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MG MGB Technical - Clutch Slip and Jenny Craig

I'll remain anonymous for this inquiry.

I am experiencing some clutch slip when going up hills in my late model MGB. I plan to have it changed before next driving season, but before I do I thought I would poll this board regarding a possible contributing factor.

When my wife and I are both in the car we exceed the stated 410 pound load capacity of our MGB by around 50 pounds - primarily my fault. Is it possible that our weight is contributing to the slip, or would a new clutch solve our problem whether we lose weight or not?

It would be cheaper to lose weight than have a clutch installed, but the clutch would be easier!

Also, if I have a good MGB mechanic do the installation, replacing the clutch assembly, resurfacing the flywheel, and installing new motor mounts, along with appropriate seals, can someone give me a very rough estimate of the cost?

Thanks!
Fatback
Fatback

Dear Fatback. Great post!

In answer to your question, my experience is that the factory clutch will hold up quite well, over many years, if you do not make a practice of holding the clutch pedal down at stop lights/signs and do not make "jackrabbit" starts on a regular basis.

As to the weight issue. I have a friend whom I like to take for drives in my MG. In fact, we have considered filming him inserting himself into the GT or roadster, then, trying to exit it. Have known this fellow for many years and he is one of my best friends. Hence, his willingness to get into the MG. Our combined weight is about 480 pounds (I weigh 180 in my old age). We have covered a lot of miles together over the years and there has never been a problem associated with "too much weight". Car does not accelerate as fast when he is in it, but no mechanical problems associated with the "excess" weight.

Thus, I suspect some other form of problem if you are getting premature clutch wear. (I do not know how long they last. The clutch in my original 79, purchased new, was fine when it was sold with 65K on the odometer. We replaced the clutch on my daughter's 77 at about 96K when the engine was rebuilt--old clutch was still working and the throwout bearing was now worn to the metal yet--believe this was the first new clutch the car had seen from the PO's documents.)

As to cost, the labor to remove and replace the engine and transmission costs about $500 locally. Add in the cost of a new clutch kit and, if necessary, the cost of rebuilding the master cylinder (clutch) and the slave cylinder, along with a new flex hose. Resurface of the flywheel is about $25 locally and the pilot bushing should be replaced if necessary. Under $1K if done professionally. If you do the work yourself, you can purchase an engine hoist, of good quality, for about $250. Mine has been used on a number of MGs, an International Scout and a Bronco. An engine tilt device may be had from Checker, and other sources, for about $50. Thus, my engine hoist paid for itself on the first job and has been used, for a number of years, by myself and my friends. Breaks down into about a one yard square tool which makes for relatively easy storage.

Les
Les Bengtson

Do you get the slip action when driving alone?

This summer, my wife and I climbed the Rockies straight up at nearly full speed...well exceeding max gross weight with the boot and behind the seats fully laden and me, well...a few pounds too many...estimated weight on board with all our spares and luggage...+500 pounds, with no clutch slip.

I would venture to say a full clutch job as you describe r&r = $800 to $1200.
Paul Hanley

Les / Paul,

Thank you for the quick responses. I believe the clutch is probably original, based on the master and slave, so its right at 90,000 miles now. I hardly ever drive the car alone, so I'm not sure about the slip when by myself - I'll go for a test drive and see - there's a good hill in our neighborhood that should give me a good idea. I'll let you know what I find.

I told my wife that my best guess was around $1000 for the replacement, so I was in the ball park. I like the idea of doing it myself, but I don't really have a place to do it - I plan to build a garage next spring, but I'd like to have the clutch in by then, too - and I'm not particularly mechanical, anyway.

Still,
Fatback
Fatback

Fatback. You are quite correct that trying to do such a job without a space to do it and the proper equipment if both frustrating and foolish. With the proper space and equipment, it it well within the means of most people.

As to, "I'm not particularly mechanical", few of us are. But, these cars are rather simple in design and most of us have learned to do most of what is required over the years. I, myself, am not particularly competent. Reasonably good at many of the mechanical things, but, utterly worthless at things electrical. At least in the past. However, over a period of years, many people here, especially Paul Hunt, have shared their knowledge with me. I sometimes think that Paul was forced to put his instructions in "baby talk". Their patient instruction has, however, born fruit over the years. I am now, reasonably, competent to discuss electrical systems and have been able to figure out most of the problems on my own--something I could not have done before joining this BBS.

Most of us are not "born competent". Most of us have had to learn from books, the help of friends and this BBS. With such help, we have developed into fairly competent mechanics--capable of keeping our cars running and running in a safe and enjoyable manner. Do not sell yourself short. All of us were new owners/new mechanics once. For the most part, we are a quite good group of people who throughly enjoy driving, and working on, our cars and will go out of our way to help those who would like to do the same.

Les
Les Bengtson

'forced to put his instructions in "baby talk"' or maybe I never grew out of it :o)

Can't see weight being much of a factor in clutch slip, or they would slip when you tried to pull away with the brakes on - they don't, the engine just stalls (unless you go really mad, perhaps). As the friction plate wears it gets thinner and the result is less pressure on it from the springs, this is usually evident in 4th initially, then progressively lower gears, as the torque on the clutch is higher in 4th and lower gears. However if the slip is in 1st and on 4th it could be the OD.
Paul Hunt 2

If the overdrive is bad, you will have significant slip in reverse, in some cases the car won't back up at all. If your clutch is good, you will stall the engine before the clutch slips.
John H

Clutches can last a looong time if driven with care. My Dad's '63 MGB had it's 1st overhaul at 127,000 miles. The original clutch still had life left even with me having driven it during my high school years!

I was taught not to use the clutch to hold the car on hills and to always put it in neutral when stopped at a traffic light. I only abuse clutches when racing. ;)
Carl Floyd

My '79B has 175000 miles with the clutch that was in it when I bought it 11 years ago with 57000 Over 120000 that I put on it I don't slip it or hold it in at stop lights
I doubt it has any thing to do with weight It may be driving style does your wife drive the car? A lot of women really don,t know how to drive a stick BTY I am the only driver of my car.
Pat in Tehachapi
patrick bailey

My car doesn't have overdrive, so that's not the culprit. My wife rarely drives, and I sit at traffic lights in neutral with my foot on the brake. I don't downshift coming into stops, either - it's cheaper to replace brakes than the clutch!

I've only had the car for 6 months, so I don't know how it was driven before. I'm going to do a hill test this weekend and see what happens. I'm also going to do the "put the parking brake on and put it in second" test - it may just be time to do the replacement - if what everyone is saying is true, I'll only have to do it once in my lifetime - especially if I don't take care of my weight problem!!

I will report back with results.

Fatback
Fatback

Fatback

Thnaks for posting this thread as one of the responss answers a question that I was thinking of posting. Overdrive slip whilst reversing.

I now know that I need to pull the engine and box and replace the gearbox unit with my spare (well the one out of the spare parts car!). That will be at some point when I can't tolerate the occasional slip in reverse.

Good luck with your clutch.

A.
A I McGee

This thread was discussed on 10/11/2005

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