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C3 Race Car Build

johng

CCCUK Member
Strange, they obviously moved the hole in later years and mine doesn't go through the inner skin just the outer.
IMGP1584.JPG
 

Oneball

CCCUK Member
The repair panel I’ve got has got the hole in the same place as yours. I’m guessing they just do one type of corner now.
 

Oneball

CCCUK Member
Turned a little corner this evening.

Diff cover removed. Unfortunately the mounting holes have been stripped at some point so that’ll need a new one.

4329

Diff carrier out in preparation for a rebuild with new bearings and clutches. Going to go with the existing ratio of 3.36:1 which will give 177mph at 7500, so a bit on the long side but we’ll see.

4333

Case cleaned and painted. First shiny bit completed instead of disassembling rusty crap.

4334
 

Oneball

CCCUK Member
What with the stripped threads I’m surprised you didn’t go for a HD diff from a Big block car?
It’s just the cover that’s stripped. The diff itself I’m rebuilding with a 400lb spring and 22 plates and uprated output shafts. Will also tap the case for a cooler.

To my knowledge the only difference between big block and small block diffs is the output shafts.
 

Corvette

CCCUK Member
It’s just the cover that’s stripped. The diff itself I’m rebuilding with a 400lb spring and 22 plates and uprated output shafts. Will also tap the case for a cooler.

To my knowledge the only difference between big block and small block diffs is the output shafts.
Correct but GM had the bolt in caps for a reason. I too have a diff cooler set up.
 

Oneball

CCCUK Member
The new output shafts are a 4130 forging with caps, as are the half shafts and stub axles. Trying to make the rear end as strong as possible in case I put a big block in later.
 

Dazaa

Busy user
Why not Helicoil the diff case? I just did 2 of the sump bolt holes on my TH400 and it took about 10 minutes!

Also how difficult a job is rebuilding the diff? I know mine leaks and will need a rebuild soon but i'm worried if I pull it apart it'll never go back together right.
 

Oneball

CCCUK Member
If it was just a sump retainer I’d Helicoil but it’s a couple of the holes that hold the diff to the crossmember and therefore hold the suspension to the car, not worth the risk in my opinion. The rear cover isn’t too expensive anyway.

If it’s just leaks, it’s relative easy to change seals. Rebuild is a bit harder as you need to set the lash/tooth interface between the crown wheel and pinion. That requires use of a dial gauge, engineering blue and often multiple assembly/strip downs. Not hard if you follow the procedure but a bit of a faff.
 

Dazaa

Busy user
If it was just a sump retainer I’d Helicoil but it’s a couple of the holes that hold the diff to the crossmember and therefore hold the suspension to the car, not worth the risk in my opinion. The rear cover isn’t too expensive anyway.

If it’s just leaks, it’s relative easy to change seals. Rebuild is a bit harder as you need to set the lash/tooth interface between the crown wheel and pinion. That requires use of a dial gauge, engineering blue and often multiple assembly/strip downs. Not hard if you follow the procedure but a bit of a faff.

ah I see, I wouldn't helicoil the mounting holes either, thought it was just the cover bolts.

It appears to have a small leak on both sides so I guess it's a full rebuild or is it just a seal?
 

Oneball

CCCUK Member
The leak could be the seal has gone or it could be that there’s so much play in the shaft that it can’t maintain a seal. You have to have a waggle to see what it’s like.
 

Oneball

CCCUK Member
Gearbox strip down today.

4336

Sidecover off, two of the threads are buggered so they’ll need helicoils.

4337

The selector forks are worn, especially for 4th so new ones of those to the list.

4338

Extension off and gears out, reverse fork also needs changing.

4339

I’m changing the gearset from the M20 that’s in there to an M22 so most of this is useless.

4340

The only bit that could have been reused is reverse gear but that’s trashed too.

4341
4342

Time to give the cases a proper clean and order a load of bits.

4343
 

johng

CCCUK Member
Looks like the cases are in your kitchen, are you going to clean them in your washing up bowl, or just in the dishwasher?
 
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