ZF master cylinder bore sizes question

[hmh800]

Hey guys-
I've had a ZF in my bronco for a couple of years now with the BC complete kit. Clutch pedal is pretty stiff- way more so than my '01 Dodge Cummins. Was wondering if Ford made master cylinders with different bore sizes. Seems like a smaller bore would give me more stroke and less effort... Anyone else run into this with their ZF??? Anyone know if there's a different MC part # with smaller bore?? Thanks

 

[NYLES]

Im running the one from BCB No compliants!

 

[DirtDonk]

Not sure about all Fords, but quite a few of them run not only the same size bore, but the exact same part number master.

Hopefully there is something out there, but I would start looking for other problems first.
Did it act like this as soon as you put the new kit in? Or did it come on slowly?
The Ford SuperDuty trucks I've driven also had a very light clutch pedal feel, so maybe something is just slightly amiss with yours.
Hmm, wonder if you got one in your kit accidentally from some large truck or something, where the throw was long and needed a larger bore? Never heard of a "power-assisted" clutch, but that doesn't mean they don't exist.

Good luck.

Paul

 

[rcmbronc]

With my ZF I had a finger clutch pressure plate and used a WIldwood 3/4" bore master cylinder. It was stiff also and over traveled easy. I was going to try a 5/8" bore but took out the ZF. May be your only choice or maybe a different pressure plate.

 

[Crush]

The f trucks have a spring under the dash that helps with pressing the clutch pedal. I know this cause the truck I got my master off of had one. I asked the guy at the yard about it and he said it helps with pressing it in so we tried it and sure enough, once it moves about two inches it almost went straight to the floor. I prefer the stiff feel myself

 

[hmh800]

Thanks for the replies. It's wierd, cause it's been the same since day 1. I replaced the clutch and pressure plate with a stock Luk clutch, no change. It doesn't take two feet, but like I said it's a lot stiffer than my Cummins. I thought about moving the pivot up on the clutch pedal (I put it where BC said to), but it could only go up about 1/2" at the most before the pushrod hits the pedal bracket under the dash. Essentially my motor/clutch/trans/MC/slave is 1995 F series equip, and I don't remember them having heavy clutches....

 

[Ranchtruck]

The pedal pushrod point of the brake pedal is the right attachment point to get full travel out of the factory ford ZF master. The clutch pedal has the hole already drilled in it. The problem is it puts the master in a hard place to mount, so BC recommends installing it lower on the pedal, which reduces the mechanical advantage of the pedal and makes it stiff.