My clutch is misbehaving - HELP!
Orig. Posting Date | User Name | Edit Date |
Oct 27, 2014 01:24PM | Earwax | |
Nov 24, 2013 04:36PM | Craig | |
Nov 24, 2013 11:39AM | Air2air | Edited: Nov 24, 2013 11:53AM |
Nov 22, 2013 02:04PM | Jemal | |
Nov 22, 2013 04:18AM | turbodave | |
Nov 21, 2013 09:03PM | turbodave | Edited: Nov 21, 2013 09:10PM |
Nov 21, 2013 08:34PM | turbodave | Edited: Nov 21, 2013 09:09PM |
Nov 21, 2013 06:45PM | JiMINI | Edited: Nov 21, 2013 07:03PM |
Nov 21, 2013 05:13PM | Jemal | |
Nov 21, 2013 01:21PM | Craig | Edited: Nov 21, 2013 02:16PM |
Nov 21, 2013 12:16PM | Jemal | |
Nov 21, 2013 05:14AM | turbodave | |
Nov 21, 2013 04:49AM | turbodave | |
Nov 20, 2013 09:23PM | Jemal | |
Nov 20, 2013 07:15PM | DRMINI | |
Nov 20, 2013 06:27PM | turbodave | |
Nov 20, 2013 12:11PM | Jemal | |
Nov 20, 2013 07:22AM | Dan Moffet | Edited: Nov 20, 2013 01:19PM |
Nov 20, 2013 02:23AM | Cup Cake | |
Nov 19, 2013 09:07PM | Craig |
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Stick with Turbodave and the doc, they know their stuff.
the other possibility apart from all the clevis pin wear etc, is a tiny leak in the slave cylinder under the rubber cap... well more of a displacement as often no noticeable fluid is lost..... it seems the older internals of the slave cylinder kit have a different cup inside and sometimes the newer cups in their forward and backward movement create a little vortex for air bubbles to hold onto and stay.. so that tiny bit of air is taking up your travel. worth getting a torch and peeking beneath the rubber boot to rule out.
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I believe what the problem is that the "adjustment" is not what we would expect it to be and many of us become confused with the results we get. There is no way to adjust for clutch disc wear as there is for other systems. The MGAs and Bs I've had also have a hydraulic clutch system, but there is adjustment allowed that will reposition where the pedal is relative to release of the disc in use.
The best way to get the pedal to be as high as possible when the clutch is released is to have all parts of the system is as good a condition as you can, or otherwise "new". It seems that my problem is that the spring force of the orange diaphragm is great enough to deform the diaphragm conic or some other related bits before the disc is released. I say this because I have watched the diaphragm as the pedal was pushed repeatedly by my very nice wife. Did I say how much I appreciate having her in my life?
Anyway, I got frustrated by replacing almost everything and having the adjustments made exactly per spec with little or no improvement in pedal function. That led me to posting this question to ask if I had missed something. I got my answer, "No". So, I think we're done here. I hope that anyone asking this question in the future on this forum will first do a search and find this thread.
Peace.
'72 Morris Mini - 1310cc, K1100 head conversion
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Well this thread certainly reminds us why drag racers know their clutches.
Turbodave I wish I knew a quarter of what you're talking about, and you had a Powerpoint to accompany it. Or crayons.
I'm going out to the garage now for my monthly attempted clutch adjustment after watching this or that youtube or webpage. And for the next week I should be able to get into first without backing into second. Maybe. The adjustment will last for a few days.
Nobody - anywhere - has written a professional, complete article on the subject. Each article addresses only 50% of the entire project, so is a complete waste of time and only raises additional questions:
Example: //www.7ent.com/pages/articles-tech-tips/article-easy-pre-verto-clutch-adjustment.html
Because people write incomplete material, all you can do is piece together a bunch of it to create your own version. I know mine is wrong for that reason.
1. Remove spring.
2. Remove arm clevis pin that holds the slave pushrod
3. Adjust the 7/16" freeplay adjustment bolt for your 20 thou. For about the millionth time.
4. Reassemble and discover no change whatsoever.
5. I cut off the 15/16" plunger end and nuts per Jamal's recommend, so fortunately can't add those to the confusion.
Finally, out of my evident frustration I got the SRacer adjustable pushrod and just extend it until I get a reasonably high pedal release point. I don't smell anything so maybe it's working...beats me.
