6 pots & 4 pots = larger master cylinder...?
#1
6 pots & 4 pots = larger master cylinder...?
Right then,
A bit of a technical one, but I hope someone can help out.
I am about to install some Porsche 6 pots 335x32mm onto the front of our GC8 MY00 track car, then move our current Compbrake 4 pots 295x20 onto the rear... once I have designed and made all of the brackets etc!
Now by doing this i'm increasing the piston surface area by quite a bit over standard, so i'm thinking we need to upgrade the master cylinder to help things out a bit...?
Is the newage master cylinder larger to start off with, and does anyone have any info regarding cylinder bore sizes from 01 upwards...?
Cheers,
Kim.
A bit of a technical one, but I hope someone can help out.
I am about to install some Porsche 6 pots 335x32mm onto the front of our GC8 MY00 track car, then move our current Compbrake 4 pots 295x20 onto the rear... once I have designed and made all of the brackets etc!
Now by doing this i'm increasing the piston surface area by quite a bit over standard, so i'm thinking we need to upgrade the master cylinder to help things out a bit...?
Is the newage master cylinder larger to start off with, and does anyone have any info regarding cylinder bore sizes from 01 upwards...?
Cheers,
Kim.
Last edited by MY94BlueWRX; 18 February 2010 at 03:22 PM. Reason: add image
#4
Yes they are the Porsche 6 pots that i'll be using...
We have the sti 2 pots on there now (red subaru type, not brembos), just thought with putting the 6's on the front (adding 2 pistons effectively) then adding 2 on the back kept things even...?
We have the sti 2 pots on there now (red subaru type, not brembos), just thought with putting the 6's on the front (adding 2 pistons effectively) then adding 2 on the back kept things even...?
Last edited by MY94BlueWRX; 18 February 2010 at 04:59 PM.
#7
AP use 4 pots on their rear kit (CP7615) with 41.3/38.1mm pistons generally, and that is exactly what our compbrake 4pot has...?
So i'm not following why you say it doesn't work like that. Surely if you increase the front axle braking capacity by 20% then increasing the rear axle to match makes perfect sense...?
Plus the impreza is already biased to the front a lot IMO... so some more rear axle braking couldn't hurt, especially on the track. As long as it's not pushed to far obviously.
So i'm not following why you say it doesn't work like that. Surely if you increase the front axle braking capacity by 20% then increasing the rear axle to match makes perfect sense...?
Plus the impreza is already biased to the front a lot IMO... so some more rear axle braking couldn't hurt, especially on the track. As long as it's not pushed to far obviously.
Trending Topics
#9
Scooby Regular
Join Date: Oct 2009
Location: Enginetuner Plymouth for 4wd RR Mapping Apexi Ecutek Simtek Proper Garage More than just a laptop!
Posts: 71
Likes: 0
Received 0 Likes
on
0 Posts
Ignoring it? Im sure that was the whole point of the question based around M/C size etc, I doubt it will hit the floor but there may be some more travel on the pedal, best to do some research I think there are some quite good explanations on the wilwood site describing master cylinder ratios etc and what works best with what. Of course the other way is try it and see how the pedal feels and how well the brakes work
Last edited by Trevcoss; 18 February 2010 at 06:23 PM. Reason: fat fingers hitting the wrong keys
#11
Thanks Trevcoss... I'm not ignoring the M/C size at all, my initial questionwas should I be looking at a different M/C size..?
I have done some calculations for the bias using the piston/disc/pad sizes for all three setups, apollogies as they're in inches but here they are...
As you can see the proposed setup actually brings the car closer to the original Subaru bias setting, providing I have my maths correct that is!!
Also am I correct in saying that a bigger M/C size may increase pedal feel/hardness but will actually decrease the torque seen at the discs, and visa versa with a smaller M/C... softer pedal but more transmitted torque...?
I have done some calculations for the bias using the piston/disc/pad sizes for all three setups, apollogies as they're in inches but here they are...
As you can see the proposed setup actually brings the car closer to the original Subaru bias setting, providing I have my maths correct that is!!
Also am I correct in saying that a bigger M/C size may increase pedal feel/hardness but will actually decrease the torque seen at the discs, and visa versa with a smaller M/C... softer pedal but more transmitted torque...?
#12
Scooby Regular
Join Date: Oct 2009
Location: Enginetuner Plymouth for 4wd RR Mapping Apexi Ecutek Simtek Proper Garage More than just a laptop!
