Solid differential crossmember bushings: '63-'79
Thread Starter
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
Solid differential crossmember bushings: '63-'79
I was discussing these in another thread, but it started to seem like a hijack, so here we are.
They appear to be based off of something noted (but not pictured very well) on page 6-4 of the Chevy Power Manual, 5th edition. They totally eliminate the rubber bushings - the stepped portions fit snugly into the crossmember bores. I'm fairly sure that they're steel, but I'm not 100% certain. All dimensions are approximate.
Upper ring dimensions:
total thickness - 9/16"
thickness of wide section - 7/16"
thickness of narrow section - 1/8"
diameter of wide section - 4"
diameter of narrow section - 3 13/16"
diameter of hole - 2 9/16" (it appears to taper a bit as it goes downward - it's around 2 1/2" - 2 17/32")
Lower plate dimensions:
total thickness - 7/8"
thickness of wide section - 7/16"
thickness of narrow section- 7/16"
diameter of wide section - 4 1/4"
diameter of narrow section - 3 13/16"
diameter of hole - 1/2"
I have no idea where they came from, I got them with a used crossmember and spring assembly. The original blue finish looked like a factory job, but it also looked quite old and worn.
They appear to be based off of something noted (but not pictured very well) on page 6-4 of the Chevy Power Manual, 5th edition. They totally eliminate the rubber bushings - the stepped portions fit snugly into the crossmember bores. I'm fairly sure that they're steel, but I'm not 100% certain. All dimensions are approximate.
Upper ring dimensions:
total thickness - 9/16"
thickness of wide section - 7/16"
thickness of narrow section - 1/8"
diameter of wide section - 4"
diameter of narrow section - 3 13/16"
diameter of hole - 2 9/16" (it appears to taper a bit as it goes downward - it's around 2 1/2" - 2 17/32")
Lower plate dimensions:
total thickness - 7/8"
thickness of wide section - 7/16"
thickness of narrow section- 7/16"
diameter of wide section - 4 1/4"
diameter of narrow section - 3 13/16"
diameter of hole - 1/2"
I have no idea where they came from, I got them with a used crossmember and spring assembly. The original blue finish looked like a factory job, but it also looked quite old and worn.
Melting Slicks
Joined: Nov 2003
Posts: 2,362
Likes: 1
From: San Antonio TX
So what is the ? . And you are correct about the Chevy Power Manual but you would weld them to the cross member. And I feel it would be worth while to make enough notes to be able to duplicate them. 
But the ones you show look as though you could put them in without welding. The power manual shows how to make them but they are welded in. It looks like you have something special.
As I for one would be very interested.
But the ones you show look as though you could put them in without welding. The power manual shows how to make them but they are welded in. It looks like you have something special.
As I for one would be very interested.
Last edited by SHAKERATTLEROLL; Jan 18, 2007 at 01:27 AM.
Pro
Joined: Jun 2005
Posts: 583
Likes: 61
From: USA
I had gotten a set of those a while back (more than 10 yrs ago), made of solid aluminum, with anodized blue finish. I don't see them being sold any more, only the bottom aluminum disk part which goes on the bottom of the factory rubber bushing to help hold the diff crossmember more solidly. I might've gotten them from Guldstrand perhaps, but they don't sell the spacer that goes between the crossmember and the frame anymore.
Separately, to get completely away from the rubber bushing a la Chevy Power Manual, I had some steel spacers machined up at the local machine shop. I took the factory rubber bushing out of the crossmember, and separated the steel center "cup" part from the rubber and steel outer shell. then I welded the center "cup" portion to the steel spacers, and welded this assembly to the crossmember, top and bottom. It worked out pretty good, using the aluminum biscuit for the front diff mount.
This mounts the diff solidly to the chassis. there wasn't a lot of gear noise transmitted while driving. I've done this for two C3 diff crossmembers.
Separately, to get completely away from the rubber bushing a la Chevy Power Manual, I had some steel spacers machined up at the local machine shop. I took the factory rubber bushing out of the crossmember, and separated the steel center "cup" part from the rubber and steel outer shell. then I welded the center "cup" portion to the steel spacers, and welded this assembly to the crossmember, top and bottom. It worked out pretty good, using the aluminum biscuit for the front diff mount.
