Do I uprate master cylinder??

[Farmer306]

Hi, I am currently converting my 2.0 xsi to a road rally car. Have uprated to gti6 calipers and discs. Seem to be getting alot of brake fade though when testing. Do I need to uprate the master cylinder as well or is there something else I should be looking at doing??

I am running comp spec pads and I don't believe that tge fade is coming from them!

Any advice will be greatly appreciated thanks.

[darrenjlobb]

Upgrading the master cylinder wont effect the way the brakes fade, thats just heat / poor pads / to smaller brakes etc..

The master cylinder size will simply effect pedal travel due to the larger / smaller bore moving more / less fluid...

[CJ_Derv]

I was going to put same thread up but will hijack ive got a Dturbo and going to be upgrading brakes would this still be the case as darren says or would it improve braking with a good set of disks and pads

[darrenjlobb]

Technically if you run bigger calipers with bigger pistons, you should upgrade the MC to keep the pedal travel normal..

But personally I like the extra travel, so if anything prefer running the stock one with the likes of 6 brakes, altho I upgraded for the 302's as the travel was un acceptable...

[C.A.R.]

The braking force is effectively still better as Darren points out this is not 'brake fade' so to speak, it's just that you are literally trying to operate bigger pots with the same amount of fluid, so pedal travel is excessive. I upgraded mine, as the brake feel wasn't wonderful with the standard MC designed for use with the 266mm brakes.

Also, braided brake lines do nothing for this problem, they are only a worthy upgrade if you actually are getting brake fade or do a lot of fast-road driving / track work. Or if your rubber ones have perished and you fancy a bit of bling....

[CJ_Derv]

Nice one chaps, think i will upgrade as will be going all out with this pug had brembos on last pug with std MC and travel was a tad bit too much,

Just planning on running 266mm on this with a good set of disks and pads and braided hoses and bigger MC just for peace of mind really

When changing the MC is there aq variety i can go for or just the GTi6 as an upgrade??

Cheers

[Ed Doe]

What fluid are you running? Did you bleed it through properly? What pads are they besides the label 'comp spec'? Are they carbon Lorraine pads, or just Mintex 1144s? Discs provided they're not completely shot will not make a difference.

[C.A.R.]

I believe the Master Cylinders are measured by their diameter, although whether this is internal bore or external overall size I don't know.

What I do know is that there were are generally 2 different sizes of master cylinder and it's the larger one you want.
I don't claim any of the below to be 100% accurate, but it's as much as I know!
MC Diameter =
19.0mm - Fitted to very early 1.4, 1.6 and 1.9D cars (probably phase 1's) without ABS
20.6mm - Fitted to early 1.4, 1.6, 1.8, 2.0 and 1.9TD cars with or without ABS
22.2mm - Fitted to virtually all cars and engines it would seem after the phase 2 (16v 1.8's/2.0's) came about, most also had ABS - this is probably the one you have!
23.8mm - Fitted to all GTi6's and then from what seems to be the late phase 3's (2000-on) no-matter what size engine was fitted (this is what late HDi's / XSi's have installed) - this is the largest MC and the one which you want!

[Mattcheese31]

i have a 21mm MC, (i know because it says on the side) gti6 brake set-up and it's great, i wouldn't want any more bite at the top of the pedal as it's easy enough to lock the wheels up as it is . .

[CJ_Derv]

I believe the Master Cylinders are measured by their diameter, although whether this is internal bore or external overall size I don't know.

What I do know is that there were are generally 2 different sizes of master cylinder and it's the larger one you want.
I don't claim any of the below to be 100% accurate, but it's as much as I know!
MC Diameter =
19.0mm - Fitted to very early 1.4, 1.6 and 1.9D cars (probably phase 1's) without ABS
20.6mm - Fitted to early 1.4, 1.6, 1.8, 2.0 and 1.9TD cars with or without ABS
22.2mm - Fitted to virtually all cars and engines it would seem after the phase 2 (16v 1.8's/2.0's) came about, most also had ABS - this is probably the one you have!
23.8mm - Fitted to all GTi6's and then from what seems to be the late phase 3's (2000-on) no-matter what size engine was fitted (this is what late HDi's / XSi's have installed) - this is the largest MC and the one which you want!

thanks for that Repped!!

[Farmer306]

Thanks for the replies. It seems that the pedel will go right down yet the brakes will fade as this happens. I have blead them a few times now and it doesn't seem to make any difference.

It is running good quality discs and in previous experience discs will warp rather than cause fade so have ruled that out. The pads are EBC red stuff that I bedded in properly.

I am running comp fluid. I run the same fluid in my group A 106 cup car which runs 4 pot AP's so I am fairly confident that I am not boiling the fluid. I haven't braided the lines yet so that could be a possibility I suppose but looking at the standard ones I don't think they have got too hot.

So on your advice if I change the MC any ideas what I should upgrade to and is it just a case of swapping or do I need to mod anything else??

Thanks again for the advise.

[CJ_Derv]

i think i may have an answer how long have you had these on for??

i found this on EBC site

Being a hard wearing pad, bed-in times can be as long as 1000 miles and drivers must be patient until the pad takes up the shape of their disc (brake rotor). This is a truly impressive fast road pad for repeated heavy braking.

CJ

[Ed Doe]

Red stuff pads sound a bit shit... have you tried something like Mintex 1155s or Ferodo DS3000s? You sound like you know what you're doing, but imo EBC should be avoided at every opportunity... and I know from experience the Mintex 1144s are brilliant fast road pads; 1155s should be better still at the cost of some cold performance obv...

The competition brake fluid you're using; did you properly drain the old stuff before putting the new in? If they've mixed it could be the reason you're having issues...