Author Topic: Ryan's IROC Thread (Read 46085 times)

Andy · « **Reply #950 on:** April 19, 2014, 03:52:18 pm »

Helicoil not an option?

FUBAR · « **Reply #951 on:** April 19, 2014, 04:02:36 pm »

I don't have anything like that, + would that work on this were a pressure seal is needed?

A pair of new rear callipers from RockAuto is £145 + import Tax which is not bad. i'll just get those.

Jamieg285 · « **Reply #952 on:** April 20, 2014, 10:28:30 pm »

Are you sure it's the caliper that's stripped and not the nipple? I had the same thing a few years ago. I'd expect the nipple to be softer than the caliper.

Titsy · « **Reply #953 on:** April 20, 2014, 10:41:39 pm »

Quoting: FUBAR

would that work on this were a pressure seal is needed?

This should work just fine as the seal is from the conical end of the nipple seating into a conical seat at the base of the thread. The thread plays no part in the seal, so long as then preparing the calipare for the helicoil you dont damage the seat it'll work just fine.

Andy · « **Reply #954 on:** April 21, 2014, 05:33:21 am »

Add to the above, Helicoil threads, if prepared properly are much stronger than just standard threads cut into cast aluminium.

FUBAR · « **Reply #955 on:** April 21, 2014, 10:17:27 am »

Its definitely the calliper, I think the new bleeders I bought (M10x1mm x 36mm in length as per the stock ones) may be stainless steel

the ebay ad doesn't actually say.

Its in at the moment and has just enough thread left to lightly seal the brake fluid in so its not all draining out while i'm waiting for the new callipers to arrive.

I ordered these (i'm changing both rears) from Rockauto, £190 including higher priority shipping including taxes etc.
about 4 years ago when the rears seized up over winter I replaced them from US Automotive, cost? £418 for exactly the same thing!!

Unbelievable rip-off.

The good P/S used calliper will be going on flebay.

FUBAR · « **Reply #956 on:** May 07, 2014, 06:53:56 pm »

Well I got the New callipers fitted at the weekend and the system fully blead through with brand new fluid & new braided flexi lines. all good, sort of.

The Handbrake now does absolutely sweet FA and it worked before

they are the same exact callipers and there doesn't appear to be any bits missing from the new ones which were on the originals.

This leaves me the fun job of adjusting the Handbrake.

So I then redid the same test I did before with the rear wheels jacked up and the car locked in 1st gear... the wheels still rotate slowly with the brakes fully on.

some googling this evening reveales that this is probably normal... typical

Quoting: CHP

Brake Bias
Q: I have been having a problem with my '89 IROC-Z's rear brakes. The car is a four-wheel disc brake system from the factory. The brakes just don't seem to hold well at all in the rear. If I jack the car off the ground and leave it in gear at idle, the wheels still turn. I was restoring the car from the engine back, so I have literally replaced every component on the brake system except the flex connectors to the back brakes at the wheels. I have even tried different brake pads, from regular asbestos to Wagner race brand. I have had the car to a Chevy dealer and a Midas center to fix, with no resolution. When I bleed the brakes, I get plenty of fluid to every wheel. The pedal always has a solid feel to it with no sponge in it. It never bottoms out on the floor, and when I take the caliper off, the pedal pushes the pad out about 3/8 inch with one push of the pedal. I also had this problem on an '88 Z28. I am at wit's end! Any help would be greatly appreciated.
Mike Huelsman
Mentor, OH

A: First of all, I think that you're running into a couple of things. Disc brakes are not a self-energizing braking system; they only have the force that the caliper can apply at any given time. Drum brakes have the rotation of the brake drum to force the brake shoe into the drum. The hydraulic force from the wheel cylinder pushes the primary (front) shoe into the drum, and the shoe is rotated, putting pressure into the secondary shoe and into the reaction pin on the backing plate. This is why you have so much holding force with drum brakes. That is why most "foot brake" drag racers will use drum rear brakes, so they can hold the car on the starting line at a higher rpm against the converter. With disc brakes, the rotors and pads must be up to operating temperature before you will have any braking force at a dead stop. Yes, you could increase the line pressure (install an adjustable proportioning valve) to the rear brakes to aid your dead stop issue. The only problem I see with this is when you get the brakes up to operating temperature, you will have way too much rear brake bias and the rear brakes could lock during spirited driving. When going into a turn, that's the last thing you want to happen.

If you would like to do a quick test to confirm this, drive the car and get the brakes up to temperature. Bring it home and immediately jack up the rear of the car and redo your braking test. The rear brakes will hold once they have some heat in them. Also performance (i.e., racing) pads will only aggravate the problem. Most performance-compounded pads need more temperature to create the proper coefficient of friction to perform properly.

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Author Topic: Ryan's IROC Thread (Read 46085 times)

Andy

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Andy

Roadkill

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