Guest brad Posted July 24, 2000 Share Posted July 24, 2000 Does anyone have comments on the good points and bad points of a hydraulic throwout bearing? Quote Link to comment Share on other sites More sharing options...
DennisK Posted July 24, 2000 Share Posted July 24, 2000 Brad, at this point I'm PLANNING on using a hydraulic bearing either from McLeod(self adjusting, but expensive) or the Howe unit shown in Jeg's. I was introduced to this set-up by two customers of mine that use them in circle track racing. They both claim excellent performance, and ease of installation. The one guy works for a performance warehouse and uses a 5/8 bore master. This would be perfect, as that's the stock Z bore. Both are using small block Chevies with muncie 4 spds. If anyone here is using one, we'd both benefit from feedback. Quote Link to comment Share on other sites More sharing options...
pparaska Posted July 24, 2000 Share Posted July 24, 2000 I have the McLeod unit in my car. It's not running, but I push the pedal every once in a while (I'll get to why later). The first push has a sticking point that's stiff at the top. After the first push, it is like a normal hydraulic clutch. I greased things when putting it together, so I don't know what the problem would be, other than an interla sticking in the hydraulic TO bearing. The reason I push it every once in a while is that I've heard of them leaking if you don't keep using them. Some versions are different than others about that, I would suppose. The McLeod unit is nice, but not cheap ($260). The nice things about the Mcleod unit are that it's self adjusting (some aren't?) and the swivels for the hoses look to be very rugged. Very trick looking having the braided lines going in an out of the blowproof bellhousing with grommets on a custom access plate over the fork hole. Quote Link to comment Share on other sites More sharing options...
Guest brad Posted July 24, 2000 Share Posted July 24, 2000 Hey guys, thanks for the info, but ummm, I was looking for a bit more *basic* stuff. Like what the heck is the difference between a hydraulic TOB and a regular TOB? Quote Link to comment Share on other sites More sharing options...
pparaska Posted July 24, 2000 Share Posted July 24, 2000 A hydraulic TO bearing is a cylindrical thing that slips (snuggly) over the bearing retainer like a regular TO. Think of it as a hollow slave cylinder that has a TO bearing at one end against the clutch had and pushes against the bearing retainer at the front of the transmission case at the back end. The hollow cylinder has an annular volume for the hydraulic fluid and a ring shaped piston in it that pushes on the bearing to make it move forward. Two lines run to it from the outside of the bellhousing, one for actuating it and one with a bleeder in it so you can bleed the clutch hydraulics from outside the bellhousing. Hope this helps, Pete Quote Link to comment Share on other sites More sharing options...
DennisK Posted July 25, 2000 Share Posted July 25, 2000 Pete, George at McLeod told me to use a 7/8" mcyl. The Howe unit adjusts with washers, and the circle track guy says he's using a 5/8" with this. What bore master are you using? Quote Link to comment Share on other sites More sharing options...
pparaska Posted July 25, 2000 Share Posted July 25, 2000 The following is from my web site http://www.tidalwave.net/~pparaska/TremecInfo.htm . I started with a 7/8" cylinder, but went to a 3/4" to get a less stiff pedal. The 7/8" gave me too firm a pedal, the 3/4" gave a good pedal pressure, but the throw is kind of long. I have a Chevy diaphram clutch PP from the 1LE Camaro, for a point of reference on clutch hat stiffness. That Corvette 13/16" MC sounds like it would be a great partner to the Mcleod TO bearing. The thing to note on deciding clutch master cylinder sizes is the pedal ratio. Alot of American cars have a pedal ratio (ratio of length from pedal pivot to foot pad, and pedal pivot to MC pushrod connection) of 4:1. The Z is about 6.2:1 So when deciding on what MC to use given advice based on American car applications like the Camaro, you need to realize that the throw of the master cylinder pushrod will be 2/3 that for an American car, for the same pedal throw. Also, the stiffness of the pedal will be 1.5 times that of the American car. BTW, this is supposedly (according to JTR) the problem that some people have with using the Datsun 5/8" bore MC and OE slave cylinder with a some stock length clutch forks. Although, I've seen a few posts recently that say this ain't so! quote: [From my web site: Clutch Hydaulics: I used a Mcleod hydraulic throw-out bearing for a GM T-5. It's a pretty nice piece, and costs (ouch!) $259. I calculated that for the clutch pedal height to be the same as the brake, and the resulting short clutch master cylinder movement, I'd need a 7/8" diam. master cylinder. Another $200 for an AP Racing short version from TrueChoice Motorsports. Ouch! I tried this part (and sold it) part number CP2623-194. The clutch pedal was quite stiff and the total throw of the pedal is 4 inches. Since then, I've installed a Girling remote 3/4" diameter master cylinder and remote reservoir mounted to it with AN fittings. This give more throw than I'd like (from brake pedal height to the floor to get the full 0.030" clearance Mcleod recommends for a diaphram clutch) but the pedal is just a bit stiffer than any manual trans car from the factory.] [This message has been edited by pparaska (edited July 25, 2000).] Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted July 25, 2000 Share Posted July 25, 2000 I am using the Tilton hydraulic throw-out bearing in my 5.0 / T5 Ford powered 260Z. The pedal action is very smooth and as light as the factory Z clutch. I am using the Tilton 74-875U universal master cylinder to operate the clutch. The master cylinder has a 7/8" bore, and bolts directly to the firewall using the factory studs. The clutch disengages about 1.5 inches above the floor, but is not bothersome. I have only been driving the car for about 2 weeks but so far I really like the clutch. The part numbers for the Ford T5 setup are 61-601 for the bearing itself, and 61-612 for the adapter. The adapter replaces the input bearing retainer, and the bearing screws onto the adapter. The adapter also provides much sturdier support of the input bearing than the stock T5 unit. Finally, the Tilton master cylinder, hydraulic throw-out bearing, adapter, and all necessary hardware cost me 423.00 from J&J racing. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 31, 2000 Share Posted July 31, 2000 Pete,Do you have a source ar phone number for that bearing? Thanks Mark Quote Link to comment Share on other sites More sharing options...
pparaska Posted August 1, 2000 Share Posted August 1, 2000 I got mine at Darkhorse Performance http:// http://www.darkhorseperformance.com/chevrolet.htm[/url] But you should be able to find it at any performance shop/business. I hear the Tilton one is nice because it replaces the front bearing retainer and is a very clean install. ------------------ Pete Paraska - 73 540Z - Marathon Z Project - pparaska@home.com">pparaska@home.com - Quote Link to comment Share on other sites More sharing options...
DennisK Posted August 1, 2000 Share Posted August 1, 2000 Pete, if I'm not mistaken, McLeod's original design used the bearing retainer plate replacement set up. They should still have this style. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted August 1, 2000 Share Posted August 1, 2000 Pete, Is the tilton a self adjusting unit? Mark Quote Link to comment Share on other sites More sharing options...
pparaska Posted August 1, 2000 Share Posted August 1, 2000 Not sure if the Tilton is self adjusting. Kind of strange that somebody would make one that isn't! Quote Link to comment Share on other sites More sharing options...
DennisK Posted August 2, 2000 Share Posted August 2, 2000 The only self adjusting one as of last February(last I checked) is McLeod's. All the rest, Howe, Tilton use washers to adjust. Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted August 2, 2000 Share Posted August 2, 2000 The Tilton unit isn't self adjusting. The adjustment is set when the unit is installed. The adjustment is made by threading the hydraulic throwout bearing onto the adapter/bearing retainer and locking the bearing hydraulic assembly in place. The initial installed height is set such that there is 0.15" clearance between the fully-compressed bearing and the clutch fingers. A self-adjusting feature would be nice, but the initial set-up of the Tilton unit wasn't difficult. Quote Link to comment Share on other sites More sharing options...
pparaska Posted August 2, 2000 Share Posted August 2, 2000 Hmm. I understand that the initilal setup adjustment is not difficult, but you have to do the same thing (threaded thing on the trans end of the bearing assembly) with the Mcleod. But what I took for "self-adjusting" was the ability of the TO bearing assembly to make adjustments in the gap between the clutch pressure plate fingers and the bearing front surface. I'm not sure how the McLeod unit does this. I do know that the instructions said to leave room for the brake fluid to move into in the master cylinder reservoir to take up fluid from the TO bearing as the clutch wears (and the clutch fingers move toward the trans). My guess is that the way the unit fits on the bearing retainer with O-rings is how it kind of sticks in place. Quote Link to comment Share on other sites More sharing options...
Greg SmileZ Posted September 11, 2001 Share Posted September 11, 2001 I searched the archives for more info on experience on hydraulic throwout bearings (HTB)and did not come up with much. If it has been covered else where I apologize.... I have a T-56 and a Centerforce flywheel and Dual Friction clutch. Does anyone have experience using a HTB with that combination? A HTB sure seems like an easy way to solve the slave cylinder problem that many have discussed on this forum. In advance, thanks....BTW tomorrow I plan on calling Centerforce, Mcleod and Tilton to findout if any of them can help with my question. Quote Link to comment Share on other sites More sharing options...
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