Reaming Rear Radius Arms Bearings
#1
Posted 26 February 2017 - 07:18 PM
Many thanks
Matt
#2
Posted 26 February 2017 - 07:59 PM
#3
Posted 26 February 2017 - 08:35 PM
#4
Posted 26 February 2017 - 08:52 PM
#5
Posted 26 February 2017 - 09:44 PM
#6
Posted 26 February 2017 - 10:19 PM
#7
Posted 26 February 2017 - 10:22 PM
#8
Posted 27 February 2017 - 08:18 AM
Is this not a DIY job then ?
#10
Posted 27 February 2017 - 08:53 PM
Is this not a DIY job then ?
not if you want it done properly. it requires a rather expensive special tool to do it right.
basically the radius arm casting is not great on tolerance. to work around this the bushes are undersize and are reamed once fitted. however they must be reamed inline with the bearing at the other end. get it wrong and you will be doing it again very soon.
#12
Posted 28 February 2017 - 07:01 AM
Many thanks
Matt
#13
Posted 28 February 2017 - 09:37 AM
When did they go to bushes ? All the minis and metros I've ever done have had two roller bearings in each arm.
Are the radius arms the same ? can we not use roller bearings in the arms made for bushes ? would make it easier and lets face it, they last long enough.
#14
Posted 28 February 2017 - 12:04 PM
Sadly, no you can't directly use roller bearings both ends. The bore in the arm is different because the needle roller bearing is thicker than the plain bush. In most arm castings there is not enough metal to safely bore it out.
The other problem, which will be disputed by some, but emerged when I tried to machine an old pin to make something else entirely, is that the hardening, at least on an original MK 1 part, was very different in the area of the needle rollers, and the other end may be too soft.
I find it a major annoyance!
A possible solution is to find a metric needle roller bearing that is only very slightly larger on OD than the bush, and line bore the arm to that diameter less the appropriate interference fit. Then turn down the end of the pin (MUST radius the diameter change carefully to avoid creating a stress raiser) and fit the appropriate hardened inner sleeve for the metric needle roller. If you are equipped to do that, you will never need to ream a bush again.
#15
Posted 28 February 2017 - 12:14 PM
Only Metros have roller bearings at each end of the trailing arms. Minis have a phos-bronze sleeve at one end. If fitted correctly and greased regularly they last a very long time.
You can buy a 13/16" reamer and DIY as it's not difficult. Buy your own reamer, then you can do the arms for other people
.
If the reamer is not long enough there is an acceptable 'bodge' to make it ream parallel with the roller bearing. What you do is to remove the solid bush first, then fit the new one in that end. Build up the diameter of the reamer shaft with a suitable tape until it just slides through the old needle roller bush after adding a bit of grease. That will make the reamer go in parallel enough. Once the solid bush is reamed, remove the needle roller bearing, clean up inside, fit the grease retention sleeve and fit the roller bearing, followed by the pin. Grease thoroughly and it'll be fine.
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