Hydraulic Throwout Bearings
 

Initially I posted this within another existing thread, but decided it should be a stand-alone thread.

I've always had a master and slave cylinder set up connected to a standard Ford mechanical clutch fork. I haven't been fully satisfied with high rpm shifting. It seemed there wasn't quite enough TOB extension and the gears felt like there wasn't complete disengagement of the single disc clutch. The bellhouse was a Lakewood unit, and the master/slave cylinders were Girling.

This year I had installed a Quicktime bellhouse and McLeod Twin Disc clutches and still had the same master/slave cylinder/Ford fork set up. The problem of incomplete clutch disengagement was a bit more evident than the old Lakewood bellhouse and single disc. I'm concerned with premature synchro wear.

Last week I purchased a hydraulic throwout bearing from David Kee Toploaders. His description of this type TOB indicates it will provide substantially more TOB travel (extension) than my prior set up. Next spring after I've sorted through other more serious issues, I'll install the hydraulic TOB and look forward to easier shifting.

If any owners who already have a hydraulic TOB would like to post your satisfaction or lack of satisfaction with the HTOB, I'm interested in your opinions.

Thanks,
David

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Got rid of mine. In a big block Kirkham, the engine and interior has to be pulled to service it (mine leaked). I prefer visual inspection and adjustment external to bell housing. I had a Z06 with one and had no problems. I think all new Vettes have them.

601,
I posted on the other thread.

John

I have one in my car. I really cannot tell the difference. As with 4 pipes, it would be a real nightmare if it started to leak and I had to replace it. That would be my biggest concern.

Maybe a pertinent question also is which HTOBs have a good reliability record, and which ones don't.
I will have to use one in my setup (SBF/QT/Toploader) because of lack of room in the tunnel for the lever ....and I'm aware of the amount of work involved in changing a faulty bearing.

Cheers,
Glen

Mine was a McLeod. But it was 10 years ago, maybe they've improved the breed.

I'm in the process of changing my gearbox. After all my research , I decided to stay with the fork and slave. Those HTOB just seem to leak. There are some racing ones with double and bigger o rings..but they still leak.......

Can't you change the master cylinder or slave size to provide more travel?
Also check for any cracks to see if the fork is flexing to much. Try reinforcing it.
JD

I appreciate your responses, and it appears the nays may rule the yays. I've searched the internet for comments and it seemed many of the negatives were posted in 2010 and earlier. I hope that may be an indication of better quality components being marketed now. The seller of the unit I recently bought said early on there were leak issues but improvements have been made in recent years.

jaydee,
Earlier this summer I did install a larger master cylinder which did increase slave cylinder extension. Moved from a 3/4" bore to a 1" bore, but the increase in pedal pressure was unacceptable.

I returned to the 3/4" master cylinder, moved some of the mechanicals around and eventually did get more clutch fork travel. But the means to achieve the end wasn't some of my best work. I expected it may not be the answer to long term reliability, so I'll give the HTOB a shot. :D

I'm still interested in more feedback!

Thank you,
David

I've had a Quartermaster HTOB in my cobra for 9 years now without a problem. Light pedal pressure and a joy to drive. Russ

Not sure what master cylinders you are using but there is a 7/8 inch Tilton MC that I settled on with my ERA. The pedal throw was too long with a 3/4 inch. At first I thought the 7/8 inch was a little too heavy but after putting some miles on it, it feels about right. When adjusting the clutch the slave cylinder needs to be bottomed out and the rod adjusted to where it's pushing the TO bearing just shy of contact with the clutch fingers. That way you gain full advantage of the slave cylinder travel. A fork return spring is usually used to keep the TO bearing from riding on the clutch fingers. But it's important to check regularly because as a clutch disc wears, the fingers will retreat towards the rear of the car as the pressure plate compensates, using up this small amount of free play.

Sounds like you have your mind made up to go to a hydraulic throw out bearing. They sound good in principal - lighter pedal pressure and so forth - but if one goes bad with a hydraulic leak what a pain in the butt.

The McLeod HTOB is in place and am hoping for good results. Someone who has seen the photo said "Hope it works as good as it looks." TBD!

I questioned the seller of the McLeod unit again about prior failures. He said the majority of the issues were with the original hydraulic line connections at the body of the unit. They were essentially banjo fittings that weren't up to the task. The current connection of the lines has been modified.

David

http://www.clubcobra.com/forums/pict...ctureid=14401/

I guess I will always be "old school" and don't dig the idea of juice inside of my bellhousing so near to the clutch.:eek:

I have the older style Mc Leod with the banjo style fittings.
10 years and 40 thousand miles, not a drop has leaked, no adjustments required and easy on my 73 year old leg.
Craig

Htob
 

I have the Mcleod unit but have found if the clutch needs adjustment, because of bellhousing clearance restrictions I have to pull the engine and gearbox to get at the clutch or HTOB a real PITA
Cheers, Bryan

Bryan,
That adjustment process seems to be a lot of effort and nuisance.

McLeod offers 2 types of HTOB; the 1300 bolt-on, and the 1400 slip-on. I purchased the 1300 series and mounted it on a Toploader transmission. The product description for the 1300 series states the bearing will always touch the pressure plate fingers, without exerting pressure.

After I mounted the HTOB to the Toploader, I connected the wet lines to a bench-mounted Girling master cylinder which enabled me to measure the excursion of the throwout bearing while I operated the master cylinder's piston rod. It became apparent the bearing's face would always remain in contact with the pressure plate fingers. The bearing retracts only by the amount of pressure plate finger movement, when full clutch engagement has been reached.

I hope this design will eliminate the adjustment PITA you described. **)

David

http://www.clubcobra.com/forums/pict...ictureid=14403

Hi David,

I've got a 482Ci / TKO600 / McLeod RST Twin clutch disks kit installed on my car (CSX4000) but after investigating about McLeod HTOB I've seen that many people met problems with that part. Instead of McLeod I've installed a TILTON HTOB and after 5000 miles I strictly have no problems and I'm very happy with it (very soft clutch pedal and of course no leaks !).

OliveR

http://i298.photobucket.com/albums/m...n/DSC00472.jpg

I used this one from Keisler. It is OEM for numerous makes, Corvette and BMW for instance. If it is good enough to be OEM, then it is good enough for me. It has excellent feel, and was easy to bleed.

Oops, Keisler filed for bankrupcy, looks like Liberty Gears bought their assets.

wolf k,
Its good to have options on these htob's. Thanks for your input.

I looked through your photos.....very nice ERA you have!

David

I think there is some confusion about the Ford clutch set-up. Ford has been using a "constant contact" T/O bearing for many, many years. It is used in conjunction with a clutch fork that pivots on the pass. side of the bellhousing. They are designed to be contacting the pressure plate at all times with 3-5 pounds of pre-load pressure. Not enough pre-load will cause them to rattle. If you try to adjust them where they are not contacting the pressure plate, you will not have enough travel to fully dis-engage the clutch like the problem the O.P. is having. No return spring is needed or used by Ford with this clutch. The old school clutches from the 60's & 70's use a drivers side pivot on the fork and need to have clearance between the T/O bearing and the PP.