rear track rods

[stag8manod]

As requested, Son showed me how to upload pictures. Brackets are all steel fabricated, mig welded, heli-coiled and lock-tighted to the Trailing arm. The Poly bushes are front radius arm bushes machined slightly smaller. Cheers Ian A
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[Motorsport Micky]

That looks nice, Is that a standard fitment as used to be offered by Monarch ? or is it your own variation ?

In the first picture of the attached files there appears to be a definite crack in the trailing arm in front of the trailing arm mounting bracket, is it a "trick of the light" or something else ? I'd be worried myself that the drilling of the trailing arm for the bracket attachment would introduce a potential fail point, all other factory holes in the arm are fitted in the plane of arm movement and swing ie up and down, whereas these holes work across the car and have compressive and elongating forces applied (sometimes rapidly) that's like wiggly woggling a piece of metal to fatigue it and cause it to snap.

Micky

[stag8manod]

Hi Mickey, I don't think so but I will run it over the pit and double check. For the the refurbishment both Trailing arms were run over with a needle gun(descaling air tool) which gave them dimpled effect. The center pivots are probably very close to, or the same as Monarchs due to the available space. The outside mounts are all my own design and make.
Cheers Ian A

[Lingen]

Mickey.
I may be wrong here, but the manner in which the trailing arms are mounted on the car creates negative and positive camber in the rear wheels as the suspension flexes. Surely these radius rods, attached as they are to the diff back plate, will strongly resist this movement. Hence the crack (if it is). The Monarch (?) diff mounting had a swinging pivot at this point of attachment that allowed a balanced lateral movement to each arm.
Mike

[Motorsport Micky]

Mickey.
I may be wrong here, but the manner in which the trailing arms are mounted on the car creates negative and positive camber in the rear wheels as the suspension flexes. Surely these radius rods, attached as they are to the diff back plate, will strongly resist this movement. Hence the crack (if it is). The Monarch (?) diff mounting had a swinging pivot at this point of attachment that allowed a balanced lateral movement to each arm.
Mike

Dunno… I've found this photo of the advertised Monarch set up and it looks like the outside of the track bar attaches to a ball joint which attaches to a bracket plate which then passes underneath the trailing arm sharing the same area as the shock absorber mounting platform. There's a separate nut showing in the photo which I take to be a vertical nut and bolt attaching the track bar through an additional hole drilled in the corner of the shock absorber platform.

Stag tramp bars.jpg


As you say the track bars being non flexible will cause a degree of negative or positive camber as they swing through their arcs hinged from the diff plate, the only flexible mounting point are the trailing arms bushes to the subframe further "up country". If we were talking a track car the compromises in suspension movement and geometry and twisting of the trailing arm might not be acceptable but we are using these on a GT tourer with great lolloping wheels and tyres as big as can be wedged under the arches, any pretence at needle sharp handling can be put to one side as long as we can stop the Stag "twitch" caused by unsticking driveshafts.

Micky

[Lingen]

Mickey.
Then the one I saw wasn't Monarch. The attachment on the diff back plate was a centrally pivoted vertical link, not a fixed one. This allowed the trailing arms to pivot normally during suspension travel, but would control them during the sudden release of the splines unbinding. I think there was something similar on the rear axle of a rover SD1 to control lateral movement.
In practice, I have found that slightly firmer poly bushes and multi splined driveshafts have eliminated it on my Stag. The way I drive it anyway!
Mike.

[stag8manod]

As the track arms were part of a major refurbishment. all Poly bushed, CCD CV axles, 3.45 diff, new Quill shaft bearing(SKF), Quill shaft housing strengthened, 3/8 UNC/ 5/16 hub studs, new seals in the diff and straightened the twisted diff mount to the body. It must have been like it all the time I've owned it (25yrs), The rest of the body area is undamaged and original, A mystery. Because of all the changes I don't know which has contributed most to the improved although firmer ride and handling.
Cheers Ian A

[Ian928]

Interesting. If the arms are lower at the Wheel than at the diff, it will create more toe-in when the suspensjon is compressed. That would create a passive rear Wheel steering by twisting both rear Wheels into the turn when the car lean over. My Porsche 928 has a system that does almost the same, although this uses forces on the Wheels instead of pivoting.

[stag8manod]

An update over a couple of concerns voiced.
1/ I have thoroughly checked both trailing arms and have not found any evidence of stress or cracks.
2/ The car when back on its wheels with the suspension settled the track arms are virtually level.
Any comments accepted.
Cheers Ian A

[Motorsport Micky]

That's reassuring, difficult to judge in photos, glad it's ok. See how you find it in operation

Micky