Funny you should ask that question today, since it was just this morning that I phoned in my order to Dark Horse for a hydraulic throwout bearing and JMC brand MC kit -- $549!!! That includes a replacement bearing, but still.
Anyway, the reason was that, beginning in October 2004, about 10,000 miles into my ownership of this '65 289 fb with 3-spd toploader w/diaphragm clutch, the Z-bar setup decided to start popping throwout bearings. What happens, as best I can tell, is the TO bearing gets cocked on the bearing retainer and binds. The clutch fork rides up on the backing plate and pops off the two spring clips, which screws up the whole works.
I replaced everything, some things more than once, including two bearing retainers. Each time, a few hundred miles later, boink, another busted throwout bearing. In desperation, and since they don't make brand new bearing retainers for 3-spds, I decided to go with a '95 T-5z. Just yesterday (Monday 1/2/06) I got the Z-bar stuff back together and hop in the driver's seat in giddy anticipation of the smooth new clutch effort. Boink! Busted again.
So thaaaat's why I'm going hydraulic, and also why I don't even care that it's costing me $549+ to do it. If this doesn't work, I'm switching to an automatic!
I wanted headers on my 351Cleveland with a 4 speed and didn't want the hokey z-bar anymore. So it seemed like a must. I pieced mine together buying the hydraulic throwout bearing from a local speed shop and the master cylinder from a local off road supply house--they also had the hoses and the reservour. I fabricated everything else I needed. Saved me over $250 off of the JMC kit price.
I was doing a T5z swap, replacing my stock 3 speed stick and when researching Z-Bar versus cable clutch versus hydraulic, there was a clear advantage for issues like header clearance and smooth operation. You can make the cabel clutch setup work with many headers, but I read many posts where the heat from the headers started to cause the cable to bind and eventually fail. Also, the cable setups look pretty bad in my opinion the way the cable is routed. The only negative was the price ($400 for the JMC), but the extra couple hundred bucks spent to avoid clearance and reliability problems were worth it in my opinion.
I use a cable clutch, cost-effective since it was free (guy gave me a 5.0 cable). I had to jockey a header primary around a little to make it work, but well worth it for the 350.00 I saved
There are many reason that the guys have already stated and with some applications its the only option as it was with my t-56. I have it bolted up but have not looked into the work that will be needed to attach its rod to the pedal along with the needed pedal stop. I hope at it will be much easier on the leg with this Mcleod clutch also. Anyone with pics of thier pedal stop?
reasons:
1) had issues in my '65 with Z bar shifting and rods bending
2) had a 91 Ranger with hydraulic clutch and liked it
3) thought it would be easier for my wife to drive. She has a problem with pushing the pedal still, good thing because I know my car will be in the garage.
shaken66, I don't have pictures, but what I did was weld two all thread rod coupling nuts together. One screws to the bolt that holds the hyd clutch master on the firewall (I have a Wilwood master). The other holds a Mustang hood rubber stop (thing that mounts to the radiator support). This allows me to easily orient the stop with the pedal and adjust limit of pedal travel at two points. I also installed nuts on both bolts to lock it in place.