rear brake calipers

[Guest]

I found that the o/s/r pistons are seized on my carrera,while trying to change the pads anyone had the same problem and how did they solve it,or do i need a new pair of calipers.If thats the case can anyone recommend a firm to get them from.Thanks Steve.P.s i left a post about oil to use for a carrera and went for mobil 1, which seems to be ok.

 

[ClubSport 911]

In the back of 911 & Porsche World (and Porsche Post I think) are a company called Classicar. for about £60, they strip, re-build and test your brake calipers. What's more, they re-coat them in a Zinc passivate to make them look all brand new.

It seems the Carrera 3.2 has a known issue with rear brakes sticking / siezing, so welcome to the club

Rgds

 

[Jamie Summers]

Mine seized, just bought new ones which have been on back order from ATE for about six months. Worth buying new as re-cons are sometimes not brilliantly done YMMV ! I got mine from Porscheshop.

Jamie

 

[Guest]

Re-did mine about a year ago; they where tight.
re-built them myself. Piece of piss.
Kit cost around 15 or 18 big ones, and I painted them red when I finished.
Makes em go faster.

 

[plhorner]

Pete, out of interest, did you have siezed nipples? [][]

Just thinking about doing some brake work on mine and dreading shearing my bleading nipples off!

 

[Guest]

Phil,
Thats a very personal question.... how did you know I had siezed nipples?
Ok.. no I didn't have this problem, but have had it before on other cars. The best advice I can give is:
A/ use a proper brake line spanner - these enclose the nut properly unlike an open-ender.
I think the nipples are 9mm?
B/ If your removing the caliper to repair it - then if the nipple is siezed don't hesitate to heat the nipple with a torch ( not a pen light - you idiot!).
Then lash-out and buy a couple of new nipples from the local parts shop ( should cost a whole pound! Gosh! that much!)
That should fix em.
My Turbo gas torch is one of the best tools you can own... nothing is siezed anymore! Hit it and Burnnnnn![]

 

[bernard tester]

If your a diy man you can rebuld them if there not to bad, parts from Bert At Berlyn services if they are to bad buy new. recon jobs sometimes more con than re! Regards

 

[Guest]

I have been told about a set of front and rear calipers off of a 993 which are for sale,but i am not sure if they will fit without a lot off modifications.My car is fitted with 16 inch wheels,anyone ever tried this mod.Thanks.

 

[Guest]

Smple answer is, no.

993 calipers are designed to work with much thicker rotors. IIRC, 32mm thick front and 28mm thick rear compared with our 24/24mm rotors. Diameters are also different. I also believe they would need an adapter to mount. It might be possible to use Turbo rotors (rears bolt on and fronts need to have a zero offset mounting bell and need pricey aftermarket or NLA rotors), but the caliper mounts still need adapting and I believe they will not fit within a 16" Fuchs anyway (might be wrong on the last part).

They only 4-piston caliper that fits easily is a Boxster caliper - which is why you see kits for USD500 - but that is not a performance upgrade, just a cosmetic one.

There are no easy and cheap upgrades. I reckon you could do a 964 front rotor/caliper upgrade like I did for circa £1,000 with used caipers and which in conjunction with removal of the PV gives a nice balance and useful increase in thermal capacity and caliper stiffness/pad size. My install is detailed on this forum. Otherwise its expensive however you look at it.

One other posibility is a Wilwood kit discussed recently on Pelican, but the calipers have no dirt seals so are more suitable for racing where inspection and rebuild is routine and regular. It was however very well priced.

Richard

 

[Jamie Summers]

Richard is correct, whilst the 993 calipers can be made to fit (but the economics may be prohibitive) the caliper / disc combo will not fit under a 16 inch Fuchs rim - you would need to go to a 17 inch rim, which may rule out the upgrade from a cosmetic point of view too. I would highly recommend the set up that Richard has on his car with the re-machined 964 front calipers - seemingly the best combination of bigger caliper and bigger disc that will still fit under a 16 inch wheel (unless you wanted to go for 930 Turbo set up which is significantly more expensive and requires the rears to be changed too (?) to get a suitable brake balance.).

