Gearbox: Loose Main Roller Bearings
#1
Posted 19 March 2019 - 08:23 PM
Thanks!!
#2
Posted 20 March 2019 - 07:44 AM
The Bearing should be a 0.002 to 0.0025" interference fit in that tunnel.
I have found some of the late Gearbox Cases though have less to the point where the Bearing floats, as you've found.
It's critical that this Bearing be firmly anchored in the Case, if it's not, it can lead to the Gearbox jumping out of gear and eventually, broken teeth off the Crown Wheel and / or Pinion.
#3
Posted 20 March 2019 - 12:06 PM
As always you are a great help! So it seems to be a thing with the later boxes! I can confidently anchor it in left to right movement due to the fact the shims, cir clip and horse shoe will do that work, but my concern is due to the lack of interference and ability to float with my hand the is a risk of the outer sleeve spinning inside the bore and causing even more damage, so i guess 3 boxes are no good!!
#4
Posted 20 March 2019 - 05:56 PM
No worries
Yes, the bearing may also spin. The 'C' Plate is not at all an effective way of anchoring the Bearing as the Bearing does not have a flange not does it fit up against a machined register in the case, but only has a thin circlip, which in itself is not positively locked to the Bearing.
The only suitable fix I can see for this is to have the Bearing Tunnel built up with some weld and machined back to size.
#5
Posted 20 March 2019 - 06:58 PM
This is crying out for a good bodge !
Have you got any way of very accurately measuring the bearing outside diameter and the oversize hole.
If so, divide the difference by two and buy the nearest thicker shim.
Roll the shim into a tapered tube, insert it in the hole and trim it to the appropriate diameter.
Put the bearing in the tapered tube and press it into the shim filled hole.
Trim excess shim with a sharp object.
#6
Posted 22 March 2019 - 06:12 PM
#7
Posted 22 March 2019 - 06:14 PM
#8
Posted 24 March 2019 - 05:48 PM
This is crying out for a good bodge !
Have you got any way of very accurately measuring the bearing outside diameter and the oversize hole.
If so, divide the difference by two and buy the nearest thicker shim.
Roll the shim into a tapered tube, insert it in the hole and trim it to the appropriate diameter.
Put the bearing in the tapered tube and press it into the shim filled hole.
Trim excess shim with a sharp object.
Would Loctite 'bearing fit' or similar also be an option here to taking up the slack and preventing bearing-to-casing movement?
#9
Posted 24 March 2019 - 06:17 PM
Shooter
#10
Posted 24 March 2019 - 07:05 PM
Chris sorry for sounding silly but you mean 0.002 milimeter or 2 thou. Measuring In milimiter makes more sense as 2 thou would make it a very tight squeen
0,002" (imperial). Being an Aluminum Casing it will expand at a greater rate than the Steel Bearing. Some tables actually suggest a tighter fit but this could result in cracking of the web.
This is crying out for a good bodge !
Have you got any way of very accurately measuring the bearing outside diameter and the oversize hole.
If so, divide the difference by two and buy the nearest thicker shim.
Roll the shim into a tapered tube, insert it in the hole and trim it to the appropriate diameter.
Put the bearing in the tapered tube and press it into the shim filled hole.
Trim excess shim with a sharp object.
Would Loctite 'bearing fit' or similar also be an option here to taking up the slack and preventing bearing-to-casing movement?
Some of the Lower Strength Loctites will gap fill to a point, but also keep in mind that, as mentioned, the Bore in the Casing will get bigger as the Oil heats up, so any gap will increase.
Dead Square's suggested 'bodge' may have some merit, not one I've tried, but I know 'speedy sleeves' are available for field repairs of worn Bearing Housings, which really are a formed shim.
Or just centre punch the hole at equal spacing,that will raise the surface then use bearing fit
Shooter
My experience with doing this (not in a Gearbox but on hubs) is that while the Bearing feels tight going in, in Service and in short time, the raised pips from the centre popping only get pressed back in.
#11
Posted 24 March 2019 - 09:21 PM
Will the interference be the same for both 3rd motion and 1st as well as the cruch on the diff bearings? So 2 thou?
To be continued ....
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