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RigMan
21-08-01, 02:21 PM
Despite my recent asertion that my McLeod Hydraulic Throw Out Bearing (hear on known unaffectionately by the partial anacronym of THROB)was essentiall 'sound' I have had to rebuild it for a second time. It is of course a Royal pain in the arse to take out the interior, and tunnel and the gearbox to get at the THROB.

In order to make up my mind (and anybody else's) as to whether I should seek alternative methods of clutch engagement, I would like everyone who has a McLeod THROB to list their experience for the greater benefit of us all!


RigMan x(

alex
21-08-01, 05:04 PM
I have a macleod throwout in my Dax. Ford 351C and Tremec box. It leaked before I had the interior fully fitted just driving in and out the garage so it wasn't too big a pain to pull it out again. Since I got a spare set of seals with it I just replaced them all.

It hasn't leaked since but I have had to pull the box out twice since the car has been on the road for other reasons so I can sympathise. Pulling out the interior and tunnel is painful. I have done 7000 miles and the throwout hasn't leaked in all that time.

Do you have a pedal stop ? It seems quiet easy to rupture the seals with over travel on the pedal.

Alex

wilf
21-08-01, 06:12 PM
Rigman - don't have one of these myself as I believe in being able to get to such items without removing gearboxes! I spotted quite a lot of correspondance on this subject on www.clubcobra.com - try going there and using the search facility. It would appear that our US friends have experienced similar problems to you. Overtravel, (plus the need to change the seals for the replacements that come in the box before you use the thing?)seems to be the problem. Sorry that your enthusiasm after the SVA pass has now been dampened - same for me as I have only just got the rear end back in (ooer missus) my own car - took me 2 weeks to sort it out and many wrenched muscles/bruises. So I can sympathise.


Wilf

RigMan
21-08-01, 06:13 PM
Yes I have a pedal stop. It is the O rings in the banjo bolts that keep going, those horrible little yellow things!

RigMan:-(

RigMan
21-08-01, 06:43 PM
Thanks Wilf for the Sympathy. The problem is that on Cobra forum people will complain and make posts, but those happy customers might not. I have always been aware of the pitfalls, but what I want is a ballanced view of this item so that I can decide whether to replace it or not.

RigMan

sparky
22-08-01, 12:15 AM
Frist had problems with this because of the clearance between the clutch and bearing
But found out The Distance between the gearbox and clutch finger was not big enough.
So machined front of gearbox and spaced gearbox from bellhousing.
Am using a 3/4 master on dax.
with out pedel stop (clutch very hard)
Think of using 7/8 master and pedel stop

ANY BODY DONE THIS ????????


SPARKY

DanH
22-08-01, 01:52 AM
Sparky,

Changing from a 3/4" to 7/8" clutch master cylinder will make the pedal firmer still, won't it? I believe a smaller bore at the pedal will give you greater pressure and more travel for a given amount of foot. Maybe a 5/8" is what you need.

I also have a Macleod bearing on my 351W Ford/ Tremec 5 speed but haven't completed the build yet to comment on the feel of my own 3/4" master cylinder- or on the leak potential. I am going to use a pedal stop, as is explicity advised in the instructions to prevent overtravel/leaking. Others here use the Tilton internal throwout bearing or an aftermarket or factory stock external slave cylinder on cobra replica builds.

Dan
North Carolina
USA

graham
22-08-01, 08:47 PM
Hi, I had a McCleod on first SRV8 and set it up accurately, servod it and worked faultlessly for good, however on this current SR I have fitted Rover slave, home made rod and clevis onto standard Chevy arm (yet to test) but I will be able to get to it! Did have to make a hole in transmission tunnel though and then made a special cover to hide the 1" moving protusion. I personally dont like the idea of clutch fluid possibly getting on clutch assembly with the centre bearing type but hey sometimes there is not an alternative.

Graham

paul
23-08-01, 07:20 PM
Hi there I'm running a Mcleod unit and guess what my one leaked from day one the reason being the swivel o-rings but at least they included a spare set after re newing these(being careful not to nick when fitting) I checked the unit out of the car by using a G clamp and pressuring up the unit by the clutch pedal and surprise no leaks the car has done 5000 miles now still with no bother from the Mcleod unit
cheers
Paul :-)

nbracken
20-09-01, 09:51 PM
I am just ordering the new Tremec for my car and am being advised not to go the McCleod route by the person supplying the box. I would be interetsed to know from others why so many people do chose to go the McCleod route - what are the advantages?

