Front Suspension Wishbone Arms

[4129R]

I am just rebuilding a chassis from scratch, and I cannot remember which was around the top arms go.

I know they are stamped L and R on one of each pair, and that the two trunnion mounting holes must line up to match the pairs, but there is a fat one and a thin one in each pair, and I cannot remember which one goes at the front, and which one at the rear.

Plus, I cannot see any difference between the two pairs for the bottom arms. Are the bottom pairs handed, or interchangeable?   

Any clues please before I delve into another car which I have not dismantled?

[BDA]

I don't remember the answer to your specific questions but this page may help: http://www.lotus-europa.com/manuals/tcparts/c/tcca.pdf

The front caster is ~2 degrees so the top ball joint is "behind" the trunnion.

I hope that helps.

[jbcollier]

Bottom a-arms are interchangeable pairs: that is, the LF and the RR are same, etc.

The original upper a-arms are marked LF, LR, RR, RF and they are not interchangeable.

[4129R]

The original upper a-arms are marked LF, LR, RR, RF and they are not interchangeable.

Sadly they are not.

Every top wishbone arm I have looked at, and I have loads of them, all from TCs, are marked LH or RH.

The chassis I have not pulled apart has the thick one at the front.

This thick at the front makes the top balljoint behind the lower trunnion, so thick arm at the front is correct.

I am surprised no-one has noticed this problem before, as it would affect the steering geometry quite a lot.

Luckily I had a spare very long 1/2" bolt, so changing over the top arms without the shock unit falling down was very easy. 5 minutes to change each side to the correct thick at the front assembly order.

[Certified Lotus]

As pictured below:

[4129R]

I don't remember the answer to your specific questions but this page may help: http://www.lotus-europa.com/manuals/tcparts/c/tcca.pdf

The front caster is ~2 degrees so the top ball joint is "behind" the trunnion.

I hope that helps.

It did, thank you.

Sadly both the workshop manual words and pictures give no clues as to thick and thin top wishbone arms.

I wonder how many have been reassembled the wrong way around. An easy mistake to make.

[Pfreen]

Page 3 of the front suspension section of the base Europa manual shows the A-arms and how they are assembled.

[4129R]

Page 3 of the front suspension section of the base Europa manual shows the A-arms and how they are assembled.

I have the Lotus Cars one, in the black plastic folder with 4 ring clamps holding the pages in.

Section C page 7 says nothing about the wishbones either being handed L & R or in matched pairs, or that they have to be fitted thick side to the front.

[tedtaylor]

http://rdent.com/manuals/index.html
even parts manual shows correct fitting (check #18/#19 of diagram and listing below)
http://www.lotuseuropa.org/images/WorkshopManual/S2_Section_C_-_Front_Suspension.pdf
page 15, figure 18 shows dimensions of upper wishbone leading half.

[4129R]

Neither of those diagrams make it clear. The two halves look very different. No diagram or words have made it clear that the thicker half goes at the front.

It would have been kind of Lotus to mark them as John Collier thought, but just stamping LH and RH on them rather than LF and LR, RF and RR.

Maybe Chunky could not afford the F and R die stamps. 

[jbcollier]

Earlier arms are stamped exactly like that.

[4129R]

As pictured below:

Thanks for that, you have just confirmed thick side to the front.

Out of the 4 chassis I have built up from a bare painted chassis, I have got at least 2 the wrong way around. I will have to check #4 when it stops raining.

[Certified Lotus]

When I disassemble cars for entire frame off restoration I buy a box of cardboard tags with wire attached to them (office supply stores sell them for about $4 for 100).  Every part that comes off the car gets tagged and a location description written on it. I also photograph each area of the car from a number of angles at each stage of disassembly for reference when it goes back together.

Most of the time the above greats adds to the ease of reassembly.

[4129R]

But don't you think the Lotus workshop manual should have identified that the 4 top arms are specific, how to identify and match the left and right pairs, and which way around they should be fitted, rather than saying zero about reassembling the top wishbones apart from      'Assembly is simplified if the top wishbone of the unit is secured to the chassis initially.' 

[tedtaylor]

now this "switching around" of the top wishbone arms, may it possibly be intentional???   what benefit might this mixed up configuration provide?  Perhaps more nimble steering?   perhaps allowing more room to adjust toe-in/toe-out?
just thinking outside the box here and thinking owners may have found a secret they're aren't sharing???   What betterment or detriment will result?