Jump to content
SAU Community

Recommended Posts

Hey guys, 

I hope you are all doing well. Seeking your wisdom on something that has me puzzled.

The OEM brake booster on my GTR was bad. So I decided why not clean up the bay and get something new in there in place of it. I replaced it with a  Wilwood Brake Booster Delete Kit (PN 260-10375) - I looked up the stock specs on a r32 GTR (non SpecV) and found that it is a 25.4 mm (1 ") bore size. I sourced a STAINLESS STEEL 4 WAY BRAKE UNION and STAINLESS STEEL 4 WAY BRAKE UNION to put it all together. There we some fittings that were needed as well but overall it is installed and front and rear have been bled.

No matter how many times I bleed it and make sure there is no air in the system. The brake pedal is soft, if I pump the brakes it'll get firm but then go soft again. Definitely not able to drive around at all at regular speeds. The guy at the shop that installed it and has my car (I been really busy with school and work and decided to have someone take a go at it) cant get it to work.

He suggest to find the stock brake booster new or have my old one rebuilt. At this point I agree. I don't know what else it could be. You all have any info or insight? 

Pending your advice and help. 

Link to comment
https://www.sau.com.au/forums/topic/482859-1991-r32-gtr-brake-booster/
Share on other sites

I don't see how an issue with a variable pedal could possibly be due to not having a brake booster.

Basically the booster adds assistance to make the pedal lighter (when the engine is running and making vacuum). Without a booster it should either be just right, too hard or too soft at all times depending on the master cylinder bore size and where the pivot is on the brake pedal (pedal ratio)

What you are describing sounds like there is still air in the system somewhere; when you first press the pedal the air compresses which is why the pedal is soft and on subsequent presses because the air is already compressed you get the proper hard pedal feel as the wheel cylinders move.  Do you have a pic of the changes you made around the master cylinder (or elsewhere like abs?) and how are you doing the bleeding?

  • Thanks 1

Duncan,

Here are a few pictures of the current changes and set up. I never had an ABS module on it when I got it. 

Let me know if this helps. 

20210929_181655.thumb.jpg.0cd99ce8733a9df65bfbb8e760730055.jpg

20210929_181640.thumb.jpg.66c22787f2f52e17ff2bb5df9e870174.jpg

Break down (hope it's not too confusing)

20210929_181655.thumb.jpg.b5cd1730ddd7ede4f0610f965a7c67f1.jpg

They are color coded to the description. 

Edited by Jjtxaz24

I think that does help; there is a high point in the "to 4 way" line which is above the master cylinder fluid level; it is possible you have air trapped there no matter how well you bleed it.  Can you re-bend/re-route so that no brake line is higher than the master cylinder fluid level?

Also, how are you bleeding; manual with a person pumping a pedal and another opening a bleeder into a (hopefully clear) hose, or vacuum bleeding at each nipple, or pressure bleeding from the master cylinder.  At least having no ABS removes that issue as you can get air trapped there too because valves cycle when the ABS actuates.

  • Thanks 1

Dam that is a good catch. I wasn't sure if that mattered or not but I feel that you are right. I can see if I can rework it. The guy at the shop built the lines and that's how he set em up i just gave him a diagram of how everything should be routed.

He said he would bleed the brakes manual. So I'm assuming 2 people. One pumps the brakes and holds pedal down, the other cracks the line, fluid pushes out then bleeder is closed. Rinse and repeat.  

Yep, so the reason I asked that is vacuum and pressure bleed can be more reliable, manual bleed you can make errors (eg allowing pedal to retract before bleeder is closed, or not using hose to ensure only fluid gets pulled back in, or simply not flushing enough fluid through to clear out all bubbles because it is such a painful process......)

  • Thanks 1
On 9/29/2021 at 7:51 PM, Duncan said:

Yep, so the reason I asked that is vacuum and pressure bleed can be more reliable, manual bleed you can make errors (eg allowing pedal to retract before bleeder is closed, or not using hose to ensure only fluid gets pulled back in, or simply not flushing enough fluid through to clear out all bubbles because it is such a painful process......)

Maybe I can try and vacuum/pressure bleed them before I redo the line to make sure there is no. I ordered a brake line kit to rework that main line so it is lower than the master cylinder fluid but it wont be here till next week. I wasn't able to source one locally.  

The front Brembo's have speed bleeders on them so theoretically it should allow air out and not let anything back in. I will rebleed the system and when the kit shows up I will redo that line. **fingers crossed** hopefully it works. 

Good news is I was able to bleed the system, used a vacuum bleeder and took about 10-12 minutes on both rear calipers,  There was lots of air. Fronts were good to go. I had speed bleeders on the brembos so took like 3 pumps and they were good. 

Current new issue is my stock and aftermarket boost gauges aren't reading anything. They stay at 0 at all times. 

  • Like 1
On 10/2/2021 at 3:19 PM, Jjtxaz24 said:

Good news is I was able to bleed the system, used a vacuum bleeder and took about 10-12 minutes on both rear calipers,  There was lots of air. Fronts were good to go. I had speed bleeders on the brembos so took like 3 pumps and they were good. 

Current new issue is my stock and aftermarket boost gauges aren't reading anything. They stay at 0 at all times. 

Are they pinned at the minimum level or are you saying they read atmospheric? If it's the first then I would trace the power and ground. If it's the latter make sure the vacuum line is hooked up properly.

