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daltonr

Original Poster:

19 posts

104 months

[news] 
Friday 29th January 2010 quote quote all
Hi guys

My venerable but very quick 1989 Porsche 944 Turbo 250SE upgrade continues. Next on the agenda are the brakes ... and I'd be really interested in your views...

Situation:
The car is driven sympathetically but very hard and I do a few track days per year. Last of the late brakers + turbo motor (less engine braking) + standard use of heal/toe (less engine braking) + v spirited driving = v heavy brake use. Regardless of pad I still get some fade, and ultimately judder from over-heated and warped discs.

Current set-up:
MO30 4 piston callipers and I've previously up-rated discs with genuine 968 MO30 Club Sport cross-drilled discs and have run these for many years. Over the past 12 years I've run the following pads on it:
- Porsche pads which lacked a little bite and faded under extreme (i.e. standard) use
- Porterfields which were faultless aside from the squeal which I just couldn't live with
- EBC green stuff which performed much as the Porsche pads (but without the brake dust)
- EBC red stuff which were adequate to start with but went off quickly so not much better than green stuff I'd say

Upgrade options:
[1] Stick with 968 CS discs + upgrade pads. Performance Friction or Pagid Blue RS421 have been recommended - can anyone recommend them or others?
[2] As [1] but upgrade front callipers/discs to 928GTS/993 turbo set-up which will give a slightly larger swept area of disc and a bigger pad - have any of you 944T chaps had any joy with this upgrade? Did you need to adjust the brake bias setup?
[3] A more bespoke setup: custom made hubs built to accept Alcon (or other) floating discs + different pads and possibly callipers

Any thoughts would be welcome. They definitely improved the bite, but as an aside I've wondered for a long time whether the cross-drilled discs are causing increased heat build-up and so fade and disc overheating. Any thoughts on this too would be fab.

daltonr

plenty

2,158 posts

72 months

[news] 
Friday 29th January 2010 quote quote all
Have you tried solid discs? Quite a few folks have reported better performance compared with the drilled versions which reportedly do suffer more from overheating and sometimes heat-induced cracking.

chfs911

688 posts

112 months

[news] 
Friday 29th January 2010 quote quote all
I went for 993TT discs with M030 spindles, custom 45mm top hats and Big Reds 993TT. Swapped to 928 bias valve and it works great on 968.

http://www.968cs.de/

Might be of use? upgraded my 968 to 993TT brakes.

DISCS for use with Big Red or Big Black type calipers (all 322mmx32mm)
965 (911-964 3.6 Turbo)
1-piece disc, cross drilled, 45mm top hat
965-351-045-00
965-351-046-00

928 GTS
1-piece disc, NON cross drilled, 45mm top hat
928-351-045-01
928-351-046-01

993 Twin Turbo
2-piece disc, cross drilled, 40mm top hat (separate disc and mounting ‘hat’)
993-351-045-10
993-351-046-10
discs are seldom used, 993RS cheaper

993RS
1 piece disc, cross drilled, 40mm top hat
993-351-045-00
993-351-046-00


DISCS for use with M030 (928 S4) calipers (all 304mm x 32mm)
968 M030
1-piece disc, cross drilled, 45mm top hat
965-351-041-01
965-351-042-01

928 S4
1-piece disc, NON cross drilled, 45mm top hat
928-351-045-01
928-351-046-01


Discs with a ‘top-hat’ (offset) dimension of 45mm will have an outer disc pad face in the same position as standard – the larger discs are thicker (32mm vs 28mm) therefore the inner pad face of the discs are 4mm further in (into the car). This will close the gap between the disc face and the track rod end – it has been suggested that heat build up from the disc can be a problem, but I have never heard of any actual experience of this.

Discs with a ‘top-hat’ dimension of 40mm will have an outer disc pad face 5mm further out than standard (also pushing the caliper further out by 5mm and closer to the spokes of your wheels). The inner pad face of the discs will be –1mm further out from standard (further out of the car) and hence remains virtually the same distance from your track rod end.

NOTE: the M030 spindle/hub assembly locates the disc approximately 3mm further out to compensate for the additional thickness of the discs from standard.