Thanks

imported_admin
25-11-01, 12:34 PM
I fitted a throw-out bearing to my GD427 after I realised that the bell-housing aperture for the standard side operating release arm was located such that it (just) interfered with a chassis rail. What I should have done is change the bell-housing!
The THROB leaked staight away but I thought I'd keep an eye on the fluid level and sort it over winter if it lasted that long. After a few weeks of use it stopped leaking and has been OK until recently when it started leaking in a big way. But that's after 25,000 miles so not too bad.
The trouble is that to split the gearbox from the engine you need to take the engine out on a GD. The easiest way to get the engine out is to take the body off the chassis . . .
I've now stripped the THROB down (the seals are knackered) but realise that one of the seals is a lipped square section. I didn't record which slot it went in. Can you help?

dave
25-11-01, 04:39 PM
If this THROB is going to be a pain? I think Repower make a system that fits a slave cylinder on the outside of the bellhousing ,it might be worth giving them a call and dumping the THROB,I know they are a little expensive,but do you really want to keep stripping the car?
I used to use the McLeod loads in the past when i was exporting cars,and at that time i never had any bad feedback on them, but on hearing the horror stories since, i won't use them anymore...I don't want to have to fill up my time putting right what shouldn't have gone wrong in the first place. Nowadays i make up an external clutch operating system (much much easier to service if the need arises).If you do decide to make up your own external clutch cylinder and you have any problems give me a call on 07785 702005...advice is free,it's only when i pick up the spanners do i charge.;-)

RigMan
25-11-01, 05:18 PM
Sorry I can't help with the seal location on the THROB, my experience is that the o rings on the Banjo bolts leak. However I now have a massive 400 miles on my THROB and it is working fine. The rule of thumb with these babies seems to be that if they last the first 50 miles then they sould be reliable. Certainly 25,000 miles in the context of the McLeod THROB is reliable, so I am now hopefull that mine is going to behave from now on. I still get nervous in stop and go traffic though!!!

Dave if mine goes again I shall convert to a slave andd forked arm arangement, but taking the seats,tunnel and dashboard ect to get the transmission out is a real effort, so I won't be doing it until it fails. Especially as the THROB costs 200 quid! By the way, is it easier to take the engine out instead of the tunnel, seats etc in order to service the bearing?


RigMan :)

dave
25-11-01, 08:41 PM
>Dave if mine goes again I shall convert to a slave andd forked arm
>arangement, but taking the seats,tunnel and dashboard ect to get the
>transmission out is a real effort, so I won't be doing it until it
>fails. Especially as the THROB costs 200 quid! By the way, is it
>easier to take the engine out instead of the tunnel, seats etc in
>order to service the bearing?
>
>
>RigMan :)

I have tried both methods of acessing the contents of the bell housing and i definately prefere to remove the engine.
I assume that your chassis has no backbone brace bars cos if you've got them the only way out for the box is in bits and from underneath ...YUK.
If you do change in the future,shorten the clutch fork,that way you will not need to scolop the tunnel.
;-)

kauri
26-11-01, 08:43 AM
Hi all

I had the intention of fitting an internal hydraulic release mechanism until I read this thread. The one I have aquired is, I think, an older model Mcleod. Although secondhand it appears to be in excellent condition.

If I do decicde to fit it does anyone know what is the prefered distance, when assembled, between the release bearing and the clutch release fingers:- should it be just touching, a running fit i.e. slight pressure or should there be a gap and if so how much?

As can be seen from the picture the unit is statically fixed by 4 bolts through the rear flange. This should not present too much of a problem as I can tap into the adaptor plate (3/4" thick) between the Chevy bell housing and Getrag gearbox.

What I would like to know is wher the unit is likely to leak from? Should I continue down this route, which at the time of purchase seemed such a neat solution to the problem, or have an external slave with the added agrivation of mounting it on the curved face of the bellhousing?

Well I tried to include a picture but for some reason the upload button failed to work and it was not forwarded to the attachment box? Am I doing it all wrong?

John

RigMan
26-11-01, 09:03 AM
John,

The McLeod unit I have just slides on over the input shaft and there is a spacer sleeve (screwd) to adjust the gap between the thrust surface and the fingers of the pressure plate. McLeod recomend, at least on the 'floating unit' that I have to adjust the space between these to surfaces to be betwen 0.1 - 0.125 inches. If the gap is too big you run the risk of pumping out the piston on the bearing, and if too close, you will risk over pumping of the fingers such that they may become stuck in the compressed position. Measure carefully several times with the feeler guage!