Yeah it's all wrong, but just as JiMini is saying there has never been an english-language step by step that completely addresses this issue. Every comment I've ever read, from the UK forums to the many articles, does not comprehensively describe how to do this job.
Instead it's bits and pieces tips - like putting a nut into the slave pushrod, etc. that we've all heard. But when mentioned without any discussion of the surrounding areas and dependencies it is just another problem created and not part of a solution process.
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I agree that the system, if you adjust it right, is good right after you adjust it. I did it this way for many years. My issue is that I don't want to adjust it every damn week, or every few hours if I'm at the drag strip. I also have a lot of stuff above this bolt that does not allow me access to tighten a bolt that otherwise would take me two minutes armed with a pair of 7/16 spanners. The only bent arms i've seen though are bent towards the water pump - not the other way as would happen if the slave was pushing against the (badly adjusted) throw-out nuts.
I don't believe that you still comprehend the spring / bearing aspect. All vehicle clutches are belivile springs, just as the mini clutch is (discounting coil, centifugal, etc). The only difference is these have fingers interated into the inner profile to act as a lever, typically providing a 3:1 or 4:1 ratio. The work done by the guy pushing the pedal is still the same - the force at the release bearing is lower - it just travels further. The same amount of work is still required to unload an 1100lb "grey" pre-verto as an equivalent automotive spring plate. Actually - the finger systm is less efficient as the fingers themselves have a compliance along their length as they are attempting to over-centre the belville portion, so result in lost efficiency.
That these fingers can take a small force is, well, simply not correct. Take an assumed 1100lb "conventional" fingered clutch spring operating at 4:1 finger lever ratio. If you put a 2lb force against the release bearing, you will have taken that 1100lb to 1092lb clamp force. The force doesn't disapear - it is reacted against the main belville spring. Now do the same with the simple pre-verto belville spring, and your 1100lb clamp force, is reduced to 1098lb.
Because release bearings don't care what distance they travel, they are only conerned about force. It is widely known that a bearings life at load ratings of 1-3% are bascially infinite, or uncalculable with confidence of variation, then putting 1lb against a bearing rated for 700lb (the pre-verto mini release bearing - i don't know that it was ever released for production with a higher force than this), is statistically better than the 1lb force applied against the pre-verto release bearing (300lb release force on the turbo) - but in reality, won't make any difference to reliability of the bearing itself.
Finally - I put forward the case that beaings, like anything else, would benefit from being bought up to temperature prior to being loaded. Starting a pre-verto mini with a clutch adjusted "per the book", and letting it idle for a few minutes before pressing the clutch, is akin to starting the engine on WOT as far as the release bearing is concerned. The first time the bearing moves, it is doing work. The cold grease in the bearing is not at optimal temperature, and is not optimal in its ability to perform its duties (theoretically). The bearing outer race is also static, and has to be accelerated to 800 or more rpm every time it is used. The pre-verto by comparison will always be at operting temperature when asked to do work (exception being when the USA-only starter interlocks are applied to a clutch pedal), and always at the correct speed without having to be accelerated violently every time its asked to do work. Obviously the stock beari has shown it is capable of meeting this seemingly agressive requirement, such that something that removes these characteristics, could/should be seen as a benefit - not a hinderance.
It's been fun, but this place is done. I have no hatred, and appreciate the good times. But this place now belongs to Tony and his pink mini.
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It's been fun, but this place is done. I have no hatred, and appreciate the good times. But this place now belongs to Tony and his pink mini.
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Craig, did you use three driving straps by chance, and not machine the backplate to compensate? And if you used the grey, did you machine the backplate lugs down?
It sounds like you dont have enough initial clamp distance, so you are having to push the pedal a lot to over-centre the spring.
Many years ago, I spent a long time optimizing a grey diaphram- 23.5mm backplate height (with two driving straps) was optimal. Additional straps means you need to machine more off the backplate lug height. All the turbo guys know this, as they use grey's more than most others.