  • Thanks 1
On 10/2/2021 at 6:59 PM, joshuaho96 said:

Are they pinned at the minimum level or are you saying they read atmospheric? If it's the first then I would trace the power and ground. If it's the latter make sure the vacuum line is hooked up properly.

Gauges just read 0/neutral spot where they land if the car is off. They don't move at all. I found a torn vacuum line leading to my aftermarket greddy analog gauge. And just replaced it ziptied and made sure all lines were tight and good to go. Still nothing. 

20211002_192949.thumb.jpg.5321dea3c2b1db561646a46ea0cace96.jpg

This one stays at 0

20211002_193004.thumb.jpg.369f283f6add218836cd5776b0fcbcad.jpg

this one goes to zero when I start it. 

20211002_193026.thumb.jpg.2aa83e55d54717c67e9647e6055cc802.jpg

Here's the stock boost sensor and an aftermarket one. The aftermarket one isn't hooked up so I'm not worried about that. The blue line goes to the balance tube where the boost signal is grabbed from. 

Edited by Jjtxaz24

I removed all the vacuum lines (to the stock and aftermarket boost gauge) and left the one from the back of the balance tube (blue line) and plugged that in directly to the stock sensor. Nothing. Stock gauge stayed in the middle. I unplugged the pig tail from the stock sensor and in doing so it let the stock gauge turn off as if the car was off and the needle dropped. So there is a signal going to it.

It has been sitting for a little while, and before it went down I was able to get a signal/read out on both gauges. Issue was I forgot to plug in the vacuum line in back of the balance tube and couldn't figure out why i was hitting a wall (oversight on my end.)

 

On 10/4/2021 at 4:31 PM, Duncan said:

Not plugging it in ......there's your problem!

The vacuum hoses is plugged in. Car runs great now. Only issue I have is the no boost gauge. 

Not sure which one you're referring to when you said not plugged in. 

I followed GTSboys advice and unplugged all the vacuum lines that I showed in the picture and only left the blue one (from the balance tube) to the stock boost gauge sensor. Didn't get any feedback on the gauges when I was in boost on a drive. 

Ok so I will be the first to admit that I made an ass of myself for assuming someone else knew what they were doing. 

Issue is fixed. Guy never plugged the vacuum line to the balance tube nipple. It was in the general area (on the throttle body rod assembly, in his defense it does look like a nipple lol) unplugged everything in frustration and realized it was never plugged in. 

Issue is resolved. GTR is good to go. Thanks for your help guys. Sincerely mean that. 

  • Like 1
  • Haha 1

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • The German place in Cabramatta was rock solid, fresh pretzel cooked to order back then. Then it went all quiet, after all the poker machines were removed, then I believe it closed for good. I did drive past the other week and noticed outdoor lighting a big screen, but no idea what is there now.  
    • Yeah I suspect even if you hold airmass per cycle/cylinder constant if you get too far away from stock you're still going to have problems running the factory tune within the bounds of the factory load scale. Cams, different displacement/rod ratio, etc. I'm just lucky that the GTIII-SS with wastegate boost + CA compliance cats is pretty much equivalent to stock turbos. When I have actual space I can finally get it tuned and modify the fuel system for flex fuel to 100% handle any detonation concerns when cranking the boost to whatever those dinky turbos can put out.
    • I would say no, why, because my daughter, who also lives in Goulburn, hasn't recommended us going there Pity, as we miss all the German joints around in Sydney, actually, the restaurants are the only thing I really miss about Sydney, and a special mention to Ishibanboshi at Bondi Junction, their Kara-age Don is heart cloggingly deliciousness (always added a special boiled egg...or 2) 😋 
    • Does that German restaurant still exist in the old place out the NW end of Goulburn? When I say "out the NW end of"...I am really being vague. It was 1997 when I was last there, and the only point of reference I can recall is that it was on the opposite side of the main drag from the big merino. And when I say "opposite side of the main drag", I don't mean "on the main drag". It was either a couple of streets back from there, or might have even been out in the sticks a bit further. Was an old farm building or mill or somesuch. And when I say "the big merino" I might actually be thinking of a completely different part of town, because I just looked on maps and the big bugger is not where I remembered him to be! The food was good, consisting largely of various German mystery-meat sausage/loaf things and kartofflen.
    • So while the second sentence is completely correct and the whole point of the conversation, the first sentence bears consideration. If this bloke is just hoping to throw big turbos on and drive it around, because there are no helpful facilities at all in his tropical paradise** then he likely has zero chance of even knowing what the TP is on the last column in the stock maps, let alone know whether the ECU is operating anywhere near it or past it. So the point is very very moot. And, per what I said before, at stock boost on those turbos, you may well be off the end of the map. **I'm just back from Vanuatu, so I know exactly what small Pacific nations can be like wrt paradise without requisite facilities. But it's not even that simple. I put a high flow on my car and had to drive it around without a proper tune because of the lack of opportunity*** to put the bigger AFM and injectors into it to allow it to be tuned. I had to turn the boost down to less than I had before, and back off the boost controller's ramp, because it was exploring parts of the map that it didn't drive in before, and really couldn't access for tuning on the dyno either, and so was pinging. It was still well within the last column, because when I first**** set up the Nistune on the Neo I rescaled all axes of the maps to give some more space to explore. ***Family dyno was broken ****This was 13 years ago, and the TIM thing wasn't a thing then and so TP would definitely grow when pushing past the stock tune's limits.
×
×
  • Create New...