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Triumph TR6 - Trunnions - what do they do?

I continue to have problems with my front left wheel. I've replaced the bearings, the upper ball joint and now the stub axel, but on lock steering to the right, the brake rotor still touches the front tip of my trunnion (bolt & washer).

Can anyone tell me, what exactly does the trunnion do? how does it work? and when do you know that it needs replacement? If it is packed with grease instead of oil, does it need to be periodically re-filled? tks
Mati Holland

Mati--Quite simply, the trunnion is the lower pivot point (the upper ball joint being the other) for the vertical link. It is made of brass and thus susceptible to corrosion and wear, particularly if grease instead of GL3 gear oil were used. The only way I know of to find out it if it's worn is to disassemble the vertical link.

If your rotor is touching the trunnion, I'd replace the grease seal with the correct felt one (there are two felt thicknesses supplied in bearing kits; I used the thicker of the two). Also verify you have the correct inner wheel bearing (if the ID is too big, it could cause the hub/rotor to contact the trunnion).

Keep us posted.

Rick O.
Rick Orthen

On my TR3A, I have never used oil in my front trunions. Always grease. The early TR's all have a grease fitting for this. I got 50,000 miles on the first set of trunnions with lots and lots of gravel rally driving and now have 108,000 miles on the 2nd set of trunions with paved highway touring and a grease job every 2,000 to 3,000 miles.

The TR3A has a type of "cam disk" that is bolted to the inside top of somewhere to limit the turning on the lock position. The hole is off center and you can bolt this cam like washer about 3/4" diameter and 5/16" thick to set the lock to lock positions to avoid any rubbing.

Maybe this can help.

Don Elliott, 1958 TR3A
Don Elliott

Hi Mati
The TR6 has a stop to prevent this happening, it is not as complicated as the TR3's but it still needs to be there, it is bolted to the inside top of the trunion with a 5/16" bolt.
Ron
R. Algie

I'm not sure I'm buying the felt ring theory as a cause of my problems, but the fit of the bearing could offer an explanation. As for the "stop" both the left and right appear to be the same size. I don't think that this item is subject to a lot of wear and been worn down.

I feel like on hard lock steering, the whole wheel leans out a little, bringing the low side of the disc closer to the trunnion. How much tilt is normal, what controls the tilt (springs,shocks etc?)

When I raise the car on jacks, I can't seem to re-produce the contact.

Mati
Mati Holland

Mati-If the trunnion bolt head or nut is contacting the rotor, the steering stops definitely need to be adjusted. If you look at the inside of the rotor face, a groove will probably be present. The bolt on the stop can loosen and cause the eccentric collar to move enough change the adjustment. I grooved 2 rotors before I found the cause.
Berry

From what it reads you didn't really go after rebuilding the front end. What about all those bushings & bearings that Moss calls the lower A-Arm kit? I replaced mine about 8 years ago, and the original nylon bushes were SHOT - I mean about worn in half. If those are worn the pivot bolt will flex, which could cause your problem. I recommend you you get an upper & lower A-Arm kit in polyurethane, and rebuild it.

Hopefully the bushes are better now, too. The ones that came with mine were drilled out pipe that were pure crap. Tossed them and got real bronze bearings - I think I have dimensions if needed.

Brent
Brent B

This thread was discussed between 13/10/2003 and 15/10/2003

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