Bristol 400 rear axle gears

[Geoff Dowdle]

Dorien,
By your description it sounds like you could have a 401 -404 type diff
fitted .
Is the pinion held in a separate housing that bolts onto the main
casting that supports the crown wheel carrier. The mesh of the CW & Pinion
is by shims between these housings.

Also check that the crown wheel carrier is not broken where the side
bearings are located.
Regards
Geoff

[Hydroglen]

Thanks Ashley,
My axle had been quiet and very nice for some years. Then last month all of
a sudden lots of noise as I drove down our driveway. In looking it over more
carefully, there is not much wrong with the pinion bearings.
It seems that the pinion is not being held in place properly and moves.
In looking over your PDF files, the picture on page 26 appears very much
like mine, BUT I have only ONE distance washer were there are 2 shown.
The description on dissassembly talkes about split rings and other locking
devices that do not show up in the picture on page 26.
I have manuals and parts books of my own and they show regular straight
bearings. So I will make up some distance washers and I should be in
business. Will need a new oil seal and may make my own gaskets.
We were in the south of France in October on a brief visit from Italy, were
we regularly tour on our motorcycles. I look forwards to your news from
Norman Geeson.
Cheers
Dorien

[Hydroglen]

Geoff,
I downloaded info from Ashley's site that I think you helped him with. This
shows the unit I have, and not the one my manual shows.
Correct and so now I see that I may have a later 401 diff. After standing
on my head and cursing 12 times, figured out that the problem is that I have
ONLY one distance washer. Hence no proper bearing adjustment. How this unit
ran quietly for all these years is a mystery.
I will make up new distance washers and then set my lash accordingly.
By the way it would be hard to adjust with shims as it took quite a lot of
tapping and pulling to get the housing off the case .
I have 6" of snow in the driveway so no Bristoling for a while!
Cheers
Dorien

About the crown wheel carrier. The trunnions where the carrier is supported
by the side bearings are very thin. I became aware of two Arnolts that had
failures there, one of which I had sold. I took a look at the differential in my
last remaining car and found that it had failed as well. The load was being
supported at that point by the half shaft. In the other two cases the gears
were scrambled so I caught mine just in time. So we had new ones made to a design
which is much stronger. This was done by picking bearings that had larger
bores. The machinist that made them made extras and the last time I spoke with
him (2 years ago) he still had some on his shelf. I don't know the situation
now, but if anyone is interested, I can contact him. I can, at least, provide
photos and bearing specs.
Bill Watkins

[Geoff Dowdle]

Dorien,
(from memory only) , the two tapered bearings on the 401/404 type pinion
are preloaded with a long spacer tube and selective thick ground shims .
This does not adjust the mesh of the pinion with the crown wheel . The mesh
is adjusted by removing or adding thin brass shims between the two castings
as described in a previous email . I've had very little experience setting
the mesh of CW&P but a good starting point is by retaining the original
brass shims that you have.
It would be worthwhile having the CW&P lapped by a diff specialist before
reassembly as Ashley suggested.
Good Luck
Geoff

PS If you find the CW&P is badly worn or damaged there is a company in
Victoria, Australia that has made a small batch of Bristol CW&P's before .
I could make enquiries to get a batch of say 5 - 10 sets made if any one
else is interested.

[412usa]

> Bill,

I would be very interested in the diff modifications.

Peter McGough> > > > > >

[Hydroglen]

Geoff,
Thanks.......yes you are correct. In essence there are 2 adjustments. One,
for the bearings using the distance washers that come in different
thicknesses, and the second with the brass shims between the cases. If
either or both are off, then this will affect the CW mesh/lash.
When dismantling it took me some 10 minutes of careful tapping to split the
case and not damage the brass shims. That is what I meant when I said this
is a hard adjustment to make. Hopefully the original shims will do the
trick.
This rear axle seems to have suffered at the hands of some strange people.
Apart from the distance washer already discussed, the main carrier to the
axle itself had 1/2 the studs stripped or broken. I realized this as I was
unbolting it. I will have to drill and tap new threads.
The CW/P are actually in amazingly in good shape.
Thanks
Dorien>

Peter:
I tried to send a picture of the replacement crown wheel carrier and bearings
but it's in the wrong format for this site. If you (or anybody) will send me
a note to wmw79@aol.com, I will try to send you the picture directly. I called
Wayne Mitchell. He has 2 or 3 units on his shelf.
He can be reached at: wtmitchell@att.net**** He has a website:
www.dogrings.com** (He makes parts for Hewland gearboxes)
Bill Watkins