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Transmission suggestions?

3K views 22 replies 11 participants last post by  Flloyd 
#1 · (Edited)
Been working on restoring a 73 GT for awhile now and its nearing that glorious moment of getting her back on the road, only problem is her Manuel transmission...i know I'm wierd but id much rather have an auto

However....

I'm willing to spend a little more time and money and put in some additional work for something a little out of the ordinary that would maybe be a better fit for me and\or give me a little more performance although this will b a daily driver

Iv been reading thru the "wierd transmission swap options" thread from 09 but ill b honest alot of it is over my head I'm not much of a car guy type just really into the Opels and wanting mine on the road again

A friend of mine at work also suggested dual clutch trans and\or paddle shifter but my research has started to show me that's not a possible viable option

So...any suggestions? Tell me what u think or what u think would fit what I'm looking for
Chevette t5? Or should I just stick with the stock auto?
 
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#2 ·
FWIW, I would stick with a stock auto.

Although it's been many years since I've driven a GT with a stock auto, my Manta and a customer's GT had them. I was NOT disappointed with the auto.
The Manta, being my car, was put through the paces a number of times. It never even thought of being a problem.
The customer's GT was also not a problem, other than the pan leak it had when I first started working on it.
Both has good response, good shift points, good snap when power shifting and good top end speed.

If you go with a stock auto, you might as well replace the clutch pack while you have it out. The clutch packs can get a little dodgy on any auto tranny if they sit for 20 years.

Plus, the upside of the stock auto is availability of off-the-shelf fitting. You will save a LOT of money and time over going with something a little different.
 
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#4 ·
Thanks so much for the quick responses but it leads me to my next question...what all would I need if I decided to go stock auto?...I've been told the conversation is easy and i saw someone selling a conversation kit for $500 but there wasn't a list of what that kit included could anyone give me a complete lost of exactly part by part what is needed to convert to stock auto
 
#6 ·
I see Ubernoob has beat me but I'm leaving mine here as well.

I will do my best to list them all. Starting at the front of the car and working backwards.

Drivetrain...
Radiator. Either an auto radiator or a separate small radiator for cooling auto transmissions.
Vacuum line for kickdown solenoid. Or throttle cable assembly. I can't remember which.
Spacer for crankshaft.
Flex plate.
Proper length bolts for the pressure plate and spacer.
Torque converter.
(possibly) Reinforcement brackets between engine and transmission.
Transmission.
Fluid cooling lines.
Automatic transmission mount.
Automatic transmission driveline.


Interior...
(optional) Automatic Transmission pedal assembly. *The brake pedal is bigger
Gear selector.
Noise reducing boot (goes between the gear selector and the transmission linkage)
Wire going from dash lights to gear selector console.

If not already on the transmission you would need a reverse light indicator and a speedo gear.

I think that's it but I could be wrong.

The rest of the parts should come from the standard transmission installation (for instance U-joint connection hardware)
 
#5 ·
I'm quoting the ad I believe you talked about, it includes:

Automatic transmission with torque 74672mi (GM Turbo-Hydromatic 180)

Automatic Transmission Drive Shaft with very nice yoke and Thrust Spring (short GT length)

Automatic Transmission Rubber Mount and 2x (13mm head) nuts

Automatic Transmission Mount Bracket (shorter than the 4 speed)

Automatic Transmission Flex Plate (with all teeth intact and undamaged)

Flex Plate Bolts 3x 15mm (to the Torque Converter)

Automatic Transmission Shifter with Neutral Safety switch and linkage

Automatic Transmission Interior Plastic Shifter Console with PRND21 Plate

Automatic Transmission Metal pipe for fluid (from and too the transmission)

Automatic Transmission Radiator after market

Intake Manifold port fitting, with extra vacuum outlet, for A/T vacuum hose

Detent Cable (a.k.a "kickdown" cable)

Detent Cable bracket on engine cross-member (near accelerator pedal)

Automatic Transmission Brake Pedal (wider than 4 speed pedal) and cover Pedal Bolt (shorter than 4 speed bolt)

Automatic Transmission Wire Harness (from neutral safety switch to starter)

Automatic Transmission Throttle Linkage (has external spring near pedal)

Original gauge showing 74672mi. W=1062

Oil dip stick

Miscellaneous bolts and nuts included.
 
#7 ·
Awesome thanks again for the speedy responses I think stock auto is the direction I will go especially after reading First Opel talk it up so well now I just gotta start searching and gathering up all those parts listed for the conversation...

Thanks again guys :)
 
#8 ·
I've had autos, or junked the 4sp and converted to auto, in my GT's since the late 80's. It's almost impossible to break them or wear them out.

I'd go with a seperate tranny cooler: The engine will run cooler and it's much easier to find non-auto radiators. Forget the kick down cable that's attached to the throttle linkage, it's pointless and causes problems if you have a Weber, which requires more throttle movement than a Solex. If your car is properly set up, the tranny will downshift on it's own when you floor it.
 
