Welcome to our resource for MG Car Information.
Triumph TR6 - Cause - Broken Spacer Ring in Gearbox
|I asked this on the TR3 site, but I know that more experience lies with the TR6 owners - so I repeat my question here as well.|
Over the winter, I found steel metal chunks attached to the magnetic drain plug for my gearbox. I had it all re-built in June and found that the steel spacer ring was in about 10 or 12 pieces. Now after another 2300 miles, I have drained the oil from the gearbox and found 5 pieces of the new spacer ring which account for about 25% of the new ring recently installed.
Anyone have any ideas as to the cause of this ?
The gearbox in my early TR3A came with no synchro in first gear. ie - It only had synchro in 2nd, 3rd and 4th gears.
Could it be that a groove for a cir-clip is worn and not supporting the clip properly ?
As an aside, my starter has been acting up and if the car won't start, and if I've parked it on a hill, I usually let it roll, engage the clutch and this starts the engine.
I have been also been starting the TR in reverse if that happens to be the direction of the slope. Can anyone confirm that a rolling start in reverse is the cause of the broken spacer ring in the gearbox ? I would not have thought that this would be a problem.
My goal is to understand the problem and implement a solution so I won't have to pull the gearbox out every 2 months to do this. BTW, the overdrive is working fine.
Don Elliott, 1958 TR3A, Montreal, Canada
|Don, I assume that you are talking about a washer on the first motion (input) shaft or the third motion (output) shaft by bearings and gears, not the distance piece on the layshaft (countershaft) since you mention a circlip. This is how the TR6 is set up and I don't see the earlier non-syncro first boxes being that different in basic set up. I can't necessarily say that bump starting in reverse is the root of your problem, but can say that it will send a nasty shock through the driveline. Severe driveline can break anything in its path, just depends on what is weaker and you find the targer. Bump starting in reverse is not something that I would recommend. When bump starting, forward and high gears are the way to go. Less shock through the driveline than low gears and you turn the engine faster making it easier to start.|
On the circlip groove, I would think that it would be just wide enough for the circlip with a depth such that about half the the circlip would protrude from the groove. I don't know of a source for the specifications and tolerances of the grooves, but am sure that someone, somewhere has that information tucked away.
|I must agree with Steve.|
A bump start in reverse is not a good plan. Tis geared WAY too low for such goings on. Same reason we don't bump start in first, what?
|I appreciate your help and thoughts on this. I now agree that it is not a good plan to to this. My question really is, "If I stop doing this roll start, or push start or bump start in reverse after I get my gearbox fixed and re-intalled, will I never have this problem again ?"|
Or is the problem somewhere else in the gearbox ?
Have you ever heard anyone say definitively that this will cause breakage of parts in a gearbox ? Because it has happened to them or someone they know very well ?
I have never heard any experts say. "Don't do it because . . . . . this or that will definitely break."
Have any of you ever heard that kind of concrete statement ?
Don Elliott, 1958 TR3A
|My older brother is (was) a mechanic by trade. When I was young, I had a few "clunkers" that I occasionally had to "pop start" - that's what we called it anyway. He never said "don't do that because..." (of something definite) he usually told us "don't be doing that all the time - find out why it won't start and make it right". |
I've never heard of anyone breaking something doing it. Even my Dad has recounted stories of pop starting his 40's and 50's cars (although you needed a bigger hill for those beasts)
I would agree that 2nd or even 3rd gear (depending on the degree of slope) is easier on the car.
Wish I could answer your real question!
MIke G. '56 TR3
|Don, as stated above I cannot say with certainty that bump starting in reverse is at the root of your broken spacer. Nor can I say that I have specifically seen anything fail catastrophically purely as a result of bump starting. I can however, say that I have seen driveline shock fail u-joints, gears and crankshafts. So which spacer is this, the splined one on the third motion shaft? Also, what is nature of the failure? Are the faces hammered any or did it just crack out from the ceneter or corner to the periphery?|
|I DON'T HAVE A TR6 EXPLODED VIEW OF A GEARBOX BUT IN THE TR3A EARLY GEARBOX IT IS LISTED AS A SPACER WASHER THAT FITS BETWEEN THE 2ND GEAR ON THE MAINSHAFT AND THE SYNCHRO RING FOR THE 1ST SPEED INNER HUB THAT SUPPORTS THE 1ST SPEED STRAIGHT CUT SPUR (NON-SYNCHRO) GEAR. THE ORIGINAL SPACER WASHER WITH 160,000 MILES ON IT WAS IN BITS WHEN WE TOOK IT ALL APART IN RICHMOND VIRGINIA AND TODAY I PULLED OUT THE GEARBOX AGAIN, TOOK OFF THE TOP COVER AND THAT'S WHERE ALL THE PLAY IS RIGHT NOW.|
I have 5 bits of this new spacer washer (4 weeks old) broken about 1/4" long froM the inner diameter to the outer diameter. I suppose the rest of it (or the bits) are still inside.
In the meantime, I have put in my spare 4 speed non-overdrive gearbox till I have time to take my O/D gearbox all apart and re-build it. I haven't tested the spare yet - but I'm hoping it's OK. I'll know tomorrow AM.
Thoughtfully, when we took it all apart in Richmond and put it all together again, I took about an hour of video how to do each and every step myself this next time. But I didn't think that the next time would be so soon.
Thanks for your help.
Don Elliott, 1958 TR3A
|Well, I'm somewhat stumped then. That location would correspond to annular spacers in an all syncro box. I am having a hard time reconciling a failure there instead of at a splined washer. They're smooth, they're round, no good places for natural stress risers in that configuration. At least in a splined washer, you have corners and short edge distance regions, all natural stress risers. Sounds like it may be time to draw on the heavy hitters you know in the UK for a better explanation.|
|Thanks Steve for your input. The short term quick fix was to pull it out and put in a non-overdrive gearbox I had as a spare. It looked OK with the top shifter assembly off and shifted nicely just before that. The oil was clean when I drained it so I hope it's OK. That was Monday. This afternoon, I was ready to give it a test run and found I have no pressure output from my clutch master cylinder. So out it has to come !|
I better work a little harder to get to know the hidden gremlins in my TR a whole lot better.
BTW, I totally rebuilt the starter and it working marvels now. It starts every time. If it had been working when I was doing those bump starts, roll starts etc in reverse, maybe I wouldn't have needed to do the gearbox twice. The problems inside the gearbox, (same piece both times) might not have ocurred if I hadn't dome the reverse rolling starts.
Like you say, maybe some of the "chaps" in England would know.
Don Elliott, 1958 TR3A
This thread was discussed between 09/07/2004 and 14/07/2004
Triumph TR6 index
This thread is from the archive. The Live Triumph TR6 BBS is active now.