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Gearbox Suddenly Noisy in 1, 2 and 3


Henry Boler
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Hi All,

 

Driving to and from work today highlighted something new in my gearbox.

 

I drive my car a lot, almost every day and this has started today.

 

Seems to be whining quite loudly in 1st, 2nd and 3rd gear, I haven't checked reverse yet, but 4th seems quiet.

 

The gearbox is usually silent, even with the tunnel cover off.

 

Would this be likely to have something to do with the Needle Roller Bearing between the input shaft and the main shaft?

 

Let me know your thoughts!

 

Henry

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I also have whiney 1st, 2nd and 3rd but not 4th. It's been like it for years, a gradual decline, you may be able to get away with it for a while. These gearboxes are surprisingly hardy and will still run with a lot of damage. The last one I took apart had been running but I found the needle rollers in the bottom of the box.

 

What I would like to know is why is yours and mine are not noisy in 4th?

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I'm a bit worried as the new main shaft and input shaft cost me a lot of money a few years ago and I'm reluctant to damage them if I can help it.

 

When I took my gearbox apart years ago that needle bearing was a load of sludge in the bottom of the box and it just about still worked!

 

http://www.canleyclassics.com/triumph-gt6-mkiii-constant-pinion-countershaft-and-reverse-shaft-gears/

 

Look at part 144782, that's the suspected bearing. The reason they are quiet in 4th is because both the input and main shafts are going at the same speed, and the bearing doesn't need to move.

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Ok, 4th gear, now I understand. We have a similar  problem except mine is a gradual decline while yours is a sudden failure. I think yours is going to have to come apart asap. Bad luck!

 

I'll be very interested to know how you get on and what it costs!

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mine failed after a couple of years and i ended up with a 18mm spigot  ( dolly 1850 shaft ) and a  Mick Papworth modified input shaft to suit the 6 cyl

 

 early failures can be early if the bore in the stem gear is damaged from a previous bearing failing ,  

 

as far as i know its still going but never hear from the guy who bought it ,  there again he used to have an MG 

Pete

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ive got a shaft with a removable spigot ,, its a fix done by someone somewhere, it was a loose spigot that wrecked the stem bore on the slave box i got for bits,  and it had single rail 1st hub with wrong reverse sleeve .. with the extra teeth 

someone spent a lot to make a nice non functional mixture of incompatible parts,

 

surprising what you come across. 

 

Pete

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Hello ... hope you don't mind, thought i'd use this to test my understanding.....

I've only ever rebuilt a gearbox once and that was not particularly successful, so I'm no expert.

But i'm just wondering if the mainshaft tip bearing was the issue why is the gearbox quiet in 4th?

I'm thinking the difference about 4th is there is no load through the layshaft, so is it more likely the issue is the layshaft needle bearings?

 

Just some thoughts,

Mike

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I've had second thoughts since my drive home last night. I'm not 100% sure about the lack of noise in 4th, also if it was the mainshaft tip bearing I assume I'd be correct in saying the whine would be a higher pitch in 1st, lower in 2nd and then again in 3rd and silent in 4th? If so that's not the case, it seems to be a speed related pitch.

 

So does that mean it would be on the output side of things? Part of me was suspecting the diff, but the gearbox feels funny in gear changes etc...

Correct me if I'm wrong, but assuming a constant road speed, the Layshaft runs at different speeds in different gears and the main shaft remains the same? Which would point at something at the back of the box or the overdrive?

 

Also, do bearings actually whine? This sounds like a gear whine to me...

 

I'm confused... Either way I think I'm gonna have to pull the engine and gearboxes out and inspect them.

 

Henry

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you say the change is feeling a bit odd,, this can point to the mainshaft circlip has broken at the rear case bearing bearing

 

bearings whine, especially needles.....  as can gears if the meshing is displaced.

does it make a racket when idling, this can be the input(stemwheel ) bearing, if you press the gear stick without pressing clutch does it

go quieter,  this action just baulks the selection and the load removes all the gear backlash chatter  may help in,   is it gear profile whine or bearing whine

 

the OD has seperate bearings and thrust bearings inside but these are all mainshaft speed

 

if the whine heightens with revs rather than road speed then its pointing to gearbox

well something like that ....cant put it in words 

 

Pete

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I think the change is feeling a bit odd, but then again you know when these things happen, suddenly your senses heighten and everything feels wrong!!

 

Also forgot to mention, she jumped out of reverse last night whilst I was having a listen to reverse which is quite noisy.

 

There is no noise at idle whatsoever. I'm not 100% sure but I'd say gear profile.

 

The whine is a road speed related whine. So if the mainshaft case bearing has displaced, that could be a bearing fault that is causing gear noise as without the bearing in place the gears wouldn't mesh right, could also explain the reverse problem right?

 

Is there enough room for the mainshaft bearing to come right out into the overdrives space? Enough to allow the mainshaft to lose concentricity?

 

And I assume I could fix all this by taking just the overdrive out of the car, which I could do with doing anyway (going for whatever sounds easiest!!).

 

Henry

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the main brg is trapped in place by the OD adaptor hsg.  it cant move much  what can happen  is behind the brg is a circlip which holds the shaft and all its gears in position, if this pops off the shaft can move inwards outwards depends on drive or overrun the helical thrust shifts the gears up down the shaft . causes gear stick to move , can add to jump outs 

reverse does take a pounding and the straight teeth can get quite worn , this can aggravate reverse jump outs.

 

you can take the od off in car by lifting unit as high as possible ,,   getting back on is a faf.

 

if you still have your old shaft drop it in the OD as soon as its off

if the splines dont line up use two drivers to lever the operating plates up and it frees the cone to all realign

 

as this is road  speed  not eng. revs related and sounds like gearbox zone  , there could be a OD bearing on the blink

 

you need an assistant to ride with you , get on his knees and use a large wooden handled screwdriver onto the case and as with a stethoscope move around to find which end /where the whine is eminating   

even a good gearbox will make some alarming noises , when gear changing , but you shuld be able to trace the rough location

 

dont stick it in the propshaft , or you need A & E to remove it 

 

Pete

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Okay, that makes sense and from what I can feel and hear when driving sounds a very likely option.

 

As far as worn gears go, I would hope they are okay as they were all immaculate only two years ago!

 

Good shout on the overdrive, never considered doing that! I'm well aware of the huge faff of lining up the splines, usually get down there with a long screwdriver and try and flick them back straight!

 

I'll get the tunnel out when I'm home and I'll get someone to drive me about whilst I have a poke about.

 

Hahaha, that made me chuckle!

 

Henry

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the old ideas are the best ,,,sure someone  said that somewhere

 

now youre closing in on the problem, doubt you will wear the tooth profile that takes a lot of use 

 

dont forget its a classic ,, when you cure the culprit the problem remains      they do this on purpose

 

Pete

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Thanks for the offer Neil, Hope you had a good evening!

 

Update: I got as far as nearly unbolting the overdrive, but when I drained the oil, so much stuff fell out I just gave up there and then!! Gonna have to clear the workshop out and get her in for a full engine out job now!

 

Henry

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Nothing wrong with the engine, in fact, much the opposite!

 

I wanted to take the overdrive off for a bit of a service. Thing is, I've tried numerous times to get the gearbox from a spitfire with no success and I found I could get the whole thing off with the engine in about 45 minutes in the end! I'm also reluctant to scratch anything on the inside if I can help it...

 

I'll keep you up to date! Don't worry!

 

Henry

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