Technical > Dan Dishon's Transmission Den

Stock Case vs Aftermarket

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jspell:
Hey Dan,
At what point do you recommend an aftermarket powerglide case. I currently have a stock case 1.76 full length glide with upgraded internals with transbrake.  My dragster weighs 1450 with me in it, the small block chevy made 725hp on the engine dyno.  Should a stock case work?

Thanks,

bikeguy307:
Good Question.

The most common problem we see with a stock case is bell housing cracking, this happens mostly in door cars. With the info you gave I would say you should be fine with a stock case. I have seen stock cases in some of our Div3 super quick cars, and they seem to work fine. If someone is starting to run faster than 4.50 most trans builders (myself included ) run more line pressure to insure good clamping force of the clutches and band, This will result case flex in low gear as the band apply piston tries to push the adjuster out of the case. I guess if I had to draw a line in the sand it would be around the 850hp range. I personally run them in both my cars, and recommend them on all new builds. If you were thinking of making the switch do it when your current shields go out of date, this makes the actual cost of the case less because you would be replacing or re-certing your shields.

Thanks for asking,
Dan

Paul New:
I don't know the answer to this but I ran a stock cased glide in my car up until I changed over to a pedal clutch and B&J. I ran 6.50-6.70's and up to 211mph I ran these numbers for years

PSweeney:
depends on how much flex there is in your chassis.  The case will fail if the case becomes the stressed member.   I'd say as a general rule anything much over 550bhp would benefit from a Reid case.  In a dragster that'll be low 9's and 1.2 60 ft's @ 5700-6000 launch so you'll be hitting it hard anyway.

bikeguy307:
Well there is no doubt the stock powerglide case has far exceeded it's design standards. We have beat on them for years and they take it for the most part, not bad for something designed for 170 hp!

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