Thursday, March 17, 2011

Two less things to go wrong

Picture this: you're in your Herald or Spitfire, GT6 or Vitesse. Maybe you're in town weaving around roundabouts and other traffic-calming slaloms, maybe it's Sunday morning and you're out in the country. Suddenly the front of your car slams down to the tarmac and you frantically try to steer to the side of the road, hauling on the wheel to stay away from oncoming traffic. As you sit there in a cloud of dust and hot tar, you realise that you've just joined the Broken Trunnion club.

It's not very exclusive.

A well-known weakness of small Triumphs is in their front suspension. The lower part of the cast iron uprights sits in a brass trunnion, and has a drilling up the centre for oil. It's that drilled section that fatigues and breaks, not the trunnions themselves, and there's rarely any warning. A former New Zealand Warrant of Fitness tester told me that when Heralds and Spitfires were new(ish), testers often had the uprights from cars with wide tyres crack tested. The Broken Trunnion club has been around a long time.

Last year I was lucky enough to get a ride to Prescott with Roy Lacey in his white GT6. His car's well cared for, so I was surprised when he joined the Broken Trunnion club a few months later. Car and owner survived, but the poor GT6 suffered a few dents and scrapes. Ouch!

There are several ways to reduce your chances of joining the Broken Trunnion club. Stripping and inspecting the uprights isn't foolproof, as small cracks and rustpits almost too small to see can act as stress risers. New uprights are available, so you can change them every few years. Another solution is to replace the uprights with Caterham 7 ones. You see, once upon a time, Lotus 7s used Triumph uprights. Caterham bought the rights to build 7s from Lotus, and eventually decided to get out of the Broken Trunnion club. Their solution was to replace the trunnions with a spherical lower joint - the rest of the upright's the same - and as the spherical joint doesn't need oiling, the drilling was eliminated.

A spherical joint kit for Triumphs is sold by Canley Classics.When I heard that Roy's car had broken an upright, I decided to try the new uprights on my Herald, and ordered a kit from Canleys. Just knowing that the car doesn't have a built-in suspension weakness any more, and that it's not going to drop it's nose on the ground, was worth the cost. I finally got around to fitting the new uprights the other day - see below. The red tart is booked in for a wheel alignment on Monday.

I painted the new uprights, and fitted the top joints and wishbones originally destined for the GT6 - that now has adjustable top wishbones instead.

My Herald has Vitesse brakes and front suspension, so Herald conversions may look slightly different. The red brake hose is a special braided version. And yes, I cleaned the surface rust off the brand new stub axles before the hubs went on!


Blogger Darren Holliday said...

Hi I was wondering if I can chat about the Herald uprights with you?

Could you email your adress to dwholliday at gmail dot com

if thats ok?


8:32 pm  

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