Hi people,
might need to do a swapout of the DG 250 trans for possibly a GM 700 R4. This seems to be a relatively straightforward change. Known as a Quarterbreed upgrade in the States using a John’s Cars adaptor plate and various bits. Wonder if anyone has had this experience. Gear ratios seem better and the OD unit means quieter and more economic cruising revs.

 

Nothing useful to offer here, other than the fact that the worst thing about my Mark IX is the 3 speed tranny that makes that poor 3.8 spin feverishly to stay above 60 MPH. I mean, the steering isn't great, and all that weight on tall-sidewall bias-ply tires makes steering a real competitive sport. But the worst thing is the tranny.

I'm already so over-extended into this car that I'm loathe to spend another $4K (or more) to swap out the DG250, but it's certainly something to consider. I'm really interested to see if you move forward on the endeavor.

Good luck,
Doug

 

Just for sport, I called my buddy / mechanic to see if he had done one of these before. He hadn't done one himself, but he has an XJC where the old 3-speed was replaced with a GM 700 R4, and he said the difference is night and day. Aside from the adaptor plate and the tranny itself, he noted the following:
- Shifting will be obviously different from the PNDLR sequence that's on the DG 250
- Drive shaft needs to be adjusted (length and slip yolk)
- Mounts probably need adjustment
- Speedo adjustment

Might have been a few other bits that he rattled off. He figured install would be somewhere pretty close to $2K.

 

There is talk, John's Cars is retiring, so get one quick.

Rob

 

thanks Rob. Onto it.

 

Graham Whitehouse offers an alternative to John's. It's a ZF 4 speed. It's probably more expensive as he swaps the bell housing rather than use an adapter plate.