This mounts the diff solidly to the chassis. there wasn't a lot of gear noise transmitted while driving. I've done this for two C3 diff crossmembers.
Thread Starter
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
I had gotten a set of those a while back (more than 10 yrs ago), made of solid aluminum, with anodized blue finish. I don't see them being sold any more, only the bottom aluminum disk part which goes on the bottom of the factory rubber bushing to help hold the diff crossmember more solidly. I might've gotten them from Guldstrand perhaps, but they don't sell the spacer that goes between the crossmember and the frame anymore.
Separately, to get completely away from the rubber bushing a la Chevy Power Manual, I had some steel spacers machined up at the local machine shop. I took the factory rubber bushing out of the crossmember, and separated the steel center "cup" part from the rubber and steel outer shell. then I welded the center "cup" portion to the steel spacers, and welded this assembly to the crossmember, top and bottom. It worked out pretty good, using the aluminum biscuit for the front diff mount.
This mounts the diff solidly to the chassis. there wasn't a lot of gear noise transmitted while driving. I've done this for two C3 diff crossmembers.
Separately, to get completely away from the rubber bushing a la Chevy Power Manual, I had some steel spacers machined up at the local machine shop. I took the factory rubber bushing out of the crossmember, and separated the steel center "cup" part from the rubber and steel outer shell. then I welded the center "cup" portion to the steel spacers, and welded this assembly to the crossmember, top and bottom. It worked out pretty good, using the aluminum biscuit for the front diff mount.
This mounts the diff solidly to the chassis. there wasn't a lot of gear noise transmitted while driving. I've done this for two C3 diff crossmembers.
-------------------------------
I started this new thread to stop hijacking another one with the discussion. Other than the source, I don't have any questions about them. However, several posters were curious about the dimensions, and I figure that if anyone wants to have a set made up they might find it useful.
Thread Starter
Team Owner
Joined: Oct 2004
Posts: 23,831
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From: Springfield MO
St. Jude Donor '07
Race Director
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From: WI
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Melting Slicks
Joined: Jan 2006
Posts: 3,028
Likes: 2
From: North NJ
There must have been a reason GM went thru the trouble of making the diff xmember removable with rubber inserts. I'm sure it would have been easier and cheaper to just weld or bolt them together. I would think the rubber would not trasmit any vibrations thru to the chasis from the diff. RPLO98 says he didn't feel much vibration but there has to be a reason, maybe the small constant vibrations would losen chasis bolts?? just throwing out ideas.
Pretty cool though.
If I auto-x'd i'd buy a pair.
Pretty cool though.
If I auto-x'd i'd buy a pair.
Thread Starter
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
There must have been a reason GM went thru the trouble of making the diff xmember removable with rubber inserts. I'm sure it would have been easier and cheaper to just weld or bolt them together. I would think the rubber would not trasmit any vibrations thru to the chasis from the diff. RPLO98 says he didn't feel much vibration but there has to be a reason, maybe the small constant vibrations would losen chasis bolts?? just throwing out ideas.
Pretty cool though.
If I auto-x'd i'd buy a pair.
Pretty cool though.
If I auto-x'd i'd buy a pair.
Melting Slicks
Joined: Jan 2006
Posts: 3,028
Likes: 2
From: North NJ
Race Director
Joined: Nov 2000
Posts: 16,416
Likes: 1
From: NC,USA
My .02 is gear harmonics from the differential...
If you've ever driven a car that has the lash set wrong, the rear axle wants to jump out of the car.
Would be less than pleasing on the vetter, where you practically sit on top of it...
If you've ever driven a car that has the lash set wrong, the rear axle wants to jump out of the car.
Would be less than pleasing on the vetter, where you practically sit on top of it...
Thread Starter
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
The reinforcement discs should have the same problem, then, and I've never heard of anyone complaining. If they're annoying, oh well...I'll think of something else.
6th Gear
Joined: Dec 2014
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6th Gear
Joined: Dec 2014
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Guldstrand Solid Bushing
1979, 6379, aluminum, bushings, c3, corvette, crossmember, differential, differentials, kit, locating, plates, rear, solid, spacer, suspension
