Changing Transmissions

[whitelion]

I have a 69 that came with a factory automatic in it, when we took it out of car the bell housing was cracked. I'm not sure if tig welding will hold up of if there is some other reason for the crack. I have a 72 for a parts car with a 4 speed in it. So what problems am I going to run in to making the 69 into a 4 speed of is it not a good Ideal, and another thought on the 4 speed girlfriend can't drive a 4 speed
Thanks for any Info

[jordan]

I have no Idea why the bellhousing on the automatic is cracked, other than a lot of water freezing in it some how I don't see how it could happen in service. Welding it is a possibility, but we would have to see a picture to sort of tell if it can be done and hold up. Changing an automatic to standard in a (GT I assume) is not that big of a deal. Basically you need a 4 speed transmission, bellhousing, manual flywheel, clutch, clutch cable and cable provisions, clutch pedal, and driveshaft. After you have all of that it is pretty straight forward if you are used to this car stuff, only thing that will have to be welded is the clutch cable attachment point on the driverside firewall. If you have a different model like a manta, it's a little more involved.

[David McCollam]

Recently, I had a chance to experience your problem. Mine was the result of poor handling by a shop installing the transmission after a rear main seal swap. They forced the transmission instead of carefully installing it. The end product was shearing of the mount flange on the right side of the housing (bell housing).

All of this ended up jamming up the pump gears, which in turn cause the gears to break and the torque converter to be damaged. I had to impose on a friend to get another housing. A month later the transmission was back together, new pump, gears, torque converter, bearing sleeve and seal.

You cannot be sure wleding that cover. They usually don't just crack. Unless something hit it and it was fine before you took it out, I'd have it checked out by a transmission shop. That was my first mistake. I used a shop where good intentions got overridden by mishandling. Everything worked out fine in the end, but they learned an expensive lesson.

Good luck,

Dave

[guyopel]

You could just replace the bellhousing.Be sure to have the trans. upright to install the replacement bellhousing
to keep front pump aligned . HTH

[hrcollinsjr]

Not a problem to change over to the 4 speed since you have the donor car. It will cost you a litttle bit though. Unless you know the condition of the clutch I would replace that during the change over. Unless the '69 is different from the other's no welding is required just swapping parts! You will need to purchase a pilot bearing for the crankshaft for the tranny input shaft to fit into.

You will gain a slight performance advantage with the 4 speed and the possibility for more mpg.

HTH,
Harold

[opelwasp]

Keep the auto driveshaft though. You'll need it when you eventually switch to a 5 speed.

[opelnut10]

It was not mentioned that you will have to hang the stick shift pedals in the car and cut out the clutch cable bracket from the fire wall of the stick shift and cut, fit and weld it onto the the firewall of the automatic car, also you will have to put a pilot bearing in the crank flange for the input shaft to turn in.

[whitelion]

Thanks Everyone for the information it looks like I'm going with the standard. The switch over doesn't seem to be too much trouble to do and seeing as I have everything removed already in the 69 the cost of doing this should be very little. I've seen where an S -10 clutch is used what the difertance between that and the and factory clutch.

[hrcollinsjr]

Originally Posted by opelnut10 ...cut out the clutch cable bracket from the fire wall of the stick shift and cut, fit and weld it onto the the firewall of the automatic car, ...

ALL of the GT's that I've worked with have the hole already there, no cutting or welding required. The job can be done with simple hand tools!

You will need to use the speedo out of the donor car.

Harold

[opelnut10]

Originally Posted by hrcollinsjr ALL of the GT's that I've worked with have the hole already there, no cutting or welding required. The job can be done with simple hand tools! You will need to use the speedo out of the donor car. Harold

You are right Harold, the Manta and Ascona are the ones you have to graft the clutch cable holder to the firewall and change out the transmission tunnel. Had another senior moment

[SoCalOpelGT]

Don't overlook, you will have to rewire the
loom (to the neutral safety start switch),
and wire the reverse light too.

Also:

Do a fresh turn on whatever flywheel
you have, prior to installation.

Acquire the front bellhousing gasket,
and inspect and consider replacement
on the other gaskets and seals on the
manual transmission.

A complete list of ALL the parts required to
be swapped over (both from auto trans to
manual, and from manual to auto trans,
is in the March 1995 OMC Blitz).

[opelbits]

To add to SoCal....
Replace the side seals on the manual trans. There is info available on replacing the side seal that looks impossible (grind off a weld, drill and tap for a bolt. It'll take longer to find the info that it will to actually do it).
It may be easier to drop the engine/trans as a unit than fight trying to snake one trans out and the other in AND change the flexplate to a flywheel. This partly because to get enough angle to remove/install either trans with bellhousing attached, you have to remove the radiator and fan shroud (which means draining the coolant, removing the houses, etc....).

[hrcollinsjr]

Originally Posted by opelbits To add to SoCal.... Replace the side seals on the manual trans. There is info available on replacing the side seal that looks impossible (grind off a weld, drill and tap for a bolt. It'll take longer to find the info that it will to actually do it).

Opelspyder did this in his restoration thread. I don't recall how much detail he went into but he probably had pictures of it as well.

HTH,
Harold

[opelbits]

I know OGTS has a flyer that explains it, but I wasn't sure if there was a write up online. It's sooo easy to do, but it can't be done with the trans in the car....depending on how rusty the car is. Then again, if it's rusty enough to do that job, you probably ought not to drive it...

[SoCalOpelGT]

The manual transmission shifter seal replacement
tech tip, is also in the March 1995 issue of the
OMC Blitz.

Index to other Opel transmission/clutch tech tips:
Drive Line