If you don't machine your backplate, your spring isn't at it's peak clamp, and you have to use (waste) pedal travel to push it towards, and then past peak clamp, to overcentre, and hence release it
It's been fun, but this place is done. I have no hatred, and appreciate the good times. But this place now belongs to Tony and his pink mini.
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Thanks all for the replies, but back to my original question for just a moment...
I have the stop bolt and large OT nut adjusted as required and an S-Racer adjustable push rod installed to allow maximum piston travel. This is all on a Pre-Verto clutch. I have it working, but the clutch doesn't disengage until the last bit of pedal travel.
From everything that I have read in the posts on this and other threads is that there isn't any other "adjustment" that can be made to this set up and the adjustable push rod can improve travel a bit, but not much. This reflects exactly my experience. I have watched the actuation of the slave cylinder and push rod externally and the diaphragm internally. It looks to me that there is some spring load in the system within the diaphragm, disc and pressure plate section that occurs prior to the release of the clutch disc that is not related to the actual spring itself. I have seen the conic "cup" of the diaphragm move before the pressure ring moves on my car through the timing hole on the clutch cover.
I'm thinking that it is what it is and I won't get any more pedal than what I have right now.
Feel free to continue with your discussion on Verto vrs Pre-Verto or whatever else you feel is necessary. Again, thanks, you have no idea how much this has helped me sort out my own clutch issues!
Hi Craig, been viewing this post and as always, there's a lot of opinions and solutions. I can only speak from experience with my car and not super technical. My clutch engagement has always been fairly low (to the floor like yours), at times, gets worse to the point that reverse/1st become a challenge. Although many will say that "there's no real adjustment". I have adjusted the standard pre-Verto seems like every 6 months or so and it makes a significant improvement. 1. Back off the large nuts at the end of the lower clutch arm and get them out of the way. 2. If you have the spring on, pull it off for a bit (reconnect later). 3. Set the free-play by pulling the arm away from the engine. You said .20 OK, err on the short side. 4. Adjust those large nuts (overthrow) to 1/8" (I think you said 1/4" in an earlier post). Just use a 1/8" drill bit. Reconnect spring. This assumes you replaced that original clutch arm that I know you ordered (Part No: 22A2204 from our host). I'm sure I may be compensating for some other wear factor in my car, but seems like every 6 months or so I re-adjust and things are good again. Although I still engage closer to the floor vs. higher travel. Give it a whirl.
If all else fails, our Blackhawk Cars and Coffee (MOASF site posted) is around the corner, in December and we can bring the club gang over to my house after to sympathize, or figure it out.
(Edit: I don't claim to have the expertise of those on this forum, just saying what has worked for me without all the scientific stuff)
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Recently with my Moke project I discovered that I didn't have enough pedal to disengage a new clutch. I traced it to a missing spacer between the clutch master and the bulkhead. The way the pedal clevis pin meets the pushrod from the master cylinder affects available pedal travel. Loosen the master cylinder hold-down nuts and lift UP on it (the master). You'll see your pedal come up! I found that a 1/4 inch spacer below the master regained the full available stroke (of the master) as well as raising the clutch pedal up. Think how many LHD conversions have simply left out the spacers and thus handicap the clutch stroke. (you might say "WHAT spacers".... RHD cars have the bracket for the dog-bone raising the master, Original LHDs have spacers or thick "gaskets" that are often tossed out as leaking brake fluid turns them into a spongy mess).
The pre-Verto has the shortest required TO bearing travel to disengage of any clutch I can think of, about an eighth of an inch, INCLUDING the 20 thou freeplay! We just have to dial in exactly where that eighth inch of movement occurs! By contrast, the Verto needs at least 3 times the stroke to disengage, and that's why the mechanical components take a beating... the Verto plunger and throwout arm always seem to be thrashed.
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Thanks all for the replies, but back to my original question for just a moment...
I have the stop bolt and large OT nut adjusted as required and an S-Racer adjustable push rod installed to allow maximum piston travel. This is all on a Pre-Verto clutch. I have it working, but the clutch doesn't disengage until the last bit of pedal travel.
