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MG Midget and Sprite Technical - Clutch biting point
|Putting on a new slave cylinder, I have read the treads about the difficulties bleeding the system. So that part I have got allright. The reason for changing the slave cylinder was that the biting point was almost instant releasing the pedal. As it has been since I got the car and it has always irritated me.(As if there was air in the system) Changing the slavecylinder did not cure the problem. The mastercylinder is only five years old and is moving spot on using the pedal. The pind is also ok in the slavecylinder. Now I am asking, can it be the release bearing that is so worn that it hardly can depress the clutch?.|
Michael from Denmark
|It could be the release bearing but also there can be wear in all of the pivot points in the system. Check the hole at the top of the pedal, if it is oval you can loose quite a bit of travel, also check the actuating arm for wear. Do you have a 1500? if so check that you haven,t lost the pin that goes through the arm they are only a push fit and can fall out. The clutch can still work but will be as you describe.|
Thanks for your reply.Itīs a 1275. I have checked it all for wear and I have changed the actuating arm as it had an oval hole and the dovel was worn, but it did not help.(perhaps very little). Still there is is only about 1 cm till it engage. There is no sound from the bearing and the cluch is smooth and nice. It is strange that no one suspects the release bearing when the gearbox will not engage. At least I have not read it anywhere.
You might want to check out the thread -Clutch gone - on holiday with few tools, ideas? - this shows that the problem can definatly be the release bearing, I think people try to find the easier to fix problems first before suggesting moe major surgery. If mine I would leave as is unless I was planning an important or long distance journey. I would maybe try and eek it out until the winter arrives .
good luck Carl
Thank you for the link. Very interesting though the pedal depression on my car (still)is smoothe. And in fact it have not changed at all since I got the car 6 years ago. And yes I will let it drive on untill the winter season and then fix it, as it is a major job when I also want to clean up the engine bay now the engine is out. But when towing my camper it better be working.
PS -Warwicshire- I was in Gaydon 2 years ago attending the Spridget 50 party as the only Dane.
|Michael. If as Carl suggests, it is the release bearing, it's only going to get worse, so be careful about leaving it for too long because you may start to experience difficulty in selecting gears and the synchros will start to try and compensate for the lack of clutch, which will eventually wear the synchros themselves and that would be a shame if your gearbox is OK at the moment as it will mean a complete strip down of the gearbox. How do I know? Don't ask!|
The release bearings on our cars, ( A series) are only carbon, so can wear prematurely A good tip that I picked up on this forum is not to sit at traffic lights with the car in gear and the clutch depressed. Put it into neutral and use the hand brake.
If you get all the parts to hand before you start and get stuck in early, you could do it all in a day and be back out on the road again.
|If it isn't broken dont fix it! thats what I say :)|
I hope you enjoyed your visit to Gaydon I know I did, only a few miles from my house. I probably have a photo of your car, I seemed to photograph most.
Is there anything in the archives about differant length pushrods in the slave cylinders?
It rings a bell with me, hopefully someone else will come along with further info.
|If you have my luck do not ignore this, or any problems with the car really, as if you have my luck it cause you a lot of problems and expense when you least want or can afford it|
And it will spoil your enjoyment of the car
If you don't go far and hardly ever use the car (not what I'd recommend as you'll tell from my other posts) then yes maybe live with it for a while, if you're the lucky type too :)
|You should be able to see how much meat is on the thrust bearing by looking through the inspection hole in the bellhousing.|
|Thank you all for your comments. What puzzles me is that the problem has been there since I got the car 6 years ago and I have driven about 3500 miles every year without any change. |
Another thing is, that I noticed that the flexible hose attached to the slave cylinder looked tired and oiled Not leaking) and springy. I will fit a new one. That will perhaps help a little. I remember that I once had an old Fiat with a springy brake pedal. After fitting new brake hoses it was nice and hard.
Fortunately I have good ear for wrong engine- and gearbox noises so if I feel that the syncromesh are being stressed I will obviously fix the problem. I must admit that I am not one of them who uses their summerholiday lying UNDER the car.
Ps Pictyre to Carl
|I do remember several years ago some discussions about welding on an extension to the slave push rod inorder to extend the the reach, But im not sure why that was the case as I think back, I want to say there was some differant sized length push rods floating around at that time.|
If you have driven 21,000 miles and the bite is in the same place now as then and its done it from day one,,, Id look a little further into perhaps the push rod is not the correct one or has been shortened or perhaps the aftermarket throw out bearing is a little differant then (dare I say it)....stock.
