Layrub tips from Vic

[Keith Clements]

From August 2014 Flat Four.

Layrub Related
The Club car had a rough driveline, particularly on the overrun. The general noise in
neutral was the same as in gear. Also a curious pinging sound. It was suggested
something was loose inside the shaft. I had a reasonably close look at the Layrubs and
bolts before driving to PN, and again on return. Looked OK with no obvious fretting. I
noticed it had some substitute centre bearing, with little apparent flexibility. So we
checked the driveline with the car on blocks in the Shed. Noise was apparent although
hard to pinpoint to the front Layrub or the centre. Decided to fit a reasonable original
centre bearing assembly, but on disassembly noted one Layrub bolt slightly loose
although still pinned. Tightening this seemed to quieten. Anyway, we proceeded to
change all, and now fine, despite the front Layrub starting to deteriorate. One moral of
the story would seem to be that Layrub bolts need to be checked with a spanner, not just
inspected. To avoid damaging the split pin, try turning bolt and nut together.
Layrubs have always been a source of problems and now especially so. The few good
ones are all hard with age and rapidly fail, particularly if used in the wide angle front
position. Layrub bolt seatings should be thoroughly clean and without bUlTS. The plain
washers are intended to be placed against the Layrub to lessen the tendency to twist the
insert. The washers should be smoothed on the faces, and fitted with a hint of grease.
It is tedious to remove and fit split pins. Many simply forcibly undo, although the
hard springy type of pin will likely damage the thread. Refitting is a pain. The book says
to tighten to the next hole. This is fine for a muscular mechanic working under a hoist
but very tedious when lying on the ground. The position of the holes needs to be marked
on the bolt ends. The HT Y2 inch bolts can easily stand 60 Ibs.ft and 30 would be a
reasonable minimum, but this range can often be accommodated in less than 1/6 of a
turn. Can carefully drill an additional cross hole. A split pin is important; a loose bolt
can wipe out the hydraulic lines, and a disconnected driveshaft can hit the road and pole
vault the car, as at least one member can attest. As previous the front flange bolts
should be fitted head to the front of the car. (Many other makes are fitted with a safety
stirrup to ensure the drives haft never contacts the road. A simple mod.)
Spring washers function in two ways; maintain pressure and some types have a barbed
end which resists rotation. To be fully effective would need two of the latter and have to
delete the plain washer, with consequent severe and damaging twisting of the insert.
Possibly for a car regularly checked, and with a driver able to identify and respond to
suspicious noises, assembly very tight with one spring washer and maybe Loctite
suffices, but the local wofmay question the missing pins. (And HT UNF bolts with high
capacity Nyloc nuts are too expensive!)
On my car I replaced all the Layrub bushes about 1974. Cost was 30s each; altogether
in real terms amongst the greatest single expenditures on the car ever! I damaged one
bush fitting it to the ferrule, but otherwise all were still OK 20 years and 100,000 miles
later.
The range of strange noises with the floorboards removed is still bothering and
bewildering. I have increasing respect for my Austin Seven, which, although noisy, had
the gearbox exposed inside the car and bare metal floor, and an open hole for the
handbrake, and no mystery noises.
Incidentally, if anyone knows of a technique for softening old Layrub rubber, this
would be worth a few thousand dollars to the Club!

[Keith Clements]

I now use new Layrubs available from heath@howdon.co.uk
Howdon Power Transmission Limited.
Paganhill Lane, Cainscross, Stroud, Glos, GL5 4JT England.
Tel: +44 (0)1453 750814 / Fax: +44 (0)1453 765320

I use 1/2 BSF Nylock nuts from NamRick with Loctite.

Also discussion previously on JT.