NO BRAKES... when on boost.

[kyepan]

Hi there.

Hoping someone can shed light on a very strange problem.. When i had my last car it understeered like anything and i had to left foot brake everywhere. But at the moment in the R i cant.

Symptoms.. get no servo actuation and therefore very little braking at all when on positive boost above 0.2-3 ish bar. So say your coming into a bend on the throttle and you press the brake, there is nothing, then release the throttle and the servo kicks in and gives you your brakes back. can someone else please try this and let me know if they are experiencing the same problem, or is it normal for R's to not hold vacume on boost.

I have tested the non return valve on the line from the servo up over the intercooler and with the engine running it hisses when disconnected at the intercooler end, and then releases the vacume when disconnecting at the servo end. so it seems ok, still not sure though.

Is there anywhere further down the line that I could loose pressure, or is it holding vacume at idle but faulty when on boost?

Can anyone help, cause i feel lost without my left foot braking

Many thanks in advance.

Justin.

 

[J-GTi-R]

Funny you should say that, I had the same problem with mine. The first time I tried it in the 'R it scared this bejesus out of me, as I thought I'd lost my brakes. I naver figured out why it happend though.

 

[MarkTurbo]

The brakes wont be as good while the cars on boost cos the servo works off the vacuum from the engine. So if theres no vacuum (ie when you're on boost) then the brakes will be just the same as they would be if you were stopped with the engine off.

Or do you mean you've got no brakes whatsoever :?:

 

[antilag]

mine does the same mate always has done think marks explanation sounds correct :roll:

 

[GINGA]

Like Mark said when your on boost theres no vacuum assistance you'll still have brakes its just they will be alot harder to use, best get down the gym and build up that left leg :lol:
Other option is to convert to a vacuum less system or fit a vacuum pump from a diesel car somehow

 

[zia]

or convert it dual vaccum system or theres another way to do it but it ,s costly!!!

zia

 

[kyepan]

Or do you mean you've got no brakes whatsoever :?:

your right mark, just no servo actuation.


Thanks for all the replies guys..seems like the r doesn't want to left foot, unless i find some other way of providing a consistent vacume source.

 

[skiddusmarkus]

I've tried it too and they don't work very well at all.It's a shame as I'm getting quite good at left foot braking now(diesel turbo vans brakes still work when accelerating,maybe it's cos it's got feck all power).

 

[kyepan]

just been readin up on it, and diesils have special vacume pumps cause they have no vacume behind the closed throttles, cause they don't have throttles as such, they just pour more fuel in.. :? aparently :? Most of them are mechanical though

you can buy little electric vacuum pumps that run off 12v dc that do exactly what we need so if you hide that somewhere and stick it on the end of the vacume line.. you get brakes.. even when on boost..
they are about $250

will post a link later.. off to the pub now, thanks guys.