Learned something about rear-end swaps...
Thread Starter
Instructor
Joined: Jul 2003
Posts: 153
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From: Tecumseh, OK USA
Learned something about rear-end swaps...
I have been in the process of changing my 3.08 setup out for a re-built 3.55 setup from a 75 Vette. Mine is a 78 but it's pretty much a straight swap.... until you get to the bolts that hold the spring pack on 
. The 78 uses 4 ea. 7/16" bolts and of course when I slapped em in the holes they didn't touch!? Found out the diff cover on the 75 uses 4 ea. 9/16'" bolts! 
Guess I'll be makin' a trip to the hardware store. How come you guys that knew this didn't email me to let me in on it? Of course it would have helped if I'd known to ask huh? 
. The 78 uses 4 ea. 7/16" bolts and of course when I slapped em in the holes they didn't touch!? Found out the diff cover on the 75 uses 4 ea. 9/16'" bolts! Guess I'll be makin' a trip to the hardware store. How come you guys that knew this didn't email me to let me in on it? Of course it would have helped if I'd known to ask huh?
Instructor
Joined: Dec 1999
Posts: 101
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From: On the lake
How hard was it to install?Im doing my trailing arms now,(got the passenger side done)and next weekend Im going to be installing a rebuilt 3:55 I got from FastCorvete.com.Just wondering what I can expect.
Thread Starter
Instructor
Joined: Jul 2003
Posts: 153
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From: Tecumseh, OK USA
My 2 cents....
Originally Posted by MAC74
How hard was it to install?Im doing my trailing arms now,(got the passenger side done)and next weekend Im going to be installing a rebuilt 3:55 I got from FastCorvete.com.Just wondering what I can expect.
Somewhere down the road I'll be doing the trailing arms....
Melting Slicks
Joined: Jan 2004
Posts: 3,245
Likes: 210
From: Detroit MI
The diff cover with the 9/16" bolts is probably an aftermarket heavy duty cover. I ran into the same thing when I swapped rear ends last summer, the gear I was putting in had the standard cover, I had forgotten that I installed the hd cover on the old gear a few years ago.
Be sure to get Grade 8 bolts! I don't know that a hardware store would have Grade 8, you may have to go to a fastener shop.
Be sure to get Grade 8 bolts! I don't know that a hardware store would have Grade 8, you may have to go to a fastener shop.
Melting Slicks
Joined: May 2002
Posts: 2,508
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From: Wisconsin
Originally Posted by 69autoXr
Be sure to get Grade 8 bolts! I don't know that a hardware store would have Grade 8, you may have to go to a fastener shop.
Melting Slicks
Joined: Jan 2004
Posts: 3,245
Likes: 210
From: Detroit MI
Well, I'm lucky enough to have a good fastener shop about 1/2 mile from home, so I go there when I need something. I just don't remember the local Ace Hardware having Grade 8, just the run of the mill zinc coated stuff. I don't know.
Le Mans Master
Joined: Oct 2001
Posts: 5,145
Likes: 125
From: The Motor City
We live in suburbia... I think one could be arrested just for dressing in flannel. I'm suprised I haven't been hauled in yet just driving the Vette.
Chris, where is that fastener store near your house? I have one down in Dearborn near work that I go to but I'd like to find one near home (9 and Farmington) if I'm working on the car.
Chris, where is that fastener store near your house? I have one down in Dearborn near work that I go to but I'd like to find one near home (9 and Farmington) if I'm working on the car.
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Melting Slicks
Joined: Jul 2004
Posts: 3,248
Likes: 48
From: westland mi
Originally Posted by Scooter70
We live in suburbia... I think one could be arrested just for dressing in flannel. I'm suprised I haven't been hauled in yet just driving the Vette.
Chris, where is that fastener store near your house? I have one down in Dearborn near work that I go to but I'd like to find one near home (9 and Farmington) if I'm working on the car.
Chris, where is that fastener store near your house? I have one down in Dearborn near work that I go to but I'd like to find one near home (9 and Farmington) if I'm working on the car.
Drifting
Joined: Oct 2004
Posts: 1,259
Likes: 7
From: Ontario
It may not just be the bolts that you need to change. The 78 diff cover came in two versions for either the 2.5" or 2.25" springs. Each version also had different sized mounting bolts(in BOTH width and length). The mount in the cover is also different. There is a shim kit avail from Ecklers and others if you are putting a 2.25" spring into a 2.5" case. The other way around is a bigger issue, you will need to change the spring or cover. If you have any space at all between the spring and bolts, you need to shim....I speak from experince. Your spring will start moving in the mount after a couple of weeks.
