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MG TD TF 1500 - 3rd/4th gear crunch

Hi,
I have just got my '53 TD on the road for the first time. 1st and 2nd gears engage nicely but I get a crunch on 3rd and 4th. So far I have not managed to avoid it by double-declutching. Do these symptoms point to a particular problem?
Thanks
Pete
P Willows

Make sure your clutch adjustment is correct, slow down your shift changes. Your using 70 year old technology and the trans will not perform like a modern transmission A switch to Redline MT-90 may improve your shifts as well.

Bill Chasser
TD/c-8151
W A Chasser

Thanks Bill. It's the difference between 1/2 (good) and 3/4 (crunchy) that struck me and made me think it is a specific problem affecting just those 2 gears rather than just the nature of an old car. Might give the Redline a try though.
P Willows

Pete,

Using MT 90 oil may fix your issue, if not you have one or other (or both) of the following:

1/ The 3/4 selector fork fixing screw has become loose, in that case there is play between the selector shaft and the fork.

2/ The 3/4 syncro cones are worn.

The first case can be fixed without removing the box, you just need to remove the lid and tighten the screw, also, it should have a safety wire on it.

The second case requires removal of the box to replace the worn parts.

John
J Scragg

Thanks John - very helpful. The selector fork definitely sounds like it's worth a look.
P Willows

One other thing I've noticed is that when you put it into third gear you can continue to move the gear lever forward a bit even after it is in gear. Does that point to any particular problem?
Thanks
Pete
P Willows

when you have the top cover off check the condition of the 3rd/4th synchro hub. The channel the selector rides in should have vertical shoulders and the selector a reasonable clearance.
If not the drive dogs will not be fully engaged.
Mind you this would normally make it tend to drop out of gear.
As to the movement, there is a built in overthrow to ensure full engagement as the box wears..
Ray TF 2884
Ray Lee

Thanks Ray - I'll look at that. I think I'll drive it around for a bit more first and see if any other symptoms materialise!
P Willows

You cannot visually determine the condition of the synchro' hubs unless the gearbox is dismantled. However you can measure the condition with the top of the box off and using a feeler gauge. See the attached picture. The synchro' hub is hard up against the (in this case) 2nd gear. Unworn synchro's should give a spacing of about 0.094" and when this spacing gets below about 0.050" the synchro' hub is too worn for use.
The picture shows the procedure for the 2nd gear synchro' but the measurements and the procedure is the same for the 3rd and 4th hubs.

Hugh Pite


H.D. Pite

Just a quick 2 cents. Luckily, the MT90 worked for my little beast.
Peter Dahlquist

Thanks for all the comments etc - much appreciated and hopefully will point me in the right direction.
P Willows

This thread was discussed between 07/05/2022 and 25/05/2022

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