Hey all, have a question about "hydro throwout bearings", it's very likely I need to use this type of system on a build I've undertaken. Its a Chrysler A833 trans and aluminum truck bell for a slant 6 engine. The build is off topic, but I really need some info and comments on the use of hydraulic release bearings, types, brands, setup, etc. I cannot use a mechanical setup or a slave cylinder setup, as there is absolutely no room, because the throwout fork is so long...thanx in advance.......
Lots of info here on the subject. Google it too, lots of leak problems. When they leak, it makes a mess and lots has to be removed to get at it. Asking an o-ring to maintain a seal when it moves in and out .5 inch (x 2) on each pedal stroke is asking alot. Nailheads need a long fork because the starter is on the drivers side. Use a 1" master and 3/4 slave cyl for the extra stroke for the long fork. Been there done that. A cable can also be used, Brizio sells them for hot rods.
Don't go cheap. Buy a mcloud brand. The best out there. You get what you pay for. The cylinder diameter plays a part in how it all works. I prefer the largest willwood makes.
My neighbor had one on his 40 Ford with a five speed. He had issues and replaced it with a outside slave cylinder. He had no kind words for the hydraulic throwout bearing style.
Longevity and reliability tends to be inversely proportional to ease of replacement. I think it's a Murphy's Law corollary. As an example, I've got sixty thou miles (none of it off-road) on my O/T Jeep Renegade and I'm on my third throw-out bearing. The whole friggin' four wheel drive drive-train has to come out and why do they make these things out of plastic?
I put one on a A833 that went in a 34 Plymouth behind a 273 ran into issues with the aftermarket not having the right size, ended up having to press a sleeve over the input snout and using one for a Chevy or Ford I don't remember which. Started with a cheap one from Summit lasted 6 months, was replaced with a $400 one lasted another 6 months, now the car has a clutch cable and hasn't leaked in two years. We need to figure out what causes the failures, Car manufactures use them all the time and you don't here of many problems. This car had the 3 finger style clutch I have wondered if a diaphragm style would make a difference? Both bearings were set up with proper shims to manufacture specs and worked as they should when first installed. If you go this route make sure you have it set up so you can pull the trans easily. JJ
As said, the OEMs can run a HTB several hundred thousand miles pretty much bullet proof. All of the parts were designed to work together. Many of the horror stories about HTBs are self inflected. If you select the correct bearing for the application, use the recommended master cylinder bore size, due the proper initial adjustment, and have a properly adjusted pedal stop, they work. Biggest failure mode is due to over stroking. Bearings designed for a racing clutch may not have enough throw for a street clutch.
The only problem is WHEN they leak not IF. Brake fluid soaks the clutch material and also smokes your flywheel at the same time. You need to drop the drive shaft and transmission to fix it. An external slave cylinder is a 15 min swap job. I'm on my 3rd clutch and flywheel on my DD stock 97 Chevy PU. All from fluid leaks before the clutch wore out. Do what you need to do. Just know the consequences.
I raced and street drove my coupe for years with a mcloud. go to their site and view the info on how to set one up properly. their bearing is adjustable to get it right. a few measurements are needed prior to ordering.
McLeod, simply the best one I have researched. Mine leaked out of the gate but it was easy and inexpensive to rebuild and perfect since. It leaked the second I pumped the pedal to bleed it. But, BUT, I totally humped the bunk when I installed it and measured the clearance incorrectly, as a result it ran past the operational tolerance and blew the o ring. I removed it, swore at myself profusely, ate a large helping of crow, washed it down with Crown Black and reinstalled the bearing. Works perfect. And to the OP, nothing looks cleaner and takes less room. I have been driving it a little (no interior yet) and it works perfect!
Several years ago I bought my current roadster as a rolling chassis/body with a good bit of stuff already mocked up in it that I used in the build. Had a hydraulic master cylinder from Wilwood and the slave also from them, with an unknown lever/fork, all in a McCleod safety bell hsg. I had in the past had a couple of vehicles with similar setups, so I utilized this setup, and have wished a thousand times I had instead while I had things in a build stage instead of all painted and put together as it was when I found this setup wouldn't work as installed, that instead I had fabricated and installed a conventional mechanical setup with a Z bar. Studied about leverage,hydraulics, you name it, and changed all sorts of stuff, but never really got the thing to work, finally installed a McCleod intregal HTB system, which is working OK, but only after a helluva lot of work and expense.
The Wilwood 3/4" master cyl and bracket in our Model A has no stop provision for the clutch pedal, directly contributing to failure due to over-stroking.
Yes, about 98% of the installations I've looked at did not have a pedal stop provision. Had to fabricate one.
The Ford Ranger I drive has 374,000 on the present hydraulic TO bearing and my previous Ranger had 405k miles on the factory hydraulic to throw out bearing with no problems with either.
I have 2 vehicles with mcleod bearings , both were ordered for top loaders and are 10 years old and have never been an issue .
Mechanical linkages wear and get sloppy. Cables can stretch and break. Hydraulics can blow a seal and leak. None are without faults.
Thanx all for your posts. I was able to make room for the fork today. So a slave cyl or cable might work. Biggest hurdle on this project I tell ya..
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