Hey, Guys... just getting my baby, "The Judge" on the road, and have run into a problem that I'm concerned about. I figured that the brakes would be a little rough since in the last 3 or 4 years she's just been sitting, and the disks were pretty rusty... She makes a "shudder/squeal/rumble/vibration" sound mostly on the passenger side of the rear end/brake disk/axle. Before the attached video, I sprayed the disks/pads pretty heavily with brake cleaner, but it did not seem to make any difference in the noise/sounds. Anybody run into this and fixed it??? I also seemed to have erred in selection of a brake proportional valve as it seems I barely have front brakes, which are stock S-10's. Anybody have a specific recommendation for the correct proportional valve? I've watched some YouTubes and read about putting an adjustable "pressure reducer" on the rear brakes, too... Just have to get all this planned out before I go tearing out what I've already done.....In the video, when in reverse, there is a whine that is loudest at the passenger side wheel. The vid first part is in drive, then in reverse. Thanks for anybody's recommendations on where to start... https://49fordcoupe.smugmug.com/Rebuilding-the-Jag-Rear-End/i-9Q6wrjS/A
On the proportioning valve there are adjustable ones available that don't cost all that much. Shudder when? Just when applying the brakes or all the time? If it is when I'd think the normal check for runout or a warped rotor. If the rear came out of a wreck or unknown source I'd be having it turned to clean it up before going further. At least check it with a dial indicator. If it happens when you are running down the road and not applying the brakes I'd go back to figuring out what damage might have happened before the rear was pulled from the donor or why it became a donor. It may have been tweaked a tad in a crash.
As you can tell from the video it does it all the time but changes to more of a grinding sound when I apply the brakes. If you will check the rest of that gallery where that video is you can see that I rebuilt the entire system using a Snow White kit. We can all assume that Rusty discs cause sound problem but over the years other cars I have had with Rusty discs May Grunt a little while but pretty much clear up in a few hundred yards of driving
Check the runout on the rear discs, and replace if needed. Because these are fixed (as opposed to 'floating') calipers, they really don't like any rotor runout. Try prying the brake pads clear of the rotors and see if the noise goes away. Make sure the parking brake pads aren't dragging too. If the noise doesn't disappear after clearing the pads, then you have a bearing issue. Make sure the alignment shims are installed on the outboard side of the rotors. As to the poor brake balance, what master cylinder are you using? Firewall mounted or under floor? Residual pressure valves?
Everything is brand new including the discs, bearings, bushings, spacers, etc. I was just wondering if there is a peculiar characteristic that these things exhibit if there's just something not done right.
"Everything is brand new including the discs, bearings, bushings, spacers, etc." Did you test it at all 4 years ago? Sometimes my cars wake up half dead or worse. Gently, and carefully Cleaning the rust off the disks, checking rotor runout with a dial indicator, and parallelism wtih a micrometer, and prying gently to reveal any seized pistons is where I'd start.
The Jag rear suspension is a pretty stout assembly, but being more complicated than a standard live axle, there's definitely more room for assembly errors. If you've been into the stub axle/outboard carrier bearings, I'd think about rechecking bearing pre-load as that's critical on these. If the noise isn't the brakes, it's the bearings.... And new or not, I'd still check rotor runout.
Did you put a bevel on the parking brake pads, they need to be set up that way, could be the cause? That long ago I can't remember when I did mine, 15yrs now. The brake pads are no issue however the parking brake pads need to be done correctly. Just a thought? Also make sure the rear hub bearings are set right and torqued to spec with the correct shims on the inside bearing shoulder.
I'd be retesting it with axle stands under the bottom arms so that the driveshafts are in their correct operating position - you appear to have the suspension on full droop and that's pushing the uj's towards an unhappy place. Alternatively, the yoke and drive flanges can to touch eachother at the extremes of travel - maybe you're experiencing just the beginnings of that? Either way it's a free trial that may or may not reveal something? Chris
Thanks , Stumpy . no I don't remember doing anything with the parking brake pads but I barely remember they may have had a chamfer on them when I bought them. When I can get back to it I will be sanding the discs first. Correct me if I'm wrong but aren't the shims there to adjust the Caster camber or whatever the hell you call it on the wheels?
thanks Chris but the sound is exactly the same way whether I'm driving down the road or on jack stands
For what it's worth my first plan is to sand the discs check it again then relieve the parking brake as far as I can and check it again. Just to try to pinpoint the source
Though I could have screwed something up I was very careful with the crush sleeve and torquing everything to specs
If I recall correctly removing the handbrake (parking / emergency) pads isn't a big job and it'll run fine without them (for testing / elimination purposes only, of course). Worth a try. Chris
PROBLEM SOLVED, GUYS ! Thanks for all the advice. I sanded the discs with it running, no effect. Got my stethoscope out, nothing on the emergency brake caliper, nothing on the main caliper, touched the top mount of the rear spring upper mount. BANG... touched the upper mount of front spring and it nearly busted my eardrums...well, I had Curt Hamilton in Calif to cut down my lower control arms and build me new axles (they are BIG A$$ AXLES), and it seems the axle is in contact with the front spring on both sides. EEEEASY fix. A couple of washers on both ends of the shock/spring mount....check out the pics... https://49fordcoupe.smugmug.com/Rebuilding-the-Jag-Rear-End/i-S82vN5Q/A
Those coils seem to be larger diameter than mine in the photo. I have cast 1/2 shafts and I've seen other Jags with larger diameter tube 1/2 shafts and the coils clear them. Did someone narrow the distance between mounting flanges to bring the coils closer together? FYI, there are 2 x styles of OEM rear brakes, Girling and Dunlop. There are also 2 x types of OEM coilovers.
Thanks again, Stumpy... I have the type on the lower part of your picture. The assembly is said to be a '85 XJS... anyway, I just put those washers on the mounts to move the shock about 3/16" further away from the axle...no more weird sounds ..... Had I been a bit more observant, or thought about what it sounds like for something to be rubbing on a spring, I'd have figured it out days ago....ahahahah
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