Re: What's up with my brakes????
Post by amphi on May 18, 2006, 11:17pm
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Ummm, so what if you've mixed the drums up...any way to get them matched up again?
How do they line'em up in the first place????
Kaiser: I am wondering the same thing? I just think the FD mixed them up or at least didn't keep them aligned as original.
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I have found as the lining on the pad gets thin,it will allow the metal part of the shoe to contact the lip at the back of the braking surface of the drum(inside edge of drum sometimes gets a lip just past where the pad wears) that ridge sticking up from the drum can contact the shoe just past the outer edge of the lining and cause the metallic sound you have described
drvn: Didn't see any evidence of rubbing at the top of the shoes but have to admit I didn't look at the bottom --- could be hitting there. I'll check later. Thanks
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A squeal is a high speed vibration or chatter. Super suggestions above. Can you see any evidence of the brake shoe frame contacting the drum like DKD mentions above? I would doubt you are getting the squeal from the shoe lining and drum. I always lube the raised pads on the backing plate. You could try replacing the brake shoes. Use quality material. I would not turn the drums at this point. They look OK plus they are rare. I scuff them up with some 36 grit and stop easy for a few days. Never had a problem with that method. If you do what I just mentioned, don't glaze the shoes by stopping to hard with all that weight. Stop very easy for about a week. I just did this on my CJ and the brakes work very well.
So... What they said...LOL
thetroublemaster : This low-pitched sound happens at slow speed just before coming to a hard stop. It doesn't sound like metal to metal (no grinding) just a deep squeal. You are right --- I wont have the drums turned but since this is a 4x4 and I can spin the two wheels on one side a time I might try the sticky-backed sandpaper trick on old shoes to true them up a bit. Ever done this?
I definitely will replace the lining with good stuff and follow your advice. Thanks
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Another point on the grease on the shoes is to use the correct grease. Wheel bearing grease will turn watery and run off if it gets too hot. For this reason there is a special high temp grease used for this.
elwenil : Will do. Thanks
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So, once I got all 4 swapped out. I took each hub and drum, put them on the brake lathe and figured out which of the three possible positions had the least amount of run out. I then stamped the hub and drum so I would be able to find it again and turned the drums to smooth. I now have no surge.
barrman: My pea brain is not quite absorbing this!! Did you grab the inside of the hub for center (bearing surface)? Did you turn the drums while mounted to the hubs with the three countersunk screws? Do you think maybe this means the hubs are machined this way at the factory?
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I did however get a very bad squeal from both back brakes when I was done. I could only stop it by backing off the adjusting screw one click at a time, drive it, listen and keep on backing off until each one was not making as much heat. Therefore, I personally feel your squeal is a result of the load you have and maybe one or two of your brakes being adjusted a little bit tighter than the others.
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Remember, drum brakes are not self adjusting and only move as far as the fluid pulse lets them on the first pump. Try pumping the brakes once or even twice the next time you hear the noise. If the noise is gone after a pump or two. Then you have at least one corner not adjusted right and not contributing to your stopping power. You take away 25% of your braking surface when you are already at max gross load and it makes a huge difference.
barman: Great idea I will do this first!!! The sound seems to be from the rear and they are worn a little more than the front. Will give it a go. Thanks
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THEM BRAKE DRUMS HAVE BEEN BLUE HOT. you can see it in the pix. what you,ve done is cristalize your brake shoes. they,ll do it from now on till you change the shoes. thats why semi,s do it because they get em too hot at times like on long down grades or panic stops loaded heavy.
bob
Robert: The color reproduced by the camera is not very good. These drums all look normal -- very bright cast steel color no bluing, crazing, cracks, or scaring. They still have some paint on the inside. The shoes, on the other hand, could be crystallized. I did see some flaking on one edge. Yes they need to be replaced with a good quality lining.
Thanks.
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I had a booster like that once on a Chevy Grain/Farm truck. It works like any of the old 1950's large truck ones, that boost using Vac. Works great when they work.
919maint: Thanks – I have no idea what this came from or where to get parts. It is a single line system hooked to the stock single reservoir master cylinder.
Thank you all for the great advice. I'll keep you posted.