(No, you dont say, aftermarket is not the exact same spec as factory... say it isnt so...LOL)
I think Id play with extending the length of the push rod 1st before id go ripping the engine out... just make sure you dont over do it and have it engaged to far up or even worse have the thrust bearing slightly engaged permently (aka riding the clutch)
Just another thought I had...
have a look at the rubbers where the fork comes out of the housing and engages the slave, see if there is any binding do to worn/parished rubbers
As a matter of fact I had the same thought But I have a spare gearbox still with the slave cylinder attached, so I pulled the pushrod out, looked at it and found that there had been weldet some lenght to it. About half a centimeter. Fine I thought, now I indeed have more lenght to the pushrod. Fitted it in and there was no difference at all. I thought it over once more and came to the conclusion that it does not matter, because it only pushes the piston a little further back. It is still the same amount of fluid that flows into the chamber coursing the piston to move forward. The pistons resting place has just moved a little further back in the chamber. So no use. So I still believe it is the release bearing which courses the trouble. When my wife push down the pedal there is immidiate action at the pushrod so I cannot see any other reason than the bearing. I hope it will last the summer and then I will fix it as I am quite curiuos. I will let you know at that time.
The rubber is soft and in good condition.
|Just for kicks and grins|
If the old slave on the old tranny is still in decent shape, and worked fine without the same issue your suffering from, it might be worth the 2 hours to try and install on the current tranny to see what happens... it would certianly answer some questions one way or the other and give you a more focased direction as to where the problem lies
| Im not sure I understand?|
DId you try installing the old push rod with the welded on addition into the new slave and it didnt work?
Heres another Brain flash...Not sure if this could or couldnt be a problem like you have...
The flywheel... perhaps it was resurfaced in another life time and had alot taken off the front that would certianly account for the push rod "APPEARING" to be to short, thus the need to add extra to the length. as the distance from the throw out bearing and the pressure plate would have increased
BTW... What about the fork any chance it could be bent making the rod having to push further in.. to achive the same required distance
The part thats interesting that really stands out is the fact that you have driven this 21,000 miles in 6 years, and the bite point is the same now that it was when you got the car. and the bite point is at the vary bottom of the peddle depression...meaning if it was a worn pressure plate/throw out bearing you should have already by now experiaced some catostrophic failure before Now... thats why I think its something stupid/odd/ and out of the ordinary...
then agian I was wrong way back in 1987 about a how to castle a rook in chess, So Im not infailable
If you havent re-bleed the system in a long time ... say 3 years? it could well have some water build up.
the 3 years is arbitary, as that about the longest Ive gone without bleeding mine do to some other issue in the way
|What also could have happened is that the fork got bend, changing the angle in wich it contacts the face of the plate.|
Maybe visible through the inspection hole, as you're there looking for the carbon thickness.
|Alex G Matla|
|It is definitely necessary to renew both clevis pins if worn. Wear in the pedal, master cylinder fork and clutch release fork and fork pivot points all translates into longer pedal travel. Be sure to lubricate all of these parts with grease as this will greatly reduce wear. They were not lubricated from the factor.|
Even so, I always found that after about 15,000 miles, I would need to go all the way to the floor before the clutch would disengage. I finally tried a push rod that was about 1 cm longer (from an Austin 1300) and this would fix the problem for another 10,000 miles or so. By 25,000 miles, the carbon release bearing would be due for replacement.
So, I carried this longer push rod and popped it in when the pedal would need to be depressed all the way to the floor.
After almost 200,000 miles (8 or 9 clutches), I finally put in a 5 speed which solved the release problem altogether.
|Carl. Did you photograph my car? I got half way there and realised I'd left my camera and video cam sitting on the kitchen table|
BRG mk3 Sprite MMF474C
I dont think there is anything wrong with your clutch if it was new or nearly new when you bought the car. In my experience all hydraulic clutches bite at the bottom of the travel when they are new or in good condition and gradually move up the travel as they wear. If its not making any horrible noises, slipping or juddering I would leave it alone (dont fix it if it aint broke).
|To Prop: I changed the slave because of little clearence but it did not help. I changed the fluide last year.|
I will let it run the summer through and take a closer look in the winter
To Bernie: You will be more than lucky if Sam has got a picture of your car as there were more than a thousant midget that dat at Gaydon and what fun it was.
This thread was discussed between 20/06/2010 and 22/06/2010
This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.