Lotus Elan

Poly bushes & Spyder bones

PostPost by: miked » Thu Nov 16, 2006 2:17 pm

Some info' that may save soemone some work or just help.
I have poly' bushes on my S4 and have Minilites (recent). Upon stripping the rear to fit new "A" frames I noticed some contact marks on the inner of the rear wheels (both). Found the cause to be front chamfered edge of outer "A" frame bush tube. Not the bolt head. So bear this in mind that I have had some contact under braking (i think). I decided to make the ploy bush fit a tad tigther on the new frames and even file a bit off in the contact area to give more clearance.

Do you know that the Spyder bones are not the same dimensions as the old Lotus ones. Centres have to be. They are strong & well made! This is of little concern if you fit standard rubber bushes and steel wheels. However for poly' ( & minilite) it has problems.

The tubes pieces used on the frames for both inboard and outboard bushes are longer. For outboard inner (position) it meant about 1.25mm file off each. It got worse for outboard outer. I had to file several mm to get to the point of where the old Lotus frames catch before taking a bit off for the Minilite clearance. Have finshed one "A" frame to were I think it will take the strut and not foul the wheel.

It gets a bit worse, I mentioned above about the inner bush tubes length. These are each about 2mm longer than the old Lotus one. I am going to have to trim these down (for & aft') otherwise I will bind up the bush in the chassis brackets. The crush tube looks buried when the bushs are assembled. I doubt I would even get them to enter the chassis brackets

It is all do-able and I am not having a pop at Spyder as they have good kit but "fitter fettler" skills are required. No "one off" the "one on" lark. Lots of measuring and square checks. Also care not to take away joint welds and weaken.

By the way this is the continuation of an earlier thread I started about back wheel alignment. Thses are the "A" frames with the adjuster in.

I will get there! Also I checked other Lotus bones to ensure I have not got rogue measurements.

I think Rohan did say (way back) that the effect of touching something on an Elan has ramifications elsewere. Well he is right.

One last point of interest was that my car has been great with the Ploy bush. When having the chance to spilt and check I did notice that the inner "A" frame ones look like they have been moving within the "A" frame tube rather than on the crush tube. By this I would think that they were a bit tight on the poly' and I did not have the crush tube nipped. I suppose the movement here is minimal anyway.

Mike
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PostPost by: Old English White » Thu Nov 16, 2006 2:56 pm

... Same with my 66' S3 (Minilite's and Poly'bushes).
I add an extra 3,5mm spacer between hubs and rear wheels to avoid problems .
Seem than on Lotus'es , it's always a"tight feet"...
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PostPost by: miked » Thu Nov 16, 2006 3:39 pm

Christian, Just to clarify. Is this a spacer that sits over the hub flange and drive pegs to move your wheel outwards. I suppose to far and you get to touch the arch.

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PostPost by: stuartgb100 » Thu Nov 16, 2006 5:45 pm

Mike,

I have an early Spyder chassis in my '71 Sprint, and had always thought it had standard A frames fitted to it ..... perhaps not.

Whichever, I also had 'fouling' problems on the outer tube. The rearmost bolt/nut had to be partly ground off. The forward facing end, ditto. I also found the forwardmost shoulder of the tube needed easing to fit freely and not foul the Minilite.

It was the same on both sides.

As the new suspension bedded in, I found the outer face of the tyre was rubbing on the inside of the rear wheelarch. Ended up grinding off some of the fibreglass both sides. Cured it for a while, only.

Finally changed to 12 inch rear springs, which allowed me to lower it further and improve the camber (now slightly negative).

So far it is fine.

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PostPost by: Old English White » Thu Nov 16, 2006 7:32 pm

... Hi Mike ,
You are right ... these spacers are at the place you describe ... and my tyres ( Dunlop SP10 165/65 13 ) as on Stuart's , are on hard cornering rubbing the inside wheelarches ...
Next winter I will try Stuart's solution , grinding off some of the fiberglass in this aera.
Stuart , if you have pictures ...
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PostPost by: bcmc33 » Thu Nov 16, 2006 8:01 pm

I have been toying with the thought of Minilites before next summer for my 72 Sprint which has the early Spyder chassis and tubular front wishbones. How do I tell if the rear wishbone is standard Lotus of from Spyder?

The bolt head clearance to the steel wheel is visually about 7/8mm, so the question that comes to mind is what is the difference in profile and diameter between the steel wheel and Minilite?


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PostPost by: miked » Thu Nov 16, 2006 9:05 pm

Guys thanks for replies. Not just me then!

I have the 2.25 inch spring and platforms so am sat quite low.

Re: ID of Spyder kit "A" frames. They do make round section which I have. They seem slightly heavier (have not weighed) and the bush tubes are longer and they dont have that little chamfer on the outside edge of the outer tubes. They have a square finished edge. Also the Lotus manual 144.3mm (as I recall) between the outer bone tubes is 140mm. They also make others that are oval in cross section to prevent flex under braking (Andy tells me). I had soem on a plus two.

