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MG Midget and Sprite Technical - Clutch slipping on new T9 conversion HELP!!

I just took the car for its maiden voyage after converting to a T9 5 speed.
Im having a profound amount of clutch slippage as the motor comes into boost/power. Any thoughts as to why this could be?


David Barrett

David was a new clutch fitted at the time?

If the clutch thrust/release bearing isnt disengaging this could happen

maybe needs a slightly shorter pushrod on the slave cylinder to allow the pressure plate to grip fully

Did you do the work or your local specialist? Time to take it for remedial work!
Bill

I'm not familiar with the T9 hydraulics, but bills suggestions seem valid. How clean was the flywheel and clutch? Oil/grease contamination maybe?
Trevor-Jessie

The clutch was brand new with the kit.
NO oil grease what-so-ever I cleaned it thoughly myself. Checked for freeplay in the pedal as well as the slave/ slave rod...there was plenty.

The Quantum Mechanics kit I have re-uses the stock slave and actuating arm witha modified pivotand release bearring.
Dave Barrett

I'd expect any clutch for a Ford Type 9 to cope with 200bhp and you aren't getting close to that with the amount of boost you're running.

You say you've fitted a new clutch is the plate and cover or just the plate?
Daniel Thirteen-Twelve

New plate
Disc
Bearing
David Barrett

All I can think is that the pushrod is slightly too long and holding the diaphragm slightly open then

maybe one a 1/4" shorter would help

but if it didn't you'd need the right one again after testing, so see if you can find a spare to adapt.

I know it's no help but I have several lengths of push rod hanging in my garage on a nail on the wall

collected from various sources over the years

I made one by welding a length of rod onto the end of a 7/16" AF nut then trimmed the nut and the length of rod to "tune in" the push-rod.

Is there any possible adjustment at the master cylinder end, does anyone know?

Would that help?
Bill

No adjustment at the master
I did shorten the slave rod for some clearance
I'm pretty sure the diaphram isn't being held open

David Barrett

Is there something causing a build up of pressure in the hydraulic system? Pinched hose?

Is your clutch pedal always returning completely? And swiftly?
Trevor-Jessie

This is a horriable thought but did you put the disk in the correct way...not reversed ....

Im sure its got to be something stupid....some blockage thats not allowing it to engage....

did you use the clutch cover(sorry..mind is gone) from the 1275....if so you might have needed to cut that rubbing ring off that holds the fingers togather ....I had to cut that off on my 1275 clutch cover...(help me out what is that cover called..sorry)

what flywheel are you using the regular one....was it glazed, did you get it resurfaced...if so did you re-ssurface to far


when you washed the parts Im guessing you used spray can brake cleaner and wiped down with a clean towel..


definatly call quntium back in the morning,,,Im curious as to there service after the sale
...

prop
Prop

No kinks in any of the lines the pedal seems to return fine
The flywheel was newly resurfaced and thoroughly cleaned with brakekleen

David Barrett

Any chance the shop that did the resurfacing wrote down the before and after measurement....Id be curious if the flywheel has reached its final stage of life....(resurfaced to many times)

prop
Prop

The flywheel has only been resurfaced once
I'm wondering at this point if I'm just making too much power for a stock type clutch
Any thoughts on that
Or who makes a good performance piece
David Barrett

I doubt you are making enough power to cause the clutch to slip that readily and noticeably.

I had problems with mine slipping and it turned out to be a bad cover. The springs were too weak to begin with and only got weaker as time went on.

What disc came with the kit? Is it possible to fit it backwards and cause problems?

What does John at QM think is the problem?
Trevor-Jessie

I had the same problem, had to play around with my slave cylinder push rod length to get the clutch working ok, if i did the job again i would probably thread the rod & to make it easily adjustable.
cheers
Brad
B Richards

Have you tried changing the condensor?

Neil
Neil Williams

I don't think Dave has been around here long enough to understand the joke.
Trevor-Jessie

Condensor??

Brad, How much shorter did you end up making the slave rod? I did shorten mine a little.

Im sure the disc is NOT in backwards.

The thing I cant understand, is the old clutch was able to hold the power well enough to blow first gear in about 5 tuning sessions. Considering the new clutch is just a modified version of the same, I cant understand why it wouldnt hold.

