Radius arm help

[vito84]

Good morning guys,

i've bought in the past a RH radius arm from a uk supplier in order to replace the rusty one on my Europa TC. I measured the distance between the center line from the pivot pin from the center line of the wheel axis. I noticed that one radius arm is longer 1cm more the other one. Do you know if the gearbox output shaft axis is algned with the rear wheel centre axis?Someone of you know the right measures for the Europa TC radius arm?

Thank you

Edo

[4129R]

Do you call the radius arm the tubular strut with rubber bushes which goes between the gearbox and the hub carrier which is parallel to and directly below the drive shaft?

[vito84]

This is the radius arm:

[Roger]

No idea why radius arms are different lengths. Maybe they are not both TC? Is one free-market and the other original?
No, the gearbox output shaft is not in a direct line with the rear wheel centre.

[rjbaren]

You could try getting another new arm for the other side and then they might at least be the same length.  I also noticed, you are the guy who makes the chassis Tee section.  Maybe you should make these trailing arms as well.  I also believe RD Enterprises sells them for about $350.00 each.   

[GavinT]

Hi Vito,
Is that a pic of the S2 radius arm?

I ask because I believe the S2 and TC/TCS radius arms are different.
The rear Y part of the chassis is wider on the TC/TCS to accomodate the Twink.
The bolt patterns for mounting the upright are also different.

It occurs to me the forward pivot point for the TC/TCS is likely different (further out) from a S2 due to the wider Y.
Perhaps that impacts the radius arm length?

[Grumblebuns]

I don't have a TC radius/trailing arm to examine but do have both an S2 and a TCS arms to measure dimensions. This is what I  discovered:

Dimension 1: Both my S2 (Pic 1) and TCS (Pic 2)  measure at around 36” from CL of front pivot point to CL of rear bearing housing. I suspect that the TC radius arm is the same. I can't explain the discrepancy between my measurement and your drawing at 32.562”.

Dimension 2:  Big difference between the S2 and TCS, S2 measures at around 20-1/16” (Pic 3), TCS at around 16-9/16” (Pic 4). Difference due to the angle of the front pivot. (Pic 5). Again, I'm suspecting that the TC measurement will be closer to the TCS.

Have you physically measured your arms and compared them to the drawing? Looking at the angle of the front pivot point on the drawing, this could be for an S2?

[vito84]

I don't have a TC radius/trailing arm to examine but do have both an S2 and a TCS arms to measure dimensions. This is what I  discovered:

Dimension 1: Both my S2 (Pic 1) and TCS (Pic 2)  measure at around 36” from CL of front pivot point to CL of rear bearing housing. I suspect that the TC radius arm is the same. I can't explain the discrepancy between my measurement and your drawing at 32.562”.

Dimension 2:  Big difference between the S2 and TCS, S2 measures at around 20-1/16” (Pic 3), TCS at around 16-9/16” (Pic 4). Difference due to the angle of the front pivot. (Pic 5). Again, I'm suspecting that the TC measurement will be closer to the TCS.

Have you physically measured your arms and compared them to the drawing? Looking at the angle of the front pivot point on the drawing, this could be for an S2?

Hi,

I took the measure showed in the attached drawing from all the 3 radius arm in my possesion:

Rusty LH radius arm measure 884 mm (i think but i'm not sure that this is the original one)
LH radius arm measure 852 mm (this is actually fitted on the car in order to replace the rusty one)
RH radius arm measure 868 mm (this is galvanised and was already fitted on the car when i bought it)

So the best thing to do is try to understand which is the correct size and than try to rebuild both arms with the same lenght and same pivot angle as you say in your reply.

[Grumblebuns]

It's odd that there is such a large discrepancy in all three of your measurements. It's possible that my measurements are not all that accurate also. I need to find a method for locating the center of the large hole where the bearing carrier and axle fit. I'll take another more accurate measurement when I do and get back to you.

Joji Tokumoto