CALIPERS
Big Reds (993 Twin Turbo calipers)
993-351-425-10
993-351-426-10
36mm/44mm piston sizes
Leading, radial mounting, bleeder screws & cross-over tubes require swapping over for trailing mounting. Pad retention springs will be upside-down. Red in colour.

Big Blacks (928GTS calipers)
928-351-423-03
928-351-424-03
36mm/44mm piston sizes
Trailing, radial mounting, bleeder screws & cross-over tubes in correct position. Pad retention springs in correct orientation. Black in colour.

M030 calipers (928 S4 calipers) (also used on 944 S2 M030, 944 Turbo S)
928-351-421-03
928-351-422-03
36mm/44mm piston sizes

Edited by chfs911 on Friday 29th January 21:01

Riverside

308 posts

104 months

[news] 
Friday 29th January 2010 quote quote all
If your brakes are overheating try to improve the cooling before you throw money at it.

I have standard medium blacks, disks & pads & they used to eventually overheat on trackdays.

I changed the fluid from dot 5.1 to Racing Blue and added 944t cooling ducts (earlier turbos had them, our later ones don't), no more overheating, minimal cost.

diver944

1,803 posts

162 months

[news] 
Friday 29th January 2010 quote quote all
If your car makes standard to 300bhp then the standard brakes should be more than adequate if everything is working as it should and you have good, fresh fluid - ATE Blue is a good, cheap upgrade with a high boiling point. As Malcolm said, a simple 3" duct from the front bumper to the back of the disk also works wonders in cooling

I ran standard brakes for many years on full race slicks and had no problems when I was around the 300bhp mark. Eventually I tried PF97 pads and they were even better, good cold grip and fantastic when hot.

I now have the 928GTS Big Blacks becase I am pushing 400bhp, but I think they are overkill for less than 300bhp
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graemel

5,019 posts

103 months

[news] 
Friday 29th January 2010 quote quote all
+1. I have driven quite a few race prepped 944 turbo's and the brakes where mightily impressive. I agree look at cooling and fluid first before looking at big brake kits.

frogisland

207 posts

131 months

[news] 
Friday 29th January 2010 quote quote all
I've tried all combination of calipers/discs/pads, indeed i wrote the original of what chfs911 posted! Started with standard calipers, then M030, now on Big Reds. Ive tended to stay with Pagid; blue, orange, yellow. Would suggest you go with solid 928 discs and orange pads. The 'holy' 968 discs (and the TT ones) are a pain in the butt for fracturing around the holes. The problem with the solid discs is glazing (i've deglazed a fair few pads on one of the Porsche Club cars!). I found the blue lacking on standard and M030 calipers when pushing on very hard with late braking. Orange were much better. Yellows in the big reds are difficult tto manage - have to get much heat into them to get them to work propoerly...and then they really do. re brake fluid, again found ate super blue (or gold) good until you start to push on very hard on full day trackday (my 968 is all solid bearings/rose joint etc) then it can over heat. I use castrol srf now - 2-3 times the price and needs replacing more often but much better, no problems with it whatsoever.
JP

333pg333

67 posts

76 months

[news] 
Saturday 30th January 2010 quote quote all
If you supply air to the rotors directly via tube ducting this will help cool them a lot. Depends on what sway bar setup you have though. I have used Mo30 setup with EBC pads (Yellow and Green) and found them very wanting. I switched to PFC pads (01's and 97's) and this improved braking distances by a LONG way. Then switched to Big Reds, but still had a bit of long pedal travel and occasional mushiness. Using a drilled rotor vs solids helps a lot to alleviate hot gas 'cushion' build up, however the drilled ones don't last too long. Next move is to use slotted rotors. Not so easy to find but you can try this place.
http://www.frozenrotors.com/products/frozen-rotors...

Can't remember the last time I saw a race car without either drilled, slotted, scalloped or all 3 vs a solid rotor?? S/Steel braided hose lines, new M/Cylinder and a high quality brake fluid. I use SRF.

