Front suspension lower wishbones & Upright

[Certified Lotus]

I have gone thru the shop manual, done an on-line search and still can’t find the answer. Are there leading and trailing lower wishbones for the front suspension. The manual clearly indicates this for the upper wishbones but not the lowers.

The reason I ask is I got 2 sets of NOS lower wishbones, one pair is 20mm wide and the other is 23mm wide. But the pair are not mirror images, meaning the 23mm is in the front on one side and in the rear on the other.

I am assuming this is incorrect, but don’t have the documentation to confirm.

Can anyone provide an insight on this?

[Grumblebuns]

According to the parts manual, there are two parts numbers for the lower wishbones, one for the bottom leading R/H and one for the bottom leading L/H with two each required. Just my guess, but I would assume that they are swapped for the trailing wishbones on the opposite side.

The upper wishbones on the other hand have four separate part numbers.

http://lotus-europa.com/manuals/tcparts/c/index.htm 

[jbcollier]

Lower wishbones changed quite a bit over the years but they all yield the same suspension geometry.  At least they do until they hit their first curb.

Earliest lower arms were not reinforced, next versions were.  After that they were splayed further outwards in the middle.  Dimensions you can check them against are in the S1/2 repair manual.

[BDA]

One of the things I hate about questions like this is that I second guess how I put my car together! (I don't remember worrying about this but it was almost twenty years ago)

A few thoughts: I would not be surprised that there might be some differences in production over the years. It is my understanding that the S2 and TC share the same effective dimensions but the TC versions have a bush welded in for the shock mount. You may have noticed that the parts manual lists two left hand lower leading wishbone halves and two right hand lower leading wishbone halves ( nothing about trailing). I didn't see anything in the workshop manual that tells me how to tell them apart for assembly. The section on "assessment of accident damage" shows the dimensions of "lower wishbone half" without distinguishing between leading, trailing, left, or right.

My guess is that if you measure the halves against the dimensions in the workshop manual, they will all be the same. Another clue is that looking at the pictures of the tubular lower wishbone halves on r.d.'s website, they appear to be the same for leading and trailing.

Edit: I know this echoes some of what jb and Joji said but it took me so long to put it together on my iPad that I wasn't going to not post it!

[Certified Lotus]

 Thanks everyone. It is still confusing as the parts manual lists leading and trailing edge bottom wishbones, But the shop manual makes no mention of this. The original lower wishbones where (almost, within .03) the same width leading and trailing edge

Will measure everything according to the manual.

[Certified Lotus]

Here is another issue. The manual states the trunnions are left and right threaded with the right trunnions having a stepped bottom. Well my Stanpart trunnions have a L and R stamped on the bottom of the trunnions but the L is on the stepped down piece which is supposed to be the right.

Confusing?

[BDA]

Probably made on Friday! Check the threads!

[Certified Lotus]

I did check the threads. Even disassembled the left side which was all together to to make absolutely sure. Everything installed properly except I have two sets of left side lower wishbones........

Two steps forward, one step back.

[BDA]

I'm confused. How did you decide you have two left lower wishbone halves? The section on determining if there was accident damage gives dimensions for only "lower wishbone half" - no mention of righ/left/leading/trailing. Did I miss something?

[jbcollier]

Lower wishbones are not location specific.  Lower RF is the same as the lower LR, etc.

[Certified Lotus]

Well JB,  now I am totally confused.

BDA,  I didn’t explain everything.  When I installed the vertical link on the right side with the new lower wishbones and trunnion, the lower wishbones twisted when I moved the vertical link back and forth, which clearly isn’t right. That’s when I started looking closely at the new lower wish bones and determined they were different sizes for the leading and following parts. . Next I wanted to check the vertical links to make sure they were in the correct place (right side/left side determined by the thread on the lower part of the link) and then re-confirm the proper trunnions were attached to the correct sides.

The left side of the suspension functions perfectly, so I am assuming I have two pair of left lower wish bones. At least that is my deduction.

What could possibly be wrong with the right side?

[Certified Lotus]

I’m completely perplexed on this. Walked away for a while and came back to look again at what is going on. Turning the vertical link with the trunnion screwed on twists the lower wishbones, but only on the right side. I even installed another right vertical link as I thought maybe the one I had was bent (doubtful, but you never know). The only thing I can think of is the wishbones are off causing this to happen.

[jbcollier]

If it twists when turned the upright is bent.  Replace both the left and right with new would be my advice.

[BDA]

I'm not sure I understand what's happening. You turn the upright (vertical link) as though you are making a turn and that twists both lower A-arms? Is the twist along the length of the A-arm halves (as though you're rolling up a newspaper)? I assume you didn't over "tighten" the trunnion so that you ran out of travel. If you disconnect the upright from the lower A-arms and turn the upright while holding the trunnion, what happens? Does the trunnion move or does the upright just turn? If it moves, the upright is bent as JB says.

[EuropaTC]

I can't tell what's wrong with your set-up but if that shot is the set-up with tightened bolts then I think I'd be getting some shim washers between the arms and lower damper mount.  Otherwise you'll never get the correct torque (or A-arm rigidity) on the damper bolt.

It might be that the bush isn't long enough or the arms are bent, but if either ends of the arms are tight (chassis/Trunnion) then I be thinking of the bush length. I would imagine the damper bush and it's steel insert should be the same dimension as the steel insert in the trunnion nylon bushes ?

Brian

Edit to add.....    on the twisting aspect, my first thought was as BDA says, that you've screwed the trunnion too far on the upright causing it to lock up. If not that then I'd be going for a bent upright, but if you've tried 2 seperate uprights now, that idea becomes less likely (unless you are lucky enough to have 2 bent uprights    )