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Wilwood Powerlites with Fiat 124 Master cyl?
DavidW - 30/4/18 at 07:16 PM


I previously swapped to a fiat 124 master cylinder which did a really good job of improving the pedal feel on my Sierra braked Indy.

Now Iíve swapped the fronts to the Rally Design Sierra Wilwood Powerlite kit and canít get it to work.

Although Iíve found them hard to bleed Iím pretty sure Iíve managed it but just canít get a pedal. The master cylinder bottoms out.

Has anyone ran the wilwood setup with the 19mm fiat master cylinder? I know itís smaller than the 22mm Sierra master cylinder.

I can can find no brake fluid weeps anywhere in the system so donít think I have a leak.

Any ideas?



JAG - 1/5/18 at 11:21 AM

When the master cylinder bottoms out; do you have any brake torque at all? can you move the car? do the brakes drag??

DavidW - 1/5/18 at 03:10 PM

There is some braking effect when the cylinder bottoms out. Iíve noticed a very slight improvement if I pump the pedal like crazy although this is lost as soon a I release.

Brakes are not dragging.



CosKev3 - 1/5/18 at 05:17 PM

Have you checked the unused bleed nipples are tight?

How much fluid did you lose from the reservoir swapping the calipers?
Any chance you got air into the rear brake lines?

DavidW - 1/5/18 at 09:25 PM

Thanks for the suggestions.

The nipples are all tight.

Plenty of fluid was lost although I did the re-bleed the rears which surprisingly were way easier than the fronts.

CosKev3 - 2/5/18 at 03:19 AM

How far did the pedal travel with the Sierra calipers?

I've gone over to 4 pots from Sierra calipers but using a Sierra master cylinder,and although the pedal is longer now with better feel to it the increase in travel is not a lot.
So unless you had a really long pedal using Sierra calipers I can't see it being a MC size issue,must be air somewhere,especially seeing as you say pumping the pedal fast does make a bit of a brake pedal.

Rears are Sierra calipers? If so you took them off to bleed them so the nipple was at the top?

DavidW - 5/5/18 at 06:29 AM

To close this out it was hidden air in the rear brakes which only became apparent following the suggestion to remove the callipers to bleed.

I did find that the fiat master cylinder a nightmare to bleed as it seems to link the front and rear circuit hydraulically so air in one means air everywhere.

I could not quite get happy with the system a was worried about the the way that a leak in front or rear would seem to remove all brakes so swapped back to a sierra MC which whilst shorter, gives an easy rock solid pedal.

Thanks for the help!


CosKev3 - 5/5/18 at 06:52 AM

Nice one

big_wasa - 6/5/18 at 07:23 AM

Any feed back on the calipers as I am looking at them for winter upgrades ?

DavidW - 6/5/18 at 08:20 AM

Iíll report back when Iíve got the rest of the car back together.

DavidW - 17/5/18 at 08:57 AM

Originally posted by big_wasa
Any feed back on the calipers as I am looking at them for winter upgrades ?

I've now had a chance to try the Wilwoods on the road but not yet on track.

The pedal feel with Sierra MC is great. The brakes feel a bit more progressive vs the Sierra calliper so you can really modulate the braking power right to and from the point of locking the wheels.

Not sure I've noticed the difference in performance from the reduced weight although it is a fair bit.

I'll report back after a trip to Snetterton.

big_wasa - 17/5/18 at 12:24 PM

Thanks for the updates. And yes I would love to know how they are when they have had a good chance to bed in and on track.


DavidW - 6/8/18 at 09:20 PM

To close this off....

Wilwood powerlites, mintex 1144 pads on front, standard Sierra disks on rear and Sierra master cylinder. Baking hot Snetterton..

Compared to the Sierra brakes up front these seem like a significant upgrade on track even compared to Sierra calipers 1144s and Fiat m/c.

Much better feel, so much power and very progressive.

Definitely a worthwhile upgrade.


big_wasa - 7/8/18 at 07:19 AM

On the upgrade list they go, thanks for the updates.