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What's the rub? Rear end spring noise.

Joined
Aug 11, 2015
Location
Central NH
Ok - '79 245, 3.91 rear end out of a 93 I had a shop install 3 years ago. Had both rear calipers replaced 2 years ago. Have always had this intermittent rattle on deceleration, sometimes going down a hill. Figured it was just a consequence of installing my own exhaust on the ground, definitely sounded like the rear pipe or muffler bouncing a little. Tried adjusting the angles and moving the pipes around but never could eliminate it.

Fast forward to this week - trying to chase down my rear end whine with a local shop, driving it on the lift. Mention what I thought was the exhaust noise, and he notices that the squarish metal tab on the passenger side is actually hitting the spring. Driver's side is close but clears it by an inch. Think we've found our culprit.

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What the heck is this? I've been looking through exploded diagrams for 1979 and 1993 and can't find anything. Looks like some sort of shield. Also is this an indication that something else is off? All bushings were replaced when the new rear end went in.
 
Is the spring bowed out towards the rear of the car? You could try unbolting the lower spring mounting bolt, rotate the spring 180 degrees, and secure the nut on the lower spring mount. The rear spring seats are not parallel most of the time, so there is a bending effect on the rear springs. Maybe they're just..."bent"? Hard to tell from that perspective.

Those blocks on the calipers align with the big "crash triangles" bolted to the chassis, using the same bolts as the ones that hold the gas tank in the car. Does that care even have those triangles? If not, just remove those blocks from the calipers. It's for rear impact protection, chassis crushes, but the triangles run into the blocks on the calipers, transmits force to the axle....I presume to help protect the gas tank in a big rear impact.
 
Is the spring bowed out towards the rear of the car? You could try unbolting the lower spring mounting bolt, rotate the spring 180 degrees, and secure the nut on the lower spring mount. The rear spring seats are not parallel most of the time, so there is a bending effect on the rear springs. Maybe they're just..."bent"? Hard to tell from that perspective.

Those blocks on the calipers align with the big "crash triangles" bolted to the chassis, using the same bolts as the ones that hold the gas tank in the car. Does that care even have those triangles? If not, just remove those blocks from the calipers. It's for rear impact protection, chassis crushes, but the triangles run into the blocks on the calipers, transmits force to the axle....I presume to help protect the gas tank in a big rear impact.

Springs look ok. I'll see about taking off that block - hoping I don't need to pull the caliper to get to it...
 
I had something similar with the alu diff cover lowest bolt and sway bar making contact. http://forums.turbobricks.com/showthread.php?t=342319
Also had a rubbing securing plate once at the bottom of the springs. It was some simple thick sheetmetal because all the stock ones rusted away. That made so horrible noises i was afraid to accelerate hard!

Ooooh. I know my sway bar is really close to the diff cover, have to pry it out of the way to get to the drain screw. Could be it. Would a '79 sway bar be any different from a '93? Don't think I could get away with just removing mine... :lol:
 
The blocks are just held to the caliper with one bolt. Someone already removed the crash triangles referred to. Use a breaker bar and soak the bolt for awhile. They are usually very tight.

Those blocks hit on some of the volvo accessory wheels. My orion wheels hit the blocks. You can grind the blocks for clearance. But without the crash triangles they are redundant and can be removed.
 
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