Wheel stud length for steel wheels

[PXC]

Hi

Bob Lebrocq suggested I seek opinion on the safety of my rear wheel studs, which have had some length ground off them to accommodate splined hubs. As I have a plan to switch back to steel wheels at some point, and as I’ve got the splined hubs off at the moment,  I bolted on one of the steel wheels. The end of the thread is level with the top of the nut, but no excess. Is this enough? Safe to use? Or are new studs (not easy on the rears) a necessity. 
Cheers Paul

[Dale Moore]

I would get hold of the correct wheel nut for steel wheels first https://www.moss-europe.co.uk/en-gb/wheel-nut-steel-wheel-109586 and see if the thread protruded then, my thoughts are they won't.  I know the nuts are, in effect doing the same job holding the adapter on or the wheel, but the adapter nuts just don't seem robust enough for frequent removal and refitting 

Dale

[Motorsport Mickey]

Nope, not long enough. Been tried by Standard Triumph back in the 1950s early 60s and the nuts pull through causing a failure of the wheel vertical surface that the stud holes are in. BECAUSE these short nuts and studs originally DON’T hold a wheel on.
 

The short studs and double chamfer nuts hold the splined hub adaptors for knock off wheels, and those knock off adaptors have a hub adaptor vertical face thickness of about 5 mm (varies according to adaptor) which clamps to the hubs or brake drums. This thicker vertical face of the adaptor can cope with the stress input by wheel undulations because the nuts, their studs,  splined hubs adaptors and wheel clamped to the adaptor by large eared spin on caps, spread the load. But a standard steel wheel is made of much less thickness material and the clamping force of a narrow double chamfered nut with shorter studs cannot be spread over the surface sufficiently causing localised “ wiggle wiggle” of the steel wheel material around the nut which fractures breaking the stud holes material from the wheel.
From memory Standard Triumph issued a service bulletin about it. Short answer…don’t.

Mick Richards.

[Lebro]

Makes perfect sense, I had forgotten that the nuts are a smaller size across flats that the correct ones for steel wheels, & I guess the bigger nuts are also deeper, & so the stud thread will not even reach the end of it.

As I offered before Paul, If you gan get the hubs off the axle I will happily drill them & insert the new studs.
Several tools for separating the hub are scattered around the country (I know, I made them !) so someone close to you may have one.

Bob

[stuart]

18 minutes ago, Motorsport Mickey said:

Nope, not long enough. Been tried by Standard Triumph back in the 1950s early 60s and the nuts pull through causing a failure of the wheel vertical surface that the stud holes are in. BECAUSE these short nuts and studs originally DON’T hold a wheel on.
 

The short studs and double chamfer nuts hold the splined hub adaptors for knock off wheels, and those knock off adaptors have a hub adaptor vertical face thickness of about 5 mm (varies according to adaptor) which clamps to the hubs or brake drums. This thicker vertical face of the adaptor can cope with the stress input by wheel undulations because the nuts, their studs,  splined hubs adaptors and wheel clamped to the adaptor by large eared spin on caps, spread the load. But a standard steel wheel is made of much less thickness material and the clamping force of a narrow double chamfered nut with shorter studs cannot be spread over the surface sufficiently causing localised “ wiggle wiggle” of the steel wheel material around the nut which fractures breaking the stud holes material from the wheel.
From memory Standard Triumph issued a service bulletin about it. Short answer…don’t.

Mick Richards.

A very comprehensive answer there Mick and yes ST did indeed issue a bulletin in late 53 and the nuts were changed to the larger ones, the original ones were as fitted to the earlier Standard models and not dissimilar to the wire wheel nuts, when rallied hard the wheels would pull off over the nuts.

Stuart.

[PXC]

Thanks to Dale, Mick and Stuart. Yes a very comprehensive explanation, thanks Mick. I’d love to see the calculations that Standard Triumph did to underpin that bulletin, or maybe it was practical experience which informed it. Either way, I agree entirely with the conclusion. 
 

Yes Bob, Hamish has one of the tools which he will lend me, he is nearby in Cheshire; and thank you again for the offer. 

[PXC]

I also notice that Moss show different hubs altogether for steel or wire wheels. 
 

https://www.moss-europe.co.uk/en-gb/rear-axle-5-girling-tr3-from-c-ts13046-tr3a-tr4-tr-tr24--14--02--02

i guess on my car I’ve got wire wheels+ adapters, fitted onto what are actually steel wheel hubs. 

