 Rotor Temperatures, Am I getting too fanatical? |
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| dmilzoff |
 Aug 23 2003, 01:31 PM
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#1
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Member  Group: Members Posts: 67 Joined: 2-March 03 From: Ossining, NY Member No.: 377  |
Am I getting too fanatical or is this a real problem?
On my 914-6, I have 911 brakes up front and original rear brakes. I found the right rear brake dragging (smoking!). After opeining the vent clearance and oiling the emergency brake linkage, I took the car out for a 4 mile ride. Rotor temperatures using a infrared temp probe was Left Front 145 deg. F. Right Front 150 Left Rear 180 Right Rear 225 Question 1: Shouldn't the front rotors be hotter? Should I remove the brake proportioning valve or replace it with a new one to correct this? Question 2: Is the right rear too hot for such a short ride? |
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| VegasRacer |
Aug 23 2003, 02:52 PM
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#2
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ELVIRA Group: Benefactors Posts: 8,507 Joined: 27-March 03 From: Between Scylla and Charybdis Member No.: 481 Region Association: None 
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Those numbers do seem a bit strange.
My suggestion is to remove the proportioning valve. This easy fix has worked well for me. |
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| dmilzoff |
Aug 23 2003, 03:05 PM
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#3
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Member Group: Members Posts: 67 Joined: 2-March 03 From: Ossining, NY Member No.: 377 |
Should I just replace it with a tee? Is this a easy to find part?
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| redshift |
Aug 23 2003, 03:15 PM
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#4
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Bless the Hell out of you! Group: Members Posts: 10,926 Joined: 29-June 03 Member No.: 869 |
I have the same problem with a car, sometimes. It's apart right now, but I plan on T'ing it.
Why always the right side? M |
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| kdfoust |
Aug 23 2003, 03:28 PM
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#5
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Senior Member Group: Members Posts: 694 Joined: 2-January 03 From: Riverside Member No.: 71 Region Association: Southern California |
That doesn't sound like a prop valve to me. When rubber brakes lines fail (after being really, really old, like 30 years old) sometimes the inside of the line will deteriorate partially blocking fluid flow causing the caliper pistons to fail to retract completely. If you don't have relatively new rubber lines on the car I'd take a good look at them - or just replace them, they're only like $8.
Good luck, Kevin |
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| Brad Roberts |
Aug 23 2003, 03:32 PM
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#6
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
A balanced brake system will only have about a 15-20 degree spread between the front and rear (fronts hotter).
I'm going to guess your rear calipers are sticking (pistons sticking in the bore). It could be the prop valve but both sides would show equal temps if the prop valve was crap. Kevin is dead on with the brake line thoughts... I'm glad to see somebody actually using their infrared temp gun... You should see the brake temps from a factory GT3RS (400-500 degree range) B |
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| dmilzoff |
Aug 23 2003, 03:41 PM
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#7
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Member Group: Members Posts: 67 Joined: 2-March 03 From: Ossining, NY Member No.: 377 |
OK. So I will replace the brake lines. If that doesn't help, I guess BOTH rear calipers should be rebuilt or replaced. - ? Are they worth rebuilding or should I replace/upgrade?
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| VegasRacer |
Aug 23 2003, 03:42 PM
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#8
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ELVIRA Group: Benefactors Posts: 8,507 Joined: 27-March 03 From: Between Scylla and Charybdis Member No.: 481 Region Association: None
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QUOTE(redshift @ Aug 23 2003, 01:15 PM) Why always the right side? Because it is the farthest away. I agree that the problem sounds like there is more going on that a bad proportioning valve. If you're gonna replace the lines, rubber is cheaper but why not consider SS ?! If you really want to go fancy you could add an adjustable proportioning valve. (it sure is easy to spend somebody elses $$$'s) Attached image(s) 
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| Brad Roberts |
Aug 23 2003, 03:44 PM
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#9
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
While doing the lines.. go ahead and install the 9$ Tee. That way you only have to bleed the brakes once.
I would go ahead and rebuild your brake calipers (they are not exactly easy).. If you dont need an Ebrake... install stock 914 calipers on the rear. B |
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| Brad Roberts |
Aug 23 2003, 03:45 PM
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#10
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
I still havent installed a prop valve that I DIDNT run wide open. I can think of 2 turns at 2 tracks that I would need less brake pressure at.. I just deal with the car squirming a little from 100+ down to 60.
B |
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| dmilzoff |
Aug 23 2003, 03:49 PM
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#11
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Member Group: Members Posts: 67 Joined: 2-March 03 From: Ossining, NY Member No.: 377 |
I do need the emergency brake because the car is used for the street (and track). It seems that I should
1. Replace the brake lines and replace the prop valve with a tee. and, if temps are not within 15 - 20 deg front/rear 2. Rebuild the calipers. Oh joy. |
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| Brad Roberts |
Aug 23 2003, 03:51 PM
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#12
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
I'm betting you have one piston hanging up on each rear caliper.
Honestly.. replacing those rear brake lines with the engine in the car is more of a pain than rebuilding the rear calipers. Getting to the top bolt on the prop valve with the engine in the car is also a chore... B |
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| dmilzoff |
Aug 23 2003, 03:53 PM
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#13
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Member Group: Members Posts: 67 Joined: 2-March 03 From: Ossining, NY Member No.: 377 |
Correction. I forgot that the brake lines were replaced with SS years ago. I guess a Tee and caliper rebuild is in order.
You guys don't make this easy. |
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| Brad Roberts |
Aug 23 2003, 03:55 PM
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#14
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
Ha ha.. easy.. would be me coming over and doing it for you...LOL
B |
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| dmilzoff |
Aug 23 2003, 03:59 PM
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#15
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Member Group: Members Posts: 67 Joined: 2-March 03 From: Ossining, NY Member No.: 377 |
Would you (or anyone else) be interested in rebuilding both rear calipers if I sent them to you? Really.
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| Brad Roberts |
Aug 23 2003, 04:06 PM
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#16
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
I would rebuild a core set I have here and send them to you.. then ask for yours in return.
I'm about a week away from being in my shop full time. B |
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| redshift |
Aug 23 2003, 04:19 PM
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#17
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Bless the Hell out of you! Group: Members Posts: 10,926 Joined: 29-June 03 Member No.: 869 |
Hey Brad, how much? What's the turn around?
Miles |
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| Brad Roberts |
Aug 23 2003, 04:21 PM
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#18
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
I dont know the "amount" until I start pulling them apart. Some go quickly...some take forever (depending on how bad they are).
A high number would be 150$ a caliper exchange. B |
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| dmilzoff |
Aug 23 2003, 04:22 PM
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#19
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Member Group: Members Posts: 67 Joined: 2-March 03 From: Ossining, NY Member No.: 377 |
Hey. Me first. How much? What's the turn around?
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| Brad Roberts |
Aug 23 2003, 04:23 PM
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#20
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
Turn around time would depend on parts availabilty. Some times you can get the rear rebuild kits.. some times you cant.
I would just buy some kits and rebuild calipers I have sitting here collecting dust. Then send them off. I'm at least a week away from starting them. B |
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