Über Genius
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Thanks for the input guys.

I can work with a 4" length difference.

I went to the tranny shop and they had an older 700 on the shelf with the small bell housing. The width measurement is what I was after and both the 180 and the 700 have 13" wide pans, but as Bob's pics show, the 700 has a longer (front to rear), more rectangular, pan that extends back farther.

I spent a while talking to the owner and another guy who worked there and also used to have his own shop for many decades about possible other tranny's that might work. The 4L30 and the Ford A4LD. The Ford was very narrow and supposedly the bell housings are not integrated into the oil passageways and are removable/swapable without affecting the function of the tranny in any way. This would make modifying or acquiring bell housings that would be a close match for Opel engines a lot easier. I notice from Bob's pics that the 700's bell housing is an all one-piece casting with the body of the tranny. This would make the machining more cumbersome.

The former owner guy suggested a top tranny mod company called Advanced Adapters as a go-to place to maybe get some of the adapting done. Another suggestion was a company called Rockland Standard Gear.


That's what I've got so far....
If the adapter isn't much more complicated than the T5 adapter then it could probably be done by someone in the community. Problem is getting the transmission and other components in the hands of someone that can do the measuring and cad file.
 

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Just Some Dude in Jersey
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Discussion Starter · #10 ·
The Toyota 30-40LE looks like it might be a possibility. Found behind a turbo 6 cylinder, it should handle whatever an Opel 4 cylinder can dish out. Not sure about the length.

https://www.ebay.com/itm/87-92-Toyo...988401&hash=item2f0596ed95:g:0S0AAOSw6ShZREMg

Y'see all those wires coming out of the tranny? That's why we're limited in our choices of trannies: Our "dumb" cars need the tranny to shift by itself mechanically, without outside electronic control from an ECU or something.



Yeah, that pan's mighty wide at the back and may require exhaust pipe modification for clearance.
 

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Oh come on Gordo

The shift solenoids is fairly simple game.

SS1 on SS2 off 1st gear.

Second gear SS1 off SS2 on.

3rd SS1 off SS2 off.

Overdrive SS1 off SS2 on.

Two toggle switches can handle this.

You know that their is four speed auto trans that can shift purely via valve pressure within the valve body.:lmao:
 

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As far as the pressure control solenoid goes... just unplug it.

That way it'll bark the tires when shifting.
 

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Y'see all those wires coming out of the tranny? That's why we're limited in our choices of trannies: Our "dumb" cars need the tranny to shift by itself mechanically, without outside electronic control from an ECU or something.



Yeah, that pan's mighty wide at the back and may require exhaust pipe modification for clearance.
There are controllers for auto trannies, this is one.

https://www.diyautotune.com/product/microsquirt-can-transmission-controller-4l80e-subharness/

It is for GM but might be adaptable with different connectors. Worth checking out.
 

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Über Genius
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Keep in mind that a 4 speed transmission is only going to be a benefit if the gear ratio works out in the favor of the Opel differential.
 

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Gordo, I don't know if this is of any value to you, but it might help comparing GM transmissions.

http://www.crankshaftcoalition.com/wiki/General_Motors_transmissions#General_Identification

The 700R4 was later called a 4L60, but in your earlier post you called out a 4L30. I can't say that I have ever heard of that one and neither has Wikipedia. All the 4L30s they show were 4L30E which require the computer to shift. Do you have a mechanical version lined up?

Gordo, get this done quickly as I want to do it but will wait for you to figure it out! :yup:


Wrench, if the solenoid issue is so easy, why did YOU screw it up? See if you can find your error! :lmao:
The shift solenoids is fairly simple game.

"SS1 on SS2 off 1st gear.

Second gear SS1 off SS2 on.

3rd SS1 off SS2 off.

Overdrive SS1 off SS2 on.

Two toggle switches can handle this."

Doug
 

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Just Some Dude in Jersey
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Discussion Starter · #18 ·
I think the oil pan size on the 700 and the likelihood of it hitting the exhaust might be a deal breaker. Yeah, I could alter the exhaust to dodge it, but I'd rather not. I'm going to stop by the shop again and ask them to take the tranny down off the shelf so that I can trace it's "footprint" onto a hunk of cardboard. I'll cut out the outline of the tranny and hold it up under the car to see how much area it's going to take up.

I've also sent an inquiry to Advanced Adapters, mentioning the 3 trannies I'm considering.
 

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I spent a while talking to the owner and another guy who worked there and also used to have his own shop for many decades about possible other tranny's that might work. The 4L30 and the Ford A4LD. The Ford was very narrow and supposedly the bell housings are not integrated into the oil passageways and are removable/swapable without affecting the function of the tranny in any way. This would make modifying or acquiring bell housings that would be a close match for Opel engines a lot easier. I notice from Bob's pics that the 700's bell housing is an all one-piece casting with the body of the tranny. This would make the machining more cumbersome.
Gordo, FWIW the Ford A4LD does in fact have a removable and swappable bell housing. I swapped the one I have to work with the Lima 2.3 I4 motor that I have. The only issue that I see with trying to run it in a GT is that it's partially electronically controlled where it has its own computer in the pcm to lock the tq converter and control overdrive. The computer is used for 3rd and 4th gears but does not touch 1st, 2nd, or reverse and goes through the speed sensor and another wire if memory serves me right. So you'll end up needing to swap a computer in that has the parameters for it or possibly create a closed loop system. I've heard talk about making it manually operated but I've never actually seen a write up. The messages I see say some guy has x with that done and I think they did it this way.

I have it sitting out of the car if you'd like some measurements just let me know.

Also I'm not sure what gearing the Opel trans has but the Ford is:
2.47:1 1st gear
1.47:1 2nd gear
1.00:1 3rd gear
0.75:1 4th gear
2.1:1 reverse
 

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On the dyno we would lock the trans into third gear, full TCC 1:1.
Once done reverse the process
 
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