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MG MGB Technical - Locked-up gear shifter

I just had a very odd thing happen in my '68 B. I recently finished a rear end rebuild- not sure this is part of it or not. (Thanks to some of the archives, I must add)

The car was running great when I was waiting at a light, it went green, I pushed the clutch, tried to push it into gear and I could not move the stick in any direction. I was on a slight incline so let it roll back a bit. No change. I turned off the car to consider my options. Oddly, I just decided to restart it and suddenly all was fine. A slight grind to get it into gear then I limped home. I was able to get into 2nd and went home REALLY slowly (2 miles tops).

Where do people suggest I start? I plan to pull the rubber bonnet off later and just look to verify it isn't rust/ junk under there. (I doubt it). I have experience with body and mechanical on front and back, but not tranny and clutch.

Anyone ever hear of this? No idea is a bad one at this point.
SJH

I'd start by checking the hydraulic system is functioning correctly.

John
J Tait

What is your thought? Hydraulic pump to clutch isn't flowing?

I'll check the slave cylinder and hose for leaks and check the cutch master cylinder reservoir. Is that what you suggest?
SJH

Well, first check the master cylinder has fluid in it. Then get someone to check that the clutch release lever is moving correctly when the clutch pedal is depressed.

If it fails either of the checks, the hydraulic system (master or slave or both) may require an overhaul.

If all that checks out, then I guess you have some mechanical problem that will require the gearbox and engine to be separated for further investigation.

John
J Tait

As all the previous gentlemen have said, check the clutch hydrolics. If you could previously engage all gears then this occured, it sounds like your clutch was not dis-engaging, making difficult to select gears. Not a difficult job to check. Fluid level first,Any leaks? get some-one to see the clutch lever operating etc. Mike
J.M. Doust

As mentioned, your description of events points to a faulty master cylinder that is allowing the fluid to "bypass" the internal piston when you depress the pedal. Whether you rebuild it or replace it, I would take this opportunity to replace the slave cylinder and the clutch hose at the same time. They often fail after one of the major components of the hydraulic system have been replaced. RAY
rjm RAY

OK. Thanks for the tips. I checked all suggested. Also worked with another local who confirmed my worst fear... clutch needs to be pulled...

The issue was that the pressure plate wasn't moving properly. I was hoping for something easier. The biggest bummer is that it was running so well and the weather is finally getting nice.
SJH

OK. Thanks for the tips. I checked all suggested. Also worked with another local who confirmed my worst fear... clutch needs to be pulled...

The issue was that the pressure plate wasn't moving properly. I was hoping for something easier. The biggest bummer is that it was running so well and the weather is finally getting nice.
SJH

The same thing happened to me once. Hydraulics okay so I pulled the power train. The clutch pressure plate had two broken fingers and wouldn't release. Disk and release bearing were okay.

So, assume the hydraulics first then think about a clutch job.
Robert McCoy

This thread was discussed between 16/04/2011 and 02/05/2011

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.