bspvette

I'm looking to install a Powerglide in my early C4 in place of the original 700R4. One obvious problem is figuring out a way to attach the C-Beam to the tail housing of the transmission. I'm pretty sure I could find a way to fabricate some kind of bracket system, but would rather not reinvent the wheel here.

Is there somebody who offers a retrofit tail housing for the Powerglide that bolts up to the C-Beam?

Or as an alternate idea, has anybody already designed a bracket for the powerglide, like those I've seen for running a T56 in a C4?

This is for an AutoX car which doesn't need more than 2 gears. Weight savings is the big goal here.

Thanks,
BeerMan

red L98

That's a negative.. need to fab a crossmember

bspvette

Fab a crossmember, rather than a bracket onto the tail housing?? Do you then have to fab a crossmember to hold the nose of the differential?

Do you know anybody who has done this, so that I can bug them for some pictures of how it was done?

WVZR-1

How do you intend to offset the ratios for the PG, best I recall aluminum were done in only 1.76 an 1.82 1st gear maybe. ATI I believe offered a couple that did high 1.90's and low 2.10's but they certainly weren't inexpensive.

What axle ratio were you intending to use?

I would think the PG choice maybe not a good one for "MOST" but who knows.

bspvette

I currently run a 4.10 gear with my 700R4 behind an LS6. I never use 1st gear. The car leaves the line very nicely in 2nd (1.63). There is no hint of any kind of bog. In fact, I can almost never even get my right foot all the way to the floor at the start. I never have to shift, even on big National courses. (It took me a long time to jump on the LSx bandwagon, but they are truly amazing motors.) I am also helped by the fact that my current weight is around 2,250lb, so it doesn't take much to get it moving.

The 1.76 1st gear in the PG is actually steeper than I want. It will put me at 75mph with a 7,200rpm redline, so I will almost surely spend time in 2nd. I've actually looked at the 1.68 gears that ATI offers, but they are WAY out of my price range.

I agree that this is a crazy set up for most, but it should work well for me.

Tom400CFI

YES. I would think that it would be easier, cheaper, and less weight to fab a C-beam adaptor for the PG tail than to start fabbing up x-members. There are a lot of advantages to the C-beam design, so I would try to make that work, first.

C409

..... I haven't checked a powerglide yet but the TH350 tailhousing has the same 4-bolt pattern as the 700R4 and with the proper spacing , it will bolt right up to a D36 C-Beam ......

93 ragtop

Quote:

Originally Posted by C409

..... I haven't checked a powerglide yet but the TH350 tailhousing has the same 4-bolt pattern as the 700R4 and with the proper spacing , it will bolt right up to a D36 C-Beam ......

I have a friend who has a turbo 350 and it has a spacer sandwiched in between the transmission and the 700r4 tailshaft.
BTW assuming this is a street car, how do you plan to hook up the speedometer? Even if its not, don't you have to have a speed signal for the LS motor's computer to see? Of course, I could be wrong on needing it for the LS.

rklessdriver

The probelm is going to be overall length.

Powerglides are 6" output shafts. Overall they are alot shorter than a 700R4 or TH400 (which are almost the same).

With TH350's there are 4 different output shaft lengths the 3.75" used in 4X4's, 6" common short shaft , 9" used in Vans and 12" common long shaft used in trucks.

To make a TH350 "bolt up" in a C4 Corvette you have to have a TH350 with the 9" output shaft... then use a spacer block between the case and the C4 specific 700R4 tail shaft housing will bolt on and the tranny will be the right length overall (same as 700R4 and TH400).

Because Powerglide output shafts are not long enough and you can't use a spacer and 700R4 tail shaft housing you'll have to build a C Beam adpater of some sort.

This thread has a few pics of C Beam adapters people have built for a TH400.

https://www.corvetteforum.com/forums...350-turbo.html

Will

project C4

TH350 with the 2" spacer and a 9" tail shaft is a nice clean "easy" install. I have a th350 and a rear exit Hurst quaterstick in the console and absolutely love the setup.

I don't know how it is done but I have a few dirt track friends here at work. They have their th350's converted to two speed by a trans guy here in town. Maybe this would be an option for you.

just a thought