How to avoid torque load on the suspension when replacing springs etc

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warpc0il
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How to avoid torque load on the suspension when replacing springs etc

Post by warpc0il » Wed Jul 24, 2019 6:41 pm

If you disassemble the suspension to replace springs etc then you must not re-tighten all the bolts with the suspension extended, otherwise the bushes will become trapped in that orientation and, once the car is then lowered to the ground, they will become twisted adding a "rubber-in-torsion" element to the spring rate. This makes the car sit artificially high and will rapidly destroy the bushes.

The bolts that tighten the suspension arms - the ones that hang down when the car is lifted - must only be tightened when the weight of the car is "back on the wheels".

The default would be to put them in loose and lower the car fully, roll the car backward or forwards a couple of metres, and then reach under and tighten.

To gain more clearance, you can lower the wheels onto scaffold planks, or other strong timber, but you still need to roll the car to ensure that the side-thrust on the tyre tread has been eliminated, otherwise the car will still sit too high.

I use a set of motorhome leveling ramps. These are longer and shallower than garage ramps and fit under my lowered car.

Alternatively, you can place a jack under the hub, with the wheel still removed and lift until the body of the car is just starting to raise from the axle-stand, placed under the jacking point or subframe.

I'm not keen on this last approach as;
- it's difficult to judge the exact point to stop lifting.
- the jack gets in the way.
- the force to tighten the bolts could roll the car off the jack, which may or may not get caught by the axle stand before it fell on you.
- if the suspension on other side is still fully extended, then the force on the anti-roll bar will prevent the side you're working on from compressing to the normal static load position - which is the object of the exercise.
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mrspiller (Thu Jul 25, 2019 8:11 am)
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