rear hub temp high

[billcarson]

replaced my trailing arm bushings with rubber and noticed a world of difference in high speed handling.that's the good news.i have always monitored the hub bearing temp with my gun and have had around 110* front and 120* rear after a highway drive of 30 miles or so.right after the install i now run 50* hotter on the passenger rear than the drivers rear side hub.there does not seem to be more than the usual slight rub from the parking brake and the regular brakes.any ideas?

[gtr1999]

Did you replace the braking brake shoes and install SS hardware? I have to mod every new SS hardware kit I use to allow the shoes to fully collapse otherwise I found the shoes may drag a little. If you didn't and the arms are the same other then new bushings then I would look at the bearings.
Make sure you can complete collapse the shoes, leave them like that and do a test drive to see if the temps go back to where they were. I had a dragging shoe on my 69 years ago and a short drive was enough to cause the spindles to get hot to the touch. I did the same test as above and found that was the problem.

[Sly Vette]

There has to be a bit more parking brake resistance on the hot side. 50 degrees really isn't much though. Back off the self-adjusters on both sides and check it again. I am guessing they will be equal and cool.
I had a similar problem just after my restoration due to the return spring on the parking brake cable being in the wrong position on 1 side.
If this does not solve your problem you may have a caliper hanging up on the hot side due to a sticking piston or a collapsed hose. Maybe even a bad proportioning valve.
Good Luck!

[billcarson]

thanks for the quick response.i did nothing to the parking brake assembly at all and the original rivets are still in place on the rotor.can the bearings go bad so quick?my last hub reading was right before i did the bushing job and the temp was the same as the drivers side. btw no play at all at the wheel and no noise.

[billcarson]

i replaced the two rear brake hoses and felt the shoe at the rotor and was able to move it a little so i don't think it's that.the parking brake however has never been serviced and i plan on drilling out the rivets thursday,next day off.can a slightly dragging pb shoe cause a 50* temp increase?it was 164* at the hub.

[TimAT]

How is the rear alignment? Maybe possible for one side to have too much toe in/out and putting a little side load on the bearings. Just a thought.

[gmjunkie]

Originally Posted by TimAT

How is the rear alignment? Maybe possible for one side to have too much toe in/out and putting a little side load on the bearings. Just a thought.

[billcarson]

timat i had a rear toe out of 1/4" after the initial reinstall of the trailing arms.when first tested it ran hot and now with 1/16" rear toe in it still is 50* plus over the drivers side.thursday i will drill out the rotors and inspect the parking brake assembly.my question now is how much heat can possibly be generated by a bearing that makes no noise or has no play?seems to me that a dragging brake pad should be able to generate much more heat. gtr1999 i will try your suggestion on moving back the shoes and recheck the temperature then.

[6t9ttop]

I would fully retract the shoes with the star wheel on the hot side and take another drive test to completely eliminate that variable. If it turns out to be the PB shoes than correct as needed.

[billcarson]

i took another reading on the hubs after a short drive,without doing anything,and noticed a drop in the pass rear hub temp.(35* or so hotter)(from over 50*).i felt the inner shoe on that caliper rubbing more than the others so i bled the brakes again,realigned the rear wheels again to closer specs,(1/16" rear toe in),and tested again.now only 15* hotter.i put my ir gun on the rear bearing carrier and the difference is only around 7* at that point.this is not a bearing issue and it would seem that breaks can heat up a hub pretty fast.i never drilled out the rotors or adjusted the parking break.just wanted to get back to all and hope it may help someone.thanks!

[gtr1999]

The parking brake can cause a lot of problem, more then they are worth in my opinion. When I did my 69 I had them setup to hold the car locked on a 30* incline. The wheels were free yet the shake down cruise revealed the shoes were too tight and in short order the spindles were HOT. Readjusted them and were fine. I think you found your answer.

The only concern I have with 30-40 year old arms never touched is with the original grease in there. I posted pictures a few months ago of virgin '66 arms I took apart. They were mint shape but the grease was gone inside, if the car was driven like that the bearings would have failed for sure. The grease used 35-40 years ago was good but it wasn't as good as the greases today and usually is either gone or caked into a wax like ball- both useless for the intended purpose.

[billcarson]

gtr1999,yes i agree with you on the parking brake and while i would like to have it work i am not willing to overheat my 35 year old bearings to get them to hold better.funny i never thought to take bearing carrier temp readings originally as that would have led me faster in the right direction.they do not heat up as much as the rotor and exterior hub.i know the rear bearings must be done soon as i have 92k on her and it's only a matter of time.we might meet then.thanks for your help.

[billcarson]

just an update on this post.i never did open up the rear rotors for fear of a runout problem.i replaced all brake hoses and all calipers.flushed fresh fluid through lines and gravity bled then pedal bled the system.all hubs are cooler by 20* and within 5* in temp of eachother.clearly this was an issue with a dragging brake shoe and not bearing related.

[Sly Vette]

Thank you for the update. Glad all worked out well for you.