From everything that I have read in the posts on this and other threads is that there isn't any other "adjustment" that can be made to this set up and the adjustable push rod can improve travel a bit, but not much. This reflects exactly my experience. I have watched the actuation of the slave cylinder and push rod externally and the diaphragm internally. It looks to me that there is some spring load in the system within the diaphragm, disc and pressure plate section that occurs prior to the release of the clutch disc that is not related to the actual spring itself. I have seen the conic "cup" of the diaphragm move before the pressure ring moves on my car through the timing hole on the clutch cover.
I'm thinking that it is what it is and I won't get any more pedal than what I have right now.
Feel free to continue with your discussion on Verto vrs Pre-Verto or whatever else you feel is necessary. Again, thanks, you have no idea how much this has helped me sort out my own clutch issues!
'72 Morris Mini - 1310cc, K1100 head conversion
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I don't seem to have seen any swearing, but ok.
The pre-Verto diaphram can (as we all know) put a HUGE amount of loading onto the crank thrusts, the equivalent verto is about 1/3 of this due to the internal leverage. Obviously the highest force on the thrusts is just prior to overcentreing the diaphram (just before the typical bite point at the pedal). This is the higest load the clutch sees.
The same crank thrusts are used on Pre-verto, Verto hydraulic, and verto cable. The verto Cable had a spring loaded sheave-push system that always loaded the release bearing, and the thrust bearings; just like every car in the past 30 years does. I never once saw a metro turbo (heaviest clutch of all the cable vertos) in stock form with burnt up thrusts. So saying that loading the stock (pre-verto) release bearing with a small spring load, and hence crank thusts with "too much clutch" is without merit, just by looking at hsitory of the clutches used in the A-series.
I don't understand your point about how the pre-verto thrust bearing must be considered unique because the diaphroam is a unique design...The release bearing doesn't car what design of diaphram it is pushing against - why would it? If the verto release bearing sees a peak release load of 280lb, and has approx 1lb force applied to it 100% of the time (as with many others), what makes the pre-verto bearing - one designed to take at least double the release force of the verto, incapable of taking a similar 1lb force 100% of the time?
I can't post pictures of the blue bearings and grooved up diaphram flange, but I don't have any that were used on any mini I've worked on since adopting the self-adjusting system.
The only time I've seen them is when someone has adjusted the throw-out bolt all the way out for some reason, and another time a very lomng time ago where it was on a stock mini and just plain worn out.
It's been fun, but this place is done. I have no hatred, and appreciate the good times. But this place now belongs to Tony and his pink mini.
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TurboDave, there is already a light spring in the pre-verto slave cylinder, it is strong enough to take up the slack, and the load it puts on the release bearing with the clutch pedal up is minimal. Just throw away the heavy return spring and wind the stop screw into the cover a bit.
I have had mine `self adjusting' like this for a year or so now, because I have the Oz freshair heater under the hood and cannot get to the clutch arm adjustment without pulling the grille out.
I have had zero problems, and the bearing is the common late one, not the early (& better!) flat faced 3W5-8.
Dr - I remember you saying this before - And forgot!
I totally agree with you that the extra spring on the outside should be left off, and let the spring on the inside do the job. I have found that two of the slaves I have here would have what I'd call very weak springs. One has a spring that is definately up to the job and wouldn't need any help for sure. These are just a mixture of aftermarket and OE used units needlessly saved over the past 20 years BTW...
It's been fun, but this place is done. I have no hatred, and appreciate the good times. But this place now belongs to Tony and his pink mini.
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Let's see photos of those blue throwout bearings, and the deep groove cut in the diaphragm spring flange when those "self adjusting" set-ups, um, run out of adjustment... Who was the bearing engineer who put up numbers showing the bearing would be fine with constant loading and such and such PSI.... sorry, they spit out their grease and turn blue!
Now don't go off on a tirade of bad language! Lets remember that we're all friends sharing our knowledge, experience, and opinion for the benefit of others....
