[Big Dave]

Hi all



Im in the process of "upgrading" my callipers to M030 fronts...



What i would like to know is...



What difference would it make if i put the original [ standard NON M030] front callipers on the rear of the car....



I am also considering fitting a 5/33 bias valve to the car....

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[flash]

a lot of work - this has been discussed heavily before



on a 968, on the street, on stock size tires, it would be highly unlikely you will see any diifference in ANY caliper or rotor upgrade, M030 or otherwise



this upgrade will likely come into play on the track though



out of curiosity, how much did the larger front rotors cost you?



as for the front/rear caliper thing, i seem to remember them being the same on a stock car - i'll look that one up

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[flash]

so far, the only part numbers i show for calipers on this car are:



951-351-422-03 and 951-351-421-03



one is left and one is right

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[rustech]

IIRC, Caliper size are the same front and rear, but the front calipers have larger pistons.

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[Big Dave]

Sorry folks.. should have mentioned that the car ,,944S2 is being used "on track" / DE,s

So the increase in braking WILL be helpfull , to say the least...

I do know the standard front callipers will fit onto the rear + also know the piston sizes are bigger ... BUT what i could do with knowing , basicaly , will it make any difference to the rear braking if i do fit the fronts to the rear....

I realise the 5/33 valve will transfer some more pressure to the backs , BUT will it then be too much + end up locking the rears.?????



Flash,

the larger front rotors are from a 928S4 + are plain ie NOT drilled...

A good friend of mine races a 968 in the British Porsche club championship + tels me that the drilled ones dont last long , "crack",are expensive + are no improvement ...

I paid aprox £100 a pair for them....BUT i also have a stock of partial used / exe race,,ones that were a givaway price.....So all ive got to by are pads ...+ ive fitted the Pagid Oranges for a starter...

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[Silver BLT]

Rustech,

You remember correctly, I just rebuilt my front calipers and they are the same size as the rears only with larger pistons. Good memory!



Silver BLT

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[Bozo]

[quote name='Big Dave' date='Jun 30 2005, 12:54 AM']Flash,

the larger front rotors are from a 928S4 + are plain ie NOT drilled...

A good friend of mine races a 968 in the British Porsche club championship + tels me that the drilled ones dont last long , "crack",are expensive + are no improvement ...

I paid aprox £100 a pair for them....BUT i also have a stock of partial used / exe race,,ones that were a givaway price.....So all ive got to by are pads ...+ ive fitted the Pagid Oranges for a starter...

[right][post="6559"]<{POST_SNAPBACK}>[/post][/right][/quote]



Today I find 928S4 frontrotors crossdrilled for about £95 ea in Sweden.

It is for my 968 M030 frontbakes.

Hopefully it is the same center offset, it looks like! Diameter and thickness is the same as 968 M030 rotors

Tell you more about it upon replacment.

968 M030 rotors = Crossdrilled 928s4 rotors????

Bozo

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[ccannon]

If you're a PCA member, take a look at the current issue of Panorama, it had a big article on brake upgrades, including surface area for 993 Twin Turbo brakes and 928S4 calipers.



July '05 Panorama

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[Big Dave]

Ok, so i think its about time i answered my own question...

I fitted the original front callipers to the rear + fitted M030 callipers to the front..

Conclusions....

If you take the car on track lots, and in the wet, expect the rear end to lock up first...+ if your not carefull the car WILL swap ends...Yes i did it on many occasions... <img src="/forum/images/smilies/968/rolleyes.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/rolleyes.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/rolleyes.gif" class="smilie" alt="" />

In the dry its an animal.. It realy brakes well , trail braking is great + if "reasonably" skillfull you can enter the corner sideways , but it takes practice... <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" /> , So you then ready to apply full power to sling you out of the corner OR drift it through....



So,

conclusions..

Ill be swapping them back to standard for this year...BUT fitting Big Reds [ 993 TT callipers] up front...+ adding a 5/33 bias valve..

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[jaap]

So this was still with the original brake bias valve? Would you see the same behavior when keeping the standard rear calipers but with the 5/33 bias valve



Jaap

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[Big Dave]

Yes all the above was with the standard valve.

