That's an ongoing debate I have with folks, and I'm not sure what I'm concerned about is an issue. But. Without a prop valve (and assuming bias is incorrect), while braking less than ABS activation, you would/could have one end of the car at say 95% of its limit, and the other end of the car at 55% of its limit. Make sense? Doesn't seem right?

 

Yea, I agree with this. The MK60 is likely programmed at the f/r proportioning of the stock E46 M3 (or what ever model its installed in). That'd be one advantage of getting the 'motorsports' load.

 

Lots to think about, maybe.....maybe my bias is out of range of what the ABS ECU expects, and it's going, WTF. It sees front pressure at 500 and rear pressure at 300 plus rears near lockup, and does something weird.

 

Ok I did some digging myself and was able to find the part numbers for these banjos.

ATEC 650.616 BK
ATEC 649.429 BK

The issue now is I cant really find where to buy them.

 

Nice find!
Is there a 651.616? I see a 650.616 in the ATEC catalog.
Yea, can't find a US supplier, or any equivalent from pegasus racing, brake quip, etc.

 

Yes there is. The "BK" is just black instead of blue. Blue doesn't have the "BK" at the end.

EDIIT: doh. I missed the 0 instead of 1.

650.616 BK is correct.

 

Nothing I see shows a US distributor. I sent an email to their UK sales addy asking if they ship to US, and will report back if I hear anything.

 

This was my thinking too. I still think this principle holds, but it doesn't matter so much in practice. The provisos being that the ABS activation doesn't upset the car particularly in a trail braking situation, and that natively the brakes are broadly balanced (say 85/100, not 55/100) . That is, you just power through the 100% end/wheel, the ABS keeps that one to 100%, and you ramp the 85% end/wheel up to 100% by continuing to increase pressure on the pedal through the ABS kick back rather than lifting when you feel it..

Having said that, balancing brake performance (by whatever means) appeals to the neat freak in me, and is something I would work towards. Intuitively, I feel that a car with a balanced brake system will be easier/nicer to drive than one in which a system is intervening. This will be most evident where brake pressures are less than ABS intervention levels, especially if the imbalance is extreme (55/100 case).

 

Well stated. I'll go a step further, and say, that when I'm trail braking (eg loading front mid-turn), I'm often at 10-20% of threshold pedal pressure (maybe even less). So, I want bias to be something under this case, and I'm not sure exactly what is ideal, but ABS isn't involved. So, ABS doesn't fix all cases of incorrect bias.

 

ATEC responded to my email, and stated they could ship to US no problem.
I'm working on the details of shipping/handling fees, etc, and how to actually order them.

 

I'm revisiting my use of a prop valve in my system after learning more about how they work. My understanding, from a thread I'll have to find later, is that they don't do anything until a "knee point" after which they limit further increases in pressure. Essentially, they're there to prevent rear lockup under hard braking and weight transfer... which the MK60 is happy to do itself.

I found one graph in a google search of mt.net that shows the bias graphs for the various stock valves. I thought there was a better one that included the min/max that a typical adjustable prop valve could do. I'll have to find it later.

The only reason I can see for keeping a prop valve in a MK60 system would be to allow a quick fix should the system fail in some manner - you could then disable the module electronically and set the prop valve to your preferred ratio and be back on your way. When the MK60 was running, you'd want the prop valve set full-open (aka, do nothing).

All that said, if you're having a flow volume problem at the rears, that could be the culprit, I'd be looking for kinked or blocked lines/hoses.

 

Most of the adjustable valves I've seen are all the same. They can be set to allow max pressure from normal to 57% of normal. But yes, they have a knee that moves depending on the setting. I also read an article, by Wilwood or Tilton I think, how to take advantage of that knee when also using a balance bar. For a braking system that's properly designed and with modern ABS, I think I agree, a prop valve may not be of high value. BUT....I could also be convinced that the guys looking for 0.1% time improvement could use it for, rain mode, spring rate changes, etc. My big thing is to stop thinking about brake bias only at threshold, but also when braking for weight management. It would be neat to spend a day with a real race team and be a fly on the wall. But maybe modern race ABS systems like the Bosch M5 Motorsport system can manage all of that stuff?

An update on my issue, I'm emailing with Doug Wardell (he's an expert when it comes to the MK60). I've got a plan for this coming weekend. Doug will get my business if I need anything for my MK60 setup.

 

Has anyone taped directly off the MK60 pressure sensors as inputs to a data logger?

 

Oh, to the previous notion of checking for restrictions. I did on the rear circuit, and none found. Haven't checked the front yet. I will say, by far, the flow rate is defined by the piston port in the master cylinder. The rest of the 3AN stuff and fittings looks like a bathtub compared to that little hole. I'm still not convinced this isn't an attribute of the Wilwood M/C, but wow I'd be surprised if no one has used an MK60 with Wilwood M/Cs. So. Still figuring this out.

 

Did you properly bleed the Mk60 by switching it to bleed mode while at it?

 

I'm not 100% sure on "properly", but here's what I did.
Ran INPA routine about 3 times for each caliper. (Press pedal, start INPA routing, open nipple, close nipple)X3.
Then bled system normally.

Off to VIR. I have a few things try. If I don't learn anything, I may start throwing money at it.

 

Somethings sounds wrong in the system. Have you verified that the lines are properly connected to the outputs of the ABS unit? Plumbing them backwards, front to rears, can cause something like this. Also are the pressure sensors wired in correctly to the respective circuits? Did Doug do your harness?

 

I'm with you fmcokc. I thought, better check those pressure sensors. And, rather than sharing my justification of how it happened (I had them clearly and correctly marked), I had the rear connector on the front hydraulic ckt, etc.

So likely good to go! I'll report back after I get to test.

 

Correcting Pressure Sensor arrangement didn't substantially help. Pedal is still very unpredictable after an ABS event, for 2-3 seconds. FYI, with ABS off, pedal is as it should be.

 

Are you absolutely certain that you have the lines plumbed to the correct ports on the pump unit?