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| More gearbox issues than I thought https://www.ausmini.com/forums/viewtopic.php?f=2&t=99607 |
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| Author: | Morbo28 [ Sun Jan 19, 2020 6:50 pm ] |
| Post subject: | Re: More gearbox issues than I thought |
Alrighty case is all cleaned out (thanks for the advice) including a blast from the compressor and a sweep with a big rare earth magnet. Then repeat a few times. It's looking good. Winnabbey, given there are still some fittings in the gearbox, I won't do the hydroblast option. It does come up beautifully that way though. I'm getting most new bearings: 1st motion shaft and outrigger, main double row, diff, idler. Laygear bearings of course. Many of them are intact, but I don't want the risk that there is still swarf in there. The main gearset looked in great nick, I'll give it a once over, I think I'll keep it as it with respect to the bearings under the gearsets etc, unless people think that's a bad idea... Sent from my Pixel 2 XL using Tapatalk |
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| Author: | lomin [ Sun Jan 19, 2020 10:27 pm ] |
| Post subject: | Re: More gearbox issues than I thought |
Hi, i do not think many people realise that apart from the quality of steel and the heat treating done to the rollers in all these small bearings, that most of them have at least one roller less than what BMC supplied years ago. Cost cutting exercise that also drops the load capacity by up to 20%. i often use early cages and add a roller , or for my own boxes make them up from used rollers with no wear. BMC had the parts quality tested, I certainly wonder if any manufacturer of mini parts tests anything. They wait until enough customers complain. That layshaft photo ... layshaft looked hard to me ! I save used bits ... If a used part looks as new after thousands of klm, chances are it will do thousands more ...and even if you dont use it, sometimes its good to check it against the replacement part to see where they got it wrong ! Cheers Lindsay Siebler |
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| Author: | 9YaTaH [ Mon Jan 20, 2020 8:28 am ] |
| Post subject: | Re: More gearbox issues than I thought |
lomin wrote: Hi, i do not think many people realise that apart from the quality of steel and the heat treating done to the rollers in all these small bearings, that most of them have at least one roller less than what BMC supplied years ago. Cost cutting exercise that also drops the load capacity by up to 20%. i often use early cages and add a roller , or for my own boxes make them up from used rollers with no wear. BMC had the parts quality tested, I certainly wonder if any manufacturer of mini parts tests anything. They wait until enough customers complain. That layshaft photo ... layshaft looked hard to me ! I save used bits ... If a used part looks as new after thousands of klm, chances are it will do thousands more ...and even if you dont use it, sometimes its good to check it against the replacement part to see where they got it wrong ! Cheers Lindsay Siebler Brilliant words Lindsay...we are hearing more and more about smart looking OEM boxed, 3rd world or poor quality made components failing... |
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| Author: | FNQ [ Mon Jan 20, 2020 12:46 pm ] |
| Post subject: | Re: More gearbox issues than I thought |
Hi Lindsay ("layshaft looks hard to me") Are you saying the layshaft photo shows bearing swarf build up, and as the old saying goes - it'll just polish out ? I have binned layshafts with what looked like rust marks I could feel with thumbnail in the past. Should the layshaft be harder than the bearings?- or same or doesn't matter as long as they are rolling, just curious |
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| Author: | lomin [ Mon Jan 20, 2020 2:38 pm ] |
| Post subject: | Re: More gearbox issues than I thought |
Hi, as a young lad the fun of working on cars outdid my desire to finish either the mechanical engineering degree or metallurgy degree, but i did learn some basics, and use my experience to try and work out problems and answers. So this is not a pure engineering answer. I feel that the Rockwell hardness of both the rollers and layshaft would be very similar..... If you want planned obsolescence like today you would make one wear out first, otherwise bits wont fail.... That layshaft look like it has not worn badly or had hardening fail, but has accumulated a lot of melted cage and rollers etc on the outside, so maybe was overloaded ? , had poor quality rollers, ? insufficient load carrying capacity for what I think is the supercharged engine ? or as the Doc says ,inside of the gear finish ? roundness ? or size ? or maybe a combination of everything ...we will never know unless you spend money and have it metallurgically tested. In certain areas you can have rust marks, as the pitting allows a little oil storage, but never on crankshaft bearing surfaces Cheers Lindsay Siebler |
