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MG MGB Technical - 1970 B gear shift rattle

My 1970 B has an annoying rattle that comes from the Gear Shift Lever . The tranny checks out fine , oil level , shifting , syncro's . The throwhout bearing is quiet . During acceleration it's quiet , it's noticable once the throttle eases off in all 4 gears , including O.D. .
If I drive with my hand on the shifter , I don't feel any vibration , but it does stop the rattle .
Is there a thrust washer or spring in the shifter that could cause this noise if it failed or weakened ?
Other than this issue ,the car runs great , so if I can get this rattle solved I can finally wash the grease of my hands and go for a drive ...... until the next challenge .
BK Kortum

Correct me if I am wrong but the gear lever is kept into its position on the box by a ring and (was it two, bolts? I'll have to check.) If this ring is loose won't it rattle and feel loose? The other tip I had hear is putting a large rubber hose, of correct internal diameter over the gear stick to absorb vibrations? Just looked up Moss drawings, yes there is this ring and bolts with a spring washer, maybe all you need to do is to tighten a little. Simple enough trial? Mike
J.M. Doust

BK. What is rattling? Is it the gearshift lever or, does the vibration of the gearshift lever cause the knob to rattle? Do you have a factory gearshift knob or one of the aftermarket ones? The latter are famous for having a bushing insert (so the basic knob can be fitted with a number of different bushings allowing it to be used with a variety of gearshift threads) which, as the glue used to assemble the set drys up, allows the knob portion to rattle. If, when the knob is removed, the rattling disappears, it is a problem with the knob. If the rattle is still present when the knob is removed, it is a problem with the hold down plate/system or the nylon bushing at the bottom of the gearshift lever has been lost. (Need to remove the lever from the transmission to inspect for this piece.)

Worn transmission mounts will allow more vibration to develop than bushings in good order. Some of the new (last ten years) mounts will become oil soaked and deteriorate rapidly. Hence, an inspection of that part of the system would be part of diagnosing the overall problem.

Les
Les Bengtson

There is a little plastic/nylon bush between the ball on the end of the cabin lever and the gearbox lever. If this is missing the lever buzzes and rattles. In a gear, there should be no slop at all in the cabin lever, if there is then the bush is worn or missing.
PaulH Solihull

Been a while since I worked an a 70 transmission, but just reassembled parts of my 80 transmission. The gearshift lever bottom end is a ball resting in a nylon bushing inserted in the shift linkage. It's unlikely that the nylon bushing has deteriorated and fallen away. The "cover" that holds the shift lever in the top of the transmission shifting tower is held down with three bolts easily seen by removing the gear shift boot. The bolts are shoulder bolts so that the cover does not cinch down to the tower, but rides a fraction of an inch above it and there are springs under the cover on each bolt. It might be possible that one or more has broken or weakened so that the cover can rattle. It's a worth a look and easy enough to check.
Rick Penland

Thanks to everyone for the quick response to my question .
You've all given me something to ponder , since every response could certainly be correct and solve my problem !
Think I'll go with the easiest one first and work my way through the suggestions until I find the cause of the rattle .
I'll post an update as soon as I find the culprit .
One more question , any trick to pulling the cabin lever ? I would think having the tranny in nuetral would index the gear box lever , and allow an easy reinstallation of the cabin lever after removing and inspection .
BK Kortum

BK. The "cabin lever" is called a gearshift. Remove the hold down ring (oval) from the gearshift, remove the leather/vinyl/rubber gaiter and you will have access to the three shouldered bolts holding the ring around the gearshift. Remove the three bolts and pull the gearshift upwards to remove it from the transmission. If the nylon bushing is not on the end of the gearshift, look for it in the transmission. If it is not present, the shifting is sloppy and the gearshift will rattle. Not a difficult operation. When putting the system back together, a little wheel bearing grease on the ball section of the gearshift is a good idea.

Les
Les Bengtson

There is an anti rattle spring and plunger fitted horozontally at the top of the housing and retained by a rearward facing screw. Make sure that this together wioth its spring is in place. Now the gearlever knob is very important because it fitted with an aftermarket one the chances are that the lever will buzz continually but when you fit the correct golf ball the overall inherent frequency of the assembly is changed and no rattle occurs.
Iain MacKintosh

Hey Les , I know we call the cabin lever a gear shift here in the States ...... just showin' a little respect for our friends across the pond , since they've taken the time to respond .
Thanks again guy's for all the help.
BK Kortum

Don't feel bad, BK - I'm an ex-Pom who's lived in England, East Africa, New Guinea and now Australia - and never ever heard of a cabin lever! Paul H really knows his stuff, so must be a Solihull thing! John.
J.P. Hall

I said 'cabin lever' because I also said 'gearbox lever' and I wanted to distinguish between the two, perhaps I could have said 'gear lever' and 'gearbox shaft'. To me 'gearshift' could well include everything from the knob on the cabin lever to the fork that slides the cogs, just as 'transmission' to me is gearbox, overdrive, propshaft, diff, and half-shafts. But perhaps I'm just being facetious :o)
PaulH Solihull

Facetious, what you? Never!
Michael Beswick

One thing that nobody mentioned - are the driveshaft universals in line or out of line - this is what caused a shift lever rattle in a customers car.
Garth
Garth Bagnall

This thread was discussed between 18/10/2011 and 28/11/2011

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