Having said all that, I have done a fair bit of research into 951 brakes and have found a number of people around the world who are dissatisfied with their brakes overall, and that includes those with Big Reds. There is a theory that RHD cars are worse. I am also going to brace my booster. There is some movement under high loads. The next step would be to fit a Monoblock caliper from a later model Porsche. Easy on a non Mo30 car, not so if you do have Mo30.

clubracing

227 posts

92 months

[news] 
Saturday 30th January 2010 quote quote all
Why not just change between a full race pad for trackdays and a road pad for normal driving? Changing the pads is a 15 min job.

NJH

1,747 posts

95 months

[news] 
Saturday 30th January 2010 quote quote all
333pg333 said:
There is a theory that RHD cars are worse
Given that we have a bar that runs across the back of the dash, connected by 2 levers a good few feet apart I would expect that RHD cars would most certainly have worse pedal feel and response to LHD cars.

edh

693 posts

155 months

[news] 
Tuesday 2nd February 2010 quote quote all
PFC 97 pads are the solution - plus some brake cooling. 968 brake ducts work very well - if you have the later (968) lower arms. You might also look to run some ducting from the front PU into the centre of the disks.

The PFC pads are very impressive on the track - you can brake very late and very hard with them. They are one of the products that users become evangelical about - they are really that good! I never had any fade at all (300bhp 944 turbo, std weight, trackday tyres). Try a set before you do anything else - it's much cheaper than changing to big blacks etc.. Provided you use a decent high temp grease when fitting, they won't squeal either.

One other thing - when I changed my last set of discs (Sebro from Bert @ berlyn), the surface was still very clean, with no hairline cracks. This suggests to me that cooling was doing agreat job.

- there is a downside of course

They create very corrosive dust that sticks to your paintwork and eats into your wheels - very difficult to remove. I used clay bar every so often.

They also wear discs at a pretty fast rate - although wear on the pads is very good. Considering the discs are cheaper than the pads that may not be too much of an issue.

before I sold my car I changed back to EBC greens - only for road use, but it felt like I didn't have any brakes at all eek

Edited by edh on Tuesday 2nd February 12:05

chfs911

688 posts

112 months

[news] 
Wednesday 3rd February 2010 quote quote all
Yes, I can confirm Jason and Stefan have a lot to answer for!

Cost me a fortune in brake upgrades but the car is transformed.

The bias valve swap really stops front end dive under braking.

ATe blue with Goodrich hoses and Pagid RS 4-2s work well on and off the track.

Orange and yellow are track only IMHO.

Charles

big - dave

278 posts

127 months

[news] 
Wednesday 3rd February 2010 quote quote all
Ive been down the exact route as Frogisland.
But i stuck with the M030 calipers for a lot longer + just fitted some Pagid Orange pads.
Ive now upgrade to the Big Red set up, again with the Oranges + when on track, both together you cant get a "fag" paper between us, + thats at FULL speed....
The braking capabilities of these cars , when performing right is unbelievable...
The Castrol SRF fluid is THE best, but pricey....

PPS. DONT even contemplate the EBC,s,, what a load of c##p.....At least on a Porsche...

PPS what tyres are you using.??

daltonr

Original Poster:

19 posts

104 months

[news] 
Friday 5th February 2010 quote quote all
Hi guys, thanks for all the suggestions. I'm currently using Castrol SRF and have aeroquip'ed the brake lines some time ago - so those two areas are sorted (although the brake fluid is probably due for a change soon).

Improved brake cooling seems to be the next step which I will get sorted. I don't really want to change the front fogs or appearance of the front PU though - is this a given or is there another way?

I'll get set up with either PF97s or Pagid Orange (I think the ones I want are "RS 4-4"?) at the same time. Do any of you have experience of how they compare to each other I wonder?

I think I'll also go for some Sebro front discs. I will then re-assess whether I need to go with a more serious calliper/disk upgrade.

