Beware-SPF rear end mount problem

Jake · #1 (**permalink**) 03-17-2009, 06:21 AM

Just wanted to throw out there that I had a failure in the passenger side rear end mount on SPF #390. I am unaware if they upgraded the bracket on the newer cars. The metal they used on the mount is thinner then it should be or they should have added gussets to the mount (which I did). Mine sheared loose and actually had bent and tore the mount. This caused the rearend to slip down and the axle to hit on the frame, making a rotational clanging noise come through the roll bar. Just a heads up to do a visual inspection on your SPF's to see if everything looks good. I understand that this is not an isolated issue and it also has occurred on small block cars. Mine is all fixed and as much stronger then it needs to be with the new gussets.

Jake

RedBarchetta · #2 (**permalink**) 03-17-2009, 07:51 AM

Jake,

Please be more specific, as this is new news to me and I've had my car (#747) for five years and don't recall anything specific to a rear-end mount issue. SCOF would have also covered this extensively if it were an ongoing issue (you are a member of SCOF, right?). The upper shock tower brackets can be a weak link and upgrades are available through Performance Unlimited. I highly recommend them.

-Dean #747

xlr8or · #3 (**permalink**) 03-17-2009, 09:13 AM

That is a problem on the older cars. I welded in a new mount from 1/4" thick angle iron on #306 for a friend when he tore it out. The newer ones have a better mount on them and I think it was updated around #600

vanoochka · #4 (**permalink**) 03-17-2009, 11:02 AM

Quote:

Originally Posted by RedBarchetta

Jake,

Please be more specific, as this is new news to me and I've had my car (#747) for five years and don't recall anything specific to a rear-end mount issue. SCOF would have also covered this extensively if it were an ongoing issue (you are a member of SCOF, right?). The upper shock tower brackets can be a weak link and upgrades are available through Performance Unlimited. I highly recommend them.

-Dean #747

The rear-end mount issue is news to me, too. I would also appreciate any additional detail. Pics?

Here's an old thread on the shock brackets issue.

R/T Suspension Mounts

Jake · #5 (**permalink**) 03-17-2009, 12:29 PM

Dean, I have had issues posting pics to CC. The third member is held in place by a rear bracket and a right and left bracket that secures the member to the frame. The brackets on my car had no gussets and were made from very thin steel. With the amount of twisting force that the third member takes under full throttle it was way under built. The simple fix is to pull the driveline and the side and rear mounts hardware. This allows the third member to drop down enough to weld in gussets (2 per side) and reassemble. There is no need to pull the entire third member out or remove the axles. It sounds like they fixed the problem in your case. As for SCOF, I could not keep up with the amount of e-mails and never got into that scene. Another friend with a SPF said that he has read on SCOF that others have had this problem in the past.

Jake

xlr8or · #6 (**permalink**) 03-17-2009, 12:55 PM

Jake I'm sure you did the same thing as I mentioned repairing above. The front mounts for the diff were only 1/8" thick and had no gussets. The big block cars seem to tear these off the frame. The one I repaired had a hole in the 2X3 frame rail where it ripped out. We covered the rail with 3/16" plate and welded a 1/4" bracket in for the mount. Has been fine ever since and he is putting over 700HP to it on a regular basis.

You might also want to check/replace the rear upper mounting bolt on the diff. It takes a lot of twisting stress when the front mount comes loose.

Nantucket427 · #7 (**permalink**) 03-17-2009, 01:10 PM

What car number did they change the mount?

I have replaced the shock mounts, but the mounts for the rearend looked OK

Nantucket427 · #8 (**permalink**) 03-17-2009, 01:11 PM

What car number did they change the mount?

I have replaced the shock mounts, but the mounts for the rear-end looked OK

RedBarchetta · #9 (**permalink**) 03-17-2009, 01:36 PM

Quote:

Originally Posted by Jake

Dean...As for SCOF, I could not keep up with the amount of e-mails and never got into that scene.

Jake, it's easy to turn off that feature. It's set that way as a default and the user must turn it off. I think it's a Yahoo Groups issue and not a SCOF thing. You might want to reconsider, because the brain trust on SCOF is quite extensive for the SPF owner that likes to stay informed (especially for those of us that bought pre-owned).

Glad you were able to resolve this one. Check out the shock tower brackets. Four bolts (instead of two) and more steel in the right places is the ticket with these. A failure of that shock tower will send you off the road. At a minimum check your bolts to ensure they are riding on the elongated shoulder and not the threads. Aircraft Spruce sells the correct (longer shouldered) hardware.

-Dean

Got the Bug · #10 (**permalink**) 03-17-2009, 03:51 PM

Quote:

Originally Posted by Nantucket427

What car number did they change the mount?

I have replaced the shock mounts, but the mounts for the rear-end looked OK

Nantucket427- xlr8or mentioned in his post that he though it was updated around chassis #600.

Jake - Agree with Dean. I was getting the SCOF emails in a daily digest, but now I just go directly to the SCOF Yahoo group portal and read/respond to emails that way.