[Hamish]

59 minutes ago, PXC said:

 

Yes Bob, Hamish has one of the tools which he will lend me, he is nearby in Cheshire; and thank you again for the offer. 

👍

[stuart]

1 hour ago, PXC said:

I also notice that Moss show different hubs altogether for steel or wire wheels. 
 

https://www.moss-europe.co.uk/en-gb/rear-axle-5-girling-tr3-from-c-ts13046-tr3a-tr4-tr-tr24--14--02--02

i guess on my car I’ve got wire wheels+ adapters, fitted onto what are actually steel wheel hubs. 

The reason for the different part numbers for hubs is because they come with the relevant length studs fitted as rear hub stud fitting isnt really a DIY job.

Stuart.

[Lebro]

Tr2's did have completely different hubs for wire wheels, the splines were all part of the hub. Not so for later cars.

Bob

 

Edited February 5 by Lebro

[BlueTR3A-5EKT]

The comment I will make is not particularly safe.  That said I ran a short stud wire wheel type hub on my steel wheel car for a few months back in the 70’s using standard steel wheel 7/8” af nuts   I did turn the taper shorter on the nuts so the threads started at the nut face, rather than being recessed by a few threads that aids installing.

As stated the steel wheel stud hole can pull over the small sized hexagon nut that is fitted.   Austin 7 had this issue and racers used to have to fit big washers between the wheel and wheel nut.

Regarding thread protruding from the wheel nut, for it to be in safety.  

RAC MSA rule book

Chapter 12 Race, Appendix 12 para 6.2:

6.2. Have all nuts securing road wheels excepting those of centre-lock type of steel and in thread contact over
a minimum length of 1½ bolt/stud diameters. Extended or composite wheel bolts/studs are prohibited.
Vehicles of periods A to D are exempt from this requirement.

https://ebooks.motorsportuk.org/najd/p433

 

[Lebro]

If / when you do go down the change stud road, for what it's worth I use the Cambridge Motorsport ones, which ar slightly longer than standard, so useful if you ever considered alloy wheels.

https://cambridgemotorsport.com/classic-historic/12564-tr2-6-1-2longer-wheel-stud.html

Bob

[PXC]

Yes I will, thanks Bob. Thanks all. 

[stuart]

1 hour ago, Lebro said:

If / when you do go down the change stud road, for what it's worth I use the Cambridge Motorsport ones, which ar slightly longer than standard, so useful if you ever considered alloy wheels.

https://cambridgemotorsport.com/classic-historic/12564-tr2-6-1-2longer-wheel-stud.html

Bob

They are also of good quality steel, Ive had some others that were soft enough for the splines that are to stop them turning in the hole just strip as soon as they are drawn into the hub.

Stuart.

[multipletriumphsinner]

'Splines' or better known as knurling designed to deform as the stud grips the reciprocal hole.

[stuart]

1 hour ago, multipletriumphsinner said:

'Splines' or better known as knurling designed to deform as the stud grips the reciprocal hole.

"Deform" is one thing but when theyre so soft that they dont actually grip the hole is another and that was the problem with those. they wouldnt grip enough to stop the stud turning when the nut was tightened .

Stuart.

[RogerH]

Indeed the stud needs to be hard enough for its splines to cut the mirror image slots in the hole. 
This is often called 'broaching'.

Many folk often think of knurling as the lovely diamond pattern on metal handles etc to give grip. 
But the knurling can take many forms and straight knurling (as on the splines) is just another form. 

Roger

[BlueTR3A-5EKT]

31 minutes ago, stuart said:

"Deform" is one thing but when theyre so soft that they dont actually grip the hole is another and that was the problem with those. they wouldnt grip enough to stop the stud turning when the nut was tightened .

Stuart.

So in effect the studs are made from a ‘soft’ metal, or they have not been properly heat treated to harden them.  
  I think I’d avoid them for my car.

Edited Saturday at 11:51 AM by BlueTR3A-5EKT

[stuart]

8 minutes ago, BlueTR3A-5EKT said:

So in effect the studs are made from a ‘soft’ metal, or they have not been properly heat treated to harden them.  
  I think I’d avoid them for my car.

They certainly were soft, that was at least ten years ago and Ive had no problem since with TR Shop supplied and Cambridge Motor sports too.

Stuart.

[PXC]

Cambridge motor sports it is then.