owelly
|
| posted on 2/3/11 at 10:57 AM |
|
|
Oil seal sizes-tolerances?
Now I've come to assemble the type9 gearbox on to the Pug V6 engine, a tiny problem has cropped up. The sort of thing that because when I was
making the various bits and bobs for the bellhousing/converter thingy, I didn't have the gearbox out of the car. So, I need to machine the
trumpety bit off the gearbox input shaft trumpet so as to leave the register but not much else. This means the bit of the trumpet that holds the input
shaft oilseal will be turned to swarf.
However, as I thought this may be the case, I machined the hole in my adapter plate to 40mm so it would take a 28mmx40mm oil seal. Now I've come
to measure the hole, it seems to have grown to 40.8mm!!
So, do I use a 40mm od seal and hope it seals with a bit of glue, fit a motorbike fork seal at 28x41mm or machine a larger hole in the adapter?
http://www.ppcmag.co.uk
|
|
|
|
|
MikeCapon
|
| posted on 2/3/11 at 01:59 PM |
|
|
Most seals have a lot of preload on them to avoid static leakage. This can be so much it can even lead to premature wear on reciprocating
applications. I have succesfully gone 0.5 oversize on much smaller bores and would imagine that if your shaft (fnar, fnar) is in good nick you will be
alright. It's marginal but deffo worth a go.
Wrote all that then realised I forgot to mention that this only applies to seal without composite metal ODs if you see what I mean. For example most
bike fork seals are made that way.
Glue or silicone or whatever on the outside won't do any harm but I doubt it would do much good either as the leak from insufficient preload
will be at the (here we go again) lip/shaft interface........
Cheers,
Mike
[Edited on 2/3/11 by MikeCapon]
[Edited on 2/3/11 by MikeCapon]
|
|
|
owelly
|
| posted on 2/3/11 at 03:37 PM |
|
|
Cheers but the lip/shaft won't be the problem. It's the O/D of the seal in the housing that is either 0.8mm under size if I use a 40mm
seal or 0.2mm oversize if I use a 41mm.
http://www.ppcmag.co.uk
|
|
|
MikeCapon
|
| posted on 2/3/11 at 03:45 PM |
|
|
I take it that this is a composite seal then, ie it has a metallic outer bonded into the seal material? If so then, yes you're right the OD of
the housing won't affect the sealing capacity at the lip/shaft.
If it is not a composite seal then the OD is all important as this squashes the lip onto the shaft..
If it's a composite seal your best bet IMO would be to try the 41X28 fork seal if you have one.
|
|
|
britishtrident
|
| posted on 2/3/11 at 03:49 PM |
|
|
A suitable grade of RTV Silicone Gasket should bond it in OK --- let it semi-cure before you put the seal in.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
|
|
|
owelly
|
| posted on 5/3/11 at 08:07 PM |
|
|
UPDATE!
I did what I should have done without asking on here! I put the adapter back in the four jaw chuck and bored it out to the correct size. In fact, as
I'd already ordered the 41mm fork seal and a 42mm oil seal, I stepped the adapter to 41mm and 42mm so I can use both seals!!
Cheers for the replies though guys.
http://www.ppcmag.co.uk
|
|
|