Last edited by Retro78; Jan 17, 2005 at 12:46 PM.
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Factory bolts were 9/16 from 63 to 77 and 7/16 1978-1979. But you already know that.
Problems usually arise when people install the after-market spring kits which include thread inserts for the 63-77 cases because the chosen spring is wider and requires smaller bolts to fit. Then someone decides to replace the spring with a correct width (thinner) spring and the required 9/16 bolts can no longer be used unless the thread inserts are drilled out. I have drilled out a few of these and it ain't no picnic.
I purposely bought the FG spring with the correct width for both of my Vettes (66/70).... no thread inserts... 9/16 bolts.
Here's the correct bolts... JIC you're curious-
http://docrebuild.com/dr-r-web/SUSP63C.PDF
Problems usually arise when people install the after-market spring kits which include thread inserts for the 63-77 cases because the chosen spring is wider and requires smaller bolts to fit. Then someone decides to replace the spring with a correct width (thinner) spring and the required 9/16 bolts can no longer be used unless the thread inserts are drilled out. I have drilled out a few of these and it ain't no picnic.
I purposely bought the FG spring with the correct width for both of my Vettes (66/70).... no thread inserts... 9/16 bolts.
Here's the correct bolts... JIC you're curious-
http://docrebuild.com/dr-r-web/SUSP63C.PDF
Melting Slicks
Joined: Jan 2004
Posts: 3,245
Likes: 210
From: Detroit MI
Originally Posted by Scooter70
We live in suburbia... I think one could be arrested just for dressing in flannel. I'm suprised I haven't been hauled in yet just driving the Vette.
Chris, where is that fastener store near your house? I have one down in Dearborn near work that I go to but I'd like to find one near home (9 and Farmington) if I'm working on the car.
Chris, where is that fastener store near your house? I have one down in Dearborn near work that I go to but I'd like to find one near home (9 and Farmington) if I'm working on the car.
Le Mans Master
Joined: Oct 2001
Posts: 5,145
Likes: 125
From: The Motor City
Originally Posted by rosslato
SCOOTER70, could u tell me where the fastener store is in dearborn? been looking for a good one close to me since mine upped and left. i'm in wasteland. even 9 and Farmington is close. thanx
414 S Oakwood
Detroit, MI 48217
From Dearborn (Michigan Ave), it's about 4.5 miles east on Oakwood, past 94. Looks like it's technically in Detroit. Depending on where in Westland you are, Chris's place in Livonia is most likely closer.
-Matt
Sorry for hijacking the thread.... Back to your regularly scheduled posting.
Thread Starter
Instructor
Joined: Jul 2003
Posts: 153
Likes: 0
From: Tecumseh, OK USA
Yikes!
Originally Posted by Tom454
Factory bolts were 9/16 from 63 to 77 and 7/16 1978-1979. But you already know that.
Problems usually arise when people install the after-market spring kits which include thread inserts for the 63-77 cases because the chosen spring is wider and requires smaller bolts to fit. Then someone decides to replace the spring with a correct width (thinner) spring and the required 9/16 bolts can no longer be used unless the thread inserts are drilled out. I have drilled out a few of these and it ain't no picnic.
I purposely bought the FG spring with the correct width for both of my Vettes (66/70).... no thread inserts... 9/16 bolts.
Here's the correct bolts... JIC you're curious-
http://docrebuild.com/dr-r-web/SUSP63C.PDF
Problems usually arise when people install the after-market spring kits which include thread inserts for the 63-77 cases because the chosen spring is wider and requires smaller bolts to fit. Then someone decides to replace the spring with a correct width (thinner) spring and the required 9/16 bolts can no longer be used unless the thread inserts are drilled out. I have drilled out a few of these and it ain't no picnic.
I purposely bought the FG spring with the correct width for both of my Vettes (66/70).... no thread inserts... 9/16 bolts.
Here's the correct bolts... JIC you're curious-
http://docrebuild.com/dr-r-web/SUSP63C.PDF
OK, I'll need to measure the spring later today. But the spring that came out had plates on each side of it and were slightly curved on the ends (so the bolts would keep them from sliding out I assume). Are these plates from the factory or is this the shim kit everyones referring to?
AND...on another note while we're here, my spring only appears to have 6 (six) leafs if you don't count the rectangular plate at the top. SIX...not 7 or 9 like everything I've been seeing. Any ideas??
BTW- I picked up grade 8 bolts from ACE hardware.....
Last edited by c3vettelover; Jan 17, 2005 at 01:57 PM.
