12 replies to this topic

[JtP2]

Just been watching the film on Youtube of the event. Hill comes into the pits with a loose wheel (26 mins) and has it tightened. At least it gave him some ammunition to throw back at Chapman. The mechanic appears to tighten the right front wheel nut with a left hand threaded turn.This is surely normally the wrong way to stop the nuts from loosening. So is it just the way it shows in the film or did Lotus for some reason fit the RH front with a LHD thread and vice versa on the other side and if so, why/

Edited by JtP2, 30 March 2020 - 13:36.

[10kDA]

Not uncommon to incorporate reverse-threaded fasteners on a rotating asssembly, when the fastener is located at the hub of rotation. The thinking is that if the nut were stationary and the shaft turns, the threads would cause the nut to tighten on the shaft's threads. So, yes, the left-side threads would be standard. In practice it's doubtful the inertia of the right-side nut would overcome its tightening torque and loosen against its (standard) threads as the car moved forward. But never say never. It seems cars have lost wheels now and then due to loose wheel nuts. 

[BRG]

Alfa Romeo, back before they became aka FIAT used to have left-handed wheel nut threads on one side of the car.  Not sure if it was effective, but none of our wheels fell off during the three rallies I did in one.  The oil filter did, but that is another story.

Edited by BRG, 30 March 2020 - 17:48.

[JtP2]

Alfa Romeo, back before they became aka FIAT used to have left-handed wheel nut threads on one side of the car.  Not sure if it was effective, but none of our wheels fell off during the three rallies I did in one.  The oil filter did, but that is another story.

 

What, only the oil filter?

[JtP2]

LHT nuts were common on commercial LH wheels in period.

[Garsted]

This has been discussed before here, without reaching any firm conclusions as I recall.  I think the thread starter got pretty close to the crux of it

 

https://forums.autos...er#entry5881107

 

Steve

[Ray Bell]

Perhaps the Graham Hill incident led to people being circumspect about the knock-ons used on the Lotus 39 and 59...

 

Or was it just that Leo lost a wheel (photographs exist on this forum) braking for Mountford Corner at Longford in the 39?

 

For whatever reason, when Kevin Carrad took over the preparation of the 59 on behalf of Bob Johns, the took steps to avoid the problem. I have related this story before, he drilled and tapped into the hub and put a stud in there, right in the centre, left hand thread for the wheels with RH knock-ons, right hand for those with LH, turned up caps which fitted over this stud and the centres of the hub nuts and then put a nyloc nut on to hold them there.

 

If a hub nut started to undo it would tighten its grip on the new stud and nut and find it very hard to go any further.

[Allan Lupton]

The thread logic of centre-lock wheels depended on the conical load-bearing surfaces of hub and wheel - when the thing is slack the hub drops a few thou causing the hub and wheel cones to touch (and bear the load) where they have slightly different diameters. What is then required is that the rotation with those dissimilar diameters drags the nut in the tightening sense, for which one needs handed threads.

The conventional nut had a female cone locating on the wheel's male cone which gives the easily-remembered "right-hand thread on the left-hand side/left-hand thread on the right-hand side" logic. Lotus confused many folk with the Elan which had the female cone on the wheel so the left was left and the right right.

What has been proven time and again is that if someone fits them swapped over the wheels do stay on if the nuts are very tight but come off the moment there's a bit of slack.to unwind the nut.

In racing cars that may have all changed by now, but not in 1967, I'd say and as the OP has seen the "left-hand thread on right-hand side" it all hangs together.

Edited by Allan Lupton, 31 March 2020 - 11:48.

[BRG]

What, only the oil filter?

Well, come to think of it, the whole car fell off - the road that is, after a fundamental disagreement between me and the Ordnance Survey.  We would have been OK in the ditch if there hadn't been a pesky tree in the way.

[Bloggsworth]

My Elans both had RH & LH threaded knock-offs, and all the cars I worked on which used knock-offs had the same. I suppose that, in the event of a loose nut, if the wheel locked up under braking, it was thought that the nut might have carried on spinning.

[Allan Lupton]

My Elans both had RH & LH threaded knock-offs, and all the cars I worked on which used knock-offs had the same. I suppose that, in the event of a loose nut, if the wheel locked up under braking, it was thought that the nut might have carried on spinning.

a) please read my post 8 but

b) with the normal handing, if the drive splines strip, the nut slackens under braking but tightens when driven. I drove a car home after a rear wheel spline let go - it was fine so long as I didn't use the rear brakes, so I'd disconnected them!

[JtP2]

Well, come to think of it, the whole car fell off - the road that is, after a fundamental disagreement between me and the Ordnance Survey.  We would have been OK in the ditch if there hadn't been a pesky tree in the way.

  Are you related to Nigel Mansell? Did someone nip out and place the ditch and tree where they shouldn't have been?

[BRG]

  Are you related to Nigel Mansell? Did someone nip out and place the ditch and tree where they shouldn't have been?

If you had seen the sorry excuse for a moustache that I grew back in the 1980s, you wouldn't think for a moment that I had any Mansell connections!

 

The OS showed a crossroads, where we were meant to go straight on.  The actual roads weren't like that.  It was what was known as 'Not As Map'.  I was calling 'straight on onto white*' but the tarmac road curved right and then suddenly turned sharp right and we were going too fast to make it, fell into the ditch where we bounced along and would have been OK but a tree had grown in the ditch and we struck it square on the little Alfa grille and stopped abruptly.  When we got the car out, the sump-guard had come off as the bolts had sheered.  The engine moved back and punched out the diff although that didn't come to light until the car had been fully rebuilt and they tried to drive it!

 

* ie. a unclassified road or track shown in white on the OS map  

Edited by BRG, 02 April 2020 - 18:10.