The unit I had leaked around the small o rings on the banjo bolts. Inspect them and make up the unions as tight as you dare. These units get bad press of course, but when they are working they perform very well with good sharp response as well as there space saving qualities. I suspect there are many satisfied people out there with these bearings, and that you only hear of disgruntled people like me. I can't believe that McLeod still make these bearings if they had anywhere near the 50-60% failure rate that this forum might suggest!

RigMan

:7

dave
26-11-01, 11:27 AM
Hi Nigel
the McLoed takes up no room around the bell housing .So the only space you need in the tunnel is for the bell housing, and no extra space is needed to fit a clutch fork and slave cylinder which can be a little awkward on some cars where space is limited due to the engine being set quite far back in the chassis for weight distribution perposes.
;-)

imported_admin
26-11-01, 06:38 PM
Hi,

My unit leaked from the main piston seals - the banjo fitting were fine.

Nick

callum
27-11-01, 07:00 AM
It will hurt Dave to hear it but the 'Repower bracket' for a conventional slave & lever set up is a GD made part. Mine works a treat and by extending a piece of brake tube from the nipple location to the bottom of the gearbox and driling a 6mm hole in one of the gearbox casting 'webs' you can securely relocate/bolt up a remote bleed nipple for easy acess. Andy Burrows is not a fan of McLeod bearings for all the reasons described.:7

dave
27-11-01, 10:15 AM
>It will hurt Dave to hear it but the 'Repower bracket' for a
>conventional slave & lever set up is a GD made part.

Not at all ,GD's engineering is excelent,as i said once before-If my wife would let me i would have a rolling GD chassis with a glass top on it as a coffee table in my living room.
the only things i dont like about the GD are my personal preferences-deep dish rear wheels and the steering wheel angle.
;-)

RigMan
28-11-01, 07:15 PM
John,

The body of the bearing is similar to the free floating variety that I have. How will you bleed and feed this unit when it is attached to the input shaft with the bellhousing on the engine? My unit has 8" steel braided lines which make up to the feed/reservoir and a bleed nipple which both make up just out side the bellhousing apature where the fork arm usually goes. The hoses are made to the body with banjo unions which allow them to swivel. The required small o rings which keep it from leaking is what has given me a problem in the past! I guess because your unit is fixed, you could make up hard lines to the unit thus dispensing with the flexible/swivelling arangement. This would make it more reliable but more difficult to work/ perform maintenence on!


RigMan

kauri
29-11-01, 06:57 AM
Rigman

Hopefully the unit will bolt on to the adaptor plate between gearbox and bell housing. I have tried mating it up at the front of the gearbox and fortunately the flange fits perfectly into the reccess with a few thou to spare. The clearance between the bore of the unit and the outside diameter of the input shaft is also a few thou. Machining a very thin sleeve for fitting purposes should make alignment but a simple matter.

Looking at the picture there are two tapped holes just inside the flange, the one on the right will be positioned at the top as bleed conection and the other the main feed. Rigid pipes will connect to the outside through the bell housing where the original lever fork went. The bleed line can terminate here, just outside the bell housing or run to a more accessable position in the engine bay. That's the theory at this stage. I guess a flexible connection will be required from the here to the rigid pipe line on the chassis.

Would you recommend 3/16 or 1/4 brake pipe for the rigid line back to the master cylinder as I'm not sure if the smaller pipe would restrict the rate of pedal application?

I may have to set it all up on the bench as at this stage I do not know if the capacity of the master cylinder, 3/4 bore is sufficient to move the bearing far enough to release the clutch or whether a clutch stop will be required. Do you know the approximate travel of the clutch release fingers from engaged to disengaged?

I should finish the running gear this week so hopefully the machine will then be on on four wheels. Next bit will be to mate engine, gearbox and clutch then to drop it in. Then it will look more like a car! Will keep you posted.

Cheers John

PeteV
29-11-01, 12:43 PM
Hmmm...

Is it called a 'Throw Out' bearing because thats what you'll eventually end up doing with it ? :7

Pete.

kauri
07-11-02, 08:21 PM
Rigman

Thanks for the clearance figures which I guess will suit my unit. I would like to use the unit for the reasons I put in my last post but I will wait for more response before committing myself. The input and bleed connections are through two tapped holes at 90 degrees on the barrel, 1/8 NPT. A single threaded steel pipe came with the unit but it looks like the pipe had been twisted during tightening from the wrong end as the hexagon nut on the threaded end had been turned off so will have to make another one up.

Will try again with the photo but I didn't get much luck at the first attempt.

regards John