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Author Topic: Brakes Question  (Read 2578 times)

March 23, 2010, 10:43:04 pm

Runt

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Brakes Question
« on: March 23, 2010, 10:43:04 pm »
I can't believe the trouble I am having with this car right now.
91 jetta TD.  91 Passat 16v brake upgrade.  I have swapped everything spindles out, and the master.  I have a couple simultaneous problems, but the biggest is sticking rear calipers.  Did I just have bad luck with calipers, or does the jetta (drum) proportioning valve have check valves in it?  I wanted to keep the jetta prop valve to maintain the factory balance, so I didn't swap it.
Thanks for any help.
Keith


One DD 92 Jetta, One 91 Collision write-off, and One 92 rust free shell, beautiful, stripped, waiting for diesel-ization.

Reply #1March 23, 2010, 11:25:00 pm

burn_your_money

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Re: Brakes Question
« Reply #1 on: March 23, 2010, 11:25:00 pm »
I think all drum brake prop valves have a residual pressure valve in them, but I'm not an expert on the subject.
Tyler

Reply #2March 24, 2010, 01:24:27 am

Runt

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Re: Brakes Question
« Reply #2 on: March 24, 2010, 01:24:27 am »
Thanks, I figured as much, with the troubles I'm seeing.  I guess I'll swap in the passat one.  I'll be going to the corrado brakes (and maybe the Audi Girling 60 calipers, any opinions?) fairly soon anyways, so my next question would be... Anyone with any good advice on adjusting the prop valve to maintain good brake bias?
One DD 92 Jetta, One 91 Collision write-off, and One 92 rust free shell, beautiful, stripped, waiting for diesel-ization.

Reply #3March 24, 2010, 09:51:19 am

GEE-BEE

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Re: Brakes Question
« Reply #3 on: March 24, 2010, 09:51:19 am »
I DID A MKII PEDAL SWAP, Installed 16 v prop valves on the master cylinder with a new booster
removed the body rear prop valves/ and made new lines to the prop valves on the new master cylinder,

I did larger master cylinder and g60 brakes , had all new s/s hardlines made front & rear axle.

I purchased the seats and brakes for 400.00.

GB
1.9 AAZ, CHD 5spd with Peloquin
KO4/KO3 Hybrid turbo
Giles Pump OHC
Complete Techtonics 2'5 S/S DP and Exhaust
Coilovers, MKII Pedal Swap,G60 BRAKES
MK1 JETTA DASH
675MM 16V radiator (MKII) PASSAT DUAL FAN
42K original miles , South African Front End
15x6 Le Casletts 195-45-15

Reply #4March 24, 2010, 01:09:19 pm

bajacalal

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Re: Brakes Question
« Reply #4 on: March 24, 2010, 01:09:19 pm »
I think all drum brake prop valves have a residual pressure valve in them, but I'm not an expert on the subject.

I'm not 100% sure on this either but I thought drum brakes required residual pressure to overcome the strong brake shoe return springs when braking. Disc brake calipers don't require as much force to move the piston when you step on the brake.

Reply #5March 26, 2010, 12:09:59 am

AudiVWguy

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Re: Brakes Question
« Reply #5 on: March 26, 2010, 12:09:59 am »
You don't need the prop valve, especially if you are going to upgrade the front brakes even further.About 80% of the stopping power is being done by the fronts. The 10.1 rotors with hawk HPS pads will lock up racing slicks. That being said, bigger does look cooler!  8)
Cheers,
-JB

Reply #6March 26, 2010, 02:59:14 am

Runt

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Re: Brakes Question
« Reply #6 on: March 26, 2010, 02:59:14 am »
Yep, the 256's that I put on there will lock up the 205-50-15's no problem.  However, my concern is not whether they lock them up once, but how well they make the long stops from highway speeds, or some of the BC mountain twisties.  One of may favorite roads posts "13% grade next 11 Km", and it's a series of switchbacks. It's also in the middle of nowhere, so the posted speeds are just, kinda, well... suggestions...   ;)
Mexican Highways are also a blast, at 145kmh I was just barely middle of the pack, ran a little bit of 160ish to keep up with the faster cars, but backed off after 5 or 6 minutes at a time for fear of the poor thing coming apart with the 4S 3.94 final drive.  Tranny swap in the nearish future.   8)
Anyways, that is why I'll eventually go to the 288's, and probably the Girling 60's  I couldn't get the caliper carriers when I needed to do the front end, so the passat stuff went on for now.  I'd like to keep the prop valve (factory dynamic) functional, because I run empty (driver only) a lot, but then I turn around and put the three kids and the wife in and load up the trunk with luggage.  I like the idea that the car compensates at least a little.
One DD 92 Jetta, One 91 Collision write-off, and One 92 rust free shell, beautiful, stripped, waiting for diesel-ization.

Reply #7March 30, 2010, 07:39:00 pm

Doakster

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Re: Brakes Question
« Reply #7 on: March 30, 2010, 07:39:00 pm »
Stupid question....are your rear caliper slide pins well greased?
1991 VW Jetta 1.6TD (Formally an ECO), Giles LDA Pump and Injectors, Techtonics 2.25" Down Pipe and Exhaust system, Rebuilt Trans with 3.94 final drive and a Peloquin Limited Slip Diff, Front H&R Sport Springs, MK4 VR6/1.8T front brakes, Single Round Headlight Conversion.

Reply #8March 31, 2010, 03:46:19 am

Runt

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Re: Brakes Question
« Reply #8 on: March 31, 2010, 03:46:19 am »
Yep, they are well lubed, and slide freely.  Unfortunately the pistons slide a little less freely, I swapped the prop valves just to be sure, and it is definitely a sticky caliper.  Oh well, CPR (calipers,pads,rotors) what's another couple hundred bucks, right.  Sadly for me, I went with the cheap offshore rotors (ya,ya, I know better!  :-[ ) and they had just a tiny bit of wow in them before I turned one blue, but the parts store will never take them back now.  I dislike wheel bolts (and yet I've got vws & a mercedes... go figure), so I drilled and fitted them with studs.  No more warranty.  At least I know everything will come apart nicely. 
BTW what does anyone use for e-brake cables?  Do the passat ones line up alright and fit at the front end?
One DD 92 Jetta, One 91 Collision write-off, and One 92 rust free shell, beautiful, stripped, waiting for diesel-ization.