Edited by daltonr on Friday 5th February 16:07

daltonr

Original Poster:

19 posts

104 months

[news] 
Friday 5th February 2010 quote quote all
plenty said:
Have you tried solid discs? Quite a few folks have reported better performance compared with the drilled versions which reportedly do suffer more from overheating and sometimes heat-induced cracking.
I did indeed, albeit about 10 years ago. I'm sure you're right re solid discs re heat but I was never really happy with them, particularly with the initial bite. That said, at the time I was running standard brake flexys, standard fluid and standard pads. I spent time time with a 993 C2 and decided that I wanted to replicate the bite and confidence I'd experienced in that. So started 10 years of on and off mods to much of the car!

daltonr

Original Poster:

19 posts

104 months

[news] 
Friday 5th February 2010 quote quote all
chfs911 said:
I went for 993TT discs with M030 spindles, custom 45mm top hats and Big Reds 993TT. Swapped to 928 bias valve and it works great on 968.

http://www.968cs.de/

Might be of use? upgraded my 968 to 993TT brakes.
Edited by chfs911 on Friday 29th January 21:01
Great stuff. Nice drifting - like me you clearly believe that a car is handling best when its going sideways!

Do you think the 928 bias valve be a worthy upgrade in its own right for the standard callipers, or just if I want to go up to a bigger calliper/disk/pad at the front?

daltonr

Original Poster:

19 posts

104 months

[news] 
Friday 5th February 2010 quote quote all
Riverside said:
If your brakes are overheating try to improve the cooling before you throw money at it.

I have standard medium blacks, disks & pads & they used to eventually overheat on trackdays.

I changed the fluid from dot 5.1 to Racing Blue and added 944t cooling ducts (earlier turbos had them, our later ones don't), no more overheating, minimal cost.
I'm sure you're right. Wasn't aware of early 944Ts having cooling ducts - where do they vent from?

daltonr

Original Poster:

19 posts

104 months

[news] 
Friday 5th February 2010 quote quote all
diver944 said:
If your car makes standard to 300bhp then the standard brakes should be more than adequate if everything is working as it should and you have good, fresh fluid - ATE Blue is a good, cheap upgrade with a high boiling point. As Malcolm said, a simple 3" duct from the front bumper to the back of the disk also works wonders in cooling

I ran standard brakes for many years on full race slicks and had no problems when I was around the 300bhp mark. Eventually I tried PF97 pads and they were even better, good cold grip and fantastic when hot.

I now have the 928GTS Big Blacks becase I am pushing 400bhp, but I think they are overkill for less than 300bhp
312bhp after a few upgrades over the years - but I'm aiming for 360-375 this year and for once I want to be prepared! I think I'll hold off on the big blacks until I try cooling and pads as suggested.

daltonr

Original Poster:

19 posts

104 months

[news] 
Friday 5th February 2010 quote quote all
edh said:
PFC 97 pads are the solution - plus some brake cooling. 968 brake ducts work very well - if you have the later (968) lower arms. You might also look to run some ducting from the front PU into the centre of the disks.

The PFC pads are very impressive on the track - you can brake very late and very hard with them. They are one of the products that users become evangelical about - they are really that good! I never had any fade at all (300bhp 944 turbo, std weight, trackday tyres). Try a set before you do anything else - it's much cheaper than changing to big blacks etc.. Provided you use a decent high temp grease when fitting, they won't squeal either.

One other thing - when I changed my last set of discs (Sebro from Bert @ berlyn), the surface was still very clean, with no hairline cracks. This suggests to me that cooling was doing agreat job.

- there is a downside of course

They create very corrosive dust that sticks to your paintwork and eats into your wheels - very difficult to remove. I used clay bar every so often.

They also wear discs at a pretty fast rate - although wear on the pads is very good. Considering the discs are cheaper than the pads that may not be too much of an issue.

before I sold my car I changed back to EBC greens - only for road use, but it felt like I didn't have any brakes at all eek

Edited by edh on Tuesday 2nd February 12:05
Thanks for that. Some questions...

Do the 968 brake ducts replace the front bumper fog lights or do they fit somewhere else?

Sebro discs look interesting - fraction of the price of OE! http://www.eurocarparts.com/ecp/c/Porsche_944_2.5_... As a matter of interest, which pattern have you gone for the full cross-drilled or the single lines of holes? [Edit: Actually on closer inspection it looks like the minimal cross-drilled ones are for the rears only]

Do you find the PF07 brake dust worse than standard Porsche pads? I think this is the only real advantage of EBC - no dust!

Edited by daltonr on Friday 5th February 16:08

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