two piece brake rotor assembly Q's
 

Need answers ASAP :D on assembling a two piece rotor set, i.e., bolting a rotor to an alloy hat. Both hat and rotor are new.

1) What kind of loctite? AL hat, steel rotor (duh) Bolts threaded into the rotor

2) What is the torque spec for the mounting bolts

3) Do you use the usual star pattern tightening sequence? Is there an intermediate torque spec before full tightening?

I've seen folks warp brand new rotors by not getting the assembly quiet rigth so I want to do this right

TIA
Crispy

Just assemble them in the normal star pattern, but do them up evenly. Dont just do them fingertight, then tighten the tits out off them!!

Torque?

As much as you can give it!!!

Loctite does not seem to last. Make sure to use aircraft or better locking hardware(lock washers in your case). these are then safety wiried together to prevent them from comming loose. gradually tighten assembly and check the run out when completed. turn rotors straight if necessary.

I would think the best thing to use are metal lock nuts of the type that deform when you tighten them on the bolts. This is the only thing I know of that positively won't come apart due to vibration and heat.


http://www.rocklandboat.com/locknut.gif

safty wire it!

Crispy,
WARNING I'm 3/4 crazy and 1/4 nuts but I just hand tighten in a star pattern with no lock tight and have not lost any bolts or had problems with brake wobble. Mine are just allen wrench heads with lock washers behind them. When I take them off I have to hit the allen wrench with a hammer because of rust build up from the brake dust. The brake dust itself seems to act as some pretty damn good lock tite :)

How do the rear hats and rotors look I should have some coming my way soon :)
Fritz

Damon - these are not through bolts so locknuts ont eh backside are not an option unfortunately. This is the method I would have much preferred. This is the way my fronts are done.

Skunks - bolts aren't long enough. (I know get longer bolts!)

Fritz - I installed the entire rear setup today. Looks yummy. I'll hopefully have pics up tomorrow.

Crispy

Oops, forgot. You've got the little machined ovalish shaped "nuts" that attach the rotor to the hat right?

https://www.rx7club.com/showthread.p...13#post2372513

Bottom of the page. This is the assembly I'm speaking about. Not that it matters much but it will illustrate the situation better than I can describe it.

Crispy

Crispy,
Another awesome addition to the web site :) I Just got mine today and they look really cool I especially like the hats. I can't wait to put these bad boys on but need to use up my regular 99s. By the time I see you again I may have a new front bumper, another oil cooler (its about time), and a single turbo OR.... I may wait another year or so. I just got my car back and it has a new engine with a big street port, eccentric shaft plug, silicone o rings, and new harness. Oh and I sold my fluidyne and got a koyo and switched to evans. I'm going to VIR this coming weekend so I will come back with a full report on the coolant. So far it looks really good. I drove around for about 1/2 hour today with the rpms no lower than 4000 and the temps never went over 84c.

Man you don't play around I love the way you operate your web site,
Fritz

Fritz,
Yes pelase do bring back an update. WIth more power formt he streetport there is no way I'm gonna be able to keep up now! :)

Crispy

i've had success with red loctite and no safety wire, but i think that safety wire is your only "sure" bet. theoretically, i think red loctite is only good to 400F (or something like that), so it shouldn't be enough.....but i've always had to work to remove them despite very hard track use so it does seem to survive higher temps than that.

the torque is usually quite low......my porsche/movit set up called for 10-15 ft-lbs on each bolt, tightened in a star. call the manufacturer to get the right torque. don't guess, and please, don't just "tighten the shit out of it."

good luck
fabian

Fabian,
Per loctite website high temp high strength red is good to 450deg F. the stuff I ended up using.
I torqued to 200inlbs in increments of 50inlbs in a star pattern
Crispy

the problem with relying on Loctite is the repeated heating and cooling. this will quickly breakdown any versions of Loctite(one day I will give the details of how I discovered this problem). use lock washers and safety wire. it is the only way to prevent the bolts from coming loose. through bolts with locking aircraft nuts would be best, but this sadly is not the way most rotors are setup.

Tim,
Absolutely agree. I will be watching my setup like a hawk. I inspect brakes after every track weekend
Crispy

tims

I agree about the safety wire. But what are lock washers?
http://www.bestnutsbolts.com/lockwash.html (The standard ones or the toothed ones?)

http://www.wicksaircraft.com/gotopage.php?page=74

personally I am refering to the split type washer when I say "lock washers", sorry. there are many different types but the split type seem to work the best. and when reusing them make sure the washer has not flattened out as this reduces its effectiveness.

I had some hugh two piece Wilwood Rotors on a Mustang I used to have. I just evenly torqued the Allen Bolts down and then safety wired them through the already existing holes in the heads on the Allen Bolts. WOrk with no problems for four years until the car was wrecked. Miss that car..... sniff...

-John

actually, most engineering types agree that the split, or spring, type lock washers are worthless. it only takes a few ft-lbs of tourque to flatten these washers, and once they're flat, they are simply flat washers and have no real "locking" function; they just can't apply enough force to the fastener to add anything to the inherent lock effect of the initial tightening. the toothed type of lockwasher will work to some extent if the material it is "biting" into is soft enough. otherwise "squeeze" style lock nuts (for high temps) or nylock lock nuts are effective, as is safety wire obviously. loctite is actually very effective in most applications.

i too was hesitant about using loctite for the brake application. however, after a couple of years of use on my porsche rotors/hats, i'm was amazed at how well it held up.

this is a good general tech thread, since most of us take trivial little things like fasteners, washers, etc for granted. Carrol Smith, the guy who wrote the series of books "Tune to Win," "Engineer to Win," and "Prepare to Win" has a book devoted solely to race car fasteners and plumbing. it's a little dry reading, but it's filled with little details like the lock washer thing above. everyone should read it.

regards
fabian

Good call on split washers, Fabian. They are worthless. For brake hats proper torque should be all you need. Only use safety wire for positive locking if you feel the need.

I have found on a dedicated race car Loctite of any variety will not hold up to the temperatures generated by the brakes while racing(well over 600*F on my car). I have had good luck with the split lock washers and safety wire. I agree with Carrol Smith on alot of things but I have had failures with the star type washers and loctite. not with the split washer, sorry. All of my experience in this area is with race cars not open track cars or part time street cars. Just because you have your car on a race track does not subject it to the type of abuse a real race car goes through during a race. I see alot of responses to racing questions from people who have never owned a race car or raced wheel to wheel ever. I am sorry open tracking and hot lapping are not the same as racing.

well, we can't really make generalization about things, the context is quite relevant. my "open track" FD generated brake rotor surface temps of about 720-750 F. the brake temps on my C-sport radical under race conditions are similar. frankly, i think my "real" race car is actually asking less of it's brakes under full race threshold braking conditions, than my rx7 was doing hard open tracking. you could probably simplify it into a car weight vs. brake swept area comparison. my radical weighs less than 500 kg. the 7 weighed more than twice that.

i don't think we should just dismiss "hard" open tracking as being less demanding on equipment than "real" wheel to wheel racing per se. while i agree that many are in cruise mode during open track events, its certainly not true of everyone. i do both, and i think they both have their unique set of demands.

having said that, if anyone doubts that their fasteners will stay on.....just wire em!

regards
fabian

Well put, Fabian. Having raced and open tracked, the abuse on the car is about the same. Open tracking puts WAY more hard miles on my car than racing does. Personally, I do not trust lock washers in hevay vibration or heat conditions. I prefer safety wire for secure locking needs. I don't need to talk about how many 1/16" bits I have broken drilling safety wire holes even using a jig, drill press and flushing lubricants.