Also the little metal patches pieces are heavier and the welds have more content.

Ps got some new files and will have go at the weekend.

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PostPost by: stuartgb100 » Fri Nov 17, 2006 7:37 pm

Christian,

Lots to do this weekend, including watching Le rugby (why do I bother ?), but I will try to take photos and post this weekend.

Just to clarify: The TTR adjustable 2.25 springs/platform as standard are 14 inch. As you lower the bottom platform, it comes dangerously close to the top of the rear brake disk. I couldn't lower mine enough. I think this problem varies from car to car. Some are lucky, I was not.

At this point, I still had (just) positive camber. I reasoned that if I could lower it further, then the suspension geometry would take it to negative camber (which I wanted) and also hopefully ease the problems of the tube and wheelarch contact.

Suspension is still bedding in, but with Minilites, Michelin XAS ff's (set to 24 psi front and 27 psi rear) I have ground to u/s cill clearances of 125mm front and 135 rear. No rubbing so far ... touch wood.

PS: Mike, a bit of judicious use of an angle grinder is ok if very careful.
Then a dab of paint on the bare metal. When it's dry, back on the road and then check if the paint is marked. Also check wheel inner rim. When I've got this licked, I will look at the need to beef up what is left of the arms.

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PostPost by: miked » Fri Nov 17, 2006 8:29 pm

Stuart,

Thanks for advice.
I am same XAS FF and Minilite per Steve W's.
I take it you are exactly the same with the need to grind/file away. Am I right in thinking that you mean to strengthen with some more weld and maybe re enforcment patches to compenste for the metal you have removed?

Are you on Spyder bones? Doh! Just read your earlier post!!



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PostPost by: steveww » Sun Nov 19, 2006 4:47 pm

I found that the new springs took some time to bed in. At first I could not get the ride height low enough. After loading up for Classic Le Mans and driving to Portsmouth we arrived at the ferry with the suspension resting on the bump stops. I had to do a quick adjustment in the car park to raise the ride height.

125mm and 135mm sounds rather low. The standard ride height is quoted as 6" or 152mm. I already have enough problems with speed bumps :roll:
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PostPost by: stuartgb100 » Sun Nov 19, 2006 6:35 pm

Here are pictures of the 'easing' of the A frame outer sleeve. They are not too clear because all is painted in black. In some cases I had to grind off part of the bolt head and washer, as well as the shoulder of the sleeve.

I am reasonably happy with what has been done, but will continue to check at regular periods. It may well be that some additional strengthening around the ground-off areas will be prudent.

The wheelarch relief work was also necessary on both sides of the Sprint (and yes the body is square on the chassis). The arch flares inwards at one point (just above the lip/rim) and it's here that the tyre was rubbing. Fortunately the layers of fibreglass were fairly deep, allowing for the necessary grinding off.

Fingers crossed.

Steve........... next job during the coming week. I've put some miles on recently, but still surprising how much it has settled.

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Rear Suspension mods 005.jpg and
Rear Suspension mods 002.jpg and
Rear Suspension mods 008.jpg and
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PostPost by: miked » Mon Nov 20, 2006 9:28 am

Stuart,

Thanks for Pic's. I see what you mean. I did a fair bit over the weekend.
One thing that was good. I got to file (without touching much weld) on the inner A frame tubes. I did a lot of measuring and believe I am better centred with each at both sides. When I nip the crush tubes on these I think It will be better job. Pretty sure I was binding a bit before with irregular clearance.

Just got to slip the washers in the sides between the out poly bushes and the ally strut to finish.

Did you use stainless or just zinc.

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PostPost by: Old English White » Mon Nov 20, 2006 7:30 pm

... "the Blacks were too good , It 'll be hard , really hard not let them take the world cup ..."
Ok ,Stuart , Mike , I see than we had the same problem , and cure them the same way ... My Minilite's are 5"X13" and yours ?
About ground clearance , I still need to mesure it (car still on stands for bearing change!)but I think I should be close to a 145mm rear and 130mm front .If you were at Le Mans Classic you maybe have a picture of my car near or close to yours ... If not look in the gallery!
http://lotuselan.net/forums/viewtopic.php?t=13222
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PostPost by: M100 » Tue Nov 21, 2006 4:41 pm

Stuart, by using minilites and presumably adding lightness I hope you've not put it all back on again with those wheel weights.

Maybe you're just stockpiling lead :)
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PostPost by: stuartgb100 » Tue Nov 21, 2006 6:52 pm

Martin,

Well spotted !

Have had all four wheels balanced and this particular one double-checked.
Promptly went to another company for a check .. no difference !

Will soon be putting the old 'winter wheels' on (semi-storage) and will whistle the Minilites off for yet another opinion.

If the answer is still the same, then I'm half inclined to ring up Minilite and "compliment" them on outstanding quality control. On a new rim, I can never remember anywhere like this number of weights being required.

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