8 replies to this topic

[Curley]

Afternoon Guys, I've been doing some research and wanted to get some feedback. 

 

I've been running negative camber bottom arms on all my mini's for years and never had any issues with the top arms. However I recently came across an old Abingdon ST manual for the 1275GT & Cooper S. There is a section in this that states that a metal plate needs to be added to the underside of the top arms:

 

 

I also note that Mini Spares makes reference to this on a number of their Negative Camber products (http://www.minispare...px|Back to shop) where they claim this is to stop undue strain on the drive shafts.

 

Given the fact that the forum is not full of people claiming broken drive shafts, can somebody please help me understand how changing the camber can affect the driveshafts - after all this is what CV joins are for - and how adding some metal to the top arms fixes it?

Edited by Curley, 28 November 2014 - 06:44 PM.

[nicklouse]

iirc it is just a small plate which is placed under the small angled return bump stop which just means the wheel does not drop as much as it could before the bump stop contacts the arm.

 

it helps control wheel movement and any steering effect cause by this extra movement.

[Ethel]

How many Minis have lost their rebound rubbers at some point over the years though? Your shockers will also limit the rebound travel of the upper arms.

 

Since neg camber is achieved by longer bottom arms it does follow it'll lengthen the driveshafts by pulling them further out of the inner joints. It is hard to see that about 3/8" less droop would make much difference though. 

[Spider]

The early cars had a different  Lower Arm Inner Pin (less of a wiggle in them) and it was intended to prevent the drive shaft contacting that, this pin was changed (I think in the late 60'S?) and that was no longer an issue,

 

however,,,,,

 

it is very necessary, espeicaly if the ride hight is around standard or higher, to prevent ball joint bind (that is when the ball joint pin cocks over and contacts the cup, but there is still travel in the suspension) on the upper ball joint at all times and the lower ball joint when not steered in a straight line.

[Curley]

it is very necessary, espeicaly if the ride hight is around standard or higher, to prevent ball joint bind (that is when the ball joint pin cocks over and contacts the cup, but there is still travel in the suspension) on the upper ball joint at all times and the lower ball joint when not steered in a straight line.

 

Makes sense - especially if you're getting your Mini off the ground like your Moke :)

 

It sounds to me like this 'risk' is less of an issue for a trackday/sunday toy slammed low?

[Dan]

When ST Abingdon was around and making these suggestions the Mini didn't have plunging joints at the inboard end of the shafts. The older cruciform joints and UJs use sliding splines in the shaft to let the shaft accommodate suspension travel. I can imagine that near the extremes of travel the motion wouldn't necessarily pull straight along the shaft and the splines could bind or even lock.

[Curley]

Thank you Dan - just goes to show how important context is! I had completely forgot there was a time of magic wands, hydro suspension, drum brakes & no pot joins.

Sounds to me like this is an none issue for "later" car - unless as previously suggested you're worried about drooping (snigger)

[nicklouse]

It is still useful if you are not using lowered shocks as you end up having so much vertical wheel movement you get undesirabke wheel angles on full droop.

Does not matter on the inboard UJ all types manage with lowered cars. Ok the rubber crosses can struggle.

[Curley]

Always tried to avoid lowered shocks. By that I mean ones with less travel. I'd rather move the top mounts as required and retain standard shocks.