Without wishing to hijack I might be interested in the 933 front calipers if you're prepared to tell me where they're for sale ? (They will fit under the 17 inch wheels on my 964)

 

[Guest]

Thanks for the comments,i think i will stick with the orginal ones,the 993 calipers are on ebay.

 

[Guest]

993 calipers in 16" wheels.

 

[ClubSport 911]

Followed that thread - interesting conversion methinks. I wonder if he encountered brake balance issues, and how he solved them ??

 

[Guest]

Read the thread;
An excellent conversion - something I think that is finally really worth doing to the 3.2. The 3.2 has always had media-oka brakes.
Has anyone costed it here yet?
I might send the list to Mathew at Type 911 and see what he says?

A thought ( yes I do have them on occasion),
Another cause for rear brakes to sieze could/can be the brake hoses. These can perish internally, breaking down. The internal rubber lining collapses and actually acts as a one-way valve. When you apply the brakes, the pressure stays in the calliper because the hose is preventing it from de-pressurizing when you release the pedal.
Make sense?
On of my next projects is to replace all the brake hoses.[]

 

[Guest]

This is just the 930 brake upgrade with 993 calipers - though it is nice to see that it fits inside 16s. I always thought 993 calipers on 930 rotors were too big for 16s but that is obviously wrong. One note of caution I would add is that the front wheels on that car look like 944 Turbo Fuch which have more room for calipers than 911 Fuchs. To my eyes, it looks like the wheels have the recessed lug nut holes - hence they are 7 or 8x16 944 Fuchs. These are very rare in the UK so good luck finding some.

I seem to recall reading about a 3.2 with 993 engine and 993 brake in 911 World which had the 7x16 944 Fuchs. I also believe that Josh Sadler's Autofarm RS had this brake set-up (with a 3.6 Motec engine!!) and the artcle said that car had 7.5x16 Fuchs - which sounds like a custom banded/welded wheel.

The great thing about this kit is that it is a reasonably priced bolt-on kit. If you can source all the discs locally (no reason why you can't get Wilwoods in the UK) you could just ship the rest over from the US for a very good price. Other than the discs, all this stuff is quite light weight. I copied the price info:

The kit included:
rotor adapter X 2
Caliper adapter X 2
Caliper adapter bolts X 4
Caliper bolts X 4
OEM 1998 993 Front pads w/out sensors X 1
NAS bolts, K-nut rotor mounting X 16 each
UL-32 Directional Vane rotors 309mm X 32mm X 2 each

Total: $415 plus Shipping

GT Directional Vane Gas Slotted rotors 309 X 32 X 2 each
ADD: $235

To this you need to add rear rotors (stock 930 readily available), almost certainly new brake lines are needed, rear pads and of course the calipers. You also need to remove the rear proportioning valve, the rear calipers need the throats opened to fit over the 930 rear discs and, I think, the mounting bolt spacing needs to be filled and re-drilled and you need a 930 master cylinder. You probably also want to rebuild the calipers. IMHO, you will still be closer to £2k than £1k once you are done and dusted. This set-up is arguably the best brakes you can get for a 3.2 and it sure looks pretty. I doubt however that it will stop any better than my 964 type set-up (in round number £1k all in), though I admit it has significantly better thermal reserves. It may be overkill for our cars.

HTH
Richard

 

[Guest]

I'm pretty sure the 7" 944 Fuchs are the same as 911 ones (911 part #). The 8" rears from a 951 are different but I don't think the guy in question is using them.

 

[Guest]

No, they are not the same. They have more clearance for calipers. To be precise, the extra caliper clearance is equal to the depth the lug nuts are recessed into the face. This is about 6-8mm at a guess. You may need to run a 5mm spacer if you use 911 7x16 Fuchs - which should be possible if you are prepared to dial in as much negative camber as you can get and roll the fender lips. Using 205 front tyres rather than 225s also helps. I don't think 6x16 Fuchs will work as they have even less caliper space. I was told they would not work with my 964 brakes (though I never got around to bolting them on to check). I don't have a picture of my 964 brakes from the inside but I can assure you that it is a tight fight in a 7x16, there is not much clearance in any direction.

