Master cylinder upgrade

[Screacher]

Hi,
I'm looking to upgrade the M/C on my E30 track car. I have heard that the E32 7 Series M/C is the one to fit. However, there are quite a number. Partno 34 31 1 156 643 seens to be recommended. This has a 25.4mm bore. Are there any other alternatives with the same size bore which will fit the E30?

Stu

[BadDave]

E32 750 is the one you're looking for(25.4 mm)
Alternatively an E30 M3 one fits (23.?? mm)

BTW a stock M/C works fine with 4 pots and the M3 one works fine with 6 pots
M3 one has a 10mm and a 12mm outlet,so.you'd need to make up a new line.

HTH

[Screacher]

Thanks. Can't find any 750i ones at the moment (other than new, which is expensive ). As I said, there are loads of others with 25.4mm bore, but the end where it goes into the servo is different. Would it be possible to fit a complete servo and master cylinder from one of the other 7 series models? Or would the linkage and cross-bar to the pedal be totally different?

Running standard 325 front calipers. Just want to shorten the pedal travel etc.

[BadDave]

Some of those with M5x conversions are using 25.4 mm clio M/Cs with a spacer from the plastic winged cars.


I've no idea re other 7 series servo/master combo's fitments

You will get a noticeably firmer pedal with less travel which lacks "feel" if you move up to a 25.4mm M/C

[DanThe]

Its the clio servo that gets used Dave, not master, the standard E30 master is kept and needs a spacer.
Ive tried a 750 master cylinder with 325i standard brakes before and literally couldnt press the pedal hard enough to stop the car, maybe the clio servo added to the problem, not sure

[BadDave]

Sorry Dan,

I somehow recalled it to be the other way round.

E30 M3 master would probably be the better option then,unless you've got a set of powerlifters thighs

[703]

I got my 750 master cylinder from rockauto in the us, it was about $40 but by time it got to my door was about £100 just search part no. 34 31 1 156 643 (shopping) im sure its one off the first ones that come up

[Screacher]

Thanks 703. What setup are you running it on? Is it as hard to brake as Dan says above? I'm on standard 325 calipers with after-market grooved & vented fronts with grooved on the rear. Currently running EBC Blues all round but previously ran Pagid RS29s on front and cheese on the back Might return to the RS29s if budget allows.

[703]

Im using it as i have e36 m3 front brakes (5 stud conversion) so not sure what it would be like on your set up

[djs325]

Most of the guys running E30Racing Cars in Australia changeover to the <1988 735/750 Master Cylinder; just needs a t-piece adaptor for the non-ABS Cars with 2 outlets on the front axle.

No issues of being unable to push the pedal, shortens the travel up making 'sponginess' or other fading/poor performance more noticeable i.e. quicker.

[Mikey_Boy]

I run a 750 master cylinder with the standard servo on my track car. I have 8 pot calipers at the front with 330mm discs and standard rear brakes. No issues with pedal effort or feel - the extra piston area in the master cylinder is needed to shift the extra fluid for the bigger front calipers so BadDave's summary is spot on.

Might be the Clio servo causes the extra pedal effort (being smaller diameter?) but I am just speculating...

Worth spending the £££ on brakes - best mods, and of course safety critical...

[DanThe]

It probably is to do with the smaller servo, I will be doing some experimenting to see what else I can do/fit to get the brakes up to scratch

[keri-WMS]

A proper pedal box is what the RHD E30 could really do with, not ideal for most people though. The less links/rods etc the better!

[ross_jsy]

I'll have to take a picture of the pedal box I have.

Made by one of the rally boys over here, it's a modified standard box so it all bolts up like stock, but allows you to use twin M/C's with a balance bar.

If anyone is interested, I might be able to get a couple made but he won't do large batches.

[keri-WMS]

I think Theo's got a balance-bar box too, just a bit much for most people - especially road cars.

[ross_jsy]

Here we go, let us know if you want more detailed pics of any specific bits:



Here you can see where an extra section has been welded onto the standard pedal box:



M/C's attach here. You can make out where the threaded push rod from the M/C's attach, and the threaded bar for adjusting brake bias:





The brake pedal has been extended with a metal tube which houses a spherical bearing.

Hope that helps

[Demlotcrew]

Thats is pretty cool! I like it

Andrew

[MrBenn]

Anyone ever tried one of these?

http://www.ebay.co.uk/itm/BMW-E30-Brake ... 1c2224e959

[Demlotcrew]

I have seen those, but from the Negative press ive had from Theo about his solution, its just one of those nice to have's, so im going to invest on other modifications instead.

Andrew

[DanThe]

What are the bad points Andrew? Looks an ideal solution for me TBH, gets the pedal back up and gets rid of the servo thats too small anyway. £190 from their website, good value IMO!

[redcar]

Is it hard to press compared to the servo assisted ones

What are the disadvantages of the pedal box? Over the servo assisted stock setup

[Demlotcrew]

Like redcar has said, the pedals were way too heavy, no real confidence in them, he also complained of them being inconsistent.