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| Author: | FNQ [ Mon Jan 20, 2020 2:53 pm ] |
| Post subject: | Re: More gearbox issues than I thought |
thanks lindsay, and good luck with the rebuild morbo |
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| Author: | drmini in aust [ Mon Jan 20, 2020 9:41 pm ] |
| Post subject: | Re: More gearbox issues than I thought |
FNQ wrote: Hi Lindsay ("layshaft looks hard to me") Are you saying the layshaft photo shows bearing swarf build up, and as the old saying goes - it'll just polish out ? I have binned layshafts with what looked like rust marks I could feel with thumbnail in the past. Should the layshaft be harder than the bearings?- or same or doesn't matter as long as they are rolling, just curious Layshaft case hardness is same as the rollers. HRC 61 or 62 minimum. Preferably more. Edit: You can't run rollers direct on a soft shaft. |
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| Author: | Morbo28 [ Sat Jan 25, 2020 10:26 am ] |
| Post subject: | Re: More gearbox issues than I thought |
Reassembling the gearbox - the std thrust washer on the small end of the laygear is too thick. Would it be okay to reduce the thickness of the back (case) side of the thrust washer to get it in spec? EDIT: I've found the smaller thickness thrust washer, only available in the UK or US from what I can see. 22g856 I think I should wait for that to arrive rather than try to thin down a thicker one, I'd be worried about getting it even |
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| Author: | drmini in aust [ Sat Jan 25, 2020 2:40 pm ] |
| Post subject: | Re: More gearbox issues than I thought |
If you have a micrometer or digital caliper, sand the back down and measure as you go. |
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| Author: | Bill B [ Sat Jan 25, 2020 3:30 pm ] |
| Post subject: | Re: More gearbox issues than I thought |
According to this Mini Spares parts manual, it is diagram No. 14. Part Number 22G856 is the thinnest. There were 4 sizes altogether going up by about .002" each one. https://www.minispares.com/catalogues/c ... spx?1~4~37 The original one in my box was 22G856 and it gave .009" end float but .006" is max. Happened to have a thicker one (22G858) but it gave me no end float at all. Linnished it like Dr says - on a piece of 120 paper on the edge of the workbench and took off required .003" very quickly. I would not worry about "getting it even" as you are removing so little. As long as you can get a feeler gauge between .002" to .006". Besides, from looking at 30 years of running, the cluster gear does not appear to wear into either thrust washer enough to alter their thickness for the life of the box. |
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| Author: | Morbo28 [ Sat Jan 25, 2020 4:20 pm ] |
| Post subject: | Re: More gearbox issues than I thought |
Cheers guys, I will linish it down to spec. Sent from my Pixel 2 XL using Tapatalk |
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| Author: | Morbo28 [ Mon Jan 27, 2020 7:07 am ] |
| Post subject: | Re: More gearbox issues than I thought |
There are differing recommendations regarding pinion retainer clearance/preload against third motion bearing?? MED: 2 thou preload Mini Minia: Zero clearance / zero preload [also Classic Mini DIY: Zero clearance aimed for, but he's an amateur and doesn't actually measure it correctly IMO, he may be inadvertently preloading the bearing without knowing] What do you recommend? Also, MED leave out one of the four retainer bolts, would you recommend doing this? My main concern would be that there would be no more lock tab to keep the other bolt in place that shares the two-bolt lock tab - maybe loctite? |
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| Author: | drmini in aust [ Mon Jan 27, 2020 10:00 am ] |
| Post subject: | Re: More gearbox issues than I thought |
Q1 The shims don't change preload, they just squeeze outer bearing ring against the circlip. Less shim is tighter. Most boxes had 1 shim. Q2 I would use the 4 bolts if hole not stripped. Later A+ cases had no hole there that's why stronger. |
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| Author: | TheBoy [ Mon Jan 27, 2020 8:06 pm ] |
| Post subject: | Re: More gearbox issues than I thought |
As DrMini said above it only loads against the circlip on the outer of the bearing most only had 1 shim. The MED video was an A+ box and doesn’t have a hole for the 4th bolt it just has a lock tab that locates in the old hole. If you have a 4 bolt one use the 4 bolts. Also, the short bolt goes in the bottom hole furthest from the diff. You won’t get reverse if you put a long one in there. |
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