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TurboDave, there is already a light spring in the pre-verto slave cylinder, it is strong enough to take up the slack, and the load it puts on the release bearing with the clutch pedal up is minimal. Just throw away the heavy return spring and wind the stop screw into the cover a bit.
I have had mine `self adjusting' like this for a year or so now, because I have the Oz freshair heater under the hood and cannot get to the clutch arm adjustment without pulling the grille out.
I have had zero problems, and the bearing is the common late one, not the early (& better!) flat faced 3W5-8.
Kevin G
1360 power- Morris 1300 auto block, S crank & rods, Russell Engineering RE282 sprint cam, over 125HP at crank, 86.6HP at the wheels @7000+.
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but that would leave the bearing in contact with the diaphragm all the time; it wouldn't last very long like that I'm sure.
This seems to come up every year, or just long enough for the last time it was posted to have fallen off the back of the board....
The eBay spring thing will not help. In the same way, that the factory instal of the spring betwen the arm and the slave is not helping. If the OP has the spring in place, the first thing I'd do is remove the spring, and let the hydraulics try to take up the slack.
The best way to help the hydraulics let the clutch be fully self-adjusting (like the verto) would be to actually put the tension spring between the inner fender and the arm. This would basically pull the arm, so the release bearing is always in contact with the clutch cover, and give a good pedal every time, whether the clutch plate is new or old.
Every clutch pedal of almost every car built in the last 30 years has done this - exactly as the Verto clutch did. It will not wear out, all it'll do is work better than it does today.
The only times that this won't work is if the arm/pin is worn out, damaged, whatever, or when the slave piston runs out of travel. The way the verify if you need a longer pushrod is to remove the slave, pull the arm towards the inner fender, and hold the pushrod in the approx location where it would sit normally. The end of the pushrod must be at least up to a line between the centre of the two bolt-holes that held the slave in place. If it is on the water-pump side of this line, that is ok (a good target is 3/8" to 1/2"), but if your pushrod end doesn't even make it to the line, then you are close to running out of slave travel.
I really must make a sticky somewhere, or copy this text, so i casn just copy paste it back into another message 367 days from now LOL
It's been fun, but this place is done. I have no hatred, and appreciate the good times. But this place now belongs to Tony and his pink mini.
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I don't think that is the problem here though. A couple of possibilities... light flywheels are usually thinner where the straps that go through to the backplate mount. Make sure you have spacers here, usually provided with new flywheels, but easy to forget if the flywheel changes hands. You want those straps PARALLEL to the friction surfaces and disk when the clutch is engaged.
Another overlooked area... it is very easy to install the straps backwards on light flywheels. The hubs are more open such that the straps can be oriented to "push" the backplate. This will make it very unhappy! Study your assembly in the normal engine rotation and make sure your straps are oriented correctly (PULLING the backplate around) and are not in a flexed state to reach the backplate.
The only other possibility is that your diaphragm spring or flywheel have been used with other components that have deformed the cone area of the flywheel hub or the spring... the area of contact that deflects the spring to push the backplate and disengage the disk. When everything works right, it is no exaggeration that the clutch (blue spring) can be operated with TWO fingers on the pedal.
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Re Cupcake's link:
Wouldn't that spring remove all the slack between the throw-out bearing and the diaphragm, resulting in premature throwout bearing wear or worse, friction on the diaphragm? Isn't that the reason for the 15 or 20 thou clearance as Jamal inddicates?
EDIT: after Jamal's post I now see the spring is outside the WOK, pulling the other way.
.
"Hang on a minute lads....I've got a great idea."
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I've often wondered about how these work? Might help.
The power of accurate observation is commonly called cynicism by those who have not got it. G.B.S. Sarcasm is the lowest form of wit. Oscar Wilde
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Yeah, I thought that might be an issue so I ordered one and a new release bearing. Not sure if that will make it better, because it seems as though the adjusting the stop bolt would eliminate that issue. It is the last thing I haven't replaced other than the pedal and pedal box. Those two things didn't have any slop in them when I had them disassembled. I just don't understand why I'm seeing soooo much travel in the arm prior to the pedal force increasing and the clutch really releasing.
'72 Morris Mini - 1310cc, K1100 head conversion
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