Rear ARB drop link adjustment

[StevehS3]

The drop links are adjustable in length and I wondered where there was any guidance about how to set the correct length? Strangely on my factory built car the N/S is set longer than the O/S. I have read somewhere they should each be set as short as possible. Any thoughts? 

[Paul Richards]

I don’t think there are any problems with length. Important thing is that there is no pre load when car is on flat ground. 

[John Vine]

2 hours ago, StevehS3 said:

 I have read somewhere they should each be set as short as possible. Any thoughts? 

You're correct.  The Assembly Guide says:

 

This photo is from CC's Workshop Notice 460 ("Rear ARB and Wheel Speed Sensor Assembly"):

JV

[StevehS3]

Great information thank you both. Much appreciated. 

[John Vine]

Looking more closely at WN460 (I can send you a copy if you want -- just PM me your email address), it appears that the droplinks could well be unequal length depending on whether the car has Watts rear suspension.  Earlier cars with Watts tended to suffer a pre-load on the ARB due to drop-link mounting brackets of unequal length.

What year is your car and do you have Watts?

JV

Edited December 10, 2023 by John Vine

[Colin_T]

 

i had one of mine disconnected when doing the corner weights on level platforms.

then reattached it adjusting the length longer/shorter so that it went through the hole with no lifting or pulling of the roll bar. Was also handy to see it on the scales making sure the corner weights didn’t change when it was tightened up. 

[StevehS3]

2 hours ago, John Vine said:

Looking more closely at WN460 (I can send you a copy if you want -- just PM me your email address), it appears that the droplinks could well be unequal length depending on whether the car has Watts rear suspension.  Earlier cars with Watts tended to suffer a pre-load on the ARB due to drop-link mounting brackets of unequal length.

What year is your car and do you have Watts?

JV

Thank you John. I have sent you my email address.

[John Vine]

Steve, YHM.

Reading the WN again, I seem to recall that the problem came about because the original RHS bracket, which was used to carry the speed sensor, had different dimensions to the LHS bracket required for cars with the ARB.  This led to a pre-load on the ARB (as Paul mentioned above).  The fix was to use a revised RHS bracket to match the LHS (I think).   Although my car has Watts and an ARB, I'm not sure the "Watts" reference itself is relevant.  The WN seems to relate more to (early) cars with a rear ARB, with or without Watts -- but I stand to be corrected! 

It would be worth checking whether your ARB brackets are symmetrical.  If they aren't, maybe that's why your droplinks have different lengths?   Also, you could detach one droplink with the car is on level ground, and check whether that droplink still lines up with the ARB arm (as Colin-T mentioned above).

JV

[StevehS3]

3 minutes ago, John Vine said:

Steve, YHM.

Reading the WN again, I seem to recall that the problem came about because the original RHS bracket, which was used to carry the speed sensor, had different dimensions to the LHS bracket required for cars with the ARB.  This led to a pre-load on the ARB (as Paul mentioned above).  The fix was to use a revised RHS bracket to match the LHS (I think).   Although my car has Watts and an ARB, I'm not sure the "Watts" reference itself is relevant.  The WN seems to relate more to (early) cars with a rear ARB, with or without Watts -- but I stand to be corrected! 

It would be worth checking whether your ARB brackets are symmetrical.  If they aren't, maybe that's why your droplinks have different lengths?   Also, you could detach one droplink with the car is on level ground, and check whether that droplink still lines up with the ARB arm (as Colin-T mentioned above).

JV

Got the WN thank you John. The above makes sense. I will take a closer look at the brackets but that may well be the reason why one droplink was set longer than the other. I am fitting new droplinks over winter. I am thinking that I will fit the O/S that was shorter first and see how the N/S one lines up then check for preload with the car sat on the floor.