Brake pedal travel with Wilwood dual master

[RiverPatrol]

I can't seem to find a thread where someone has documented the complete process to converted to a Wilwood dual brake master cylinder, and since I haven't done one myself I don't have the experience.

The shop doing the work on L60Boerne's latest Patrol installed a Wilwood dual brake master. It's working well but there seems to be what I deem as way too much pedal travel before actual braking. Not having worked with one before I don't know if this is typical of the Wilwood or if there is something else that needs to be done. There doesn't seem to be much adjustment on the pushrod. Thoughts and ideas from those who have made the conversion?

[r1lark]

Good question!

[L60Boerne]

Thank you RiverPatrol. Plateaucal has installed one too and he has offered a bunch of info on the forum too.

[RiverPatrol]

Thanks but these don't answer my question. Let me simplify.

Could someone who has installed a Wilwood dual brake master in their Patrol and is has driven it with the Wilwood installed please tell me how much travel there is on the brake pedal before actual braking happens? Is there more travel with the Wilwood than there was with the stock master? If not, was there a certain modification done to correct that? I'm looking for real world results, not conjecture.

[plateaucal]

Here is some good advice from Wilwood.

https://www.wilwood.com/PDF/DataSheets/ds439.pdf


The freeplay needs to be no more than necessary to create a small gap between the piston and the plunger. According to my previous comment, this is not much. In the range of 1/16" or so. You just need a gap. Then you need to be able to stroke the piston to its max. before the pedal bottoms out, obviously with the bleeder valves open. Per Wilwood "WARNING:
The master cylinder push rod must bottom out in the bore before the pedal stops against the floorboard. The inherent
safety feature of tandem master cylinders is the ability to still build pressure in one circuit if the other fails. In the event of a
circuit failure, the push rod (and pedal) may travel 50% - 80% of the total stroke before starting to build pressure in the other
circuit, allowing emergency braking to stop the vehicle."

If you can get full stroke, with whatever freeplay adjustment you have, then you are good. Check your manufacturer's data sheet. You could have a 1/4" or whatever of freeplay as long as you get the 1.10 inch of movement specified in the above data sheet. So in a sense, the freeplay is arbitrary as long as you get full stroke. And make sure you have a return spring... and a cold beer while you are doing panic stops.

This assumes you are using the above referenced master cylinder. If not get the mfgr's data sheet.

[plateaucal]

And the best part is you can leave you foot on the brake without actuating them, like L60Boerne does on the scary trails. His foot oscillation never exceeds 1/8". BTW, I installed a Protex. Similar, but the same I don't know. But it would about throw you through the windshield in a panic stop from 60 mph.

[RiverPatrol]

If you can get full stroke, with whatever freeplay adjustment you have, then you are good. Check your manufacturer's data sheet. You could have a 1/4" or whatever of freeplay as long as you get the 1.10 inch of movement specified in the above data sheet. So in a sense, the freeplay is arbitrary as long as you get full stroke. And make sure you have a return spring... and a cold beer while you are doing panic stops.

This assumes you are using the above referenced master cylinder. If not get the mfgr's data sheet.

Ok this is good stuff, more like what I'm looking for, thank you. The master in question is the one recommended for the Patrol - the Wilwood 260-8794. It does get full stroke, only it's at the lower end of the pedal - it never bottoms. It definitely has a return spring, that's not an issue. My only concern is that there might be some panic during the first 2 inches of travel, until one gains confidence that the bottom of the pedal is solid, only because I am used to a actuation at a higher point on the stroke. Definitely you can leave your foot on the pedal and it doesn't sink, it's just lower than what I'm used to. I've had one other Patrol that had actuation at the lower end of the stroke and that was with a stock master, straight replacement. It was a little unnerving until I gained trust in it. Since this is for L60Boerne, of course I want confidence.

[plateaucal]

https://www.wilwood.com/MasterCylinders ... o=260-8794

That model also has a 1.10 inch stroke. It appears that the original Patrol master had a 1.24 inch stroke. That 0.14 inch difference could ad an inch or more to free play measure at the pedal (which should be 1/4-1/2"). Perhaps a long plunger is needed. Is there a chance that the plunger could extract all of the way out? (i doubt it, we are only talking about a little more than an 1/8")

To reiterate, the stroke depth should be check with the bleeders open so you can see where bottom occurs.

And, could the pedal upstroke stop could be adjusted to get closer to the requisite 1/8" or so stroke if the extra free play is bothersome.

[plateaucal]

I would want to make sure that you have an adequate insertion depth into the cylinder for the new master.

[RiverPatrol]

No measurements have been taken. This is merely visual observation. I'm not sure that I could get them to go to the length of taking actual measurements. And we aren't checking with the bleeders open for sure. Insertion depth is apparently adequate. So I'll try to determine which push rod they're using. Like I say, I don't know that it's an issue as opposed to something to get used to. I know personally I would prefer to have actuation at a higher level on the pedal.