• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

TR6 A few dumb TR6 brake questions

Share this page

I

ichthos

Darth Vader
Country flag
Offline
As I dismantle the suspension and steering in my car, I keep finding more new things to deal with. My front brakes have always squeeled since I have owned the car. When I pulled the front rotor, I noticed that someone appears to have hit the inside surface with something. There are about 20 small dents about 1/16" wide in a one by four inch area, but fairly shallow. My first question is can I take this in to get it surfaced out of the car? Can it still be attached to the wheel hub to get this done? (I can't seem to get the four bolts loose that hold the hub to the rotor). Also, I have the anti-squeel strips that I read are used to stop the front brakes from squeeling, but can someone tell me where they go?
Thanks, Kevin
 
My neighbor let me borrow his impact wrench, so I was able to separate the wheel from the hub. Can I take in the rotor by itself to get it surfaced? Where is this normally done? I also still need to know where the anti-squeel strips go.
Thanks, Kevin
 
Well.... You actually wanted to keep the rotor on the hub to have it machined. the shop will use the bearing races in the hub to center the rotor on the lathe.
It all depends on the minimum thickness specification of that rotor if it can be resurfaced or not. Hopefully that spec is stamped on the edge of the rotor, if not, a shop may be willing to try the machining, or they may refuse saying they have no way of knowing if they are taking it beyond safe limits.
Personally, if I wasen't 100 % sure of that stuff, I'd replace the rotors. all those little dimples sound like someones attempt with a hammer to remove the rotor at one point. I'd be concerned if that had induced any stress cracks into the rotor.
It may cost a bit more, but brakes are not something to cheap out on.
Post a pic of the strips if you can. there are dozens of anti squeal devices out there. without seeing them, it's hard to say how they fit.
 
Banjo is right. Those "dings" do not belong there and how they got there is troubling. For safety's sake, I'd replace the rotors, rather than spending money trying to cut them. There isn't that much metal there to begin with and making them any thinner will allow them to overheat and distort even faster if any hard braking takes place.
 
IIRC the manual only allows .060" off the rotors (.030" per side) before replacing them. If they are older rotors, they may well have worn more than that.
 
Sorry, more questions. Are rotors normally routinely surfaced when you replace the pads like you do on brake drums when you put in new shoes? How does a machine shop know the minimum thickness for a rotor? I could not find any markings on the rotor that would specify this. I am doing one side at a time, and have not looked on the inside surface of the passenger side rotor. Do both rotors have to be the exact same thickness, or will varying thicknesses between the right and left rotors cause uneven braking? I am sure the dings on the one side are at least .030" deep, so I imagine this means it is garbage at this point. I am guessing that replacing only one side with a new rotor would not make sense, and the consensus from your posts would be to just replace the rotors. This leads me to the next series of questions.

I looked at the price of a new rotor in a couple of the big three, and they run about between $30-40 for "stock" or "aftermarket" grade. Of course they have rotors that are "slotted" that run about $75 and some that are cross drilled/slotted that cost about $100. I agree that one should not cut corners on brakes, however, do the upgraded rotors really gain me anything? My car is stock. I drive it hard, but I do not race it.

Kevin
 
Slotting / drilling and all sorts of other games only make it more likely that the disks will crack.... Get the standard ones.
 
ichthos said:
Sorry, more questions. Are rotors normally routinely surfaced when you replace the pads like you do on brake drums when you put in new shoes?
Click to expand...
If you do that for drums, you likely do it for rotors as well. Personally, I just scuff the surface to remove any glaze and don't have them machined unless there is a specific problem I'm trying to solve. .030" isn't much, and it's all that stands between brand new and worn out. Throwing away .005" to .010" of it doesn't seem wise to me.<div class="ubbcode-block"><div class="ubbcode-header">Quote:] How does a machine shop know the minimum thickness for a rotor?[/QUOTE]Good question. They should have a book that lists it, but if not, they may ask you to supply the information, or simply ignore it. I've had it go both ways.<div class="ubbcode-block"><div class="ubbcode-header">Quote:] I could not find any markings on the rotor that would specify this.[/QUOTE]Owner's Workshop Manual TR5-TR250-TR6 1967-1975; page 97 'The minimum thickness allowed for rotors is .440"'
Long time ago, a friend of mine measured his brand new rotors and reported they were just a smidgeon over .500", hence .060" for surfacing.<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Do both rotors have to be the exact same thickness[/QUOTE]Nope. One at wear limit and the other brand new will work fine. They actually continue working even well beyond the wear limit, just a higher chance of overheating or warping. I've seen people run them under 1/4" with no reported problems.<div class="ubbcode-block"><div class="ubbcode-header">Quote:]I am guessing that replacing only one side with a new rotor would not make sense[/QUOTE]Kind of depends on your point of view, I usually only replace the damaged one.<div class="ubbcode-block"><div class="ubbcode-header">Quote:] however, do the upgraded rotors really gain me anything? [/QUOTE]IMO, no. They were quite the fad for racing, but I think even the racers are discovering that they don't work any better than non-drilled/slotted. Less braking surface means more heat per square inch and surface temperature is the critical parameter; the improved cooling doesn't make up for that.

If you do need more cooling, there is a conversion around that uses vented rotors from a Toyota truck. But they add more unsprung weight, so there's a tradeoff there. And racing compound on the pads should accomplish pretty much the same thing (tho they aren't necessarily recommended for the street).
 
Thanks for all the information everyone. Thanks for the specs, Randall. Good thing you don't live closer. I'd probably be at your house every week bugging you to help me with my car.

Kevin
 
Back
Top