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Braking Woes.

Ryan D
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Ryan D Rising Star

Ryan D

Posted
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I'm stumped.

I completed a 4 to 5 stud conversion a few years back and my brakes have never really felt right, I've replaced the master syl with a R32 GTR one, the rotors were machined before they were fitted, and i use castrol dot 4 brake fluid, Tried ferodo excel pads, bendix ultimate pads, and still am not happy with my braking power,

I have driven my brothers R34 GT and his brakes seem much bity-er, whereas i have to stand on mine at times to get the damn things to pull up. Don't get me wrong, they pass roadworthy inspections, but i personally dont feel comfortable with them when im planning to twin turbo my car in the future.

've signed up for the RDA rotors group buy and threw some EBC redstuff pads on the order to see if both those improve the situation. However my dad thinks it could be something to do with the ABS valva (which is still the stock R33GTS4 one)

Has anyone got any ideas or has done a ABS valve swap before?

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N-DAWG Mentor

N-DAWG

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I think I've got a very similar problem to what you're having.

Do you find that sometimes it's quite soft after one press, but after a couple it firms up when slowing up to an intersection? Also at times the brake pedal is way too soft?

I've done the R34 GT to R33 GTSt conversion and what you're saying sounds similar. I must say I kind of had more faith in the brakes I had before and didn't get the braking performance increase I expected.

I had slotted RDA's on the front with Bendix Ultimates, Bendix GCTs on the rear, ADR Braided Lines front and rear, R33 GTSt Calipers front and rear, R33 GTSt Master Cylinder, and Motul RBF660 and a UAS Brake Master Cylinder Stopper.

Last month I had the other master cylinder put in to rule out whether that was at fault, and had the mechanic bleed and change fluid to a DOT 4 fluid for the time being. Seemed allright initially, mechanic described it as nearly throwing him through the windshield when pulling up hard. Now a couple of weeks later it seems to be back to the softness, and having to press down a lot or several times to get it to pull up the way it "should". It's pretty much all or nothing at times. Once they warm up a bit too it's worse... apply a steady rate of braking pressure to the pedal and nothing much, push it more and car sort of lunges forward a bit.

I don't know if I'm on the right track here, but would the increased number of calipers have something to do with it? Perhaps the brake booster not being matched to the new brake setup? or not necessarily? Are the brake boosters very different between N/A and Turbo skylines?

I'll be watching this thread closely.

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Ryan D Rising Star

Ryan D

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yep, definately sounds like we are having the same issues, I was convinced the Ferodo excel pads were just crap and that was my problem, but after doing so many changes and upgrades to my braking system and still getting the same issues, I'm just lost.

By the way, the ferodo excel pads i got were ultra dusty, definately dont reccomend them to people who dont like to wash their car too often :D

Bendix ultimates have seemed to wear pretty quickly but have been good. I'm looking forward to some slotted rotors and the EBC redstuffs.

I just want some nice bitey brakes without going and paying for some brembos!

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N-DAWG Mentor

N-DAWG

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Yeah, sounds alike... I find the ultimates are very dusty! my wheels are shadow chrome though and the insides of the spokes are dark, so isn't so bad, but definitely a dust storm lol I pretty much went for ultimates and new rotors in the hope of ruling out whether it was just my rotors n pads having aged to the point of needing replacing, but the only thing left now really is the brake booster, unless there's another problem somewhere else... I just want confidence in my brakes again ~_~

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N-DAWG Mentor

N-DAWG

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I'm now more confident that it's the brake booster that's causing my grief.

My brake pedal feels fairly firm without a lot of travel, and little stopping power really, unless i give it a few presses when approaching an intersection. Once the car gets to operating temperature braking performances decreases more and it squeals! which I thought was just the bendix ultimate, but they didn't start squealing till a week or so after having them fitted at least a month ago now.

The squealing is more of a high pitch whistling type sound, variable by the pressure i'm applying and starts squealing as the car slows down from low speed.

It appears to be coming from the booster side of the front of the car, and after talking to a workmate in the know about brake boosters, he said yeah it will start squealing soon if its the booster, and that was before i mentioned any squealing.

From what I described he reckons that it's the booster and that the diaghrams probably blown out.

I must note though that before it got to the squealing stage, my brakes were like Ryan described.. in fact glass brakes is a good way to describe it, scarily smooth particularly when driving down the lookout instead it would still have a bit of play before it came completely to a stop.

I'm wondering if Ryan's problem is the same, a brake booster on the way out ? I am in no way an expert on brakes, but from what I've been reading, and based on all the other components I've isolated (everything but the booster) this appears to be my problem.