#16 ·
Forget the kick down cable that's attached to the throttle linkage, it's pointless and causes problems if you have a Weber, which requires more throttle movement than a Solex. If your car is properly set up, the tranny will downshift on it's own when you floor it.
I just don't understand why Opel went to all that trouble adding the spring loaded rod just after the accelerator pedal and that annoying useless kick down cable. Look at the money they could have saved. :thinking:

Harold
 
#10 ·
I have one sitting in my garage you can have, but I am in PA and the condition is unknown as it was going to be thrown away, but I saved it. I have no use for it. If you can figure a way to get it to your location, it is yours.

Someone would need to tell me how to tell if it is for a GT. I know the shifter linkage side is specific for the GT.
 
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#11 ·
The shifter linkage is on the passenger side of a GT tranny. I'm pretty sure that it's on the driver's side on all the other models.


The best way to go Fffllloid is to find a junk GT with an auto. The drive shafts are getting tough to come by because guys need those for the Getrag conversions. The GT auto trannies have a specific fill tube. The rubber mounts are usually shot after 40 years, but now there are heavy duty ones you can buy from our parts suppliers. The flex plate/flywheel for them requires a stepped washer that spaces the flex plate about 3/16" away from the engine. Without it the flex plate with bind against the engine. Usually the washer stays stuck to the flex plate.

Guys, correct me if I'm wrong, but I think that the crossmember that supports the tranny is the same as the one for the 4sp, it just gets mounted about 4"-6" farther back(You'll find the holes already in the frame rails, usually with plastic plugs in them. So you should be able to re-use your 4sp's crossmember and just need to buy a nice new rubber mount.

I don't think that you can get the specific to a GT coolant lines. Usually when you acquire a used GT auto tranny, the coolant lines are still attached, but they're often bent or screwed up. Or they forgot to remove the adapters that mount them to a stock GT auto trans radiator. This is another reason for just buying a cheapie after market tranny cooler, rather than trying to find an auto tranny GT radiator. I chop the radiator ends off of the oem metal coolant lines, flare them a bit, and attach rubber tranny hoses and run them to a tranny cooler that I mount somewhere in front of the radiator.

Pics in the next post.......
 
#12 ·
Pics showing auto trans with extended rubber coolant lines and trans cooler:

Wire Electrical wiring Auto part Gas
Wire Tire Automotive tire Electrical wiring Vehicle


A cleaned and painted auto trans:



Flex plate and torque converter mounted to trans and showing the spacer washer:

Auto part Tire Automotive wheel system Wheel Automotive tire


Torque converter and flex plate mounted to an engine:

Auto part


GT auto trans driveshaft measuring 9 1/2 inches center to center of both universal joints:

Auto part


GT auto trans fill tubes:

Wire Electrical wiring


A painted GT auto trans radiator:

Radiator Auto part Gas Cylinder Vehicle


My spare auto trannies and custom high stall torque converter:

Vehicle
 
#13 ·
Pics showing auto trans with extended rubber coolant lines and trans cooler:

View attachment 170482 View attachment 170490

A cleaned and painted auto trans:

View attachment 170498

Flex plate and torque converter mounted to trans and showing the spacer washer:

View attachment 170506

Torque converter and flex plate mounted to an engine:

View attachment 170546

GT auto trans driveshaft measuring 9 1/2 inches center to center of both universal joints:

View attachment 170514

GT auto trans fill tubes:

View attachment 170522

A painted GT auto trans radiator:

View attachment 170530

My spare auto trannies and custom high stall torque converter:

View attachment 170538
Oooh! Cool thread. I've never seen the auto transmission before. That sucker is a lot bigger than the tiny four speed! That drive shaft is tiny! They should have just made the auto a little longer and it wouldn't even need a drive shaft haha!
Did the auto trannies have any particular problems? How does the auto effect engine cooling, vibration, performance, etc?
Just curious! I'll always choose a four speed though:)
 
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#14 ·
The Opel auto trannies are Chevy TurboHydramatic 180's. Many cars had them, I think even some 8 cylinder cars had'em. They're tough enough for an 8-cyl, so they can handle anything that an ole Opel 4 banger can throw at them.

But, they're pretty primitive in how they control the shifting. Vacuum, load, and rpm makes them shift. I don't know much more about them, maybe Wrench or someone can fill us in on the high and low tech features of the TH180.

Performance-wise, Dan claims I'm losing something like 15% of my horse puppies to tranny slip.

:veryhappy
 
#15 ·
The Opel auto trannies are Chevy TurboHydramatic 180's. Many cars had them, I think even some 8 cylinder cars had'em. They're tough enough for an 8-cyl, so they can handle anything that an ole Opel 4 banger can throw at them.
....
GM is still using the same basic design with the six speed auto's :cussing:
 
#19 ·
He is certainly the go to auto guy.

Believe it or not I'd love to one day drive an auto opel.
 
#20 ·
It is worth repeating in this thread that while the Opel driveshaft yokes for the auto (and Getrags) have the same diameter and number of splines as the GM ones, they are not compatible.

The Opel auto and Getrags tranny output shaft has a chamfer on the spline edges. The GM yokes do not. So while the GM yoke will fit, it will bind on the tranny shaft.
 
#21 ·
So what ur saying Gary is that the GM Th180 is not the same as the stock auto originally put in the opels?

And yes scifi guy IV somehow acquired one of those...not sure where or how but I have one along with the shifter that comes up thru it
 
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