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MG TD TF 1500 - Sticking clutch

I'm making progress on Max. Got the starter working, the fuel system operational, the clutch linkages rebuilt, spark to the plugs, good oil pressure, and got it fired up after 21 years. Another TD saved from the dark and brought into the light.

However, flush with the victory of getting the engine running, I decided to take it down the street to try it out in a modest fashion. As I put it into reverse it ground the gears popped into gear and promptly lurched back and stalled. Stuck clutch! Went to the archives and found out how to unstick it. It worked up to a point. Got going and went to put into second and it didn't want to go into gear. Just ground the gears as if the cluth was not engaged. Stopped the car, put it into 2nd gear and started the engine in gear and all went well. Shifted into 3rd and went smoothly. Shifted into 4th, let out the clutch and it sounded as if the car was going to explode. Wife came running! Performed various shifts at various speeds with the need to sometimes start the car in gear because the clutch sometimes just didn't want to work.
Tried riding the clutch at times to try to remove any built up material that may have been left on the flywheel or pressure plate to no avail.
Anyone have any good ideas except for removing the tranny. I did this one on my other TD and don't feel like doing it again. Should I continue to road test it to try and free it up more? Seems as if the clutch frees up and then locks up once more. Almost feels like the synchros are not working because I can't get it in gear when down shifting and yet when the clutch is fully depressed, it will not go into any gear.
The long and short of it is that the clutch does not engage and disengage smoothly on a regular basis. Sometimes it works and other times it doesn't. When it does engage on an irregular fashion it sounds like all hell is breaking loose.

Mark
Mark Strang

Sounds like the disc may be hanging up on the splined trans input shaft, which may have a bit of rust on it. I generally put a very LIGHT coat of grease on the shaft (very light so that it doesn't get thrown off and onto the clutch by centrifugal action), as well as on the pilot bushing.

I suppose you can keep trying to free it up, but pulling it apart is really the best way. Then any residue on the flywheel can also be cleaned off. There's an inspection plate on the top of the bell housing, but I've never really been able to learn anything by peering into it...

Tom
t lange

Tom,

That's kind of what I suspect. I wish I could I could get a drop of oil on the shaft, but I don't see how.

Mark
Mark Strang

Just a shot in the dark- make sure the front motor mount and/or the welds on the rear tranny mount aren't broken. The assembly would move back and forth enouth to mess up the clutch. Probably not, but looking is quick and free. There could also be a broken spring, or the disk separated, etc. George
George Butz

George,

Good idea. I've only had "Max" for 4 days and haven't had the time to inspect it all. Been just trying to get it running to see where I need to go next. The engine was the big concern since it hadn't run for 21 years, but it seems to be in real good condition. Kind of scarey actually that it started up finally after all of the preliminary work and ran so well what with carbs that were gummed up etc. No smoke out of the exhaust except for the Marvel oil that I had put in to condition the rings and that was brief.

I know that I can get the clutch fixed if I pull the tranny but I really want to wait until this winter before I do that. Hopefully I can avoid that right now.

Mark
Mark Strang

Make sure the oil has not congealed in the sump, and that you just drained off the loose stuff - look into the drain hole. I found over an inch of thick, black tarry goo in the sump of the most recent engine I rebuilt, that filled most of the oil passages.

Tom Lange
t lange

Does the pedal release/grab position change in these different modes?
Sounds to me like either the clutch has already part disintegrated, or more like the gearbox is bust - probably bad bearings, but if you operate like that it will soon be everything. I have experienced similar on various cars, and it is always parts in the gearbox running out of position due to failed bearings, locating washers, even the nut on the driveshaft flange being loose. This causes baulked shifting as the synchros on some gears are trying to synch while you are trying to go into another gear, or pieces running into each other, etc. My guess is this is why the car was parked in the first place.

FRM
FR Millmore

Well, I guess I have several thing to look for. I'll keep checking.
FRM.
The car was parked when the owner's wife ran it into a workbench in their garage and dinged up the right front fender. The husband got mad and just parked it. He had several other MG's and started driving them instead. I've know the owner for a decade. He has built several cars that have been to Pebble Beach and places like that. Not a shady character at all. The pedal always grabs in the same position-just before completely engaging. It starts to engage smoothly and at the last minute it grabs and shudders. The car starts moving and at about 50% released it grabs.