John at Quantum' hasnt ever had this problem with this kit before. Hes going to do some research and get back to me.
David Barrett

Just a gentle warning

some of us with type9s have had cracked diaphragms on clutch covers due mainly to the slave cylinder over throwing the pressure pad too far into the diaphragm

This would also cause the problem you are experiencing

I wouldnt expect a problem first time out though

but Sod's law rules for all of us

Looking at the picture the broken diaphragm shows as the big gap betwen the fingers at the front edge of the picture IIRC

(I never did get a good quality picture of the broken diaphragm even though I had the damned things break twice, now I have a better camera which could, I sure do not wish to be in the position of taking a better one for the archives!)

this clutch cover was about a month old when it failed
[under load climbing a hill away from traffic lights]


Bill

Does anyone offer a "heavy duty/Performance" clutch for this application?

Thanks for the input Bill. I agree, this is a pre-existing condition that was here from the first drive. I don think I could have broken the diaphragm first time out.
David Barrett

There are books with data on uprated clutches for the Ford 5 speed in the Sprite/midget.

What makes you think you couldn't have broken the diaphragm first time out? If the fault is as described above it would be as likely to break the first time as any other time.

What make of clutch have you used and can you confirm it's a 6.5"?

Excessive power, which you don't have with 9psi boost (not quite in the best of the normally aspirated league) would be more likely to lead to complete clutch failure than just slipping. A slipping clutch is indicative a worn clutch or one that is not fully disengaging.

Where is the pedal bite point for the clutch - is right at the top of the pedal?
Daniel Thirteen-Twelve

What book have such upgraded clutches for the T9?

I suppose it could have broken the first time out, however I think its unlikely. It would have had to break the very FIRST time I went past half throttle.
David Barrett

>>>>>>>>The flywheel has only been resurfaced once<<<<<<<<<<

REALLY??? That maybe the problem!!! maybe they had to take an incredable amount off due to continual wear, glazing and warpage over the past 35+ years. Did the machine shop look up the tolerances and measure it, mine has been turned 3 times according to my machine shop....thats a really bad thing that the flywheel had never been turned until recently...Id think it would have at least 2 re-surfacings...after all the orginal clutch life is only 35xxx to 40xxx miles...

are you bolting the bell housing dirctly to the original rear engine plate....maybe you have an aftermarket rear engine plate...meaning its abit to thick....or maybe the rear engine plate gasket is to thick...we could not use a gasket in the datsun
conversion

In Bills pic. that is what we HAD to do with the datsun 5 speeed...is cut the diaphram off or else it would cause the same problems your discribing.....do you have to do this with the T9..

The treaded push rod for the slave is what we have on the datsun 5 speed conversion....Something Id highly recommend trying ....its fully adjustable, simple and cheap to make....but it is a pain to get adjusted.....

btw...to the other datsun 5 speeders ....I finally figured out a minor problem I was having...the locking nut threads are striped...so as to why it kept falling out of adjustment.....something to keep an eye on...(guess Im stronger then I thought)


prop






Prop

OH, OH,OHHHH.....


The original rear engine plates are notouios for cracking maybe its gotten cracked and creating a bit of concaveiness meaning its pushing the tranny back a bit further.

thus the reason for alot of aftermarkrt rear engine plates


prop
Prop

the thing you have to watch out for on high performace clutches is alot of times they are situation specific...in other words what works for the 1/4 mile or the oval wont work vary well for the street...considering how beefy that tranny is...I just cant imagine that your over driving it...after all they use this same system on various V8 conversions....


prop
Prop

David,

Try www.veloce.co.uk

Where is the pedal bite point for the clutch - is it right at the top of the pedal?



Daniel Thirteen-Twelve

Prop

since I had to take the pad off the first pressure plate (by accident due to opening the hole in the pad out to let the type 9 first motion shaft run through it when it cut itself off in the lathe, scared my ***s off, I'll tell ya!) when I bought the second one I bought a Ford one that didn't have one on it.

The off centre running of the release bearing was what caused the plate to break and that can clearly be seen in the wear pattern on the finger ends and the way the plate split and stopped with the fingers offset in a spiral sort of pattern

this was why I developed my concentric slave cylinder clutch, which seems to be working nicely.

David I see no reason to disagree with Daniel, if there is an overthrow situation the diaphragm CAN break at any stage, you only need about 8mm of pushrod movement to disengage the clutch efficiently any extra is causing undesigned stress in the diaphragm spring

In my car now I do not need any more than 1" of pedal movement to operate the clutch, less will do it happily. The only thing is that one's foot seems to naturally wish to go further down on the pedal.

