I have just made some measurements to my new +2 alloy front wheels (as fitted to S130 versions).
When placed on each hub with no centre nut fitted there is no detectable play from the 5 dogs in the hub and the holes in the wheel. I then looked at the gap between the threaded centre shaft of the hub and the inside hole edge of the wheel.
I measures a worst case difference of 9 thou on the NS hub and 14 thou on the OS hub (UK RHD)
A wheel/tyre combination weighs 12 kg. For each thou of centre offset you get an out of balance moment of 0.001 x 6,000 each side. This is roughly equivalent to a 2 gram balance weight at 6.5 inches from the centre. As the centre wheel nut is tightened up when the wheel is fitted, the dogs will prevent the wheel from centreing.
So as tyres are balanced on the centre hole, there is a likely 18 gram out of balance condition on the NS, and a whopping 28 grams on the OS!
My solution is to bore out the 5 holes in the wheels by 10 thou, giving me a float of 20 thou. If you have balance problems, measure that centre gap with feeler gauges and see for yourself.
Thats interesting and may well have explained why iv a very slight vibe after removing my wheels before christmasā¦was going to switch them around but maybe your explaination is the answer.
The alloys are new from Sue Miller at ?98 each. I believe from the year stamps that they were manufactured around 2000, but I consider them new and without any hole wear. Note that I am note blaming the wheels for this - just the fit with my hubs.
There was a deliberate mistake in my original E-mail - 10 thou oversize on the holes only gives you 10 thou float.
People with older alloy wheels may have elongated holes, but could still experience this problem - the holes will only wear circumferently (is that a word?), not radially to give the float.
If hole wear becomes a issue in the future, I will think about sleeving the holes with a steel tube section.
Thanks for that - youāre never too old to learn!
I have now been out in the car, and the previous out of balance condition is much improved - just a buzzing at 70-80 mph though the steering wheel - 1mm deflection - not bad.
The centre nuts on my car have some sideways play on their threads - a few thou. As you tighten up this nut, where does it finish up? Does it centre on the thread, or sit to one side?
If it sits to one side, a possible fix would be a thin circle of PTFE tape - but will this cause the nuts to come off? Hmmmmm.
Iād try to find a place with an on-vehicle wheel balancer. This will balance the complete assembly; hub, brake disc, wheel and tyre. And then mark the relative position of each wheel on hub
Couldnāt help but notice the input about wheel balance.
For years I put up with at times pretty severe steering wheel shake and general driveline roughness- until- I fitted a set of Minilites (this is to a sprint).
Amazing transformation- 70-80- absolutely no steering wheel flutter and somehow the driveline seems much smoother. These are 5 inch by 13 rims with the 155/80 tyres stretched across the wider rim. The steering is very slightly heavier (presumably caused by the stiffening effect on the sidewalls).
Maybe the way Iāve modified the column fixing arrangement has something to do with it as even with the dash clamp not fitted (no I donāt drive it like that) the steering wheel is held very securely- even with quite a lot of deliberate strain being fed into it.
The original steel wheels seem to be pretty variable in quality- two of mine (the problem ones) had centres that were not true to the outer rims.
I am in the middle of firming up my +2 steering column (it felt rather loose before) but I do not know about a dashboard clamp - just the clamp further down that secures the steering column tube (early type) to the engine bulkhead bracket.
I have stuck a rubber strip on the column shroud to give a tight fit on the dash cutout. The steering wheel feel much firmer now. I will try it out on the road tomorrow.
I am in the middle of firming up my +2 steering column (it felt rather loose before) but I do not know about a dashboard clamp - just the clamp further down that secures the steering column tube (early type) to the engine bulkhead bracket.
I have stuck a rubber strip on the column shroud to give a tight fit on the dash cutout. The steering wheel feel much firmer now. I will try it out on the road tomorrow.
I posted details of a steering column/brake box reinforcement arrangement on this site a few times already, have a search, get back to me if you canāt find it.
David,
I would get youself the proper dashboard clamp fitted before you drive your car again. Especially at 80 mph! There should be an alloy bracket affair which mounts to the dashboard mounting screw above the column and also has two screws through the board in the horizontal centre line of the column. Underneath is a āUā clamp which allows the column to be dropped out. This is for an ordinary Elan. Iām pretty sure itās the same for the +2.
Or you could go Seanās route.
I think Roy is correct for a collapsable steering column. My one is the fixed type with a plastic binnacle that just sits under the dash. I canāt see anywhere for a bracket, although it would help.
I have a feeling that in manufacture, the rigid column was shimmed with washers on the clamp further down the column, until the binnacle was pressing on the dashboard to offer some extra rigidity. Thatās Lotus for you!
Hi Guys,
firstly Iād like to appologise if Iām missing something here or have misunderstood something.
Surely the centering feature between the wheel & the hub is the pegs.
If the centre hole on the wheel sits closely on the hub then this would present a conflicting centering feature.
Is it possible that any inacuracies in steel wheels would be compensated by the inherent springyness of the steel pressing & therefore crudely avoiding major conflict?
My āTwo Gatesā alloy wheels were supplied with a āfree floatingā adapter ring which sits flush on a flat surface on the wheel & locates with the conical spinner, subsequently there is no conflict there being only one centering feature, the pegs.
This is an interesting point and one that I was thinking about when the thread first started. I would be more worried about forces applied to the wheel and hub due to conflicting centering features than any imbalance. With the standard, steel, peg drive wheels the nut has a very strong centering influence. The conical surfaces of the wheel and nut are wide and form something close to a 45 degree angle to the axle centerline. Reading Johnās reply just made me think that perhaps the way the steel wheel is formed is for the purpose of allowing it to flex a bit and alleviate any error in concentricity with respect to the drive pegs. I think that most wheel manufacturers consider the conical nut to be the main, centering feature. Minilite wheels have a thrust ring for engaging the nut that really canāt float much at all in the wheel. I think the Brand Lotus wheels are the same. The most extreme case is with Panasport, which due to the shape of the casting only engage three of the five drive pegs. Iāll have to look at my Minilites more closely over the weekend and see if the thrust ring can float more than I can recall.
My Two Gates wheels, ditto. The centre opening makes no contact, but this is what the wheel balancing machine uses as a centre. So Iād like the wheels balanced as they are actually centred on the car, ie on the drive pegs.