31 replies to this topic

[Other-car-is-a-1275GT]

Quick one - Should the idler gear bearing be flush in its housing? Or should it protrude slightly ~0.75mm (Rough guess).

 

 IMG_20181004_230740845.jpg   48.66K   3 downloads

 

Cheers,

Adam

[Cooperman]

It should be held in place with an internal circlip which fits into a groove in the housing. That bearing is not installed deeply enough into the housing. In fact, the circlip groove cannot be seen.

[nicklouse]

normally recessed slightly.

[Other-car-is-a-1275GT]

It should be held in place with an internal circlip which fits into a groove in the housing. That bearing is not installed deeply enough into the housing. In fact, the circlip groove cannot be seen.

 

Thanks for the reply - this is the idler gear bearing not the outer support bearing for the 1st motion shaft (which does have the circlip like you say)

[Other-car-is-a-1275GT]

normally recessed slightly.

 

Will hit it some more.

Cheers

[nicklouse]

did not think the later boxes had the C clips.

but check the gear side for any groove.

Edited by nicklouse, 04 October 2018 - 11:24 PM.

[imack]

Earlier boxes with smaller idler bearings are retained by circlips.
Don't know if the later bearing uses circlips but either way it can't sit proud of the surface as the idler thrust washer will contact the bearing rather than the gearbox case.

Attached Files

•  20181005_053747.jpg   53.21K   0 downloads

[Spider]

No clip in the later Gearboxes with the bigger bearing & shaft.

 

I set them flush to get a little more life from the thrusts, but now given up on them completely.

[RooBoonix]

No clip in the later Gearboxes with the bigger bearing & shaft.

I set them flush to get a little more life from the thrusts, but now given up on them completely.

Out of interest, what are you referring to when you say you have "given up on them", the thrusts? If so why?

[Spider]

 

No clip in the later Gearboxes with the bigger bearing & shaft.

I set them flush to get a little more life from the thrusts, but now given up on them completely.

Out of interest, what are you referring to when you say you have "given up on them", the thrusts? If so why?

 

 

The Transfer Housings, despite being Doweled, are seldom ever in true alignment, and with these late Idler Gears, the Thrust Faces are quite small. We all go to lengths to shim them up, just so, but it doesn't take long with most, before they start the familiar 'clackty-clack'. Despite this, I do feel with the up-rated bearinsg, this set up is better than the earlier types.

 

When I say 'I've given up on them' I now convert them to Tapered Rollers;-

 

 

and that's the end of all Idler Gear issues.

[grizzler73]

Moke
So you machine them out to take a tapered roller, like a wheel bearing but smaller? Can you expand on that a bit? It seems a worthwhile thing to do on a race helical box.

[Spider]

Moke
So you machine them out to take a tapered roller, like a wheel bearing but smaller? Can you expand on that a bit? It seems a worthwhile thing to do on a race helical box.

 

Yes, I make these from a stock gear, and it took a few years to design & develop. I have a few fitted sets out there now, on 'live test'.

 

I'll point out though, that they do use a custom bearing, not the way I wanted to go and was a huge hold up in it's design, but I couldn't find a way around it while maintaining equivalent (or better in this case) bearing load ratings. I wanted a step up, not back !!

 

[Ethel]

Minispares used to do something similar, no more by the looks of it.

[grizzler73]

Moke

So you have put a fixed shaft in where the needle rollers are and a tapered roller on the gear?

I assume then all the load now sits against the taper so no need for a thrust face, what did you calculate the loading as?

I looked at a needle roller of 35mm o/d by 12 wide and the radial load was noted as 14700 N! I can see why you had to get

a custom bearing though, smaller diameter are hard to find.

[nicklouse]

Moke

So you have put a fixed shaft in where the needle rollers are and a tapered roller on the gear?

I assume then all the load now sits against the taper so no need for a thrust face, what did you calculate the loading as?

I looked at a needle roller of 35mm o/d by 12 wide and the radial load was noted as 14700 N! I can see why you had to get

a custom bearing though, smaller diameter are hard to find.

have a look at

http://www.med-engin...set-roller-type

straight cut so no side loads so can get away with Cylindrical Roller bearings.