Thanks,

Mark
Mark Strang

You could try spraying brake cleaner in ....might just clean off enough dirt from the shaft ?

Dave
Dave Moore

Mark-
Regardless of owner's credentials or believed past history - memory being often deficient, your description of clutch action sounds perfect, until the gearbox starts to turn. I have a Mazda sitting here that is similar, and I have bought Rovers and MG for very good prices and the exact description - and rebuilt all the gearboxes.

I have also parked cars for reason X, only to remember Y, Z, M, P, Q & 7 when I resuscitate one!

At the price of gearbox parts and the catastrophe that a single failed ball bearing or broken layshaft can cause, I'd not try to avoid a few hours work.

FRM
FR Millmore

FRM

Advice well taken!

Mark
Mark Strang

Mark,

From your description it sounds as if you may have both a clutch and a gearbox problem.

For the clutch: check the linkage for slack, you don't mention if it is a cable or rod.


For the gearbox: try removing the drive shaft from the gearbox end and run the engine through the gears and listen for noises.

John


J Scragg

I'm pulling the gearbox. Now I am more than curious to see what is mucking up the drive train. Hopefully I'll have it out late today after other various commitments. Got the interior gutted last night.

Mark
Mark Strang

Be sure the rear spring u-bolts are tight.
MW Davis

Mark -
Several guys have had gearbox trouble due to loose nut on the 1st motion shaft in the last couple of years. Archives or post for "gearbox, shifting etc."

FRM
FR Millmore

The jury is in and the verdict is a stuck clutch plate to the flywheel. I had to pry it off with a sharp thin edged stiff putty knife. Took a couple of whacks and it came loose. Sure seems like it should have come loose with the techniques mentioned above but apparently it didn't. The pressure plate side had been stuck also but it was loose. It was a sort of sticky substance that was holding things together. Must have been something in the composition of the clutch material along with the temps and humidity here in Virginia reacting over 21 years. New clutch, pressure plate, pilot bushing, and a throw out bearing will be on order today along with bunches of other little things that I spotted during the last couple of days .

The bad news is the that the rear mount for the tranny was mostly broken. The good news is that I found it now. Had this happen to my other TD when I did the restoration. I'll weld it or buy new. Rubber mounts look good.

The pedal box has a lot of slop in the shaft. I can't recall but I think that there are bushings in there that must be replaced. Might as well do it while I have the interior out. Should be a lot easier.
At first glance, the tranny is smooth and all gears seem to be okay when just turning by hand. I'll look into this and see what suprises I find at a later time today.

Hopefully the clutch is the problem. I can't find much else to blame the problem on.

I'm going to try to submit a photo of the clutch plate stuck to the flywheel. Never done that before. Hope it comes through.

Thanks for the help.

Mark


Mark Strang

Mark-
This does not match your description above. You have another problem, or your are the worst describer on record - well close! If the driven plate were that stuck, the clutch would not ever work, and other than grinding teeth getting into gear, there would be no noise.
Bad bearings or broken shafts in the gearbox may well not show up under hand turning with no load, yet give major problems under car drive load like blow the case apart and break every single gear.
Pursue my post above, remove the bell housing and check the front bearing and nut, remove gearbox cover and check everything. And remove the layshaft -it is very false economy to be at this point and not examine the layshaft. Stand the box on end and push the layshaft out with a dummy, in the unlikely event you can just put it back - keeps the bearings and thrustwashers from falling out of place.

RM
FR Millmore

Will do.

Mark
Mark Strang

I had a frozen clutch last year, just as we got the '51 TD out for the GOF Central. It backed out of the shop as the engine fired with the clutch in.
I "drove" it back into the shop stuck in 1st, verifying my diagnosis.
Fortunately, we have a car hoist. With the wheels off the ground, I fired it up in 4th gear with the clutch in- it shuddered for a second and the clutch was free. No problems, right?
Drove it up into the box truck without any issue and headed for the GOF.
I was anxious to run the supercharged TD with stock 5.11 gearing in the Funkhana. It was quick enough motoring through the cones, but when it came to backing down the track, the back end started bucking up and down violently out of control, so I had to creep backwards, wasting a bunch of time. The shudder on the hoist had shaken the shock links off!
JIM NORTHRUP SR

Jim,

Well, I did find that the tranny mounting holder was broken. Not a very sturdy piece in the first place. I'm still going through the car trying to figure out if I have done any other damage like you experienced or if there are any other obvious weak links. Thanks for the input.

