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73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => Topic started by: BANDOLERO Z-28 on October 17, 2011, 11:04:46 am
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Ok guys so this is what happened, on Saturday I asked my wife to drive my truck as I followed her in my Camaro so I could check out my truck on the road, well I was devastated the back tires don’t trail straight, I was like "ahhh man the frame is warped!!!”. So we got home and I got underneath only to discover that the passenger side U-bolt that holds the rear diff. in place with the leaf springs came loose and the diff. slipped back about 2 inches.
To fix this, do I just lift the truck, slip the diff. back in place, and retighten the bolts? Is there any special thing I have to do? Do these bolts have to be at a certain torque? Thanks a lot for the help
I’ll take some before and after pictures tonight when I get to fixing it
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I would put everything back where it belongs and tighten it down. You'll want to check them (depending on how often you drive it) fairly regularly until they don't tighten up anymore. U bolts tend to stretch some, so it may not be that the nut backed off, the bolt itself could have stretched enough to allow this to happen.
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Also, make sure everything is ok with the center pin on your leaf spring. If it looks damaged, I would consider replacing it. It's not difficult or expensive.
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At minimum I would jack up the truck enough to raise the spring an inch or two. You need to make sure the spring pin drops in to the receptacle of the support thats is welded to the axle housing. Then buy new springs nut, enough to double nut the u-bolts.
Or, you could yank that sucker out of there and do a spring pin.
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Remember, as Isaac said, you have to be certain the pin is not sheared. it will not be obvious because the brake would be concealed by the leafs. If your sure the problem was caused by the nuts backing off, then our repairs mentioned before will work. But, it been my experience the spring pin is probably sheared. Look perpendicular to the spring you should be able to tell if the top and bottom of the spring pin Is travailing straight through the spring.
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the head of the center bolt is about 1/4"+ so the bolts would have to back off a bit for the spring to back off without damaging the head. take the nuts to the spring off then jack up the frame and inspect the head might be in the axle perch
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Also, make sure everything is ok with the center pin on your leaf spring. If it looks damaged, I would consider replacing it. It's not difficult or expensive.
If it moved 2 ", then I am with Irish, your center pin is probably not attached to your spring no more.
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You should get new U bolts as well. I have reused them before but only if they are in like new condition. Even then you are not supossed to.
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Thanks to everyone for the help, I was able to work on my 78 last night. I lifted the truck, and put everything back in place, the nuts on the u-bolts had backed up enough to cause the problem. I checked the spring pin and it was a goner, someone had replaced it with a bolt. I went to autozone and just like any good auto parts store they didn’t have the spring pin, so I replaced it for now with a new bolt. Tighten everything and she is back on the road again.
Does anyone know where I can buy a spring pin?
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i ended up buying a bolt for mine then ground the head round looked and still is the new center bolt
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If you go that route, I'd go with either a grade 8 or hardened bolt. Their sheer strength is alot higher than the grade 5 stuff at home depot.
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never would i use anything lower than 8 ace hardware has them. now if its a odd bolt for something thats not holding any weight if i cant find 8 then i go with the next best thing. but 8s is my first stop just to be on the safe side