[zms968]

I have a client who wants to trade me a set of 996 turbo brakes for my stockers for another car... Long story. Anyways, has anyone done this? I know about the big red stuff, and have a set of those with adapters and the proper valve sitting on the bench, but hasn't put them on yet due to differing opinions and associated costs- rotors etc. if the 996 ones work, and would be free, I would be happy to swap. Will it work??

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[flash]

i don't know if those will fit, nor do i know if the suspension can handle that much unsprung weight without making some changes, but whatever you do, make sure you do the same thing to the rear as you do the front. the worst thing you can do is increase the front braking without addressing the rear. that actually results in less overall braking. the car actually needs more rear brake a lot more than it needs more front.

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[zms968]

It would be all 4 corners-

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[craigawoodman]

Issue when changing brakes is mounting (is it possible to fit them) and then once that hurdle is overcome, can the brake master cylinder supply sufficient brake fluid to make them work. The last part will be down to the number of pistons, piston size, brake pad thickness and wear (I.e. the stroke of the piston and therefore the volume of fluid required to be delivered) and whether or not they are compatible with the ABS calibration of the car.



If you are going from a 4 piston to 4 piston calliper and the pistons are roughly the same size, then there should not be much problem. If you are going to a 6 piston calliper from a 4 piston, then someone in the know needs to have a look.



As per Flash's post, you would also need to change the brake bias valve to suit. The 911 turbo valve may send too much rear brake pressure, due to the weight at the rear of a 911 versus a 968.



I am running "Big Blacks" on the front with the standard rears and a different bias valve - seems to work well. Question is, why do you need more brakes? Stainless lines and a racing pad and brake fluid will work wonders. Bigger brakes increase unsprung mass and rotational inertia, so it is always a trade off. If you are going racing and have some very big brake applications, then go for as much brake as you can get. If it is for street use, pads, lines and fluid will work.



I am about to go back to Bathurst and the track there. There are some massive brake applications on that track (6th gear, 250km/h to a second gear corner, followed about 15 seconds later by 4th to second, and then 10 seconds later 4th to 2nd again - in a S/C car).



When racing, big brakes makes you look like you have big balls, but it is the brakes that are flattering you.



Hope that this helps.

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[craigawoodman]

Sorry, should have also added, check that your rims will still fit. Big Reds/Blacks require 17 inch rims up, not sure about the 996 turbo brakes, but pretty sure all 996 turbos were on 18 inch rims. Your rims may also foul the callipers due to the calliper size and disc offset/position relative to the rim spokes/lacing/arms.



From memory as well, the 996 uses a different wheel mounting arrangement - through bolts, not studs and nuts.

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[zms968]

I guess I'll try and see what happens. This client wants bigger brakes on his turbo, and will give me the stock turbo brakes in trade fr mine, which he wants to put on his 914 3.6. It's a bit convoluted, but if it works, and is free, why not!

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[Cloud9...68]

Agreed - for a street car, I never understood the reasoning behind adding more brake. I've been driving for 37 years, almost always sports/GT cars, and the number of times I've been involved with a panic stop in which more powerful brakes would have been an asset is - zero. On the track - absolutely. But for a street car, I just don't understand the logic. Even if you're getting them for free, there's potentially a lot of work, and possibly expense, involved with getting them fitted. Not trying to talk you out of it, just trying to understand why the interest.

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[zms968]

There's really no need for it at all. I do think it would be cool and unique. They are 4 piston, and I already have the proper bracktry for big blacks/ reds, which appear to mout the same way. I guess if it doesn't work, nothing lost, if it does, good for me.

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[craigawoodman]

Simple logic says that unless you have a tyre that can provide the grip to use the additional braking capacity, then all you are going to do is invoke the ABS earlier. And when racing, while it may enable you to steer, it is not as effective in slowing the car down versus maximum cadence braking - you can feel the drop in brake performance and have to cascade brake to release the abs anyway.



The only other benefit provided is thermal mass and energy dissipation/resistance. On the road, this is not a problem and unless you are running a semi race pad and racing fluid, these will most likely be the limiting factors first.



There is one other benefit - they do look better, filling the rim. If anyone has seen a new Boxster on 20 inch rims, the brakes look puny, so small in such a massive rim.

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[flash]

the other thing to consider is the disadvantage of the extra unsprung weight and rotational mass. it will make the suspension less nimble feeling, and the larger rotors will cost in acceleration.



lots to consider.



i've had a set of aluminum hats here for a few years now, and have hesitated to build up a kit because of the downsides of larger brakes. i really don't use all the brakes i have now (crossdrilled zimmermans, porterfield R4-S pads, stainless lines and blue ATE), so unless i could make them lighter than what i have now, i have a hard time justifying the time and expense.

