Rear tie rods - SH type
Discussion
Could have done with a set of these when I bent one a couple of years ago! IIRC I paid 90ish for a set of second hand (unused) ones. SHPUB delivers good value yet again!
I would imagine that due to the reduction in compliance (the originals have effing huge rubber bushes) accurate adjustment is VERY important. Not a criticism just a warning.
When I fitted mine I adjusted the link length so the fixings went in easily when the suspension was set at normal ride height. I presume that this means there is a small amount of toe in steer with suspension compression and an equal/opposite amount of toe out on droop.
I would imagine that due to the reduction in compliance (the originals have effing huge rubber bushes) accurate adjustment is VERY important. Not a criticism just a warning.
When I fitted mine I adjusted the link length so the fixings went in easily when the suspension was set at normal ride height. I presume that this means there is a small amount of toe in steer with suspension compression and an equal/opposite amount of toe out on droop.
I bent mine by about 6 inches which prompted the design The bend effectively shortened the bar by about an inch or so. Doesn't do much for the rear suspension and handling. The bushes are not that big - to be more honest they vary in size - and the compliance isn't that great. The bending is caused by the length adjustment in the centre which creates a weakness. Pressure on the bar then causes this weakness to bend or in some cases actually break.
The toe change happens anyway as there is compliance in the A frame bushes. The tie rod effectively limits this movement and provides stability.
The most critical point is that they also effectively define the toe in and this does need to be set up correctly. By simply twisting the bar and then locking it using the lock nuts it makes this job very easy indeed. The tube is square so it makes it easy to turn with a spanner. The bar is also offset so that it is moved in by about 12 mm which helps with wheel clearance.
I suspect a lot of cars out there simply run on the setup they had originally - which is far from optimum.
The toe change happens anyway as there is compliance in the A frame bushes. The tie rod effectively limits this movement and provides stability.
The most critical point is that they also effectively define the toe in and this does need to be set up correctly. By simply twisting the bar and then locking it using the lock nuts it makes this job very easy indeed. The tube is square so it makes it easy to turn with a spanner. The bar is also offset so that it is moved in by about 12 mm which helps with wheel clearance.
I suspect a lot of cars out there simply run on the setup they had originally - which is far from optimum.
Edited by shpub on Saturday 29th December 15:55
shpub said:
...The most critical point is that they also effectively define the toe in and this does need to be set up correctly. By simply twisting the bar and then locking it using the lock nuts it makes this job very easy indeed...
I thought toe was set by the adjuster on the A-frame and the link was used to keep it in spec under accel/decel?shpub said:
...I suspect a lot of cars out there simply run on the setup they had originally - which is far from optimum.
Any recommendations for either of a road or track setup?I seem to recall a discussion on this some years ago where Joolz Lane thought that the tie rod was trying to act as a torque reaction arm but was located wrongly relative to the axle line (no leverage)... and the huge front bush was necessary because the arc that the A-frame swings through (or is supposed to, given sound bushes) means that the tierod would have to alter length as it moves, which it obviously can't, so the bush has to be massive to allow it to deflect instead. In other words the whole thing is a crock of poo.
But he could be wrong...
and as I've said before, why the hell TVR didn't just amend the original trailing-arm setup like Lotus did with the otherwise identical installation on the Esprit will have to remain a mystery...
Both of my tierods are bent at the threaded section however the tyres don't wear unevenly.
But he could be wrong...
and as I've said before, why the hell TVR didn't just amend the original trailing-arm setup like Lotus did with the otherwise identical installation on the Esprit will have to remain a mystery...Both of my tierods are bent at the threaded section however the tyres don't wear unevenly.
shpub said:
The bar is also offset so that it is moved in by about 12 mm which helps with wheel clearance.
That sounds useful Steve - with the cerbie wheels on there the clearance is quite tight. 12mm will do the job!I reckon mine are set up just right at the moment, I'm thinking a good way to keep the alignment would be to hang a plumb line from the wheelarch to line up with a mark on the hub, should be good to within a 1/2mm.
The ARC swinging is an interesting point. The movement on the bushes is not enough to compensate and given the rather hard composition of the bushes the real give is really in the A frame bushes as there is nothing triangulating them at all. Without the tie rod, they move sideways and it this movement that the tie rods control and make predictable.
When my tie rod bent 6 inches, it effectively shortened the rod by about 1/2 to 1 inch. It was difficult to remove but it does show how much potential play there is in the A frame. I only noticed the problem because the rear wheel was a lot closer to the wheel arch than it was on the other side. Based on the big bush deflecting argument, this shortening would not have been a problem as the bushes should have deflected, but instead the bar simply bent. Again indicating that there is little or no movement in the tie rod bushes. Putting the tie rod back to its correct length and the wheel went back into its correct position.
I also am a great believer that there is too much vertical wheel travel at the back anyway and this is what contributes to the short life of the UJs.
When my tie rod bent 6 inches, it effectively shortened the rod by about 1/2 to 1 inch. It was difficult to remove but it does show how much potential play there is in the A frame. I only noticed the problem because the rear wheel was a lot closer to the wheel arch than it was on the other side. Based on the big bush deflecting argument, this shortening would not have been a problem as the bushes should have deflected, but instead the bar simply bent. Again indicating that there is little or no movement in the tie rod bushes. Putting the tie rod back to its correct length and the wheel went back into its correct position.
I also am a great believer that there is too much vertical wheel travel at the back anyway and this is what contributes to the short life of the UJs.
Edited by shpub on Saturday 29th December 21:32
shpub said:
...I also am a great believer that there is too much vertical wheel travel at the back anyway and this is what contributes to the short life of the UJs.
Isn't UJ life more to do with absolute angle rather than travel? eg if the driveshaft is at 45deg to the input and output shafts then the life will be a LOT less than if they are all in-line? Obviously if suspension travel increases the angle, this is detrimental but I would have thought this dynamic situation is less significant then the normal ride height angle. This presumes that most of the time the ujs are nearer to the ride height angles. Under acceleration (squat) the angles become lower so better suited to UJ longevity but conversely under breaking (greater torque than under acceleration) the opposite is true.Not contradicting you Steve I'm just trying to get my head around the subject.
If you look at the full suspension travel and the resulting angles that the UJs go through, at maximum droop and compression, the UJs are out of their sweet spot for reliable operation. I limited the travel (for other reasons) and haven't had to replace a UJ for 5 years now despite running 350/400/525 bhp and slicks on the car. It is the extremes that cause a problems. Variations in ride height still keep the UJ in the sweet spot. I have also severly lowered the car as well. The key to long UK life IMHO is to keep the UJ angles in the sweet spot.
TVRleigh_BBWR said:
Wedg1e said:
TVRleigh_BBWR said:
Lol somthing else for me to buy.
Could they be adapted to fit a trailing arm set-up.
anyone got the spec's of what lotus did to up-date the esprit design.
Thanks
Leigh.
Yes, they added a top link.Could they be adapted to fit a trailing arm set-up.
anyone got the spec's of what lotus did to up-date the esprit design.
Thanks
Leigh.
Thanks
Leigh.
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