Input Bearing "Nip"?

PostPost by: vincereynard » Wed May 03, 2017 11:30 am

As the input bearing has an adapter ring I can assume it is the later wide one??

p1050165.jpg and


The manual mentions calculating the nip by, basically, relying on the crushing of the gasket. But on the "wide" one that would only push on the ring not the bearing. Mine (the housing) seems able to bolt home completely without a gasket. Therefore it is not applying any nip to anything! I can put a thin smear of "blue" on the ring and it is not transfered to the adapter.

What is the recommended float on the input shaft please?

Where is the gearbox breather?

Anymore of this and I could do with a few "nips" myself!

Vince
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PostPost by: mbell » Wed May 03, 2017 6:27 pm

vincereynard wrote:As the input bearing has an adapter ring I can assume it is the later wide one??


That is an early narrow one I believe, same as mine. The wider bearing, as per later eclat boxes, would protrude from the casing, needing the spacer from the narrow bearing removing and nose housing machining, a spacer ring between it and the casing due to the reduced diameter.

To try and be clear:
- Narrow Bearing: Sits below casing surface, has spacer between bearing and nose housing
- Wide Bearing: Protrudes from casing, narrow ring spacer between bearing and gearbox housing, no spacer between bearing and nose housing.

On the nip I am not sure if there is a spec. As I understand it the nip is just there to hold the bearing in position, so the exact nip isn't too critical just enough to hold it firmly in place.

As I've mentioned my box was missing the spacer so I had to get one machined up based on my measurements.To to fine tune the nip I used a few Mini diff spacers I got from my brother, these are a perfect fit for the bearing and cheap/easily available in multiple thickness. So if you feel the nip isn't sufficient enough you can adjust using these spacers. I think I spaced my out for a few thou over gasket thickness.
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PostPost by: vincereynard » Wed May 03, 2017 10:12 pm

HeyHo, another brick in the wall.
I suppose I had better consider the necessity of changing the bearing or , going by its present performance, it will go 100 yds down the road on the first run.

I seem to remember that there was a series of posts on the conversion recently? Can anyone point the way?

Thanks for the Mini Diff reference, they at least should be easy to find. (Assuming I don't change the bearing!)
Last edited by vincereynard on Thu May 04, 2017 5:11 am, edited 1 time in total.
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PostPost by: mbell » Thu May 04, 2017 2:20 am

I don't remember any recent posts on the bearing upgrade but must be some. The basic info is in the pdf that covers the mods to improve the box. Pretty sure it been linked on one of your posts.
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PostPost by: john.p.clegg » Thu May 04, 2017 4:57 am

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PostPost by: vincereynard » Fri May 05, 2017 1:29 pm

Right , let's see if this makes sense.

The spacer depth is 0.202 (inches) 5.15 mm. Thinner than shown in the manual.
Recess in Box 0.098
Recess in cover 0.100
--------
0.198

A "nip" of 4 thou - if it has no gasket.
Add a 0.010 (0.25 mm) gasket and assuming (!) it compresses by 50% gives a "negative nip"
of 0.001 thou.
Add a 6 thou Mini shim and it gives a total nip of 5 thou.

Enough to hold it in place but allow no movement?
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PostPost by: mbell » Fri May 05, 2017 6:21 pm

I think I'd recommend buying a selection of spacers. Then test fitting without the gasket and see what spacers you need to leave an approx gasket thickness with what feels like the appropriate amount of tightness on the nose housing. (If that makes sense.) You could test fit with some matching gasket paper inserted under the housing to test gasket compression.

I know I have the spacer measurement written down, from top of my head I think it was 13/64" which lines up with your spacer ( :D ). I am struggling to remember exactly what I fitted shim wise. I am pretty certain i fitted at least 3 shims, but not sure on their thicknesses. I think it was two thicker and one thin...

I guess it doesn't really matter as thou as there will be some variance between boxes. But I'll try remember to dig out the noted down measurement I have on this.
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PostPost by: vincereynard » Thu May 25, 2017 7:39 pm

I swapped my spare clutch plate for an Elite front cover with a nice smooth tube.

It has a small number of differences. A/ The tube is straked as mentioned above (?) and B/ there is a small hole just after the oil seal. Which I presume is a drain for any oil that escapes.

I did find that both front covers were distorted, presumably by being tightened down hard with an excessively large spacer. I had to grind both down on a steel plate to get a reasonable contact.
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