Upgraded Brakes and Proportioning Valves

[ianl]

I am going to upgrade the front brakes on my S3 and will probably go for a 283mm kit from Godspeed. Has anyone used them before?
I’m thinking of fitting an adjustable proportioning valves to allow the from to rear bias to be altered. Does anyone know of a suitable valve (with the right fittings) that will swap for the existing one on top of the drivers footwell.

Thanks
IanL

[johno]

Demon Tweeks do a number of Brake Bias Valves, as do Merlin I think and probably Godspeed.

I wouldn't bother though unless you are changing the rears for Discs aswell as upgrading the fronts as the drums will not offer as good as response as discs IMHO.

I know Peter Humphries uses a lever style bias adjuster similar to that which you see in Gas systems. Hopefully he'll read this and post as he knows considerably more than most on this subject ! All I know is there are number of variations available....

Cheers

Mark

[roulli]

Mark and IanL,

what is actually the motivation to upgrade the brakes of an S V6. Does it make sense for road use as well, or mainly for encountering fading during trackdays.

I'm asking because I'm only getting to know my S, and currently it doesn't give me the level of confidence to approach limits yet, as did for instance an Opel Speedster or a Lancia Delta integrale, the first time I tried them. So breaking power is not yet an issue for me.

Cheers
Patrick, looking forward to find out more about his S, on the road, in a couple of minutes from now...

[ianl]

Roulli,

I have had a couple of occasions when the brakes have wilted on me but they were when driving very hard. Once hassling an (admittedly not very well driven) Evo 6 and once on the mountain road going down into Gap in the French Alps. I’m going to try a few sprints and track days this year and as the discs and pads need changing anyway I thought I’d upgrade at the same time.

[johno]

Roulli,

Similar experiences to Ian in this dept. I have suffered brake fade whilst chasing an Elise and a Boxster to the point of concern !!

I have never been happy with the braking of the car. Its always seemed that it could be much better. This is considering that I have put new discs, pads, servo and ,master cylinder on the car. I will be doing a couple of track days this year and do not want to have to worry about whether the brakes are going to work or not.

It is possible to improve bite and response by changing to fast road pads, braided lines and grooved/drilled discs. However, the only way to increase braking power is to increase the braking circumferance, hence bigger discs. Better calipers would be the next level in terms of performance and cost aswell. I don't think my driving or demands on th car requires this level of upgrade and therefor I am just going to space the existing calipers to take bigger discs and change fluid, lines and pads to higher spec equipment.

Cheers

Mark

[M@H]

I just ordred EBC grooved discs and Greenstuff Pads for £105 all inc. to improve the standard setup on the S2.. it made a massive difference to my Puma even though the rotor size is still the same.

I'm thinking this should be enough for road use, but at £105 its not too much to look upon as a lost leader if I need to upgrade further someday in future.

Cheers.
Matt.

P.S> Demon Tweeks wanted £146 + delivery for the same parts so I'd give them a miss for off the shelf stuff.


>> Edited by M@H on Tuesday 2nd April 17:16

[johno]

I drove PaulV's S2 the other day and he has done the same upgrade using Green Stuff and Blind drilled and grooved discs and it does make a difference to the response and bite IMHO.

You should notice a difference.

Cheers

Mark

[GreenV8s]

quote:I am going to upgrade the front brakes on my S3 and will probably go for a 283mm kit from Godspeed. Has anyone used them before?
I’m thinking of fitting an adjustable proportioning valves to allow the from to rear bias to be altered. Does anyone know of a suitable valve (with the right fittings) that will swap for the existing one on top of the drivers footwell.

Thanks
IanL

I assume you've got 240mm vented discs up front and drums at the rear? Taking the fronts up to 285mm will move the brake bias forwards (make the fronts more likely to lock under heavy braking), but the change is not all that dramatic. On the V8S I found it was better this way as the original balance was too far back, making the car slightly unstable under heavy braking. With the bigger front brakes I could trail brake into corners and on the limit the car would actually straighten up slightly, very reassuring when you're piling into a corner with a tail happy TVR. Don't know whether the S3 suffers from the same excessive rear bias, but it seems common to Griffiths and Chimaeras and I assume TVR set them up like this deliberately, for some reason. Suggest you try it with the standard brake balance valve, find some private land with a huge run-off, corner hard at maybe 30 mph and jump on the brakes. If you end up looking back the way you came, you've got too much rear bias. If the front washes out, you've got too much front bias. If it slides gently sideways, you're not far off.

[Paul V]

I found the green stuff pads and drilled and grooved discs make some difference but mine always stopped nicely anyway, when I drove Johno’s car the brakes didn’t seem to be great so I can see why he’s upgrading and look forward to comparing his to mine once he has his big brakes done.

If the pads have a higher coefficient of friction surly the braking power must be higher, more friction will generate more heat, so it must take more power to get that extra heat?

[M@H]

PaulV, I assume I ordered the right discs 1.8/2.0l Sierra non ABS ??

Cheers
Matt.

[johno]

quote:
PaulV, I assume I ordered the right discs 1.8/2.0l Sierra non ABS ??

Cheers
Matt.

Yes.

PaulV,

Mine stops aswell as yours ! I just don't weigh as much !!

Dropped the discs off at Hispec this afternoon and will pick them up on Friday. Not bad for £15 a disc to be skimmed.

Cheers

Mark

[M@H]

Arrived Yesterday... less than 24 hours after ordering (free delivery too) complete with complimentary tube of copperslip..!

I would now highly reccommend RM Carspares for Price and Service!

www.rmcarspares.co.uk/

Cheers
Matt.