Technical > Dan Dishon's Transmission Den

Changing cases and have questions on drilling modifications

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FEDNV:
So I cracked my case and a friend gave me his good old case (he switched to aftermarket case) and while inspecting it before putting my parts into his case I found some differences.
Let me also say I am no expert on automatic transmissions and this is my first teardown and rebuild. This is a full manual valve body powerglide going into a FED.

First I see that his case has a hole plugged that I have read needs to be enlarged with its corresponding hole on the bottom of the case.



old case




He had this in a drag car so I do not know why this would be plugged. Can anyone tell me why this was plugged and should I drill this out? It was drilled out on my old case. Are there any other modifications I should do or can do to a stock case to make it better?

This is from some of the instructions I found online on what to drill.



Also, I found this in the bottom of the pan. The internals have about 20 passes and when we took it apart it took 6 full turns to tighten the band. Is this band material since it was so loose?  We inspected all the clutches and they still look new and the band does not look bad.



Thanks
Scott

bikeguy307:
My guess is the hole is drilled, you should be able to tell by looking from the piston sode of the case. Some builders plug the hole on the back side to help prevent any leakage that may occure to the the rear. If you are using a non-transbrake balve body the drilling the hole is not needed. I noticed in the pictures that your old case has a 2nd hole drilled for rev feed, again not needed if you have just a manual VB. Your old case appears to be a rear pump case and the is not. If your case is a rear pump your rear pump body will not work on the new case with out a block off plate, or you will need the matching rear support. As far as the pan goes, if the band and clutches are good, then I'm not sure, that is a lot just to be cast iron dust. The band was out of adjustment, if the band is ok check to see if the band adjuster is bent. Something had to have changed for it be that far out.

Hope this helps, Dan

hemidakota:
Scotts transmission is a trans brake. Does have the front pump. What do you see that I am missing? Sorry I am asking due to I am the one that tore it down. I am under the impression that both holes need drilled as for the one up from the valve body. The hole is not drilled thru the case behind the plug to the piston side. Thanks for your info Dan...

bikeguy307:
Ok, misread he said manual VB. If he has a Trans-brake then make the same modifications to the new case that are made to the old, remove the plug and drill the passages. As far as the other issue, look at the 11 o'clock position in the pictures. The old one has a hole, the new one doesn't. If that hole geos thru to the piston area then your rear support will not work the new case, without a blocker plate.

hemidakota:
Ok makes perfect sense now. Thanks. I do think it already has a blocker plate. Thanks for the help! Sometimes the obvious is not so obvious...

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