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Just had the original diff rebuilt and have it all mounted except for the leaf springs. I decided to order replacement bolts for mounting to the diff. Ordered the 3.5" bolts for this 9 leaf spring from a major supplier. The original bolts measure 3.5" from the tip of the threads to the top of the head. As you can see from the attached photos that the new bolts are about .25" longer than the originals. Leaf spring, bolts, mounting bracket and diff are all original. I read about the critical nature of the bolt lengths to avoid damaging the diff case. Will the new bolts be too long?
Thanks
Mike
Last edited by mtcarl; Yesterday at 02:30 PM.
Reason: replaced photos
I've had one bolt break at the half-shaft yoke cap and one at the end of the rear stabilizer to the bracket on the trailing arm. Took a lot of work to get the broken stub out of the (brand new) yoke. Both were original bolts and before reaching torque.value. You might say I'm a little gun shy. Maybe I'll try to rig up a bench test to see if the original bolts can make it to 60 ft lbs. Another option might be to cut off the new bolts to match the originals. Return postage for the new bolts probably won't leave much credit.
Inside a rear cover that had the wrong bolts installed. Cracked the boss, oil leaked out, cover was wrecked.
Check hole depth, spring thickness, thread length to figure if it will work.
From: At my Bar drinking and wrenching in Lafayette Colorado
Originally Posted by mtcarl
Just had the original diff rebuilt and have it all mounted except for the leaf springs. I decided to order replacement bolts for mounting to the diff. Ordered the 3.5" bolts for this 9 leaf spring from a major supplier. The original bolts measure 3.5" from the tip of the threads to the top of the head. As you can see from the attached photos that the new bolts are about .25" longer than the originals. Leaf spring, bolts, mounting bracket and diff are all original. I read about the critical nature of the bolt lengths to avoid damaging the diff case. Will the new bolts be too long?
Thanks
Mike
Why don't you just shorten the new bolts to the correct length? It would take about 5 minutes, which is less time than you've spent discussing the matter on this thread...
Your original bolts were fabricated in the USA by a company based in the USA to SAE J429/ASTM 354 standards. In today’s world, I doubt most suppliers are willing (or able) to identify the source of what is sold, let alone the specifications to what material they are fabricated from and the manufacturing standards.
From your pictures, I would not hesitate a New York minute to reinstall them.
69 Leaf Spring Bolts at Diff
