FOT'ers
I have NEVER in all the 19 years that I have been associated with these cars,
even heard of anyone losing control of a GT6-3 due to a problem with a rear
hub letting go.
It is usually the half-shaft/drive-shaft that does that trick, or very
occasionally the front vertical link inside the trunnion, or the stub axle,
after accident damage.
Of course, if you have the newest GT6, it has to be at least 27 years old by
now.
so therefore do the rear hubs, if they are original.
The bearings are supposed to receive grease every so often, and if they do
not...well.
In my opinion, if hubs have done less than 100,000 miles and have had their
bearings greased, (with the correct grade of grease), then they 'should be'
fine in normal road use, with normal road tyres.
But if they have done more miles, been greased less, been used with much
bigger,stickier race tyres and had a hard life out on the tracks,
then...perhaps not.
On (rubber 'dougnut' CV joint) rear suspension, the lateral cornering forces
are transferred by the wheel bearings through the hub directly from the
vertical link to the wheel. (swing axles, by contrast take nearly all the
cornering forces down the shaft to the stub axle bearings).
Consequently, 'rubber doughnut' rear suspension wears wheel bearings out
usually for three reasons:
1) Allowing the car to stand for a long time permits moisture to damage the
sensitive tapered roller bearings.
2) Incorrect assembly with the wrong preloads
3) Driving very hard with high cornering forces and inadequately rated
grease.
To make this suspension work properly, five improvements are needed:
1) A stiffer rear spring with an option of changing the ride height.
2) Telescopic Shock absorbers of adjustable rate.
3) A method of making the rear trunnions move more freely.
4) Reinforcement of the shock absorber mountings on GT6s.
5) Modification to the wishbone mounting bracket to allow camber adjustment.
The method that we have used for the trunnions, was to line bore the
wishbones and fit small replaceable ball races and spacers. Bearing No. KLNJ
1 1/8.
We also used stainless steel end caps and rubber O-rings, a cadmium plated
long bolt, and stainless steel grease nipples in each outer arm of the rear
wishbones.
The ride height can be changed by adding plate(s) under the rear transverse
spring.
This will also give more negative camber, but requires a lot of
experimentation.
(I left my road car as standard for now)
The only worthwhile rear telescopic shock absorbers, in my opinion are Konis
The Wishbone brackets will usually have to be lengthened by approx 1/2" to
increase negative camber.
To aid the understeer situation, I suggest you fit a firmly mounted rear
anti-roll bar of modest dimension 1/2"-5/8".
Whatever you do, don't go fitting stiffer front anti-roll bars. The limit is
the 1500 Spitfire 3/4" bar, in certain cases only, otherwise you will get a
feeling of less oll, more stability certainly, but go sailing straight on at
every corner! (ask me how I know)
One company had the gall to call this the 'ideal competition modification!'
GT6s fit softer springs than the Vitesse with shorter travel, and the fronts
particularly need stiffening from the standard 230 lb to about 400 lb.
Fitting adjustable height and rate Spax will then allow you to get the front
off the deck. The final road behaviour will depend very much on choice of
tyres. 175/70 are really ideal, (as the Avons on my Vitesse), permitting some
roll. 60 series tyres are much more fussy. Pirelli 185/60 or Goodyear Eagle
185/60 work well, as do Uniroyal 185/60.
Most of the other demonstrate very nervous performance in the wet. Use them
on a
5 1/2" or 6" wide wheel.
Back to the hubs!
X-raying and or Ultrasound Analysis may find faults.
If you are not planning to race your car etc, then the expense of having
special hubs cast and machined may simply not be economically feasible,
however, it is your money!
Secondly, John Kipping Triumph Spares in Coventry, England has/had a small
stock of brand new original factory rear hubs fairly recently, at a cost of
about 120 GBP per pair.
(another company called John Hills was also advertising new rear hubs for a
lesser cost, but those were, apparently, non original items, and thus I
bought some of Kippings)
Finally, I would recommend that instead of using the large nyloc nuts to
retain the hubs onto the rear axle, that you instead use the rather better
hig-grade nyloc type nuts which are usually found on the output flange of the
gearbox on the 1500 Spitfire.
(check that with Kippings) These are not so deep, so the nylon should
definitely reach the thread on the axle, and are better quality also.
Léon F Guyot
Triumph Sports Six Club
International Liaison Secretary
1963 Triumph Vitesse 2-Litre Convertible
Wimbledon, London, England.
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