Replacement Wheel Nuts

[AdC]

Morning all. I'm looking to replace my rusty chrome nuts and before I push the button wanted to ask if there are any gotcha's or words of wisdom anyone has?

Apart from the thread size (3/8 UNF) and the seat angle (60 degrees) is there anything else to consider? Can I go 'open' (I don't like the amount the domed nuts stick out), Also, will all nuts have the same length of taper (I'm thinking if it's too short then they won't tighten enough.

These are the ones I'm thinking of.. Thanks all.

http://www.ebay.co.uk/itm/Set-Of-4-Wheel-Nuts-For-Formula-Ford-3-8-UNF-x-11-16-Socket-/151493056985?pt=UK_Cars_Parts_Vehicles_Wheels_tyres_Trim_Nuts_ET&hash=item2345b099d9

[Jonathan Kay]

There's lots on this in the archives, and there are some rules of thumb for minimum length of engagement of bolt on stud.

What sort of wheels do you have, and what's the length of the protruding stud?

Jonathan

PS: I wouldn't buy unbranded wheel nuts from a supplier I hadn't heard of. 

[Damo V]

Can't you just get yours redone? Or dipped and coated if you don't want chrome anymore?

[SM25T]

CC do stainless nuts .... certainly of the closed type. Work well with my anthracite 10-spoke alloys.

[Ian B]

You could try emailing Dave Davies the Wheel Nut Man.

No website but knows his nuts 

[AdC]

Thanks, I spoke to the Speed Shack and found there's very little choice - chromed, either closed or open. The zinc plate FF ones on eBay apparently wouldn't work as I need a bulged shoulder behind the taper.

[ECR]

Hmmm, don't quite understand the wed for a bulge. Your original nuts have that ?

 

[Geoff Martin]

I have a full set of closed chrome nuts that were used to hold the minilight type wheels on my old 97 DeDion K series. You are more than welcome to have them. All the chrome is in pretty good nick and shiny.  

[AdC]

Thanks Geoff - that's a kind offer but I have open ended, chromed, "bulged" nuts on their way from Speed Shack. Not ideal (I didn't want chrome) but as the ebay seller didn't reply to my email, I don't know if the zinc plated FF nuts would have been okay, although both taper and thread were correct.

My concern was to do with the length of the taper. If the nut was not bulged, and the taper on the nut too short, then I wondered if the hexagonal nut would cut into the alloy. Essentially I was asking if the length of a nuts taper is 'industry standard'. Or maybe I think about these things too much...

 

ECR - no, I'm not sure I understand either :-). The current tatty ones do...

[AdC]

Fitted the new open nuts on my new wheels today and was surprised how much thread on the nut is visible - the end of the stud is buried a long way inside the nut.

- old KN Minator wheels, old closed / domed nuts = 12 - 12.5 turns to lock

- old wheels, new open nuts = 11 turns to lock.

- new wheels, old nuts = 10.5 turns.

- new wheels, new nuts =  9.5 - 10 turns.

So with my arts background, non engineering head on, I googled for info and discovered that 1.5 x the thread diameter is considered a safe amount of thread to be covered by the nut. If so, my calculations are as follows...

3/8 UNF (9.5mm) diameter studs. Therefore I need  14/25th / .56 inch (14.25mm) of stud thread covered by the nut. With 24 threads per inch, if I'm only turning the nut (new nuts, new wheels) 10 times, that's approx .42 inch (10.7mm), i.e. short by about 3.5 turns!

 

Question is, are my assumptions correct? Is my maths correct? Do I need new studs? And is it an easy / cheap job? :-)

[Jonathan Kay]

Isn't that a bit complicated: why do it in turns rather than length? You need to know the thread diameter and the safety factor and then check you have that length of protruding stud and nuts with that minimum axial length of thread. (And that's why I asked that in the first response.)

There are several reports of short studs in the archives. I've never replaced them but it doesn't sound too hard. Let us know if you can't find the procedure.

Jonathan

[AdC]

Hi Jonathan. If you look at my listed figures... 14.25mm minus 10.7mm = 3.55mm. At 24 threads per inch that's about 3.5 turns. The thread diameter I've also listed as 3/8th (9.5mm). The safety factor I've also listed as 1.5 x diameter (taken from the net). It may not be the way you'd look at it (I've just done a house rebuild and have learned that with three tradesmen all working the same thing out, the route to the same answer is invariably different) but I was hoping someone would either disagree or agree with my answer, and also with my assumption that 1.5 x thread diameter is sensible.

It looks like new studs will be required, so thanks for suggesting I search for "short studs". That and a google suggests it's not that hard with judicious use of a hammer.

[revilla]

My studs are the same as yours; it worried me too. I raised it on here and the general response seemed to be that, despite what you read as being good engineering practice, it's quite normal for the studs on a Seven and doesn't cause problems. Still worried, I raised it with Nick Potter when the car went in for some work a year or so ago. His response was along the lines that most of them are like that and even the race teams just don't have problems, they never come loose, if you really want to change them for longer studs for peace of mind you can but honestly no need to worry. I haven't changed mine and they certainly haven't shown any signs of coming loose. I don't know about yours but on mine it's only really a problem with the rear studs; if and when I do have another reason the strip the rear hubs I'll probably put longer studs in but in the meantime I've just them as they are.

[AdC]

thanks for your post revilla. I tried to be 'scientific', but more than that it just 'looks wrong' with such an amount of unused nut thread (6 or 7) and the stud hiding all the way in there... I'll leave them as they are and maybe mention it to PGM when I get the new suspension fitted next month. Can't see myself using it much in the meantime anyway.

[SM25T]

Original studs were 32mm.

When I bought my Roadsport SV with 15" anthracite alloys, the studs only engaged about 4 threads into the nuts !!

CC wouldn't agree that this was not good engineering practice 

I bought a set of 16 x 40mm studs and replaced them all.

Easy job ... involving a big hammer.

[aerobod - near CYYC]

Assuming the wheel stud and wheel nut are matched in strength (i.e. 8.8 to 8.8 or 10.9 to 10.9), a standard nut will shear the stud before the thread fails. In the case of an M12x1.5 thread, a standard M12 nut is 10mm thick, leading to 10/1.5 threads of engagement, i.e. 6.5 turns to the nearest 1/2 turn. Assuming the thread isn't damaged, 6.5 turns of engagement should be enough to shear the stud under excessive tightening force as easily as any more threads of engagement could do. I know on our BMW 135i that the hub thickness is 10mm for the five M12x1.5 10.9 strength wheel bolts that are tightened to 120Nm (compared with 75Nm for the four Caterham wheel nuts), giving the same 6.5 turns of engagement.