FRM

I like your interesting sense of humor. I'm not a technical writer just a simple mech engineer. Wish I was better at writing for your sake.

Let's give this another go and see what we can come with. In addition to my first posting I tried the car again yesterday. Got it on the steet and started it in 1st gear. Clutch wouldn't work but the car ran well. Couldn't change gears. Tried starting and driving in 2nd, 3rd, and fourth. The car ran well with no noise from the gearbox or other areas of the car. Ran it up to about 30mph in 4th and all was quiet. Just could not get the clutch to work. Now, this is different than the first time I tried the car which from time to time would allow me to shift using the clutch although with a lot of noise from all over the car. If this was my first post without the shudder it would seem to be a typical stuck clutch. Is this correct?

Now, let's assume for a minute (you've obviously got more experience with odd things than I do) that the clutch plate did on day one loosen up a bit but not enough to completely free it causing the erratic behavior that I described. Then I ran it on day two and it would not work at all. Note that I indicated that it seemed to be real sticky on both sides but really stuck on the flywheel side. Perhaps it actually did come loose on day one and "worked" to point but because of the stickyness of the parts it was grabbing real hard and gave off large shudders which made the noise. Then it stuck to the flywheel real good after the heat of running.

I took your advice and removed the bell housing and checked the input shaft nut. It was firmly in place. I will assume for the time being that this bearing has a typical C3 clearance so I observed no abnormal play. I examined all of the teeth on all of the gears and they looked fine. The shift forks are in very good condition and I noted that there was no sign of any wear on the other parts that I could see. All parts where necessary were saftey wired and in good shape.

I'm curious as to why you think that I should remove the layshaft. I have a dummy shaft to use to allow this to take place so it's no problem. Do you want me to inspect the shaft proper? Are you suspecting that the shaft might be bad. I'd like to know what to look for.

Waiting to hear your comments.

Mark
Mark Strang

Mark-
Para one is good - a stuck clutch.

Para two is weird - an adhesive that comes and goes, randomly and quickly or partially - not met such before - must be a sales possibility for an applications engineer! But it must be, as I see no other possibility. When the clutch actually releases and you can put it in gear at a standstill, there is NO drag at all. I can shift without the clutch, but most people cannot, and the synchros are not good enough to overcome much drag.
In my experience, clutches tend to stick differently on different cars, apparently a result of flywheel material, since in some cases they are using the same clutch facings. Jaguar stick a lot if they sit, but you can always break them loose. MG rarely have much problems, Spitfire/midget 1500 are horrible - when they stick (after about a year sitting) you take the engine out and chisel the driven plate off.


Now you have checked the gearbox you can rest easy - worth a lot, glad to hear good.

Layshaft is the usual beginning of problems, since all the load is always on a very small arc at the loaded side of the small diameter and non-rotating shaft, and worst at the low gear end, from the torque multiplication reactions. The needles pit the shaft from fatigue failure, and then the gears are loaded on the tooth tips, and then they break, and the broken bits get between other gears, and the shaft breaks and sometimes takes the case out. I have an Austin America box that did that when my wife was backing out of the driveway at 2mph - nothing salvageable - ugly. Layshaft is always the thing to check and worth it on any box you have not recently examined personally; sometimes even the needles are still good, because they rotate and revolve and share the job.

Then your biggest problem is known crap repro layshafts, and I do not know what to suggest. Some suppliers make their own, as TRF for Triumph, and somebody in Oz for MGA/MGB, but I don't know on T series. TRF say that the repros were not only hardened incorrectly, but the lube holes were not clocked right, so the loaded area did not get correct lubrication, which doesn't help a bit.

FRM
FR Millmore

This thread was discussed between 29/07/2012 and 01/08/2012

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