QUESTION
I am finally installing the polyurethane front suspension Bushings I got from you some time back.
The steel tube sleeve that came with the Polyurethane Bushing set is a bit shorter than the width of the Bushing, when installed. Is this “correct”?
I thought that the steel tube needed to be a bit longer than the width of the Bushing so that the end Washers would contact the tube first, rather than rubbing on the Bushing face, so that the Bushing would be free to move with the motion of the A-Arm “wishbone”.
If I install as it is, then are the flat washers supposed to compress the Bushing material slightly before contacting the steel tube?
Approx measurement with my cheapo caliper, as installed in the Upper A-Arm inner pivot…
Length of the Bushing is about: 1.47” [1-15/32”], 37.34 mm
Length of the steel tube is about: 1.44” [1–14/32”], 36.57 mm
I will very much appreciate any clarification you can provide.
J.R. - Bellflower, California, USA
ANSWER
If you look at the original rubber bushes installed in the Elan front control arms, the crush tube is indeed slightly longer
The original rubber bush design and how it functions is totally different to Polyurethane bushes
The rubber bush has the outer steel jacket bonded by rubber compound to the inner crush tube
This means the inner crush tube is not free to rotate within the bush
With the Polyurethane bush the design is completely different and the bush is free to rotate around the crush tube
With the Polyurethane bush you do not want the inner crush tube to be longer otherwise this will allow lateral movement of the control arm during acceleration and braking
By making the crush tube slightly shorter this allows small amount of compression of the Polyurethane material which in turn prevents lateral movement of the control arm
Assembling the bushes - make sure the pivot spindles are dry and free from any kind of lubricant as the steel crush tube must not rotate around the 1/2" diameter spindles
The outside of the crush tube should be lightly lubricated to allow the Polyurethane material to rotate around the crush tube
These bushes then behave more like a hinge rotating around the pivot pin
Make sure you install washers at either end of the bush as this prevents end-float
Also install reduced height 1/2UNF Nyloc nuts that allows at least 2 to 3 threads to protrude beyond the nut as a safety measure
Copyright © 2023 Lotus Marques
I am finally installing the polyurethane front suspension Bushings I got from you some time back.
The steel tube sleeve that came with the Polyurethane Bushing set is a bit shorter than the width of the Bushing, when installed. Is this “correct”?
I thought that the steel tube needed to be a bit longer than the width of the Bushing so that the end Washers would contact the tube first, rather than rubbing on the Bushing face, so that the Bushing would be free to move with the motion of the A-Arm “wishbone”.
If I install as it is, then are the flat washers supposed to compress the Bushing material slightly before contacting the steel tube?
Approx measurement with my cheapo caliper, as installed in the Upper A-Arm inner pivot…
Length of the Bushing is about: 1.47” [1-15/32”], 37.34 mm
Length of the steel tube is about: 1.44” [1–14/32”], 36.57 mm
I will very much appreciate any clarification you can provide.
J.R. - Bellflower, California, USA
ANSWER
If you look at the original rubber bushes installed in the Elan front control arms, the crush tube is indeed slightly longer
The original rubber bush design and how it functions is totally different to Polyurethane bushes
The rubber bush has the outer steel jacket bonded by rubber compound to the inner crush tube
This means the inner crush tube is not free to rotate within the bush
With the Polyurethane bush the design is completely different and the bush is free to rotate around the crush tube
With the Polyurethane bush you do not want the inner crush tube to be longer otherwise this will allow lateral movement of the control arm during acceleration and braking
By making the crush tube slightly shorter this allows small amount of compression of the Polyurethane material which in turn prevents lateral movement of the control arm
Assembling the bushes - make sure the pivot spindles are dry and free from any kind of lubricant as the steel crush tube must not rotate around the 1/2" diameter spindles
The outside of the crush tube should be lightly lubricated to allow the Polyurethane material to rotate around the crush tube
These bushes then behave more like a hinge rotating around the pivot pin
Make sure you install washers at either end of the bush as this prevents end-float
Also install reduced height 1/2UNF Nyloc nuts that allows at least 2 to 3 threads to protrude beyond the nut as a safety measure
Copyright © 2023 Lotus Marques