hkc3
Well-known member
Im wanting to swap in a 75 differential in my 81 toms told me I would have to modify my cover and alter camber bracket anyone done it .I would appreciata any help
81 to 75 diff swap
- Thread starter hkc3
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Twin_Turbo
Der Maulwurf
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No need to modify the cover. You ONLY have to notch the batwing if you use 12 bolt stuff, the much larger drive flanges will otherwise not clear.
You do need to swap the camber bracket and rods to the earlier style because on 80-82 they bolt over the diff cover and diff mating flange. With the earlier case you loose half the thickness of that flange and therefore you won't be able to bolt on the bracket. The 80-82 style has the bracket positioned backwards in relation to the halfshafts and as such uses angled camber rods. The early ones have the bracket under the case and straight rods. That's why you need to swap them.
You do need to swap the camber bracket and rods to the earlier style because on 80-82 they bolt over the diff cover and diff mating flange. With the earlier case you loose half the thickness of that flange and therefore you won't be able to bolt on the bracket. The 80-82 style has the bracket positioned backwards in relation to the halfshafts and as such uses angled camber rods. The early ones have the bracket under the case and straight rods. That's why you need to swap them.
hkc3
Well-known member
thanks tt Im only making 475-500 hp so im going with the earlier case,30 spline axles and bigger u-joints ,my81 is the weakest built.I wont be going whole hog for the 12bolt conv. I wish I knew someone in this area that could do a solid axle 9inch I read about a guy doing it in c-4s
DJ Dep
refugee from the other place
There is a company on the East Coast that sells a weld-in solid axle kit for C3s. One person that we know of has done it and is very happy with the results. Unfortunately, I'm not sure he is on this forum, and I lost the link for the website for the company. 
Dep
Dep
DJ Dep
refugee from the other place
hkc3
Well-known member
Thanks im calling them tomorrow.
hkc3
Well-known member
Called accufab I would have to make a hole up above the rear and refiberglass for clearance,and do some more cutting and welding, if I had to go to that extreme I would buy that dana 60, So im back to building that 75 rear a friend of mine has .Toms website says you have to modify the case for 30 spline axles and spyders ,anyone done it themselves or know anyone who I could have do it, toms waiting list is 2months or more,Ive not had the pleasure of rebuilding a rear but Im willing to try. thanx for all the help.
DJ Dep
refugee from the other place
Just so you know....unless you are running an automatic, Tom's rear end is not really "indestructible". There are pictures posted on the Corvette Forum of it shearing off at the hub.
hkc3
Well-known member
I am running an auto-700r4,I would really like to run it at the track a few times.and not have anything break,but I dont want to trim the compartments for the 12bolt conv.
DJ Dep
refugee from the other place
Then you should be okay with Tom's stuff.
hkc3
Well-known member
I found a 12 bolt conv.rear on another forum . It looks like my camber rods bolt on the case not the cover, the older case didnt look like it had a place for them to bolt,or do they bolt to the cover ,thanx for the help.
Twin_Turbo
Der Maulwurf
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The 80-82 camber bracket bolts over the mating flange of case & cover. There are "ears" on both where 2 bolts go through on each side. The earlier iron diffs have 4 bolt holes under the diff, placed directly below the stub axles, that's where the camber beacket bolts. Because of this, you need the straight struts also, the 80-82 ones are angled forward.
hkc3
Well-known member
I will look for some good after market cmb. rods ,thank you for the help ,Also on the front it looked like the crossmember bracket was the same,He has a good price on it .I will check on it this week.
hkc3
Well-known member
Im waiting for email on a 12bolt converted rear, now all I need is best place/price for 360lb spring,offset trailing arms,heavy duty half shafts,half shaft safety loops,arp cover bolts,Ive read that you need shorter spring for offset TAs, do you order it that way or modify.Im probably fergetting something,but this will keep me busy for a while,thanx guys:drink:
DJ Dep
refugee from the other place
Why do I get the feeling that this rear end conversion is gonna cost way more than the solid axle one I linked to?? :wink:
1981Z06Vette
Well-known member
No doubt. I just wonder if my idea of adapting a Strange or Moser 12 bolt F-body housing, or a Strange S60 could be done more cost effectively than trying to put 10lbs of **** in a 5 pound Vette housing bag. I'm sure I could find a broken or empty one somehwere to play with...
hkc3
Well-known member
I was all set to order the 9" conv. untill he told me I would have to cut a hole in the floor and fiberglass a hump to clear the housing travel.
stinger12
Well-known member
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- Mar 28, 2008
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I was all set to order the 9" conv. untill he told me I would have to cut a hole in the floor and fiberglass a hump to clear the housing travel.
Yeah, but how much extra are you willing to spend on a unit that is inferior to the dana 60, and still is going to cost you more money? Fiberglass is easy to work with. Its a no brainer to me. Not only are you getting a stronger unit, but the rebuild was done by Mike Dyer - he's been working on vettes his entire life and he knows his stuff. You can't get much better quality than Mike Dyer or Gary Ramadei, they do the same type of work.
stinger12
Well-known member
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I didn't want to comment anymore on the other forum regarding that 12 bolt that you are planning on buying. Tom Watt polishes his posi cases - its a known fact. THe one this guy is selling has a cast posi case.
http://forums.corvetteforum.com/showthread.php?t=2007583
This 12 bolt you are planning on buying has a regular cast posi unit. I don't care what the seller says. That is a mod Tom does to strengthen the casing and to prevent cracking. You polish the windows and seams to remove stress risers. Here is the one I did for my diff rebuild...
A stock posi case (rough casting)
Polished posi case
I'm not trying to be an ass. I wasn't going to say anything to begin with, but I would hate to see you get burned on that 12 bolt deal. Why not send those pictures of the 12 bolt to Tom Watt and ask him if he built it? He definitely doesn't use springs in his setups, so thats another red flag.
Good luck.
http://forums.corvetteforum.com/showthread.php?t=2007583
This 12 bolt you are planning on buying has a regular cast posi unit. I don't care what the seller says. That is a mod Tom does to strengthen the casing and to prevent cracking. You polish the windows and seams to remove stress risers. Here is the one I did for my diff rebuild...
A stock posi case (rough casting)
Polished posi case
I'm not trying to be an ass. I wasn't going to say anything to begin with, but I would hate to see you get burned on that 12 bolt deal. Why not send those pictures of the 12 bolt to Tom Watt and ask him if he built it? He definitely doesn't use springs in his setups, so thats another red flag.
Good luck.
turtlevette
The Turdle
stinger12,
didn't take you long to become an expert on differential rebuilding.....did it.
i see you are publishing a paper on CF that looks to be just like Garys.
that's thievery
HELLO?
didn't take you long to become an expert on differential rebuilding.....did it.
i see you are publishing a paper on CF that looks to be just like Garys.
that's thievery
HELLO?
