Squishing O-Rings.

[Dougal]

Anyone got some tips for me?

When replacing some of the large orings in my LT230R (like the intermediate shaft) I find the new orings have enough interference that they won't compress into their slot and let the shaft slide through.

Are there any special tricks to squishing them in? Grease isn't enough, holding pressure on the shaft while working around the oring to push it back isn't working either.

I can't make a curved cone to seat it as the front case would need to come off to pass the cone through.

[350RRC]

Use thinner O rings?

I've had the same prob before in other applications. Its not easy to visually match old with new O rings because the old ones sometimes have got squashed over time giving the impression that replacements should be thicker than they need to be.

cheers, DL

[Dougal]

Use thinner O rings?

I've had the same prob before in other applications. Its not easy to visually match old with new O rings because the old ones sometimes have got squashed over time giving the impression that replacements should be thicker than they need to be.

cheers, DL

The groove for this one is ~3.7mm wide, the o-ring I'm trying to fit is a 3.5mm which is a pretty good match to the one which came out. The next step down is 2.6mm which would be both too small and one I don't have.

If it was an external groove I could just use a smaller oring which will stretch itself a bit thinner, but for an internal groove it'll just get trickier.

[rovercare]

CAD drawing wont fix it:p

Rubber grease, not just normal grease;)

[Dougal]

I had two other oring sizes smaller.
From a 223 to a 222, then a 220.

The 220 with a lot of grease and persuasion went in.

[langy]

You'll fiind that whilst the LR engineers tried to make things simple to maintain by using common parts, it appears that the beancounters did their bit and threw a spanner in the works by using o-rings that were a bit different in sizes you'd find in an o-ring pack.

This is a good example, as the LR parts for the intermediate shaft ( and on a 300tdi the oil separator o-ring) slide right in without a fuss, whilst generic o-rings ( which do work eventually) you have to fight to get them in.

[Dougal]

You'll fiind that whilst the LR engineers tried to make things simple to maintain by using common parts, it appears that the beancounters did their bit and threw a spanner in the works by using o-rings that were a bit different in sizes you'd find in an o-ring pack.

This is a good example, as the LR parts for the intermediate shaft ( and on a 300tdi the oil separator o-ring) slide right in without a fuss, whilst generic o-rings ( which do work eventually) you have to fight to get them in.

Funnily enough, the oring size that eventually fit, was the same as used on the other end of the shaft.
Manufacturing oddity or designed in spares compatibility?

[Davy]

O rings generally come in two flavours, imperial (BS) or metric, which probably explains why stock from a standard metric selection won't fit.
LR seem to use the BS O rings

[Dougal]

O rings generally come in two flavours, imperial (BS) or metric, which probably explains why stock from a standard metric selection won't fit.
LR seem to use the BS O rings

I used imperial o-rings. The BS 4518 actually seems to reference metric sizes (1.6, 2.4, 3.0mm etc) compared to BS 1806 which uses the 1.52, 1.78, 2.62, 3.53mm etc of the imperial o-rings.
So the question becomes: Which BS?

Fitting a 3.0mm oring instead of the 3.53mm imperial oring wouldn't have fit the back end of the intermediate shaft properly. The front end I could probably have got away with.
The orings in the hi-lo selector shaft were tight at 1.78mm, 1.6 would have fit better there. If I had some smaller diameter 1.78mm they would have stretched down and fit easier.