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MG MGA - Transmission woes... I think

1958 MGA 1500, 150 miles after refurbishment, that's all the experience I have driving this car.

During a short run today I experienced a significant problem which I'll summarize:

- parked the car in 2nd on a shakedown run
- came back and car would not shift out of 2nd
- engine runs with clutch depressed
- let up on clutch and car rocks and will stall
- rear wheels are "locked" except for a small amount of play
- during towing I spun one rear wheel by hand and the other spun in the opposite direction

I discount the clutch as the problem since the engine will run when it's depressed. I discount the differential since the shifting in compromised. The problem is not the parking brake. Which leaves to my thinking something nasty going on in the transmission.

If my thinking is flawed or if there are other ideas please send them my way.

Brian Denis

Brian Denis

Was it making any noises before you parked, or were you having trouble shifting?
Dominic Clancy

Brian you say the car will not shift out of 2nd gear can you move the gear lever, to select another gear, or is the gear lever locked in the 2nd gear position.
Andy Tilney

Will it drive forward in that gear? Your comment -- "after refurbishment" -- did you refurb the gearbox?
Barry.
Barry Gannon

Gentlemen, good questions and thanks for your interest in my problem.

Dominic, the shifting has always... all 150 miles... been "clunky". I attributed this to me being new driving the car, but there were no noises before I parked.

Andy, the gear lever is pretty much locked in 2nd. It does move toward neutral but I don't think it goes far enough.

Barry, no, the car will not move forward. It just rocks a few inches. And no I did not refurbish the gearbox.

Since I posted originally I have received some more information. The shop where I had the car towed believes the gearbox is stuck between two gears. Unfortunately replacing or rebuilding the gearbox is above them so I had the car hauled back to my driveway this morning. A club member who also runs a shop suspects the "stuck between two gears" diagnosis although he hasn't seen the car. So that's two professional votes for this situation.

I will add that I was diligent in changing the gearbox and differential with the proper oils before driving and I didn't see anything unexpected come through.

At this point I'm pretty much resigned to pulling the gearbox and replacing it which will probably kill the driving season. I will drop the drive shaft to make sure the car rolls just to completely eliminate the differential as the issue.

Again, thanks for taking the time to weigh in on my problem.
Brian Denis

this problem may not need replacing the box, if its locked into two gears at once, it is possible that the locating bolt on the 1st and 2nd selector fork has come lose allowing you to select another gear while 2nd is still engaged, I am sure if you strip the box you will easily see what the problem is,
Andy Tilney

I'm with Andy.
There is an inspection plate on the side of the box. I think you can see the selectors through this although you need to remove the box first (or the tranny cover)
Art Pearse

Andy and Art, thanks for your input and especially your confidence that I could identify then fix the problem but unfortunately that confidence is misplaced. I'm just beginning to scope out what's available for replacements, at what cost and timing. I wasn't enthused with the shifting anyway and attributed it to my newness with the car but maybe it was more than that.
This 60 year old car probably has it's original 60 year old gearbox. I've got a lead on a local operation that would stand behind a rebuild. Provided the sticker shock isn't extreme I'll scope that out as a first option.

Brian Denis
Brian Denis

Brian

If you have to go the complete rebuild route I would hazard a guess that there may be numerous original MGA boxes available in the marketplace. The 5-speed conversion has been extremely popular in recent years so there must be plenty of good originals available. I see them advertised frequently on Ebay for very reasonable prices.

Steve
Steve Gyles

Might have bent as shift fork, or as Andy suggested, have a selection issue. Good luck - should be apparent once the side cover is off.
Bill Spohn

Epilogue... or the rest of the story.

The gearbox was removed and I'll be installing another that was inspected and found to be in good shape. For curiosity a shop owner and I opened my old one to see what the issue was.

The gearbox was locked in both 2nd and third... so the theory of it being locked in two gears at once was correct. As to why that happened, the gears and synchros all looked acceptable and the lock bolts were tight and appropriately set. However, the interlock arm assembly showed significant wear as did the selector ends. So the theory is wear in the selector mechanics allowed the gearbox to end up in 2nd and third simultaneously.

Again, I thank everyone who was interested in my problem.

Brian Denis
Brian Denis

This thread was discussed between 13/06/2018 and 02/07/2018

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