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[Dubai944]

[quote name='craigawoodman' timestamp='1361490958' post='139037']

I am about to go back to Bathurst and the track there. There are some massive brake applications on that track (6th gear, 250km/h to a second gear corner, followed about 15 seconds later by 4th to second, and then 10 seconds later 4th to 2nd again - in a S/C car).

[/quote]



With a 2:40 lap restriction , you can go just go slower down conrod <img src="/forum/images/smilies/968/smile.png" class="smilie" alt="" />



I can't see much point of bigger brakes on a road car, but if you already have a set of big reds and adapters and you want the look do those rather than try and customise a fit for the 996 callipers. I did my first two race seasons with stock M030 big blacks and with proper ducting, pads and fluid etc. they were more than adequate even for a dedicated race car on standard width slicks. You really won't see any improvement with the 996 callipers over the big reds, and unless you are on some very big and sticky rubber you probably won't see any improvement with either of them over your stock set-up.



Customising a brake setup and actually ending up with an improvement is not as easy as people think. I now have big 355mm rotors and Stoptech ST60 callipers setup on my car, but it took a lot of fiddling to get it right and was only really justified when the car got a lot faster and I went to a wide body with big 300mm wide race slicks on 12 inch wide rims.

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[zms968]

The reason I am hesitant to install the big blacks I have is because I don't have appropriate rears. This would be all 4, and free, so it seems intriguing. I'll know more next week when I install the big brakes on the turbo and get the 996 cals.

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[craigawoodman]

ZMS,



I am only running "Big Black" front rotors and callipers wih the standard 968 rear callipers and discs at the rear. I am pretty sure Paragon sells a kit along with the correct bias valve for this set-up. I changed the front rotors and calliper a plus the bias valve and have not had any problems.



Even fitting the 996 brakes all round, you will still need to play with brake bias, as the 996 can carry much more rear brake due to the weight distribution, particularly under braking with weight transfer.



Simpler option - go with the Big Blacks and a replacement bias valve. Done, no fiddling.

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[zms968]

That is probably the best idea- but I may fiddle with it a bit anyways, kinda curious now. Haha

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[craigawoodman]

ZMS,



The one thing I have had to learn the hard way - fiddling and exploring unchartered territory with any form of Porsche - equals lots of heartache and lots of dollars. Plug and play is the cheapest way to improve the car. Take what someone else has gone through the pain with and simply install it. Never, the less, if you want to mount up the 996 brakes, I for one would like the hear of the result and what is required to make it work. Just factor in tripple the amount of time and costs you think it will take.

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[zms968]

Will do- keep in mind that I'm a Porsche tech, so parts and labor/time are greatly cheaper. Also- don't want you to think I am ignoring your advice- that's not the case at all.

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[craigawoodman]

ZMS,



Some of us are just stubborn,etc. I had my Waterloo (and am still doing battle) with a 938 Motorsports supercharger. So you are not on your own going off into uncharted territory. I personally blame Star Trek.



I am all for giving it a go and would like to see it work and understand the benefits,etc. Modern mono block callipers are great, rigid and light. So there are benefits. Also, technically, if you can get it to fit, it opens up the door to ceramic brakes for the 968, as I am assuming that the GT2 callipers and brake rotors would also fit (and I think the last of the 996 Turbos, 2004 S model) came with carbon ceramic brakes.



When you get the initial proof of design done, would be interested to know just what is possible. Perhaps the Alcon upgrades/replacements for the Porsche carbon brakes would fit.



It is always a slippery slope when you start modifying cars.



Make it so, Scotty! (Or insert your favourite Star Trek saying here). Good luck Captain, and keep us informed of how it goes via your Captains Log back to Star Fleet command.

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[zms968]

Haha will do- did some quick measuring on the calipers, and the spacing between bolts is 10mm bigger than the big reds/blacks, so we are going to mill some bigger adapters. Other than that, it looks quite promising. Well see next week.

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[zms968]

Just an update, installed the 996 brakes tonight. Haven t replaced the bias valve yet, but got the brackets fabbed up and am quite pleased. The braking difference is noticeable, but wasn't needed. I am not sure which valve to go with, as the brakes seem to be working nicely as they are. I wonder if 996 brakes are better suited to the factory valve than the big reds/blacks? They sure look better though. Really fill out the wheels. I am quite pleased, and the whole thing was cheaper than replacing the stock brakes, which needed to be done.

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[Rap]

Craig nice to see you back. But you should make your info more vague! Lol

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