Clutch Master Cylinder Bore?

[V8Z4]

What is the "standard" (if there is such a thing) bore that BMW uses for it's clutch master cylinders? I'm trying to get an idea of what my Z4 clutch master is (without taking it apart). Reason I ask is that I have always liked the feeling of a 7/8" bore master with the LS1 slave (quick yet not heavy).

Thanks,
Chris

[Maynor]

The E36 M3 master is 3/4". That's the only data point I can offer.

[V8Z4]

That's a start. thanks. I'll go cross reference and see if PERHAPS they are comparable in the aftermarket.

[Maynor]

I should add, I am running an aftermarket 7/8" master in a dedicated track car. The majority of the LSx conversion E36s I'm aware of are happy with the stock master. At least on the street or dual purpose cars.

[V8Z4]

Where is your master mounted (is it in the engine compartment or under the dash)?

I have personally found the 7/8 just feels better. It's a touch heavier but makes a shorter/crisper release (for me).

[Maynor]

Under the dash in place of the original. However, it does require a custom mounting bracket and a compact master due to space constraints.

[V8Z4]

I was going to use a wilwood master under the dash. What did you use? Any pics?

[Deano1712]

If you go into conti-online you can see all the details of the cylinders:

http://www.conti-online.com/generato..._parts_en.html

Click on brake parts then Catalogues, 'parts' and then you can search for your vehicle.

Looks like 3/4" bore.

[asinapple8805]

this is what i pulled off of Tongboy's thread:

The bore diameter of the stock e36 clutch master cylinder

.716" is the bore diameter

it puts it somewhere between the 5/16" & 3/4" aftermarket master cylinders.

it's 18.11mm.

[Pzary3233]

The stock master is fine for 95% of the people in this forum. I can see the need for the 7/8" at certain times...But I think I might drive a little harder then most. Drift days, HPDE, Etc.

[V8Z4]

As I said, it's just a personal preference for me. I have always been very happy with a 7/8" bore master when using the internal LS1 slave (it just feels right to me). It does take a bit more force, but I'm 5'5" so I like the release to be higher so I don't have to stroke the pedal as far.

[Pzary3233]

With enough money and more importantly fabrication skills anything can be done!

[birdman2447]

the pedal effort with stock master and gm clutch is very light, other than swapping out for an aftermarket is there a way to increase pedal effort? Like swapping a master from another bmw model that happens to use a different bore? Just trying to weigh my options

[twinscrewed]

I find the clutch pedal too soft and since I will be replacing the master in a pedal box conversion, I was curious what MC sizes have been used to firm up a pedal.

I have read guys are going next size up for 3/4 to 7/8 is that correct? I would think this would depend on the bore of the slave on the ts6 vs z3?

Little knowledge is dangerous.....

[V8Z4]

I find the clutch pedal too soft and since I will be replacing the master in a pedal box conversion, I was curious what MC sizes have been used to firm up a pedal.

I have read guys are going next size up for 3/4 to 7/8 is that correct? I would think this would depend on the bore of the slave on the ts6 vs z3?

Little knowledge is dangerous.....

7/8" to 1" is the ideal size range. The 3/4" master is just too small from a performance standpoint. I had a 7/8" master in my T56 truck and while it worked fine, I plan to run a 1" master when I do the LS1/T56 swap in my Z4.

[twinscrewed]

7/8" to 1" is the ideal size range. The 3/4" master is just too small from a performance standpoint. I had a 7/8" master in my T56 truck and while it worked fine, I plan to run a 1" master when I do the LS1/T56 swap in my Z4.

Thanks - Schitzo shared this post with me... I was thinking of running a 1 inch as well - so I appreciate your post. I should be able to choose a pedal for clutch on pedal box that will not effect this. Going to call Tilton this week. At least now I have a good base to work from.

http://forums.bimmerforums.com/forum...1&postcount=24

[V8Z4]

Thanks - Schitzo shared this post with me... I was thinking of running a 1 inch as well - so I appreciate your post. I should be able to choose a pedal for clutch on pedal box that will not effect this. Going to call Tilton this week. At least now I have a good base to work from.

http://forums.bimmerforums.com/forum...1&postcount=24

Sure thing. For reference, in the old 98-02 f-bodies (which our T56s mostly come from), the aftermarket mcleod direct swap master is 7/8" bore. When I had my 01 Z28 this master worked but it was still very soft (for my tastes) and occasionally had issue when the fluid got hot. I came to believe that 7/8" just does not have the extra "reserve" capacity to deal with hot/thinning clutch fluid. The 1" bore gives that little extra buffer to ensure the slave gets full stroke.

That setup you posted is really slick (going in my reference folder)!

The Tilton masters are nice but just so expensive!

I have always just used Wilwood masters on my projects, but I'm interested to see how your final adaptation comes out. Please post.

[sdobart]

I've got a full size Wilwood 7/8" master that I'm going to mock up in my e36, but from posts I've read I suspect it's not going to fit and I'm going to have to get a compact one.

[V8Z4]

I've got a full size Wilwood 7/8" master that I'm going to mock up in my e36, but from posts I've read I suspect it's not going to fit and I'm going to have to get a compact one.

I'd like to see the end result. I wanted to use a Wilwood master on my Z4 project (due to cost and availability) but now that you mention it they are kind of long and may not fit.

[Maynor]

You need a compact slave if you want to make it fit. You can see it in the link above and here are the pics under the dash of my car with the Wilwood compact slave. Its tight in there..

http://forums.bimmerforums.com/forum...3&postcount=99

John

[Tongboy]

don't forget master cylinder size isn't the only part of the equation - ratio and arm movement is also important.

My swap thread detailed a few different masters in the stock location and how well they worked or didn't with the ls7 clutch

[V8Z4]

don't forget master cylinder size isn't the only part of the equation - ratio and arm movement is also important.

My swap thread detailed a few different masters in the stock location and how well they worked or didn't with the ls7 clutch

Have a page number/mind posting your results? I used a 7/8" bore with my LS7 clutch and it was still softer than I like (worked but I like more reserve).

[Schitzo]

That setup you posted is really slick (going in my reference folder)!

The Tilton masters are nice but just so expensive!

Yes those Tiltons cost a good penny new. Keep an eye out on eBay. Often times race teams will discard them after a race or two and sell them for a fraction of the original cost. I got mine for ~$70 a few yrs ago. Has worked fine 20+K miles.

[V8Z4]

Good point. I guess I'll be watching for a master as well (in addition to LS6, supercharger, LS7 clutch, etc).

[driver3232]

I am looking for a 1 inch master cylinder for a 95 bmw 318 is , can anyone help