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trunnions, what do they do?

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trunnions, what do they do?
#1
  This topic is about my 1976 Triumph TR6
caddyfixr Avatar
caddyfixr Gold Member Randy Warren
Norman, OK, USA   USA
ive been watching videos on restoring front suspensions and totally understand all the parts involved except for one. the Trunnion. i would like to know what purpose do they perform/serve or any other info/advice i can get being the first timer that i am. i searched google but can find nothing that explains their function.

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JOEVACS Avatar
JOEVACS Joe Carter
Hickory, NC, USA   USA
LFMTR4 Avatar
LFMTR4 Lou Mijares
Scottsboro, AL, USA   USA
This has an explanation, to go with the breakout above.

http://rareparts.com/trunnion

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caddyfixr Avatar
caddyfixr Gold Member Randy Warren
Norman, OK, USA   USA
not sure what you meant to send me with that "link" but all it shows is an illustrated parts break down of the suspension components. i have all of that and know where the trunnion goes, i just dont know what they do.
thanks

caddyfixr Avatar
caddyfixr Gold Member Randy Warren
Norman, OK, USA   USA
after going back thru the video again i can see that its just basically some odd engineered "ball joint". since that is the case, does anyone make some type of ball joint kit that you could install instead of the trunnion? or maybe even a new lower control arm/ball joint assy.

Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
Yes they are available from Canley Classics, but are they better? and if so how?

The front trunnion units have been used since the 50's even on formular 1 cars. They can have issues if neglected, but have a zillion miles of reliability behind them.

ng19delta Avatar
ng19delta Scott Roberts
Merchantville, NJ, USA   USA
1974 Triumph TR6 "Gypsy Rose T..."
Just go with the trunnion. Time proven, bulletproof, and as long as you use the OIL they call for, and NOT grease, which they are not engineered for, they last a good long time.

Scott

Krom Avatar
Krom Paul K
San Rafael, CA, USA   USA
Randy- the trunnion essentially provides a point of support and rotation for the vertical link and a connection for the lower control arms and spring pan to the vertical link. The trunnion provides a softer-than-steel home for nylon bushings through which run a steel bolt, which secures the lower control arm/spring pan assembly. The bolt holds the control arms to the trunnion and the bushings and bolt allow the trunnion to rotate versus the control arms as the wheel travels relative to the car.
The swiveling of the vertical link, by means of machined threads in its lower extremity, which mate with the internal threads in the trunnion, allow the left to right movement of the wheel.
The trunnion is the part that allows the up and down and the back and forth of the wheel to take place. There will be a quiz on Tuesday.

Fogspawn, CA, USA   USA
1974 Triumph TR6 "Machine"
trunnions swim with grunions.
their lubrication is often ignored.
they take a bit of stress as a steering pivot
get hammered when wheel hits
road pits. respect them.

tirebiter Jeff Garber
Dighton, MA, USA   USA
Yes an older style of steering joint that ball joints have replaced everywhere. The threads in a trunnion makes that side go up a little when the steering is turned. Not advantageous at all, in my opinion. I don't believe any new vehicle uses a trunnion anymore.

Replacing the entire steering knuckle and front wheel spindle/axle that utilizes an upper and a lower ball joint is the only way I can think of to delete the trunnion. I have never seen an available kit to do that but it probably would be advantageous.

Uberxy Avatar
Uberxy Steve Fox
Va, Charlottesville, USA   USA
I’m surprised also that someone hasn’t made a kit that uses one piece a arms top and bottom with bottom ball joints. I have seen a top tubular a arm for the GT6 that uses a simple rod end for the camber adjustment instead of shims.



SR
73 TR6
86 930

Anchor2 John Glynn
La Quinta, CA, USA   USA
One other thing not mentioned…..people see the brass trunnion and say “ its ashamed they don’t build cars like this anymore”

Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
In reply to # 1595495 by Uberxy I’m surprised also that someone hasn’t made a kit that uses one piece a arms top and bottom with bottom ball joints. I have seen a top tubular a arm for the GT6 that uses a simple rod end for the camber adjustment instead of shims.

Yes anything is possible. But really if it an't broke why fix it?

That trunnion was used on many other cars (such as Lotus, TVR and many race cars) Shure there are things on our cars that are dated and can be improved, but IMHO the trunnion is near the bottom of the list, if there at all!

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