Thread: GMR chain question (Maybe Dave will know?)

So, as most of you are aware there were two types of GMR chains/gears:

- 1" x 3/8" pitch: 2.93, 3.29, or 3.69 (rated at 800 hp)
- 1" x 7/16" pitch: 3.52 or 3.74 <--(I think that is correct) (rated at 1200 hp)

My question: Does the 7/16" pitch chain require any further modification? In the GMR Race Trans catalog I think they said they had to machine the stator support for clearance?

"

The O.D. of the drive sprocket support (stator support) is

cut to clear the 1

9 wide x 7/169 pitch drive sprockets.

(Fig. 137) The modified part is shown on the bottom of

Fig. 137.
"
Thanks

I have never personally seen a 7/16 pitch 1" race chain and this item is something you may never see unless you have an authentic GM Race trans from the race team. You cant use the stock reluctor wheel and have to arrange an aftermarket speed sensor pickeup when using this setup and the pics of what had to be done to accomodate this are all shown and mentioned in the GM 4T65E race trans buildup guide which can be found by doing an search on the internet. The 4T80E used a 7/16 pitch chain also and when you compare it to a 3/8 pitch chain it is a monster and is larger in every direction. To place the speed sensor like they did in the 4th acc housing area you basically are getting rid of the 4th accumulator. The race trans eliminated 4th gear so it was not a problem, but for a street car that you want 4th gear it is going to be an issue.

Thanks Dave for the response. Sent you an e-mail.