Bristol 400 rear axle gears

[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.

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[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