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alternate master cylinders/swaps

Posted: Fri Aug 03, 2018 10:52 pm
by Piledriver
Looking for a list of source vehicles or (preferably) part numbers for larger bore master cylinders.

I know the late Bus masters (22mm/22mm) are a good option in an iron master cylinder.
From memory (and other posts) they need the pushrod shortened about 10mmish.
22 or 23mm is about the right range for my setup, brembos out back (2x28,2x30) with padgid factory pads, wilwood superlites out front(4x31.75") with pfc14s..

I'd personally prefer an aluminum master as they seem a bit more (internally) corrosion resistant.

Some of them may need the pushrod shortned, or nuts on the master side and such.

I'm lookin at it as my setup works awesome, but the travel is a bit more than I'd like, and the pedal effort is actually too low for my taste.

Re: alternate master cylinders/swaps

Posted: Sat Aug 04, 2018 3:07 am
by Ian Godfrey
coolrydes (Mendeola) has a aluminium master cylinder that is close to your description
https://www.coolrydescustoms.com/store/ ... INDER.html

Re: alternate master cylinders/swaps

Posted: Sat Aug 04, 2018 3:28 am
by davidt
Hi, you could try changing the brake pedal ratio. This requires you to cut of the plate that the push rod connects to and weld on a longer version. This will increase your pedal effort and reduce the pedal travel. I fitted vented front discs with Volvo 4-pots, rear discs with Suzuki SX4 rear calipers and a 68-69 L/H/D T2 master cylinder into my R/H/D 1302 Superbug. I still had about 2-3in of pedal travel but after changing the pedal ratio, I now have about 1in of travel and a nice firm pedal which gives great brake modulation and control.
Hope this helps as it is a great mod.
Hooroo

David Thiele

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Re: alternate master cylinders/swaps

Posted: Sat Aug 04, 2018 11:33 pm
by Lanner
The mendeola one is a vw mk4 golf mc..

Re: alternate master cylinders/swaps

Posted: Wed Aug 08, 2018 2:33 am
by Piledriver
Lanner wrote:
Sat Aug 04, 2018 11:33 pm
The mendeola one is a vw mk4 golf mc..
Thanks for that, precisely the sort of info folks need to know to make purchase decisions.

I'm hoping to put some part#s to the various compatible masters, and what caliper they would be best used with.

Re: alternate master cylinders/swaps

Posted: Wed Aug 08, 2018 10:43 am
by Piledriver
OK, std power Mk4 masters are 19mm, so the larger bore version seem to be for manual brakes or a big brake mk4, gtI/GLX, vr6 critters etc.
The -90 cabriolet master looks ~identical to the Mk4, but is 13/16" bore. (likely same as Mk1 GTI)


VR6 critters (GLX et al) get the 23.8mm bore version,
Vanagons had 23.8mm, with horizontal flange. 251611021C
Looks like late bays were 23.8mm too. 211611021
(earlier) Bay busses 22mm
-90 Cabriolet, 20.6mm
Stock late T1/T3 19mm
The water cooled masters have an angled flange like a 1302/1303 so some mods needed to car to install depending on target.
All these can be had from $35-$180 depending on brand and supplier.

It appears that some Mercedes use the same masters as VW, and may have a 25mm flavor, Googleresearching...

I will come back and add part numbers if someone doesn't beat me to it.

Re: alternate master cylinders/swaps

Posted: Wed Aug 08, 2018 5:24 pm
by H2OSB
Pile--

I'm trying to confirm the 19mm size for the MK4 MC with the angled flange. Can you link?

I certainly don't need anything larger than 19mm for my brakes, however, I would interested with regard to quality and corrosion resistance

H2OSB

Re: alternate master cylinders/swaps

Posted: Wed Aug 08, 2018 6:55 pm
by Piledriver
https://www.dormanproducts.com/p-78223-m630833.aspx is an example.
non-abs.
If you are staying at 19mm, I would only consider the swap if replacing the master anyway, as the lines will need adapted for layout.

