| Author |
Message |
    
Cliff Biggs
Experienced User
Username: cliffy
Post Number: 192
Registered: 09-2021
| | Posted on Thursday, 01 January, 2026 - 14:56: |    |
Just wonderin if anyone has first hand experience replacing the rubber drive shaft u joints on SZ RRs. Mine are of course original and I want to replace them in the next few months. I have the manuals but looking for any first hand comments.
I understand the correct bolts are un-obtainium?
I'm thinking Grade 8 bolts will work- any ideas out there? Reuse the old bolts? Mine are in perfect shape. |
Robert J. Sprauer
Frequent User
Username: wraithman
Post Number: 886
Registered: 11-2017
| | Posted on Friday, 02 January, 2026 - 06:53: | |
Use the originals, ie keep the DNA together. |
Jim Walters
Frequent User
Username: jim_walters
Post Number: 399
Registered: 01-2014
| | Posted on Friday, 02 January, 2026 - 08:25: | |
I've replaced them many times, usually after they have failed. I don't reuse the old bolts, I cut down new SAE grade 8 bolts and use Loctite on them when assembling. The original bolts were fully threaded with no shank so there was not a lot of surface area contacting the sides of the flange bolt holes. I think this contributed to them loosening over time. I cut off the extra threads on longer bolts leaving enough thread for the nuts to torque up with just a couple threads left inside the flange bolt holes so that the shank of the bolts is making full contact through all three flanges. This requires reaming all the bolt holes slightly larger as I use SAE bolts replacing the original Metric ones. This also cleans up minor wear usually evident in the holes. I often see the flange bolt holes worn oval and the spigot on the spigot flange badly worn or even broken off. The rubber bushings in the driveshaft that the spigot locates into are usually shot too. The first indication of failure of any part of the driveshaft coupling assemblies is usually a vibration felt through the seats in the car, the faster you drive the worse the vibration. Before you dismantle the couplings, have a look at both, if they appear to be off centre in relation to the transmission or differential flanges you should order in the spigot bushings for each end of the driveshaft, if badly off centre with torn up couplings you will probably need spigot flanges too. Minor wear in the flange holes will usually be rectified by reaming larger for the SAE bolts I use, excess wear can be welded up and reamed to size. I will sometimes repair the spigot flanges by welding up oval bolt holes and welding in a new spigot pin if the old one has broken off but I have lathes and mills to do this, most will just have to buy new ones if they are damaged. If you are preemptively replacing the couplings before they show wear you can keep with the metric bolts, but I suggest replacing the original fully threaded bolts with shanked bolts. It's just not good engineering practice to have fully threaded bolts through flanges especially in a high shear load application like these driveshaft couplings IMHO.
SRH8505 SRH10557 LRB15211 SRC18015 SRE22493 NAC-05370
www.bristolmotors.com |
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