Stiff brakes

[jimjim150]

Ongoing problem.

Brakes were really stiff to use, I located what looked like air leaking from a fairly shoddy vacuum set up. (On ITBs) Danny at 519 has made a nice tidy replacement job for that - which improved pedal feel slightly, but did not solve it...

Put some new discs (Brembo HC) and pads (Mintex 1144s - cheap shh) on at the weekend. Again pedal feel improved and bite is a lot better. But still not fixed!

What does CS reckon? Water in the brake fluid? Has ATE super blue at present. Could flush it out with some of the gold stuff??

Can't really think what else it could be other than faulty master cylinder or servo...


Also feel free to help with this > http://www.cliosport.net/forum/show...light-adjuster-problems&p=7954309#post7954309

 

[Cupman29]

Do you mean stiff pedal or the calipers are stiff?

Water in the lines would make the pedal spoungy.

 

[sideways danny]

It's got a very hard pedal like you get if you pump the brakes with the engine off. Car had brake issues before with the previous owner, and a new one way valve improved it. I changed the shoddy servo vac pipes on it as they were leaking, kinked and too soft so being sucked flat. so there's actually a bit of travel there now, but it's not right.

before

After

Could be the servo itself (although thats a very rare item to fail on any car) or it could be down to a lack of vacuum at idle, and the way the ignition is mapped (seen it makes quite a significant difference on a couple of cars). Was difficult to tell before as the EBC blue pads were well past it (looked like they'd been on fire) and the discs were glazed

 

[jimjim150]

Cheers Danny. As above it's the pedal that is hard, going to check over TPS before looking at map regarding the car running lean.

I do feel as if it is a vacuum issue still though - as the brakes are better/have more pedal travel the longer the intervals are between braking. Don't really have any experience with servo's though!

 

[sideways danny]

Well now you've changed the discs and pads I can confidently say it's doing the same as Wobba's mk1 did when it was mapped by APD. Your throttle opening at idle is very very low meaning the idle is being artificially raised with too much ignition timing. Closely related to why the cold start is so bad also.

the synchrometer was seeing 3kg/m of vacuum, and I'd want to see around 6kg/m on an F4R, but opening the throttle to achieve that without making changes to the idle settings would just raise the revs

 

[Dean.]

Woah that is a terrible servo setup. Who installed that??!

 

[jimjim150]

Woah that is a terrible servo setup. Who installed that??!

As far as I'm aware, all of the throttle body related work was carried out at TDF.

Dan, well I'd hate to start messing with the wrong thing. I think possible problems on the list would be - TPS, body balance (though i know you looked at this), poor map, faulty brake servo???

The poor fueling is of less urgency than the brakes currently - unless they are caused by the same issue?

 

[mr.pink87]

As far as I'm aware, all of the throttle body related work was carried out at TDF.

Dan, well I'd hate to start messing with the wrong thing. I think possible problems on the list would be - TPS, body balance (though i know you looked at this), poor map, faulty brake servo???

The poor fueling is of less urgency than the brakes currently - unless they are caused by the same issue?

That´s quite shocking as TDF seems to have a great reputation on here especially for professional mapping. :S

 

[Cupman29]

Well now you've changed the discs and pads I can confidently say it's doing the same as Wobba's mk1 did when it was mapped by APD. Your throttle opening at idle is very very low meaning the idle is being artificially raised with too much ignition timing. Closely related to why the cold start is so bad also.

the synchrometer was seeing 3kg/m of vacuum, and I'd want to see around 6kg/m on an F4R, but opening the throttle to achieve that without making changes to the idle settings would just raise the revs

Surely this would only be a brake problem at idle then rather than all the time?

 

[sideways danny]

Dan, well I'd hate to start messing with the wrong thing. I think possible problems on the list would be - TPS, body balance (though i know you looked at this), poor map, faulty brake servo???

The poor fueling is of less urgency than the brakes currently - unless they are caused by the same issue?

TPS....unlikely, it's too smooth going by my previous experiences of faulty ones. Bodies were balanced to account for leaks, once the leaks were fixed they had to be adjusted as they were quite far out. Idle setup is definitely not right. Servo itself is a definite possible issue

 

[jimjim150]

If I were to replace the servo would replacing the master cylinder aswell be prudent? As I'm thinking it would have to be a leak from the master cylinder that would cause it to become faulty?

 

[Fred@BTM]

who's car was it before?

EDIT

Dave's?

 

[jimjim150]

who's car was it before?

EDIT

Dave's?

Yeah that's right, it did have a BTM sticker in the window at some point...

 

[Fred@BTM]

yeah we fixed the PAS line when it snapped, brakes felt ok when i drove it in terms of servo feel, the car didn't stop very well though which i put down to the rubbish (and melted) EBC blue pads

 

[Icarus]

For reference from that cars build sheet:

Idle Air Mass:

Cyl1: 5.2
Cyl2: 5.3
Cyl3: 5.2
Cyl4: 5.1

Anything between 5 and 5.5KG is acceptable. If you can get them back to that (via the pair of throttle shaft stops and four idle air screws) it should be okay again.

Also what throttle pot is on it? Can't make out if it's one of ours or not from the picture. That car should be 0.87V at idle.

Oh and JimJim it's still under warranty if it's Daves old one! So get it over to us and we'll sort this idle issue under warranty. From what Dannys said regarding the low air mass at idle it sounds very much like someones had a fiddle, especialy as there is several bits missing from the brake vacuum circuit.

Cheers
Matt

 

[sideways danny]

they were all around 3. I opened the throttle but that just raised the idle. Assume auto zero is off as key off/on made no difference, and spark idle seemed to be doing very little as it's now sitting up at around 1200rpm