You need to remember that a 16x7 Fuchs is a less than optimal wheel for brake clearance as its centre is the same as a 15x7. So, in a lot of respects, you are really trying to fit the brakes into a 15 inch wheel. With custom 3 piece 16s you can go as big as 964RS brakes without a problem.

Richard

 

[Mike58]

Richard
i accept your superior knowledge on this subject but i have to report a significant increase in stopping power having fitted Boxster monoblocs on the fronts a couple of years ago.
I went through all the pad/fluid/hose changes you could think of but the bottom line is that it stopped quicker with the 4 pot monoblocs and standard discs. This is tested in extremis approaching Knockhills hairpin regularly.
I will let you guys know how it copes at Spa in May 2005!!

Mike

 

[Guest]

Hi Mike,

Apologies for the generalisation in the earlier post - I am to some extent happy to agree with you on the extra stopping power. You have added a bigger stiffer caliper and if (like me) it felt like you may never be able to lock the wheels with the standard brakes, then yes you have added stopping power. If you could lock the wheels with the standard brakes, then you have not added stopping power unless the resulting bias change has allowed you to get some more stop from the rear wheels. As you will know, there are really 2 problems with 3.2 brakes on track. The first is that they seem to be marginal in their ability to lock the wheels - so the clamping force itself is marginal. I think a lot of this can be cured with the latest track pads and some of this is the way they feel. You never seem to get a very stiff pedal, so they feel like you are pushing thru the floor to get to the point of lock-up. A long travel also makes it hard to modulate. The Boxster monobloc helps with this first problem. I guess if you need to rebuild std calipers then it may be justified on that basis alone. The second problem is lack of thermal capacity. The standard discs are fine for the road but are small for track work when a 3.2 (dry book weight 1210/1250kg for 915/G50) with full fluids can weigh in at 1330kg (which is where my G50 started with most of the usual options but no air-con) - before you add a driver and a mansize passenger, so maybe 1480kg all in! The boxster brakes do not help with the thermal capacity problem and according to some reports can make it worse as they add more heat into the already overloaded system. If they transfer bias forward then this is indeed the result you would expect. If you can live with the lack of thermal capacity by ducting lots of cool air or you have a very light car then the Boxster brakes make some sense.

In contrast, the turbo/993 brakes add much bigger rotors - a full 8mm thicker at the front and about 15mm of extra diameter. My 964 brakes add 4mm of extra disc thickness at the front and about 10mm of extra diameter and of course also use a big stiff aluminium 4 piston caliper (and there are a lot of folks who think the 964 upgrade is only of marginal benefit!). This extra thermal reserve is why you pay more.

Just out of interest, I wonder if your change in brakes coincided with a change to Pilot Sport Cups. My change coincided with a change to 225 section DO1Js and the extra stop you get from good r-compounds is pretty amazing. When I go back to my road tyres in 205 width I have to be careful not to lock the fronts as they have no where near as much grip.

Who are you going to Spa with and what date in May?

Cheers,
Richard

 

[Mike58]

truthfully I can't remember if there was a tyre change at the time, there could have been. I too am running Dunlop D1OJs but they are now worn out and I am considering Toyo track compound as well the D1s.I do have big cooling ducts fitted from AJR racing USA as recommended in the Bruce Anderson book, I know they work as a bird got stuffed in the left one and that side overheated very quickly. I am currently using Performance Friction pads 97 compound and they work very well with my setup.
A PCGB friend has booked places with Autotrack UK for 24/25 May so around 10 of us with track orientated Porsches will be going, I will as usual be bringing up the rear as most of the guys are running serious stuff -- GT3RS, RS replica wth 300BHP, RS replica 250BHP/900kg!!, GT3 full race suspension and tuned etc etc.. but I can usualy find a newer car unmodded to dice with and cause a raised eyebrow.
Do you know if bigger discs can be fitted to the Boxster monoblocs within 16inch fuchs.

Mike