Not fitted the 5/33 yet so i cant comment on that.

BUT my m8 has it fitted to his car, with the Big Reds up front + standard rears.. He says its just right...

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[Anchorman]

Why wouldn't properly sized larger rear calipers balance well with larger fronts? For example - I assume that the M030 rears are larger than the stock rears. If M030 fronts were installed on the front, why would you want to leave the stock on the rear - shouldn't they be replaced with M030 rears?

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[flash]

correct -



not sure why the car was swapping ends, i presume rotors were changed to match the calipers - i tend to think the car's balance was upset, not necessarily as a result of braking issues - was it doing it as the same speeds and weight transfers as before the change?



big reds up front and a bias valve won't balance either - many people make this mistake - it will just be front biased - it will "feel" like it's braking better, because the front will dive and you'll have that sensation of a big pull down, but in reality it won't be stopping as well - if you go big reds up front, do it in the rear too



braking systems are all about balance - there is a really good bit of info on this on the stoptech site



pete can also fill anyone in a lot on this

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[Anchorman]

That's (obviously) what I thought - I'm glad to find agreement, because that's what I'll be doing. My 928 S4 calipers will be sent from RS Barn to Goldline to be rebuilt and coated silver, then installed on my 968 - effectively resulting in my having a complete M030 brake system.

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[BerndCF]

[quote name='Anchorman' post='65837' date='Jan 20 2009, 01:00 PM']For example - I assume that the M030 rears are larger than the stock rears.[/quote]

No, Sir. Same size. The M030 has drilled rotors and other brake pads. That's all.

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[flash]

yeah - i'm pretty sure they made the fronts a bit bigger purely for reasons of heat, while still maintaining a front biased car for safer street application - i wonder if the bias valve is different on the M030 car?

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[968LS1]

Read the Stoptech site, they really explain how to balance the system. They actually recommend not doing the rears but making sure the correct piston sizes are used in the front calipers. They recommend smaller piston sizes than what comes on the MO30 and Big RED (they are both the same 36mm/44mm) in the front to compensate for larger rotor with greater mechanical leverage. I am not sure why you would have rear lock up with a stock setup possibly a sticking caliper. I have found the only real way to get the balance correct is to install a balance bar system with dual master cylinders so you can fine tune the bias. I have run Big Blacks with the 33/5 valve and it does have a little too much front bias but a lot of guys do and it will work (using different torque pads front and rear can help some). Putting your stock front calipers on the rear is not a good solution, but if you do don't use the 33/5 valve unless you want to practice doing donuts under heavy braking (ask me how I know). Bigger brakes don't make your car stop faster, they give you greater thermal dissipation so you can stop fast repeatedly with out brake fade. Stock 944T/968 brakes work great though they are front biased; adding an adjustable proportioning valve dialing in a little more rear will make for great braking without a lot of cost.





[quote name='flash' post='65843' date='Jan 20 2009, 10:00 AM']correct -



not sure why the car was swapping ends, i presume rotors were changed to match the calipers - i tend to think the car's balance was upset, not necessarily as a result of braking issues - was it doing it as the same speeds and weight transfers as before the change?



big reds up front and a bias valve won't balance either - many people make this mistake - it will just be front biased - it will "feel" like it's braking better, because the front will dive and you'll have that sensation of a big pull down, but in reality it won't be stopping as well - if you go big reds up front, do it in the rear too



braking systems are all about balance - there is a really good bit of info on this on the stoptech site[/quote]

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[BerndCF]

[quote name='flash' post='65849' date='Jan 20 2009, 05:46 PM']i wonder if the bias valve is different on the M030 car?[/quote]

No, Sir. Just the same. You know the Porsche online catalogs? --> https://techinfo.porsche.com/techinfo/VFMod...pe=GenuineParts

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[Anchorman]

Hmmm...always more complicated than expected.



I haven't compared the 928 S4 rear calipers with the stock 968 calipers; does anyone know how they compare?

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[PorscheDude]

In case you missed the pics I recently posted:

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