Thread: Spring shackle question

Originally Posted by ashhhhh

Hey all

Im hoping some spring guru can clear up a question for me, probably a stupid one.

I always thought the shackles were free to move around at both pivots. (chassis bush and spring eye bush)

Why does the manual recommend compressing the spring to a certain tolerance prior to tightening the shackle bolts?
They say it is to prevent tearing of the bushes under articulation, does this imply that the shackle only moves because of the "give" in the rubber bushing - rather than it pivoting around freely on the bolt?

Hope that makes some sort of sense...

I only ask as I am trying to troubleshoot some suspension issues I have. (clunking)

Cheers
Ash

Got it in one! The springs need to be in the normal position before tightening the shacklebolt so that the amount of movement in the rubber is minimised.

If you look at the history of spring shackles, before motor vehicles they were generally a pretty loose fit, but with motor cars they became pretty much the setup you see today except for the type of bearing. However, these were plain steel on steel in cheaper cars, steel on bronze in more upmarket ones. And to prevent rapid wear, they required frequent lubrication. The Ford T for example, had an oil cup on each one, and this needed a few drops of oil every day (with transverse springs, that was only eight). By the 1920s, most cars had grease cups, and these only needed a turn every day or sometimes less often, and refilling every service. But with four leaf springs, that was twelve grease cups. By the 1930s, grease nipples were replacing grease cups, and only needed greasing every service (200-100miles, 320 -1600km). Some cars, such as Rolls Royce and Mercedes and some upmarket US cars got automatic oilers, with a maze of thin oil pipes distributing oil to these points either by a pedal on the floor or automatically getting a shot of engine oil every time the engine was started.

Around The start of WW2, Silentbloc bushes such as the ones on the Series Landrover were introduced, and these immediately did away with any need for lubrication, using two steel sleeves vulcanised to a rubber tube, the outer sleeve being a tight fit in a hole, and the inner sleeve clamped between the shackle plates as well as carrying the load.

John