Re: alternate master cylinders/swaps

Posted: Wed Aug 08, 2018 8:53 pm
by H2OSB
That's 23.8mm

Re: alternate master cylinders/swaps

Posted: Wed Aug 08, 2018 11:06 pm
by Piledriver
My bad, thats the non-abs one.
The "normal" ABS ones are apparently 19mm.
Dormans website has search.

I will probably end up with a late bus or vanagon 23.8mm unit as it will bolt in a T3.
I'll try to find an aluminum version.

Re: alternate master cylinders/swaps

Posted: Thu Aug 09, 2018 12:02 am
by H2OSB
The Dormans site is nice, and yet, confusing. When searching for the part in question, in my case, I used a 2003 Golf, four parts were listed. Basically, one with bore of 3/4ths and one with a bore of 15/16ths. Then each is offered with a new reservoir attached. However, if you scroll all the way to the bottom for the specs list the bore of each as substantially larger (relatively speaking).

Confused
H2OSB

Re: alternate master cylinders/swaps

Posted: Thu Aug 09, 2018 5:48 pm
by DerrickfromNC
Here is some discussion from GermanLook.com regarding the use of 944 and 911 turbo MCs
https://www.germanlook.net/forums/showthread.php?t=9444

Re: alternate master cylinders/swaps

Posted: Sat Aug 11, 2018 12:32 am
by TZepeSH
I've been also reading on master cylinders to use with the 944t brakes. On germanlook, the most consider using the stock 19mm pump ok. However the original Porsche pump is 23.8mm, so I would rather consider a larger pump and mechanical booster.
Now with the 944na brakes I like the softer feeling and longer pedal travel using the bug pump. I wouldn't mind the same for the 4 pot. I also had 944 pump and I felt like I had less brake control with the harder pump.

Re: alternate master cylinders/swaps

Posted: Sun Aug 26, 2018 2:01 am
by Piledriver
Finally getting back at it, swapped the late Bus 23.8mm master in... TRW/Varga brazilian unit ~$40ish from AutohausAz, always fast and priced right.

I didn't even have to rebend a line (late T3), bolted in place (mind, my setup isn't factory as I have a pair of 2 psi EMPI residual pressure valves inline etc)
Nice high hard pedal and good modulation..,
I did need to grind down the od a bit on the larger step of the MC pushrod, as the deep pushrod guide/cup was binding on it.
Pushrod is almost all the way threaded out, but as it has such a nice high and hard pedal i can probably readjust the stop and put the pedal closer to the wall.

Mind--- the only "problem" with the 19mm master was the fact it was super easy to lock things up when jumping on it, I could violently stop and probably not squash a grape under my foot :lol: . (think very overboosted power brakes)
This is a preference thing.

Of course I suddenly find the (likely 40+ tear old) VDO brake switches have now both died...
Fortunately Oreaillys has voodoo predictive parts stocking powers and has two in stock at my local store. Seriously.
(I have not replaced a brake switch in decades, at least on my vehicles)

Re: alternate master cylinders/swaps

Posted: Sun Aug 26, 2018 11:32 am
by H2OSB
This is kinda apples and oranges, but on my one car, I have CBPerformance disc brakes f/r on the stock 19mm MC and I don't care much for the feel of the brake pedal. The pedal is high and rock solid. Though I must admit I have no difficulty with brake modulation. When I really stomp on it, the car comes to a stop VERY quickly.

On my other car I have factory n/a 944 brakes on the rear and 914 calipers over n/a 944 rotors on the front. It will be interesting to see how the pedal feels with a 19mm MC (not on the road yet)

With the 914 guys, one of the first upgrades they do is swap out the 17mm MC for and 19mm MC from a 911. I wonder if I could go the other way on my CBP braked car to get a bit more pedal feel.

H2OSB