28 replies to this topic

[MiniMadRacer]

The primary gear oil seal need to not leak

[Spider]

Ok now I know the tolerance but how should I measure it ? 

 

I've been giving this some thought since you posted the question and really, the only way I can think of is to check it in a lathe, clock in the Primary Gear in a 4 jaw chuck, then check the run out on the bushes.

While the factory tolerances on the Primary Gear may have been that tight, keep in mind here, the fitting clearance is up to 0.0045" (0.114 mm), so in operation, the Primary Gear can have 0.0045" run out and still be fine. I've removed worn gears that have had up to 0.014" Running Clearance and not leaked on the seal.

If you have a dial gauge, you could fit up your Primary Gear on to the Crankshaft Tail and then measure the Run Out to the Seal Face on the Primary Gear. Not the best or easiest way to measure it, but it'll at least give you a guide.

I always found the new A Primary Gears fine out of the box, but the late new Rover boxed A+ Primary Gears while concentric, the bushes were nearly always out of Spec out of the box, they were bad.

[gaspen]

In summary : I am not really need to worry about these gears.

[Spider]

In summary : I am not really need to worry about these gears.

 

I'd suggest checking the Bush to Crank Clearance, to make sure that's within spec (0.003 - 0.0045" or 0.075 - 0.11 mm) but otherwise, you should be fine.

[gaspen]

Well I replaced the p/g last weekend - or i just wanted it. I've checked the endfloat with the NOS p/g in place with the thickest thrut washer and it was 0.2 mm (~0.008") which is out of the tolerance. Then I measure the total length of the p/g and it was ~72.05 mm. So it was not a good deal   Fortunatley I have an other one within the tolerances.

 

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Anyway : SKF produce self-lubricated bearings. There is a suitable size to machine for the primary gear. Do you think it will be gooed enough for Mini ?

 

https://www.skf.com/...PSMF 354525 A51

 

[ACDodd]

Don’t waste your time, simply make an oversize thrust washer.

Ac

[gaspen]

Don’t waste your time, simply make an oversize thrust washer.

Ac

I see but I don not have any machine

[ACDodd]

What size do you need? And what size engine is it?

Ac

Edited by ACDodd, 29 December 2022 - 12:18 PM.

[gaspen]

What size do you need? And what size engine is it?

Ac

 

It is a basic 998cc. The endfloat with 0.118" washer is ~0.2mm. I guess 3.1mm (0.122") would be fine. But I live in Hungary 

[Spider]

Well I replaced the p/g last weekend - or i just wanted it. I've checked the endfloat with the NOS p/g in place with the thickest thrut washer and it was 0.2 mm (~0.008") which is out of the tolerance. Then I measure the total length of the p/g and it was ~72.05 mm. So it was not a good deal   Fortunatley I have an other one within the tolerances.

 

Anyway : SKF produce self-lubricated bearings. There is a suitable size to machine for the primary gear. Do you think it will be gooed enough for Mini ?

 

https://www.skf.com/...PSMF 354525 A51

 

You can get a thrust washer that's in the 0.120 - 0.122" range;-

http://www.minispare...|Back to search

 

and also a backing ring that's 0.002" thicker than standard;-

http://www.minispare.../search/classic/primary%20gear.aspx|Back%20to%20search

 

I'd say between these, you should get where you need to be. If you can't, drop me a PM and I'll make you a thrust washer to suit.

In regards to the SKF material, I couldn't pull up the specs on it, however I'm sure the rated surface speed will be well below that needed. I have been offered all kinds of exotic replacement materials over the years, but all fall short on this one important specification.

Frankly, after seeing the expensive damage cheap or 'she'll be right' type materials do to, I'm done with considering anything other than genuine Deva material.

[gaspen]

 

Well I replaced the p/g last weekend - or i just wanted it. I've checked the endfloat with the NOS p/g in place with the thickest thrut washer and it was 0.2 mm (~0.008") which is out of the tolerance. Then I measure the total length of the p/g and it was ~72.05 mm. So it was not a good deal   Fortunatley I have an other one within the tolerances.

 

Anyway : SKF produce self-lubricated bearings. There is a suitable size to machine for the primary gear. Do you think it will be gooed enough for Mini ?

 

https://www.skf.com/...PSMF 354525 A51

 

You can get a thrust washer that's in the 0.120 - 0.122" range;-

http://www.minispare...|Back to search

 

and also a backing ring that's 0.002" thicker than standard;-

http://www.minispare.../search/classic/primary%20gear.aspx|Back%20to%20search

 

I'd say between these, you should get where you need to be. If you can't, drop me a PM and I'll make you a thrust washer to suit.

In regards to the SKF material, I couldn't pull up the specs on it, however I'm sure the rated surface speed will be well below that needed. I have been offered all kinds of exotic replacement materials over the years, but all fall short on this one important specification.

Frankly, after seeing the expensive damage cheap or 'she'll be right' type materials do to, I'm done with considering anything other than genuine Deva material.

 

 

Thanks! How I couldn't find the 0.122" washers and the thicker ring ?! 

[gaspen]

So I "cooked" the gear in hot oil. But after finish the surface of the bushes became dark-greyish. I could remove it with a fine abrasive sponge only.

 

Is it normal?

[Spider]

So I "cooked" the gear in hot oil. But after finish the surface of the bushes became dark-greyish. I could remove it with a fine abrasive sponge only.

 

Is it normal?

 

Those sponges usually have Carborundum impregnated in to them and as you use them, these particles literally fall out and if working something soft, can get impregnated in to the softer material. These bushes I would class as being on the soft side, hopefully you might get it all out with cleaning.

 

I'd suggest cleaning the gear quite thoroughly in brake cleaner or something light to remove any abrasive that might be left from the sponge. Maybe heat the gear again in oil and clean again while hot, just don't burn yourself.

 

Any discolouration would have come from additives in the oil and would be OK to leave. If you do a hot oil soak,at the end of the heating (4 + hrs), I remove the gear and let it stand in a try for the excess oil to run off and let the gear cool to room temperature. Usually I do this days ahead of when I need it, so I just bag it up in a clean bag until it's needed. I don't degrease or otherwise clean the gear at this point, but leave it dripping in oil. When fitting up, give the tail of the crank a smear of oil, fit the gear up and then the Flywheel Cover. It is at this point I carefully clean the splines of the gear of excess oil.

 

[gaspen]

 

So I "cooked" the gear in hot oil. But after finish the surface of the bushes became dark-greyish. I could remove it with a fine abrasive sponge only.

 

Is it normal?

 

Those sponges usually have Carborundum impregnated in to them and as you use them, these particles literally fall out and if working something soft, can get impregnated in to the softer material. These bushes I would class as being on the soft side, hopefully you might get it all out with cleaning.

 

I'd suggest cleaning the gear quite thoroughly in brake cleaner or something light to remove any abrasive that might be left from the sponge. Maybe heat the gear again in oil and clean again while hot, just don't burn yourself.

 

Any discolouration would have come from additives in the oil and would be OK to leave. If you do a hot oil soak,at the end of the heating (4 + hrs), I remove the gear and let it stand in a try for the excess oil to run off and let the gear cool to room temperature. Usually I do this days ahead of when I need it, so I just bag it up in a clean bag until it's needed. I don't degrease or otherwise clean the gear at this point, but leave it dripping in oil. When fitting up, give the tail of the crank a smear of oil, fit the gear up and then the Flywheel Cover. It is at this point I carefully clean the splines of the gear of excess oil.

 

 

Thanks again ! I'll follow your lesson