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MG MGA - Shudder in 1st and reverse?

Hi folks. Recently my MGA 1500 roadster seems to have developed an interesting (and annoying) quirk. When I let out the clutch in either first or reverse, I get a bit of "shudder" The shudder isnt too severe. It seems to happen more when the engine is warm than when it is cold. Has anyone run into this issue before? Any ideas about what is causing it, or how to cure it? Thanks, Glenn
Glenn Hedrich

I have had this happen many years ago on my previous MGA, particularly in reverse gear and especially when reversing uphill.
It turned out to be oil on the clutch friction plate that had glazed the surface causing uneven take up in the clutch.
Fitting a new clutch assembly and release bearing fixed it.

You can also get clutch judder when the engine mounts are either broken or the rubber pads on the mountings have gone very soft.

It would be well worth having a look at the engine mounting blocks before you consider looking at the clutch!

Best of luck,

Colyn

Colyn Firth

hi glenn,

when i 1st started off in my driving career i was the proud owner of an austin A35 van and this developed the same symptoms as you describe, i was informed at the time that this was because these 2 gears shared a common shaft and that the bushings for this shaft were worn. im afraid i cant help you out with a fix as i put up with it until i disposed of the van but i would try to sort out a fix for it as i had a friend with a similar van who lost all motion in both of these gears and had to travel everywhere with just 2nd, 3rd and 4th

dave
da cook

Glenn, Mine has a tendency to do the same occasionally/intermittently. I had also assumed like Colyn that this was due to oil on the clutch plate as it seems to burn off after driving for a while. I have replaced the engine mountings recently so it is not that. I can live with it so the fix will have to wait until I have to pull the engine.
Cam Cunningham

Hi Folks. I dont think the problem is oil in the clutch, since the clutch disc, and release bearing were replaced just a few months ago. The rubber engine mounts and rear transmission mounts were changed about 2 years ago, and are still good. Any other ideas? Thanks, Glenn
Glenn Hedrich

Although I run the 5 speed box with an MGB clutch assembly I used to get something similar. It turned out to be a worn bush in the clutch operating lever allowing the thrust ring assembly to move off centre and vibrate/judder when making contact.

I guess you could give the external part of the lever a lateral waggle to see if it rocks.

Steve
Steve Gyles

Glen, I've had have exactly the symptoms you describe but in a mild form. Like yours I suspect, 2nd and 3rd gears work perfectly. I agree that its probably not the clutch but rather the gearbox bearings and possibly a worn layshaft. Its just that the box is slipping into middle/old age, it will go on for years treated carefully or until you find a good reason for pulling it.
J H Cole

Hi Glenn can also be the carbs not set up properly giving poor running, my dad had a riley pathfinder which he bought new that had the same problem they put engine stabilisers on it and all sorts to no avail until they decided to tune it and balanced the carbs which cured it at once


gordon
g c pugh

Glenn,
The shudder could also be down to the springs in the clutch driven (friction) plate losing their tension - they act as dampers for the take up of the friction on the flywheel. It only is noticeable in 1st and reverse as this is when the springs are working hardest.
C Manley

I'm pretty sure that this is not a gearbox mechanical problem but could well be oil contamination of the clutch disc. Did the clutch judder immediately you fitted it or was it some time afterwards. An oil leak has to start at some time. Engine mounts are a distinct possibility as are universal joints and possibly slack rear axle U- bolts.
Iain MacKintosh

Barny describes a procedure for injecting degreaser into the clutch/flywheel area. Its a bit tricky but a lot less work than pulling the engine. If it were to make any significant difference then this might at least point towards the culprit.
J H Cole

Hi again folks. Thanks for all the excellent ideas and comments, they are all appreciated! However, please read the following info: I rebuilt my transmission this past winter, had it completely dismantled, ad replaced the layshaft, layshaft needle bearings, all synchro rings, the clutch fork pivot bushing and bolt, and carefully checked all parts for wear. All parts seemed to be well withing reasonable tolerances, and no other heavy wear of any consequence was noted. Additionally the crankshaft pilot bushing in the engine was replaced. All named bushing were badly worn, and were replaced, after they soaked in motor oil for several days prior to installation. I rebuilt my engine about 3 years ago. It is well tuned, pulls strongly and runs perfectly without hesitation, from idle to redline. It does leak a little bit of oil from the rear main, but nothing serious. The judder I experience doesnt seem to happen until the engine warms up and has been running for a while, and seems to get progressively worse. I would describe the worse case judder as moderate. It seems that some days there is a bit of judder and some days there isnt any. How is that for a puzzler? Cheers, Glenn
Glenn Hedrich

Glenn, I have the same problem on my A. It judders badly on first and reverse. I have experienced this problem before in other cars, and each time it was a clutch problem, whether it was oily clutch or worn parts. I agree that it could also be caused by worn mountings, but a visible check should reveal what state they're in. I plan to pull the engine out around September/October time, but until then I wont be able to tell you exactly what the trouble is. If per chance you pull your engine out before I do, I, together with many others on this forum, shall be grateful to know what you find.

Frank
F Camilleri

Glenn,
You do not mention whether or not you installed a new pressure plate (clutch cover) or clutch disc when you did the tranny work.
Cheers,
Gerry
G T Foster

I had the same problem with mine. I thought it was the clutch that was gone. When it was pulled out it was all oiled due to a transmission seal leak.
I didn't think the oil coming out of the bell housing hole was significant but enough to grease up the clutch. I ended up changing it.

The problem gets worse with heat because everything expands, and probably more oil leaks...
It will happen mostly with 1st and reverse because they are the highest torque gears, which lead to slipping.

I would try Barneys 'brake cleaner' technique, see if that cures it. If it cures it temporarily then you know where the problem lies...

Gonzalo Ramos

Glenn,
I suspect you have a weak pressure plate, as Gerry mentioned or perhaps it had a blue spot or two when you changed the clutch out.
Mike Parker

Hi Folks. A rebuilt pressure plate was installed a few years ago. I dint see any blue areas on the plate when it was removed for the disc replacement. Glenn
Glenn Hedrich

This thread was discussed between 17/06/2010 and 19/06/2010

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