5 replies to this topic

[Matpaul]

I have a 15 tooth pinion gear (22G99) which at first glance appears to be in good condition. Under magnification at the base of each tooth on the drive side of the pinion where the crownwheel contacts there is a line that I can only describe as some sort of undercutting? which goes along most of the length of each tooth (I don't think it is a crack although it does sort of look like that). I don't want to fit this part unless I can be sure it will not fail beacause of this. Is this normal or should I be concerned? (I understand these gears are prone to failure). I believe this pinion is no longer available new and I need to stay with a similar ratio as it is for a Moke with 13 inch wheels. Would a semi helical or straight cut gear set available new from some of the mini suppliers be suitable? I don't want something noticeably noisy as it is for a road vehicle.
No photo at this stage as it is kind of hard to capture.
Advice appreciated, thank you.

[DeadSquare]

Turn the pinion over and wear the teeth on the other side while you find another CW&P

[Spider]

Hi Matt and nice to see your face around here mate.

 

They are NLA as you've found out. I did have a small batch made a couple of years back, but they have all gone now and then I had some 'Heavy Duty' sets made which have proven bullet proof, though not cheap. These have also all been sold. If there's enough interest, I'll get another batch done.

 

You can take to the Pinion (and the Crownwheel) with a small grinder (Dremel is good here) and grind out any of these marks you find and that will increase the fatigue life of them. 

 

Failure can be from fatigue (the tooth being bent back and forth);-

 

 

for which there's nothing that can be done is this is occurring, other than replacing the gear

 

 

Or from Cracking starting at the Root of the Teeth to the Splining on the Inside (that on the left)

 

 

 

This is the new (and up-rated) Pinions that I had made (with a new Crown Wheel)

 

 

 

and the new 'bullet proof' sets;-

 

 

 

While the Pinions are a problem, that's only one part of the problem here, the other aspect that needs to be looked at is the Gearbox Case, as this is what holds them in alignment, if they get too far out then no matter how good the Gears are, they will still break.

 

The Semi-helical sets from KAD and MED are good, but quite noisy, I wouldn't put up with them, hence why I designed and had Helical Sets made. The noise comes from them being only Semi-helical and that the teeth are not of a ground finish, but straight off the CNC. I haven't tried Straight Cuts, but I can only imagine them being worse in this regards, and unless they are made from better steels and heat treatment than the factory items, they will actually be weaker than those.

[Matpaul]

Thank you both. For now I think I will select the best pinion I can find. I think that maybe defects at the tooth root area are more critical than nicks or chips etc. on the top of the tooth? I know the soft lock tabs can allow the pinion nut to lose its torque, is it acceptable to use locktite and run the nut directly onto the pinion (i.e. no lock tab or washer)? From my background I have found that a washer is preferable when torquing a nut, perhaps there is a standard / commercial one that could be used. Depending on cost I think I would like to put my name down to get a couple of 'standard' pinions made. I do find it interesting that there are no standard replacement pinion gears available as they are a critical item to keep our vehicles useable and going. Cheers.

Edited by Matpaul, 25 August 2018 - 08:09 AM.

[Spider]

Matt, I like to 'polish' (grind!) out any defect on these gears, be it in the root, flanks or tips. Any chip or nick is somewhere for them to start 'running away' from.

 

I gave up on the Locktabs long ago, they make much more trouble than what they are supposed to solve. I polish up the Face of the Pinion Nut on a Diamond Lap and use Loctite 241, Torque to 150 ft/lb and touch wood, I've had no issues from that. Anything, like a flat washer' that you put in there, has the potential to 'crush' and so loosing nut tightness.

 

The ratio for Minis is really only competition related. It wasn't fitted to much other than the Cooper S (on special order), though some of the Morris 1100's had them (some ran a 4.1 FD Ratio), other than them, it was really only the Moke that had them and it seems there's not much of a market for them.

 

To make the Pinions 'economical' I really need an order of 10. These are up-rated from the standard types.

[nicklouse]

i have one in mine and when it is beyond help i will be going semi helical.

 

I think.