Crank Spigot Bush

[Peaks]

What are the symptoms of a worn crank spigot bush? 

I ask as I'm having no end of issues with a growling noise coming from my gearbox in 1st gear, especially when I let my foot off the accelerator.

Very long story, but the box has  been stripped and over hauled twice by two different Triumph box experts.

It was then stripped down again to diagnos the fault and no fault found, so I'm wondering if the noise is caused by something external to the box, and the spigot bush is the only thing I can think of apart from the mounts (which seem fine) that might have an effect on the gearbox operation. 

 

[johny]

That sounds more like a problem between first gear and reverse which are very close together and the same selector hub transmits drive for both. Theres been cases where the reverse idler gear still makes contact when in first gear which generates a grating noise although I thought the damage to the teeth would have been spotted on strip down...

I think a noise produced from a loose spigot bush would be more like a whine from gear misalignment and also be heard in second gear🤔

[Pete Lewis]

this does sound like the reverse selector lever is bent and as Jonny says  you are engaging reverse idler in 1st gear , its common .

crank spigot wear is more evident in clutch operations .judder, squeals and such 

it steadies the long end of the input shaft but wont affect gear noise in most conditions.

beware of Xspurts 

Pete

 

[Peaks]

Well, that would kind of add up as originally, after the 1st overhaul there was a similar but much worse occasional grinding noise in 1st and reverse.

After the 2nd overhaul (when severely damaged layshaft and needle rollers were discovered) the noise was only in 1st, reverse is better, but possibly noisier than it should be. 

And the noise does sound like something grinding against something else. 

Thanks for the replies 👍🏻

[Peaks]

So, do I need to have a closer look in this area? 

And, I guess from what Pete said, at the reverse selector arm? 

[Pete Lewis]

its the short arm that pivots on a bolt thread in the side of the case 

with the top cover removed  you should be able to see if you engage 1st that the spur gear on the sliding sleeve 

is now just making mesh with the small idler gear

the snag is you cant remove the lever to reform it until you strip the mainshaft out the way 

items 51 and 52

https://www.canleyclassics.com/?catalogue=triumph-vitesse&diagram=triumph-vitesse-mkii-gearbox-mainshaft

Pete

 

 

Edited July 30 by Pete Lewis
corrected the typo to 51/52

[Peaks]

Thank you Pete 😃 Incredibly helpful to know exactly which components to focus on 👍🏻

Do you mean 51 and 32? 

[johny]

Think thats items 51 and 52 in the drawing, lever and pivot. Theres some good threads on here about exactly this problem because it appears theres different spacers (47) and idler gears (45) so if these have been changed clearance can be compromised. Also I seem to remember if the 1st/2nd hub (11) is put on the wrong way round it might do the same although I would expect additional problems if that were the case...

[Pete Lewis]

sorry about that and thats with me new specs on  Ha   51/52 it is 

Pete

[Peaks]

On 29/07/2024 at 12:37, johny said:

That sounds more like a problem between first gear and reverse which are very close together and the same selector hub transmits drive for both. Theres been cases where the reverse idler gear still makes contact when in first gear which generates a grating noise although I thought the damage to the teeth would have been spotted on strip down...

I think a noise produced from a loose spigot bush would be more like a whine from gear misalignment and also be heard in second gear🤔

So, I've finally found time to remove the cover of the box and you're right Johny; the reverse idler is spinning when 1st is engaged. I can even replicate the noise when spinning the box in 1st. The noise can be reduced by very slightly moving the reverse selector arm, but the noise never goes away. 

I've read a few threads on this and other forums about the reverse idler spacer causing similar issues, but not really how to fix it. 

Have I got the wrong size spacer fitted? or something else? Pretty sure bending the selector arm won't work both because it's pretty substantial, and also because the reverse idler will still be able to move backwards and forward when 1st is selected no matter what shape the reverse selector is.

[johny]

If you push the idler gear back as far as possible is it touching first gear? Also how much can 1st gear move axially? The limit is very tight 0 - 2 thou so more than this will make contact with between the two more likely....

[Peaks]

Ok, very difficult to get a clear shot of what is going on. 

First picture is in neutral - no noise.

Second picture is in 1st - growling noise 

Edited September 2 by Peaks

[Pete Lewis]

there are a lot of things that can mess with reverse 

differing tooth counts on idler and sliding sleeves and spacers

its certainly much easier to change a spacer than removing the relay lever to modify the bend .

when in 1st it looks like too much travel of the sleeve up its hub   is there a thrust missing from the 1st gear wheel ??   

has the box got any rebuild history  from a previous life 

Pete

Pete

Edited September 2 by Pete Lewis

[johny]

yes certainly looks like the idler could afford to sit closer to first gear with no problem although have to confirm also that first gear cant move forward too much....