Brake feel, whats that?........

[BadDave]

Anyone ever tried one of these?

http://www.ebay.co.uk/itm/BMW-E30-Brake ... 1c2224e959

I have one of the Compbrake ones (removed from am M3 rally car).
I just haven't got round to fitting it yet.

[Theo]

The only complaint I've ever had about my brakes was when I had EBC pads. The difference when I changed to Performance Friction was huge.

The feel of a non-servo assisted setup with properly sized master cylinders compared to some lash-up combination of master cylinder and servo (with a 3ft long flexing linkage bar for good measure) is vastly prefereable.

You must have my feedback confused with someone elses Andrew?

[Demlotcrew]

Theo, I have the Video of DaveG driving your car and complaining about the brakes, I also recall you complaining about them being too heavy at Rockingham, not you?

Andrew

[Theo]

Anyone ever tried one of these?

http://www.ebay.co.uk/itm/BMW-E30-Brake ... 1c2224e959

This would be crap - the pedal ratio would be all wrong (4.25 on an e30 pedal IIRC) compared to 6 to 6.25 found on proper aftermarket pedal boxes. You would also still have the aforementioned bendy brake linkage bar.

[Theo]

Theo, I have the Video of DaveG driving your car and complaining about the brakes, I also recall you complaining about them being too heavy at Rockingham, not you?

Andrew

Is that the video on Vimeo? I don't remember Dave complaining about them, though he did drive when it had the dreaded EBC yellows so I wouldn't be surprised. They gave a bizarre feeling almost as if something was flexing, I thought maybe the calipers were flexing but this theory was dispelled when I fitted PF01's.

I had/don't have any complaints about feel - I lreally like how the slightest application on the pedal will result in a measureable braking effect, this wasn't the case when I ran servo assisted brakes.

[Demlotcrew]

Theo, I find it hard to believe that changing to a pedal box will have such a drastic effect on the brake efficiency. I honestly cannot say i have any problems at all, you just have to breath on mines. Having correctly matched cylinder sizes to the callipers is 70% of the equation to how the brakes feel, the rest is in your footwear.

Dont confuse brake feel with braking effort/efficiency.

Andrew

[redcar]

Theo, I have the Video of DaveG driving your car and complaining about the brakes, I also recall you complaining about them being too heavy at Rockingham, not you?

Andrew

Is that the video on Vimeo? I don't remember Dave complaining about them, though he did drive when it had the dreaded EBC yellows so I wouldn't be surprised. They gave a bizarre feeling almost as if something was flexing, I thought maybe the calipers were flexing but this theory was dispelled when I fitted PF01's.

I had/don't have any complaints about feel - I lreally like how the slightest application on the pedal will result in a measureable braking effect, this wasn't the case when I ran servo assisted brakes.

Hi Theo, quick question please

What is your opinion on having a suitable servo and master cylinder fabricated in on the drivers side of the car? For example, using the brake and clutch pedals from an s14.

Thanks.

[DanThe]

I don't remember Dave complaining about them, though he did drive when it had the dreaded EBC yellows so I wouldn't be surprised. They gave a bizarre feeling almost as if something was flexing, I thought maybe the calipers were flexing but this theory was dispelled when I fitted PF01's.

Maybe I should change my pads

[ross_jsy]

Does anybody know how to calculate what size M/C's you need? I seem to remember Geoff posting something about it

[GeoffBob]

Does anybody know how to calculate what size M/C's you need? I seem to remember Geoff posting something about it

I typed up a basic guide for Theo a while ago. See here.

After that I posted up a more detailed analysis in his thread titled "pedal boxes", see here
Take note that the latter specifically demonstrates the effect of a proportioning valve in-line with the rear callipers.

[ross_jsy]

Cheers Geoff

Better put it all together and get it on some scales

[nickso]

It probably is to do with the smaller servo, I will be doing some experimenting to see what else I can do/fit to get the brakes up to scratch

let me know how you get on then. I'm running a 750 master on the clio servo and it works but is not great, I'm on m3 brakes though.

Something I really want to sort out this year is the brakes.

[Motorhole]

I went through all of this polava some time ago, with some help from Geoff and Theo. I came to the conclusion that if you're going to start mucking about with different sizes of front and rear calipers, especially their proportions to each other, the only way you can really get the most out of your braking system without having to put an uncomfortable force through the brake pedal is with a proper bias pedal box. iirc, we worked out that for the E36 M3 front calipers and E36 318ti rear calipers I'm fitting, with a stock master cylinder, the rears would barely be gripping the discs and all a proportioning valve could do was reduce the fluid pressure in the rear circuit.

Expensive, unfortunately.

Couple of threads:
http://www.e30zone.net/modules.php?name ... highlight=

http://www.e30zone.net/modules.php?name ... highlight=