Bristol 400 rear axle gears

[Hydroglen]

The rear axle started wining badly. I took the main case out (not a lot of fun! ) and the problem is in the pinion bearings. They are different than what my parts book shows ( tapered versus plain) and in-fact several changes seem to have been made including an oil seal?? This changes the distance within the nose case.
Anybody done this repair?
Thanks,
Dorien Berteletti
In Canada

[Ashley James]

Dorien as it happens mine is noisy (they all seem to be) and I'm
sending it to Norman Geeson who you can read about on
www.kda132.com For many years he's specialised in overhauling and
raising the ratios of Post War Rolls-Royce and Bentley rear axles
and he does them for all the top specialists.
He's already done a 403 for someone in the club who'd twice had his
overhauled by axle or Bristol specialists and they'd done so much
damage he had to buy another Crown Wheel and Pinion. Norman did it
properly and it was quiet too.

Norman will have taper rollers ground to fit, he has the special tools
necessary to build the thing and he will spin mine up on the gear
cutter's test rig to find the the quietest setting.

Obviously your being in Canada makes it impractical to have Norman do
it, but once he's done mine, which is possible the same as yours with
the screw in pinion bearing housing, he'll have the bits you need and
be able to talk you through it.

I hope to have it out before Christmas but am currently fitting a
rebuilt Close Ratio Gearbox and MGB Clutch, so would like to see what
it's like before I dismantle it again.

I plan to tour France in it next year (we've five places left if
anyone would like to join us - please email me for details) and would
to reduce the noise as much as possible and be sure that it doesn't
brake down.

Ashley

[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

[Hydroglen]

Thanks Bill,
Certainly pictures would be good to have. Perhaps you know the Arnolt that
Bill Mac Farling owns, that he converted with a Chev 289.
He changed the rear axle, (Mercury Monarch) to handle the
horsepower.
Cheers
Dorien Berteletti

Dorien:
The pictures have been sent. I don't know Bill MacFarling but I have seen 3
or 4 Arnolts that were converted to Chevrolet. I almost did it myself after I
cracked a crankshaft, but I came to my senses and bought a new crank. The
suitability of the rear axle was one of the issues. The other was the class (with
Can-Am cars & such) that I would have to run with at the Monterey Historics. It
was only possible to qualify for entry because of some publicity that Wacky
had imported a couple of cars without engines with the intent of installing
Chevys. I asked Michael Arnolt about this and he said that his father had never
followed through on that.
Bill

[Kevin H]

The photos from Bill are attached to this post.

Tip: When uploading photos to this site, please ensure you upload individual photo files with an image file extension. The site will only accept .gif, .jpe, .jpeg, .jpg, .png - max image size 1024 x 1024 pixels and max file size 300kb. .pdf is also accepted up to 400kb

[Bellerophon]

I have previously written about the rear axle on the Bristol, but will
repeat some of what I have said.
First, all the gears for most of the 2 litre cars were made by ENV Gears of
NW London, these were precision ground gears of a very high standard. However,
ENV went out of business (not certain of the date but think it would be in
the later 50's). Bristol had to then resource, and went to Salisbury for the
rear axles which were not manufactured by the same methods and therefore not
as accurate. The result of this was that Bristol experienced noisy axles, so
much so that they had to take action, so appointed Percy Kemish their racing
engine man to sort out the problem. He told me that it took a while but found
that the problem was a quality one and was cured by better finish in
manufacturing, and a more selective fit. (not easy to get right)

Now the workshop manual gives full instructions on setting up the crown
wheel and pinion, and as they have been run together for some time now should not
cause a problem. One point to note is that the ratio is stamped on the
components, and would be most likely a 3.9 or a 4.22 on the overdrive cars.
However some cars which were used for sporting activities had the later ones fitted.

If some of our members do not have a copy of the workshop manual and intend
to work on the cars, they will save themselves a lot of bother by having the
facts to hand.

My regards,
Bellerophon

[Hydroglen]

My gears are infact stamped ENV 10 x 39. The Pinion and Crown also have the
numbers 2130 handwritten with an indelible marker.
The only damage to the sytem is some slight nicks to the bolt heads securing
the Crown. This would have happened as the pinion slid back as there was no
spacer to hold the bearing/companion flange. The faces are in great shape.
Considering I have toured England, Scotland, Wales, France and a good part
of Eastern Canada, with my 400, I conclude that I am very lucky the pinion
staid in place. It decided to move whilst in the safety of my driveway as I
was leaving for a club event in New England.
Given that you have experience on the subject, there are a couple of points
that you might help me with.

I would be curious to see a picture of the CW bearing caps and their fixed
counterparts. On mine, the castings do not match so as to make a perfect
piece. Infact there is a ledge or notch were the two halves meet. Seems as
if the bearing caps were from a different carrier / casting. Can it be
partly 400 and partly 401? I have sent pictures to the webmaster to
illustrate the point.

Some of the studs that hold the carrier in the rear axle have been crudely
welded on the inside of the case. This caused me much grief as when undoing
the nuts the stud started turning. They could not act as bolts and back
out, because of the welding. Round and around we went.
I had to carefully cut them off with a high speed grinder and now will retap
and repair WITHOUT welding.
Bodges on my car, or has this been seen before?

Regards

Dorien

[Bellerophon]

Dorien, I am sorry to read that some butcher has managed to get his hands on
your backaxle, but after 60 years with the car passing through several hands
it is sod's law that one could be a butcher.

However, when the axle was new the bearing caps matched perfectly and the
studs were not welded into position, so if you are able to fix this, it would be
good.

Now, do you have a copy of the workshop manual? if not I urge you to obtain
one from the club as the back axle is fully covered (exploded photos also)
with all the information you require. As for the missing spacer in the pinion
drive, you will see that the only major modification was to the pinion, whereby
it went from a screwed assembly to a shimmed one, hence this may have thrown
the butcher.

I am certain that with the right information you will return the car to its
former glory.
My regards,
Bellerophon

[Ashley James]

Don't forget that a full workshop manual can be downloaded from the
technical pages of www.jel450.com courtesy of Geofff Dowdle and his
chums in Oz.

Ash

[Hydroglen]

Yes, already done some days ago. It was those pictures that clued me in.
Thanks
Dorien

[Hydroglen]

Thanks .....as I suspected. Yes I have my 400 manual and parts book, as
well as having downloaded the 401 manual from Ashley.
Part of my initial confusion was that it looked different from the blowup /
parts of the 400.
Whilst surprises like these are annoyng, the upside is greater
familiarization with the car and "meeting" helpfull and knowleadgeable
people.
Thanks again.

Dorien

[RGSchmitt]

Hi all -

Bill sent me to the right place exactly 4 years ago, when I needed a
new crankshaft. I got the last one "off the shelf" from Henry Velasco at:

Velasco's Billet Crankshafts
12422 Benedict Ave.
Downey, CA 90242
310 - 862 - 3110
Fax 310 - 803 - 1221

Here's a photo before I packed and sent it by air mail to New Zealand:

http://www.frazernash-usa.com/images/crank121404b.jpg

Still ticking!

Bob