Squealing and reduced brake effectiveness after driveshaft rebuild

[Boris61]

Like the title says I rebuilt the driveshaft (all parts) on my 84 5-speed. I also replaced pinion seal (set bearing preload to 12" rolling torque), replaced outer tie rod ends and installed Koni yellow shocks on rear and readjusted the handbrake. Handles better, but normal braking is much worse and I get noise that sounds like a brake squeal when I brake moderately or corner to the right. My first concern was insufficient pinion preload, but from the videos I found that is a different noise all together and in any case it shouldn't affect breaking. I tried not to stretch the brake hose and disconnected the compensator actuator rod and supported the axle with a transmission jack while on the lift. Any idea what I could have messed up? I'm afraid to drive it now. Thanks!

[Boris61]

I guess I must've really screwed it up if no one in this vast sea of knowledge has a suggestion. Anyone here near Indianapolis that can check it out with me and help me figure out what's wrong? Or any suggestions for a Fiat mechanic in central Indiana?

[klweimer]

Alright Boris 61, I'll bite. Is it possible you kinked a hard brake line when you had the various brake calipers off to replace parts? Is the brake fluid level OK? Checked all the lines for leaks? You should also check the linkages that actuate the proportioning valve that sits above the rear axle. This linkage should move when the rear axle moves up and down, relative to the body of the car. You might also make sure none of your brake calipers are dragging. Dragging brakes will heat up the pad and can cause fading of the brakes. Jack up each wheel one at a time and see if the wheel moves easily. You might check after you've been driving and noticing the symptoms. Did you disconnect the emergency brake when you did your rear end work? Is the e-brake working correctly now? Did you do anything directly to the brakes when you did your other work? Bleeding? Changed pads?
Kirk

[lglade]

Sounds like you may have a couple of unrelated issues going on. Are you still driving with on your car's original brake flex hoses? I've seen several postings that described brake issues caused by old hoses that were collapsed on the inside. When you swapped out the shocks you may have inadvertently caused the rear hoses to fail. You might start with some new flex hoses and a good bleeding all around to see if you can restore brake function. I'd start with the brakes and then see what symptoms remained before trying to fix anything else.

And +1 to Kirk's points too. Since you were working under the car, you should thoroughly inspect your hard brake lines to see if something might have gotten kinked during the prior work.

[DieselSpider]

You did a lot in one shot.

Who aligned the car after you replaced the tie rod ends? The car needs to be laden with 150 lbs in each front seat and about 140 lbs in the trunk with the wheels on the ground when you align it per the owners manuals specs or the tires will toe out when you sit in it and squeal when you corner or brake. If the alignment is really bad the tires can rub on the frame and squeal during tight corners.

Were the front wheel bearings cleaned and packed with fresh grease while you were at it? If not they could be loose and causing the front brakes to squeal too.

If you mixed brake fluids you could cause the rubber brake lines to come apart internally reducing braking effectiveness. Best practice is to flush any old fluid out completely and refill to ensure that you have no reactions between old and new brake fluid. If you opened up the brake system while doing any of the work a pressure or vacuum bleeder is usually the best tool to ensure that the brakes get properly bled. Note that the rear axle must be supporting the weight of the car so the brake compensator will be opened in order to bleed the rear brakes as the compensator will basically turn off the flow of brake fluid to the rear brakes to prevent the wheels from being fully locked when they loose contact with the road during heavy braking or when the rear wheels are not touching the ground.

If you got the brake rotors greasy or oily and did not clean them before putting the brakes back this could also cause reduced braking efficiency. Even greasy finger prints can leave enough lubricant behind to impact brake performance.

If you changed the rear brake pads while you were at it did you turn the brake pistons back in on the self adjusters? If not then the brakes will be out of proper adjustment.

You need to verify that the brake compensator was properly reattached and go through each item you touched individually front to back since you did quite a bit more than simply rebuild the drive shaft.

[bluespider262]

Did you pull the axle shafts/carrier before settling on that pinion preload? That in/lb figure for pinion rotation is basically for the pinion assembly by itself, not acting on any other parts like the ring gear, axle shafts, etc. So its actually way too loose if you had the ring gear/shafts installed at the time and tightened until 12 in/lbs of rotation.

Not the FSM, but looks ballpark in procedure and torque specs. vs. other axles I've setup (Dana, Ford 8.:

http://vintage.mitchell1.com/PClubData/ ... 828034.pdf

[Boris61]

Wow! Thanks folks! You all make some great points and I'll check all of the above. I did not do any brake work except disconnecting the e- brake to get to the driveshaft. I did check all pads and they were good. I should've did one thing at a time to avoid this sort of situation. As was mentioned, I may have more than one issue. Of the above advice/ suggestions I think that the alignment and/or the pinion pre-load are likely to be the cause(s). I haven't had the alignment done after the tie rod ends (based on turns counted and threads showing I don't think it is too far off though) and I set the pinion nut torque with the axles and brake rotors on so it may not be correct. I have new brake lines to install later but I was really careful to support the rear end so it didn't hang and I disconnected the compensator linkage beforehand. I will get an alignment done ( I can't believe I didn't think of that myself) but I really don't know how to proceed to properly set the pinion nut torque. I've read a lot of posts here and other places and it didn't look like too bad of a job. Any suggestions? Should I just take it to a mechanic? Aside from the noises, the new Konis and driveshaft parts really paid off and I'm itching to drive!

[bluespider262]

If you can get someone to measure rotation torque with brake calipers and tires removed, that would probably be good enough. It'll probably be 150-180 in pounds with the carrier and shafts installed, i'm guessing. I know just the carrier/ring will put it at 40-80 in lbs usually.

Or just loctite red and as tight as you can get it with a hand wrench. 75-100 ft lbs or so but I wouldnt go higher. No impact tools. You gotta really torque down on it to get the sleeve to crush more usually (which you want to avoid.) Do this i think you'll be fine - you aren't the first one to not measure it before tearing it off. I've stumbled across loose pinion nuts. You don't have much choice in those cases if you don't want to rip the whole axle apart (which usually triggers the costly "while I'm in there " syndrome.)

Just keep an eye on it and if it does come loose you'll hear it start to groan on accel or decel long before it does any long term damage (unless you neglect that.) In that case go 20 lbs tighter than previous.

[Boris61]

Thanks for the help blue spider. I did use an impact wrench on the pinion nut but on med power (75' lbs or so). Then I used a breaker bar and put more torque on the nut and tested the rolling torque. Then turned a little more and retested until I settled on 12" lbs. No howling noises there so I'm gonna start with alignment and brake line inspection as suggested above and if any diff issues remain I'll follow your advice and lighten up the moving parts and reset. I have front shocks to install too. I don't think that should affect the alignment. Do you? If so I will do that before I get it aligned.

[Boris61]

Ok. I put front shocks on today and adjusted the tow-in by eye so it could be driven to a shop. It was definitely way off. So that was probably causing the squealing. As for the shocks, I have a couple of questions that I couldn't answer with the search function. First, I installed KYB Excel shocks (AR) and there were no bottom bushings like the Wayassauto originals have. Second the top bushings were much smaller in diameter and thicker and don't seat in the cup in the shock tower like OEM. Anyone experience this? If so how did you proceed? I installed as instructed but I suppose I could have reused the original top bushings but now that would mean starting over and those upper nuts are a real PITA!