Which is why I almost fitted a pedal stop to help.

Now I am used to it I won't bother but the shortness of stroke can easily catch people out
Bill

//"Where is the pedal bite point for the clutch - is it right at the top of the pedal"?//

No, its more in the middle....Thanks for the link!

Prop,
If the engine plate was cracked or bent I dont see how that would affect the clutches ability to hold. (which is determined by the available spring pressure that the pressure plate provides).
All that would do in my mind, is not allow full disengagement, when you step on the pedal and the engine plate does the flexing instead of the fingers on the diaphragm.



David Barrett

Ill check to see how much movement I get when the pedal is pushed to the floor through is stroke.

I can see how pushing the diaphragm beyond it working limit could damage it, even the first time I pushed the pedal.

But in this case initially I WASNT getting enough travel/actuation to FULLY release/disengage the clutch. Turns out the pin on the master cylinder/clutch pedal end was badly worn NOT allowing enough lever movement to do the job.
This is the reason Im skeptical thats the caused of the problem.
David Barrett

I agree its abit of a long shot guess,,,but Im just throwing paddies agianst the door at this point...my guess is, its got to be something stupid as everything is checking out...theres not much left for the clutch to be not fully dis-engaging


BOTTOM LINE

Id say make sure the slave pushrod isnt to long, OR that your not (Over throwing) the clutch slave with to much pedal, OR any kinks in the clutch line(did you use new hoses...they do collapse and look good on outside) and that the master clutch clyinder is working properly

If not that, then I hate to say it....

But its an engine out cure...your not going to know what the real problem is nor can the problem be fixed until you pull the engine and tranny and put an eye ball on it. The problem is going to be located in that 9-12 inch space between the rear engine plate and back of the throw out bearing.


sorry...Hard to belive, but Everyone on here has kicked the same rock barefooted your kicking, on some midget related project...so where all in your corner with the same broken and bleedig toes...hang in there and please keep us posted


prop
Prop

Thanks for the words of encouragement Prop!

No I did NOT replace to hoses.
Has anyone been able to remove the trans without pulling the motor on one of these T9 conversions??
David Barrett

"Has anyone been able to remove the trans without pulling the motor on one of these T9 conversions??"

Yeah, that happened right in the middle of my dreaming of seas made of lemonade!

:-( I've still not heard of someone doing a clutch replace without an engine out...
Rich Amos (1330cc Blaze Red '72)

without seeing the method of fixing your adaptation uses it'ld be impossible to say about the "engine out too" question

The way I did it I think I COULD just drop the box out alone but the prop would still need taking off first so the added difficulty would make me take them out together.

Not worth trying to save an extra half hour on the job IMO

what does your adapter builder guy suggest?
Bill

That link (www.veloce.co.uk)
is a publishing co. I was looking for a manufacturer(s) name/website, who makes a heavy duty upgraded clutch for this app.

Quantum hasnt had this problem before (I get to be the first!) Hes looking into a "beter" clutch for me.
David Barrett

I love lemonaid, I didnt know it came from a sea...lol



>>>>>>>>>since I had to take the pad off the first pressure plate (by accident due to opening the hole in the pad out to let the type 9 first motion shaft run through it when it cut itself off in the lathe, scared my ***s off, I'll tell ya!) when I bought the second one I bought a Ford one that didn't have one on it.<<<<<<<<<<<<<<<<


Now thats a Youtube vid I want to see..LOL I cant imagine what that must have been like.

prop
Prop

No beggar sees that vid Prop!

I was gently running the boring bar through the pad centre to open the hole "just enough" when the tool cut through into the recess that the fingers are held on

It couldn't come off the bar but it whizzed around at a hell of a rate of knots for nearly a minute, using up inertia (momentum, whizz power or whatever you call that stuff that makes gyroscopes work)

But it's OK now, I'm calm again

Zen and machining car components

ommm omm ommm
Bill

David,

i really can't remember now if i added or took off from the push rod, it was years ago. But i do remember it being a bugger to get right! I have a trick flywheel though, so maybe that had something to do with it.
cheers
Brad
B Richards

This thread was discussed between 03/08/2008 and 05/08/2008

MG Midget and Sprite Technical index

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