Lotus Elan

Meaning of Suspension in static condition

PostPost by: TonyA » Mon Mar 25, 2024 5:55 pm

In connection with the Lotus Elan Plus 2 Official Workshop Manual : Technical Data: Torque Loading Figures: Rear Suspension and Driveshafts: Mountings- Wishbone , does the phrase " ..tighten with suspension in static condition .." mean with the suspension bearing the weight of the car, or off the ground..?

Also in relation to wishbone bolts torque of 35 to 40 Lb.Ft, is this for the wheel hub AND chassis mountings..? Thx..

Tony
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PostPost by: StressCraxx » Mon Mar 25, 2024 6:14 pm

"Static condition" means car on the ground, with all fluids including 1/2 tank of fuel with weight of driver in the seat (bearing the full weight of the car). The reason for this instruction is to ensure all the fasteners are torqued with the suspension bushings in a relaxed state at static ride height. If the bolts are torqued with wheels off the ground(suspension at full droop), they bushings would be heavily preloaded at static ride height and quickly fail, ruining all of your hard work.

"Also in relation to wishbone bolts torque of 35 to 40 Lb.Ft, is this for the wheel hub AND chassis mountings..?"

Yes.
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PostPost by: TonyA » Mon Mar 25, 2024 6:33 pm

Wow..! Thx for such a quick and helpful response..

I noticed that there is no asterisk denoting static suspension condition re the donut bolts torque -surely an omission..?

Given that the donut bolts are 7/16 unf, why is the specified torque 35-40, which is less than under the General Torque settings of 40-45 for this bolt size/thread.

And if I repjace my donuts with CV joints what should the torque on the bolts be: 35-40 as with donuts, or 40 to 45 as with General 7/16 UNF ..? and under static or no load suspension condition ?

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PostPost by: Andy8421 » Tue Mar 26, 2024 11:36 am

Tony,

As StressCraxx mentions, the reason for the suspension bushings specifying ride height is that once installed and tightened up, the metal inner and outer sleeves of the bush don't move relative to their to the fixings, all the movement of the joint comes from the compliance in the rubber in the bush that 'twists'. If you tighten up the bush with the suspension at full droop (say), then at normal ride height the rubber is twisted and preloaded. This can shorten the life of the bush, and potentially change the spring rate and impact the ride height.

This has nothing to do with the torque of the bolts per se, its all about getting the bushings right before you tighten the bolts.

With the rotoflex, there is no 'getting the bushings right' so I would have thought the the bolts can be tightened up with the driveshaft at any angle as its all about the preload on the bolts, although practically you can't get the bolts in unless the driveshaft is pretty much parallel to the road.
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PostPost by: alan.barker » Tue Mar 26, 2024 2:41 pm

Hi Tony,
If you fit CVs the torque figures will be give by CV kit supplier.
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PostPost by: TonyA » Tue Mar 26, 2024 2:59 pm

Not so; nothing in the KELVEDON instructions and when I phoned them for advice, was told: ".. our guys tighten them, then another quarter turn.."

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PostPost by: mbell » Tue Mar 26, 2024 3:39 pm

My car uses VW CV so I looked up the figures for VW CV's which from memory was 35-40lb/ft. I also marked the bolts so i could easily check them for coming lose.

I'd suggest something around 40lb/ft would be sensible and then check them multiple times to ensure the aren't loosening.
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PostPost by: alan.barker » Tue Mar 26, 2024 3:51 pm

TonyA wrote:Not so; nothing in the KELVEDON instructions and when I phoned them for advice, was told: ".. our guys tighten them, then another quarter turn.."

Tony

Hi Tony,
I don't like hearing something like that very amateur. They claim to be professional.

With CVDS Elantriktrikbits full instructions given with Torque figures.
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