Does anyone know why GM used two different transmission bolt spacings?

Couldn't they have saved a ton of money over the long haul and offer all their trannys with the same?

 

They probably could have except Chevrolet wouldn't standardize! I mean, after all, Buick-Olds-Pontiac-Cadillac all used the same bolt pattern...

 

They used many more than that. I'm guessing you are thinking specifically about one housing in particular? What years? Far too general a question.

 

They could have saved a whole lot of money by not having five divisions with their own V8s, but we wouldn't them to all have the same engines, now would we?

Post WWII GM was one of the largest and most profitable companies in the world, but they sure didn't get there through doing things the most efficient way possible.

 

Hey guys thanks for your input.

Rocketraider: I all ways thought it had to do with Chevy pride from within.

 

I have often wondered the same thing! Or God forbid, use one of the few good ideas ford had and used removable bellhousings! Its only withing the last 10-15 years GM and Chrysler have started doing that.

 

There is probably more than a little truth to that. Seems to me the chebby engineers have always had a bit of a chip on their shoulders! Remember the huge fit chebby top brass had when the Grand National cleaned their clocks? Or GM wouldnt allow multiple carburetors on anything EXCEPT the Corvette after model year 67?

 

Actually Matt, they did use removable bellhousings on HydraMatics. Olds, Pontiac and Caddy all had different engine-to-trans bolt patterns back then and they also sold the HMT to everyone who wanted it, so those carmakers' engines had different patterns too. Each engine family had its own bellhousing (adapter, technically) to mate the HM to the engine.

Turbo HydraMatic came along and Olds designed their new-for-65 engine with use of the 62-later Pontiac bellhousing bolt pattern in mind. Cadillacs and Nailhead Buicks continued with the round top case on THM. Caddy designed their 429 engine to use the Pontiac pattern and when Buick designed the 340-430 series engines, they did too.

I'm bound to think they could have saved money by using a bellhousing adapter for each engine rather than have two bolt patterns, but GM was GM and didn't care about minutiae like that.