Jota swing arms bearing replacement

ngiles

ngiles

Senior member
Location
Sydney, Australia
I put new roller bearings in the swing arm of the Jota today.  Each one had a washer inserted prior - as shown in the parts manual.  However the washers I received were shaped to be concave on one side, convex on the other.  Whilst the parts manual describes a 24 x 32 x 1 washer these were clearly wider than the 1mm specified due to the shape, and so led to the bearing cages protruding a little.  So I took it all apart and am rethinking. Couple of questions:

- Anyone had the same issue?
- When I took it all apart there were no washers on the inside of the roller bearing cage!  So I wonder whether to leave them out - any thoughts?
- Anyone know where to get a flat 24 x 32 x 1mm washer?

Cheers, Nick
 
Supposed to be concave in order to retain the spacer tube that sits between the bearings in the correct position.
The side of the shim that protrudes should face into the centre of the swingarm as they locate on the spacer tube.
 
Ok, so I've got the washer thing figured - thanks Grant.  Next issue:

When the whole lot is put together the bushes protrude about 2mm each side, or 4mm in total, whereas they should be pretty much flush.

The measurements are as follows:

Width of swing arm pivot is 210mm
Width of spacer is 137mm
Width of bushes is 38.5 each

I am curious about what is the issue ? it is one of:

- The spacer is too wide
- The bushes are too wide

As it stands the whole lot will not fit in the frame as when I put the swing arm in place with just the outer nylon washers it is sufficiently snug to suggest that there is no space to allow for protruding bushes, and in any event it would be a weird fitting.  The spares catalogue lists the needle cages as 38mm which is consistent with the 37.9mm the ones I have.

I figure the likely answer is the spacer is too wide - anyone got one they can measure and advise me?

Cheers, Nick
 
Nope, this is correct.
The 2mm shoulder each side is to locate the plastic washer/shim things.
 
Nick,
our *17--* RGS had no inner washers/spacers and the swing arm was a loose fit into the frame when the swing arm spindle was removed. Installing the washers/spacers with new bearings made the fit much tighter. Don't forget the plastic washer fits over the bearing end.  Had to apply lube to the area to get the swing arm back in.
However, our *25--* Sprint JOTA and *26-- * CORSA both have the washer/spacers and are very tight fits into the frame with new washers/spacers and bearings.
In my experience the standard frames have an amount of 'spring' in the swing arm pivot region - the frame visibly relaxes when the S/A spindle nuts are loosened right off.
The washers/spacers appear to flatten out slightly when the swing arm is installed and the spindle nuts tighten up.

You could try preloading the washers by using packers such as washers to approximate frame thickness and tighten up the spindle nuts to ensure the bearings and washers/spacers are fully home within the swingarm.  I'm sure somebody more experienced will come along with their own observations.
 
As an aside, if you replace the wheel bearings the inner shims fit the same way to hold the spacer tube. Not a good idea to fit them backward as they then press against the inner race of the wheel bearing.
 
DavidH said:
Nick,
our *17--* RGS had no inner washers/spacers and the swing arm was a loose fit into the frame when the swing arm spindle was removed. Installing the washers/spacers with new bearings made the fit much tighter. Don't forget the plastic washer fits over the bearing end.  Had to apply lube to the area to get the swing arm back in.
However, our *25--* Sprint JOTA and *26-- * CORSA both have the washer/spacers and are very tight fits into the frame with new washers/spacers and bearings.
In my experience the standard frames have an amount of 'spring' in the swing arm pivot region - the frame visibly relaxes when the S/A spindle nuts are loosened right off.
The washers/spacers appear to flatten out slightly when the swing arm is installed and the spindle nuts tighten up.

You could try preloading the washers by using packers such as washers to approximate frame thickness and tighten up the spindle nuts to ensure the bearings and washers/spacers are fully home within the swingarm.  I'm sure somebody more experienced will come along with their own observations.
Click to expand...

The washers should under no account be loaded when the spindle is tightened.  They actually cannot be loaded if fitted correctly.  The inner bearing races should bear upon the inner spacer, this assembly should be a snug fit within the frame.  The swingarm itself is located axially by the plastic thrust washers and should have zero to a tiny amount of free play in the frame.  The outer needle bearing cages should also not be loaded axially and should be a flush fit in the pivot tube.  The dished washers' sole purpose is to centralize the spacer tube to aid spindle insertion.  They may or may not be a tight fit in the pivot tube, providing they have the correct thickness.  Too thick, they will allow the bearing to bottom and stand proud of the swing arm pivot tube.  Too thin, they will wobble around a bit, which is of no consequence at all.

piet
 
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