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Brake Issues |
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5808 |
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Posted: Sep/29/2022 at 7:12am |
I was in two minds over posting this in the brake section or here, but it is pretty much a drag race related issue, so I think more appropriate here. I did a quick bleed on the front brakes at the track, which helped a bit, maybe not 100% back to normal, but after this had massive front wheel/brake shudder when pulling up at the end of the strip. I am thinking the front brakes are overheating, on initial brake application they are ok and don't shudder, but the the shuddering gets progressively worse as I slow down. Otherwise I guess it's possible I may have toasted the pads and/or warped the rotors. I'm thinking another possibility is that the rear brakes are not pulling their weight, I did mess with the rear brake proportioning valve when I was doing the circuit work. I have since bled and adjusted the rear brakes and set the proportioning valve to give maximum rear braking effort within it's range of adjustment, however can't test this until next time I go to the track. I am currently running the factory Kelsey Hays front calipers and rotors with AMC 20 rear with 10" x 1.5" drums and factory boosted master cylinder. Braking is from 115-120 mph at the end of the run. Not sure at what point you need something better than factory brakes? Any thoughts?
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I've finally given up drinking for good...........now I only drink for evil.
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PROSTOCKTOM
Supporter of TheAMCForum Joined: Jun/20/2010 Location: Indiana Status: Offline Points: 2458 |
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I am going to guess you've wrapped the front rotors. For what it's worth 1.5" rear drums are really skinny. I have used a lot of 10" x 2.5" Mopar rear drums for drag racing rear brakes. When selecting brake shoes it's much better to have shoes that have the linnings riveted on than the ones that are just bonded. Sounds like a new winter project in the works.
Tom
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Molnar Technologies Full Service Dealer - Crankshafts & Connecting Rods
1969 AMC Rambler Rouge Race Car 1974 AMC Hornet Hatchback, Wally Booth Outlaw Nostalgic Pro Stock Race Car Project |
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5808 |
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Bugger, the season is just starting here, maybe machine the rotors and add some new pads. Correction on the brake shoes, they would be 10" x 1.75" factory spec, I do have some 2.5" rear brakes from a Matador here, maybe that is a worthwhile upgrade assuming they are a bolt on. I'd like to do Wilwood or Aerospace up front one day, but mostly from the weight saving perspective, i.e. 11" not some fancy bigger stuff..
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I've finally given up drinking for good...........now I only drink for evil.
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PROSTOCKTOM
Supporter of TheAMCForum Joined: Jun/20/2010 Location: Indiana Status: Offline Points: 2458 |
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If you can get the 2.5" wide brakes on the rear you'll be surprised how much more braking you'll have for very little time and investment. Try and find the riveted shoes when you change ove. Footbraking bonded shoes has a way of breaking the linings loose on the shoes. If changing the fronts I would use a Wilwood kit if you plan to spend the money. I have several friends that have used the Aerospace kits and had issues with them in the past. Plus finding Wilwood replacement parts is probably a lot easier to source.
Tom
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Molnar Technologies Full Service Dealer - Crankshafts & Connecting Rods
1969 AMC Rambler Rouge Race Car 1974 AMC Hornet Hatchback, Wally Booth Outlaw Nostalgic Pro Stock Race Car Project |
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jcisworthy
AMC Addicted Joined: Jul/23/2009 Location: North Carolina Status: Online Points: 2805 |
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Scarebird used to offer a conversion using Ford Sport Track rotors at around 12" but the only listing now is for a 10".
I would imagine they can provide the brackets being they used to offer a kit I have their older kit using 10" Ford Ranger rotors with rear discs and an 8-3/4 rear now. Stops great now but I do want to upgrade to larger fronts being the rears are 11"
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Specializing in dyno services, engine building, and cylinder head porting
rbjracing.com Phone Number 518-915-3203 |
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5808 |
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I've had a look through the parts catalogue and from what I can tell the 10" x 2.5" factory rear drums use a different backing plate to 10" x 1.75", assumed they would and this makes it a bit of a pain to swap over with the Moser axles unless there is a way to do it without removing the wheel bearings?
I've done a little bit of work around the front brakes previously and the Wilwood 11" kit is 42 lbs vs the factory Kelsey Hays setup at around 72 lbs, so a worthwhile weight saving from both the alloy calibers and hubs as well as hopefully stopping a bit better, which is probably why I'm leaning in that direction offset by the fact they cost a bit.
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I've finally given up drinking for good...........now I only drink for evil.
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5808 |
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Pulled the front rotors, definitely looking a bit sad: Might be a bit of a hairline crack happening here too: They measure 0.970" and 0.960", the minimum thickness is 0.940", so might have to have a look through the spare parts bin to see if I have some better ones before I break the bank on an upgrade.
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I've finally given up drinking for good...........now I only drink for evil.
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amxron
AMC Nut Joined: Nov/18/2011 Status: Offline Points: 295 |
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A trick I used on my Henry's axles is to open up the backing plate hole to the size of the bearing and make a plate from 1/8" steel to put between the bearing and axle flange to secure it. You can now pull the axles to check the bearings. Another trick is to paint a stripe along the axle shaft length to check for twist.
Good luck, Ron.
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AMXron
Fleet/Jeep Mgr. Orbit AMC/Jeep 50-1787 |
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5808 |
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Decided that the rotor wasn't cracked in the end, so skimmed the rotors, added new pads and wheel bearings, seems better now. Probably take a couple of meetings to bed the pads in.
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I've finally given up drinking for good...........now I only drink for evil.
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