1965 gran sport 400 tranny upgrade

[Robin Cook]

Flex plate is originally far as I know, to this engine and has not been removed after break in. I assembled the power train before install as well. I never knew or forgot :violent1:that the st300 converter was better choice. So when I pull the inspection cover apparently if I can get my fingers between converter and bell housing it’s the st300?

[telriv]

Since the flexplate can go on in six diff. positions AND ONLY one is correct I would be suspicious of the flexplate orientation as one of the 1st. things to check.

[Robin Cook]

Six positions? How will I know the right position?

[telriv]

Besides the six bolts that hold the flexplate in place there will be another hole between two bolt holes. This is known as the index which MUST line up with a matching  index hole in the crankshaft. The flexpate has approx. a 4 1/2 oz. imbalance. The index holes MUST line up or else the engine is out of balance.

Tom T.

[Robin Cook]

Tom, Thank you for your help on this. Hope to get at the issue this week. I’ll keep you posted.

[telriv]

Robin,

 You will have to move the trans. back to be able to access the crankshaft/flexplate bolts. The trans. DOES NOT need to be dropped or pulled.  !st. get two long 7/16th. course thread bolts about 4" long & cut the heads off to use as a dowel/guide pin. Remove 4 trans. to engine bolts. Unbolt the driveshaft from the rear yoke. Wrap tape around the u-joint cups to keep them from falling off. Maybe even take a piece of rope to tie the shaft to the mufflers. Put a floor jack under the trans. pan with a good sized piece of wood to help stabilize the trans. 3/4"x12" or so plywood.  Jack the trans. up to relieve the weight of the trans. on the crossmember. Unbolt the crossmember. Leave the trans. mount on. Now one at a time remove one trans. bolt & install the guide pin. The trans. lines normally do not need to be dis-connected as they usually have enough slack in them to slightly stretch.  Now get two good sized screwdrivers/pry bars & wedge between the block & trans. & install a 2x4 small block of wood between the block & the trans.  Do the same for the next bolt. The trans. only needs to go back about 1-1 1/2". Now you can hold the flexplate while removing the bolts.
    I used to be able to perform this task in about 30 minutes on my lift at the shop. Probably about 1 1/2 hrs. on my back.

Tom T.

[Robin Cook]

Hey Tom,

You clearly know a thing or two over your years of experience LOL. I'm getting rather excited now to get at this issue, your terrific approach will save me a ton of grief, thanks for sharing your experiences!

[Robin Cook]

Hey Tom
Gran sport fixed! Definitely need more tire lol! Wow! What’s the fix for posi?
Can’t thank you guys enough for your expertise.

[Lou Perfetto]

Great to hear Robin,
 The guys on this site are right on point. Great feeling having some real power off the line! You will never go back to a 2 speed.... I will get some pics of the way my shifter was wired 40 years ago on my 65 Riviera over the weekend. Wait till you really launch it! Glad it all worked out.       

[GS66]

Robin, glad to hear this turned out great. From my 66 GS with TH400 and 3.36 posi. Car also has a Qjet.

[Robin Cook]

Yeah buddy, that’s what I’m looking for! That’s a nice sweet launch!
What’s my course of action to turn my open diff into a posi? My car is at 3:08 I believe, regardless 8.2 diff. Or upgrade complete rear end? I have the dual quad factory setup, seems to run strong but won’t know for sure until I get exhaust system installed soon. Local guy does top drawer work. By next week maybe

[Lou Perfetto]

Alright, Nice Posi Jim.
Robin, Our 8.2 rears are good for up to 500hp+, especially with a automatic. Auburn Gear and Eaton both make a good posi unit for the Buick rear. I would get on v8buick.com and let the guys there guide you on places that have multiple gear sets. The 3:36's looked pretty good!
3:36, 3:42, 3:55 are all great gear combinations for the street. Drive the highway in your daily driver, It's always a blast to fry them at will.....