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Risking Grand Master

Risking

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Pump the pedal up with the engine off.

Push as hard as you can on the pedal and fire the engine.

Does the pedal sink at all when the engine starts??

If it does then the booster is working. If not then its not working.

What calipers??

It really sounds to me like you have a master thats too big OR a blockage in one of the lines resulting in low fluid pressure at the caliper and a hard pedal.

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Ryan D Rising Star

Ryan D

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What brake lines are you using?? Replacement stockies

What calipers?? R33 GTS-t stockies

Does it wear front pads or rear pads out faster?? Front

Is the pedal firm and hard but has no stopping power or soft and traveling along way?? - Is the pedal firm and hard but has no stopping power

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N-DAWG Mentor

N-DAWG

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I noticed when reversing into my parking the brakes don't really squeal as much, but applying brake pressure i hear like a creaking noise from the front sounds like the calipers.

I know that one of the pistons is a bit slow to pop back out on one of the calipers, I THINK it was that one. Thing is the loud squealing and also this creaking sound is coming from the drivers side that the booster is on.

Is it possible that a leaking seal on the caliper would be allowing air or water to be sucked back into the lines, and therefore creating the soft/dead brakes? and perhaps the squealing is just a result of that? or maybe it could be both booster and caliper? The last time I had it in they swapped back the old master cylinder that I had before that I know was in good working condition, and also bled the brake lines. After that it was a significant improvement! But now the problem with the brakes feeling dead is back again. The squealing never left though, just over this last week it's gotten a whole lot worse particularly after a long run.

To give an example, I was on the motorway approaching the toll gates so naturally slow down trying to slow down more through the gears than just foot on brake... but after applying brakes from a gradual slow stop at the gate, (stopping from around 30-40km/hr) the ear piercing squeal was deafening! so much that the lady at the toll booth gave me a really bad look!

I've ordered a front caliper seal overhaul kit to have the front calipers rebuilt, and also got an R33 GTSt booster/cylinder on the way too.

Either way it's going to be good to have the matching booster for the R33 brakes and front calipers seem to be in need of rebuilding.. so this will isolate both of those possibilties and hopefully that will be the end of it.

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N-DAWG Mentor

N-DAWG

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Bigger discs and calipers.

Before Brakes: 280mm front discs with 2 pot calipers. 265mm rear discs with 1 pot calipers. R34 25GT Sedan items.

After Brakes: 296?mm front discs with 4 pot calipers. 297mm? rear discs with 2 pot calipers. R33 GTSt items. R33 Brake Master Cylinder (has same part number though as my previous MC. Custom Made by Brakewest ADR Approved Braided Lines to suit.

I had purchased uprights/hubs from an R33 for the conversion, but it turned out that the bolt sizes were different, so the workshop modified the exisiting uprights/hubs to suit the R33 GTSt brakes.

When I picked it up they said that one of the pistons was a bit stuck and they had to muck around a bit with it. I thought they were just finding something to charge more for, but when I had brake pads and discs changed by another mechanic he also mentioned one of the pistons is slow to come out and if there was anything else that he'd do it would be to rebuild the front calipers.

I had the brake conversion done last quarter of last year. It's only really been over the last couple of months that braking performance has decreased and now gotten this bad, and squealing starting about a week and a bit after having new pads and discs fitted (bendix ultimates on the front). I originally changed the discs and pads as they were due, but also to rule out if that was the issue. Brakes were nice and strong after that but later got worse again

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  • 2 months later...
N-DAWG Mentor

N-DAWG

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nope... well minimal change.

The squealing and poor braking was related to the discs in the end. I had the discs machined and also changed to QFM K500 pads. The discs had glazed like a mirror in the end and bendix ultimates were like scourer on glass. Machining ended up being the last thing I done as the discs were only a couple of months old. Just wish the mechanic I took it to caught up on that to begin with... won't be going back to that one in a hurry!

I still find that i'm double braking though to get best braking performance. Just firms up quite noticeably after the second pump of the brakes, so yeah dunno... no part of my brakes is factory anymore lol

I've got an 98 model R34 Booster and BMC for sale if anyone needs to replace theirs, and also an R33 GTSt BMC. All have the same part code on them. Am keen to get rid of them to fund my 6 monthly service and Profec B install/tune soon! :blink:

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Wacky Dee Veteran

Wacky Dee

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hm I have similar issues although stock R34 GTT brakes with slotted rotors...but my BMC is leaking.

THe R34 BMC that you're selling ..is thatt of a turbo or non-turbo ? ie GT or GTT ? Has it been rebuilt? leaking ? Price ?

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