Question about Disc Brake Rotors

[Sporto]

Just a quick question about the rotors on my 70, that are from the GM kits the vendors sell. I am getting ready to tear down each side to swap pads, because I am getting a shuddering when I slow down to a stop. I am thinking of having the rotors turned just to make sure I get all of the potential culprits. I was looking at replacement rotors as they are from other Fords and are not that expensive and may be easier than taking these to a machine shop.

Anyway, my question is, the rotors in the kit are attached to the hub, and I see that I can buy just the rotor and not the whole hub online. Is it difficult to separate the two pieces to swap just the rotor? I don't remember doing that before or how they came together when we did the upgrade, but I am wondering what the process is to separate the hub from the rotor and if I can do that in my garage without special equipment.

Thanks for any insight.

Rich

 

[SteveL]

Easy enough to do. Just knock out the wheel studs and they come apart.

 

[Sporto]

Thanks Steve, I was hoping it was something like that, but I didn't want to get in over my head without understanding what was involved. Getting it ready for Tennessee, and I need to keep the project scopes from creeping on me!



Rich

 

[Rustytruck]

with the shuddering check the gap between the knuckle and the calipers. as the pads wear the caliper moves closer to the knuckle. as some point if they touch you will not get good contact between the caliper piston and the pads not allowing proper pressure with the rotor.

 

[Sporto]

with the shuddering check the gap between the knuckle and the calipers. as the pads wear the caliper moves closer to the knuckle. as some point if they touch you will not get good contact between the caliper piston and the pads not allowing proper pressure with the rotor.

Thanks for the info, so will new pads correct this or should I look at grinding the knuckles down more? I recall having to do this when I installed them on my 44.

Thanks

Rich

 

[DirtDonk]

New pads might be a temporary fix, but that's all it would be. The idea is to be able to continue to use the brakes even when the pads are wearing down. So ultimately no matter what, the knuckle has to be ground sufficiently for caliper clearance. Period.

Proper grinding is part of a proper install first and foremost.
In a pinch new thicker pads might put you back where you were, but to avoid the problem in the future you would still want to grind when you get the time.

That all said, if you have not already taken things apart, look down from the top side and see if you still have clearance between the two parts. If you do, then clearance is not your problem and you simply have warped rotors or uneven wear of some kind, or some other issue. But if you don't see daylight between the caliper and knuckle, then even if it's not the direct cause of your immediate symptom, it's still an immediate problem in need of a fix.

Paul

 

[Apogee]

You'll want to make sure that the knuckles are ground enough to accommodate pad wear down to at least 20%-25% new thickness, as this is when most friction manufacturers recommend replacing pads for optimal performance. Some will grind enough to accommodate wear down to the brake pad backing plates, but short of an oversight, your pads should never be allowed to get that low IMO.

 

[DirtDonk]

What? You don't run them until you see the cooling fins inside the rotors exposed to daylight? Man, you're not getting all your money's worth outta' the brake pads then!;D

Kidding of course. But I speak from experience of seeing several trucks run down to the fins over the years. One time by an older guy that you'd think should'a known better, but did finally say, 'Yeah, we heard some noises but didn't think nothin' of them 'till now." Oy!
Full size Suburban with about 130k miles on the clock, and they'd never serviced the bearings, hubs or brakes!

Paul

 

[Sporto]

Thanks for this valuable info. I have not torn them down yet, so I will study the knuckles and calipers to see if this is the issue. Something tells me that it is a contributing factor, as the rotors and pads probably 10K miles on them at the most. If so, I will take them apart and do some grinding to add some more clearance as suggested.

Thanks to everyone, I will post what I find out.

Rich

 

[Sporto]

Well, I have to say you all know your biz! I just looked at both sides, and driver's side knuckle and caliper are about 1/16" apart but I can see daylight, and the passenger side is touching the knuckle as predicted.

I am going to go ahead and redo the pads and turn/replace the rotors, since I am already there. The directions suggest 1/8" gap, so I will work with that number and grind some more off the knuckle if needed.

Thanks again,

Rich

 

[garberz]

These are what I used, probably the only repops available.

http://https://www.rockauto.com/en/catalog/ford,1979,bronco,5.8l+351cid+v8,1105625,brake+&+wheel+hub,rotor,1896

Mark