j_man

Oy Don't you feel guilty you're going to kill that unicorn software while some BMW guy could've enjoyed the upgrade in their street car?
Swap it for a 813.3 and make some nice profit. It won't matter performance-wise to you because the hardware/electronics is the same.

timwrx

I just bought a new one, easier than mucking around depinning - https://www.ecstuning.com/b-genuine-...g/61136954574/

trophy993

That's a great find, thank you!

yuba

After receiving them in the mail and looking at what I've got, you're right. Thank you for the heads-up.

j_man

I guess if you got the ones for a 45 degree back you can still use them if your tool can make SAE bubble flares (British Girling). If you don't know what it does - just flare one end, evaluate it and go from there

12go

Question and a comment.

Who's using the MK60 with aftermarket (Wilwood, Tilton, etc) Master Cylinders?

I'm having an odd problem. After first hard application of brakes, especially when trail braking, if I apply brakes again within a second or so, the pedal is lower and softer. My *guess* is when the ABS has to go to stage 2 (pressure reduction) the precharge/charge cycle isn't fast enough to stay up with my braking pressures at the pedal. I'm thinking the path between my fluid reservoir and the ABS pump is too restrictive (the MK60 doesn't have a separate pre-charge reservoir). It could be the Wilwood M/Cs, or I might try switching all the 3AN's to 4AN's (between M/C and ABS).

It all works, and I can drive around it, but not confidence inspiring.

As to where to mount the MK60 pressure sensors, if you're using separate M/Cs, the Tilton 76 Series M/Cs with 2 outlets (rear and top) look like another possible solution:
https://tiltonracing.com/product/76-...ter-cylinders/

thebeerbaron

iTrader: (1)

You might be on to something. IIRC (and remember, I've been wrong lately in this thread), the original BMW setup has a very short run from the master to the ABS unit, and those lines are larger diameter than the outgoing lines.

However, I seem to remember from somewhere that some aftermarket masters have a doohickey in them that's there for esoteric reasons and that modern users need to remove.

Here it is... https://www.miataturbo.net/race-prep...rake-mc-95510/

Could that be your problem?

12go

Thanks for that thread! I doubt I have that specific problem, but that's very interesting. I have a spare Wilwood M/C of the same type that are installed, and I can take a close look at it. (I have a 2 M/Cs installed, different sizes to set bias). I have read those comments from BMW about them removing the pre-charge reservoir by placing the pump close to the M/Cs and larger lines. That may be only 1/2 the story, I wonder if they did something special in the OEM M/C? Meaning larger ports.

I might call Wilwood, I've had good support from them when I actually talk to someone on the phone. (Not so much via email.) And, I've been thinking of changing rear M/C size for a while, might get a Tilton if I do that.

Re-engineering the whole braking system can be tricky.

fmcokc

BMW master cylinders have different sized pistons for the front and rear circuits.

12go

Yes, they do. How would that relevant to my problems?

I just checked install requirements for the Bosch motorsport ABS system, they require (only) 3.2mm ID brake lines (standard 3/16), and no mention of minimum distance from M/Cs.
Was just a sanity check. Doesn't really tell me much.

fmcokc

Sorry, when you asked about the various tricks that BMW M/C's might utilize, I didn't know if you knew about the different piston sizes. We have experimented with many different variations including tilton dual M/C setups and BMW M/C's and have not experienced what you are describing. You are correct that the supply line to the pump unit is 3/16".

What are the sizes of your M/C's, piston sizes for the calipers and number of pistons, rotor sizes, pad shape?

12go

No worries!
FYI, this is installed on a BMW E36 (don't hate!), booster removed, dual Wilwood M/Cs, proportioning valve and balance bar.
Details front: Brembo 4 piston calipers, 2" and 1.42". 12.8" rotor, pad height 2.4", 0.625" M/C
Details rear: BMW 1 piston caliper, 1.57". 12.3" rotor, pad height 1.6", 0.813" M/C

My math shows this at a 80f/20r bias.

It's good to hear you've had multiple configurations of the MK60 work successfully. I'm awaiting a call from Wilwood.

12go

Wilwood returned my call. For the record, he said the M/Cs I'm using (and none of the single M/Cs) have any sort of removable restrictor valve. I'm going to check my spare anyway.
He wasn't familiar with the MK60, and didn't have any recall of anyone asking this type of question prior.

Arca_ex

iTrader: (2)

I'm going to be using Tilton 76 Series compact masters, but I'll have to report back once everything is actually up and running.

My build thread has pictures of the napkin math and bench racing comparisons I used to pick the sizes. Wouldn't recommend following my lead though ha.

12go

I almost ordered a Tilton 76 this morning, but gonna hold off until I do a bit more research.
Then, I remembered something. While pressure bleeding brakes the first time after MK60 install, I remember thinking...rear bleed rate was pretty slow. Hmmmm.
I'm going to bleed again today and be methodical about pressures at the reservoir. I'll be looking for, thinking about, a restricted path in the rear circuit (somewhere prior to the ABS pump). That would explain everything.

fmcokc

Well your math is correct but why would want a 80/20 bias split. Stock is 60/40 and the CSL is 56/44. I would switch the 2 M/C's and ditch the prop valve. That would put you at 58.4/41.6.

Since you have 2 M/C's, I am also assuming that you have a balance bar?

12go

I'm at 80/20 because at 75/35 and ABS off, I get rear lockup even in straight line braking, and of course even worse in trail-braking.
Yes, have a balance bar.

12go

Hmmm...the prop valve comment got me thinking. Could the proportioning valve (basically, a preloaded spring) be confusing the ABS pump/ECU ?
When bleeding brakes, at the calipers the rears are quite a bit slower to bleed than front, at same reservoir pressure. Probably 1/2 the flow. But, they are 4x the distance.
I'd need to measure flow into the ABS pump.
I have an event early next week, so I'm not eager to remove lines and/or the prop valve as an experiment. But I might.

icantlearn

Im not sure why you would want a prop valve with active MK60. The only reason why im keeping one is in case the ABS fails and I need to rely on the factory system. Otherwise, it will stay open.

codrus

In general, I suspect that using a different proportioning system than the one that any ABS system expects is likely to degrade performance.

--Ian