Posts: 71
Likes: 0
Received 0 Likes
on
0 Posts
Something up with the 4 pot one pot setup as I cant see the single pot calliper having a larger area than the two pot callipers
#13
I thought that but apparantly it takes into account that a one pot value is a floating caliper, therefore the force is shared either side of the disc...?
I'm not totally convinced by it though... however a simple division of that value in half seems to make things look more like it??
I'm not totally convinced by it though... however a simple division of that value in half seems to make things look more like it??
#14
Scooby Regular
Join Date: Oct 2009
Location: Enginetuner Plymouth for 4wd RR Mapping Apexi Ecutek Simtek Proper Garage More than just a laptop!
Posts: 71
Likes: 0
Received 0 Likes
on
0 Posts
Nah you need to make the area read half, halfing the dia reduces the area by more than half
#15
Right then... we're getting somewhere now that someone who knows what they're on about is helping!! (Cheers Trevcoss, i'm clearly **** at maths!!)
Now it looks like our first upgrade retained similar bias values, whereas the proposed setup will give us proportionally more rear braking...?
The question is, if you increase M/C size it actually decreases the torque seen at the discs but would improve pedal feel...? I know this is all academic, and I will know more when the installation has been done!!
By the way Trevcoss, I'll be seeing you guys on saturday as we're bringing our engine down to you for a CDB 2.1 stroker rebuild...!! small world.
Now it looks like our first upgrade retained similar bias values, whereas the proposed setup will give us proportionally more rear braking...?
The question is, if you increase M/C size it actually decreases the torque seen at the discs but would improve pedal feel...? I know this is all academic, and I will know more when the installation has been done!!
By the way Trevcoss, I'll be seeing you guys on saturday as we're bringing our engine down to you for a CDB 2.1 stroker rebuild...!! small world.
Last edited by MY94BlueWRX; 18 February 2010 at 09:42 PM.
#17
So has anyone changed to a later master cylinder and noted the results...?
I'm assuming 172sport has done, what was the reason you did it and what was the difference...?
I'm assuming 172sport has done, what was the reason you did it and what was the difference...?
#19
Scooby Regular
Join Date: Oct 2009
Location: Enginetuner Plymouth for 4wd RR Mapping Apexi Ecutek Simtek Proper Garage More than just a laptop!
Posts: 71
Likes: 0
Received 0 Likes
on
0 Posts
I would go for your plan of putting the 4 pots on the back and see what the feel is like, it may be that you need a bias valve and or the bigger cyclider to get it all properly set up and feeling correct or it may be fine, I will probably be in tomorrow changing the exhaust on the waggon if im there give me a shout and we can have a chat about what may be best, we have lots of customers running 6 pots front 4 rear etc so can find out what if any mods they have done.
#20
Thanks 172sport, that's good info... have just picked up a late M/C 1 1/16" off fleabay for £20 so will see how it all pans out and use that if neccessary.
Spot on Trevcoss, we should be down there for approx 11:30am ish so will ask for you and we can have a chat... top man!!
Spot on Trevcoss, we should be down there for approx 11:30am ish so will ask for you and we can have a chat... top man!!
#23
In that case I have a spare one available, as i've just checked and we already have the 1 1/16" fitted to our car!! (MY00 GC8)
Should have checked before I went and bought one...
Am still not convinced that you would definately need a larger m/c due to a brake upgrade or increased piston size, as the new 08- WRX with Brembos has larger piston areas front and rear than even my proposed Porsche 6 + 4 setup, and that is using a 15/16" m/c...?
Bear in mind that a larger m/c will actually output less torque to the rotors using the same pedal input pressure, although will decrease pedal travel as it shortens the stroke.
Therefore ideally you want to have the smallest m/c you can get away with, bigger is certainly not always better in this case!!
Should have checked before I went and bought one...
Am still not convinced that you would definately need a larger m/c due to a brake upgrade or increased piston size, as the new 08- WRX with Brembos has larger piston areas front and rear than even my proposed Porsche 6 + 4 setup, and that is using a 15/16" m/c...?
Bear in mind that a larger m/c will actually output less torque to the rotors using the same pedal input pressure, although will decrease pedal travel as it shortens the stroke.
Therefore ideally you want to have the smallest m/c you can get away with, bigger is certainly not always better in this case!!
Last edited by MY94BlueWRX; 22 February 2010 at 12:48 PM. Reason: added info...
Thread
Thread Starter
Forum
Replies
Last Post
Mattybr5@MB Developments
Full Cars Breaking For Spares
28
28 December 2015 11:07 PM
Mattybr5@MB Developments
Full Cars Breaking For Spares
12
18 November 2015 07:03 AM