24 replies to this topic

[RallyRed]

Hi,
A dumb question.
Torana wheel studs are 7/16 UNF 20?.
When I run a 7/16 UNF 20 tap through them , it actually does a minor amount of "cutting".
Am I to think the material being cut is just the chrome plating? or some re alignment of the thread, due to the thread in the old nuts being a little " rolled over" from years of loosening/ tightening?
Or, is the thread in the nut something a little special?.
Thanks

[claysummers]

Studs have stretched?


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[RallyRed]

Ta,
to be clear, the tap is going throuth the nuts, so the studs have slightly stretched, thus the nut thread is slightly distorted?

[LJ RB30]

yes 7/16" unf

Not a good idea to run a tap through as it will possibly remove metal. 

A thread restorer is a better option though i am guilty of using a tap when no other option is available.

https://www.machineryhouse.com.au/T116

[claysummers]

That’d be my guess Col. Most used threads on a car. FB shop manual specs 55-60lbft. That is about 75Nm in today’s currency.


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[RallyRed]

Good info gents, thanks.

I have worked  in heavy industry for around 40 years, never even heard of a thread restorer.

You do learn something every day.

[Shiney005]

I just ordered a set. Never heard of them either.

[RallyRed]

I'm liking the idea of the restorers.
As the studs are newish and the nuts in question are also newish, it sounds like the go.
The initial issue was that when I cut the heads of the nuts, they wouldn't just spin on over the long studs.i.e. a bit tight. Thinking that it was just a result of the cutting off of the heads, I tried to run a tap thru them...however, even the 1st couple of turns of the tap was doing some minor cutting ( well before the tap reached the cut off head area).

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Edited by RallyRed, 01 June 2021 - 09:17 AM.

[Shiney005]

Why the big long studs?

[Heath]

I love that look!

[RallyRed]

Track type.

 

I understand you need to present ( either by rule, or to keep the Scrutineers happy )....

 

1.  threads exposed through the nut, thereby confirming the nut has plenty of thread  in play

or

2. arrive at scrutineering with a tool , and demonstrate that they are tight.

 

It's just easier to have long studs.

 

( or something like that).

[Shiney005]

I love that look!

Too much excess weight for you Heath. 

[LJ RB30]

Any threads that are chromed will definitely change the finished dimensions so unless in this case the internal (nut) threads are machine finished larger to allow for chroming they will be tight.

But doubt many wheelnut manufacturers are going to that length to provide a perfect item.

Chrome on threads isnt generally a good or long term proposition as its rarely ever even 0.001" thick (basically decorative) & will be pealed off if great care isnt taken ie low torque used.

Not usually what you want on a race car

You definitely want threads clean & free running (but not flogged out) as possible so they dont pick up on each other (usually when you least want it to happen )  so the thread restorers will help there.

Especially on our old parts that are getting hard to find.

[RallyRed]

Thanks, all good.   

 

Some follow up info.....I found that the  brand new 7/16 UNF 20 tap, from a "large national auto retailer" was a bit of a dud.  I borrowed a "real" engineering grade tap, and it just breezes through the nuts, while still giving the treads a good clean out of any crap,

Happy Days. 

Thanks.

Edited by RallyRed, 01 June 2021 - 08:00 PM.

[claysummers]

That is concerning Col. Taps and dies can be pretty dear.

The long threads seem to be common in drag racing applications. Wonder why gmh never went to 1/2” on the 4.75” PCD like Henry did on 4.5”.

[Shiney005]

Some follow up info.....I found that the  brand new 7/16 UNF 20 tap, from a "large national auto retailer" was a bit of a dud. 

Name and shame Col. Nobody else wants to buy a dud.

[yel327]

Wonder why gmh never went to 1/2” on the 4.75” PCD like Henry did on 4.5”.

Because GM didn’t.

[RallyRed]

....same colours as Mc Donalds, and even "cheaper".

[claysummers]

Because GM didn’t.

Shall I repose the question? Strike the H.

early Holden nut

[Shiney005]

....same colours as Mc Donalds, and even "cheaper".

And that was the brand of the die? I didn't even realise they had their own brand of tools.

[hanra]

I just thought those long studs were just a case of glossy magazine syndrome? 

[RallyRed]

I think the home brand is Toolpro

I just thought those long studs were just a case of glossy magazine syndrome?

Studs?, nuts?, ..hearing ya Brad

[Balfizar]

Put long studs on my commodore for trackdays.
ARP studs and new koyo long nuts.

bought quality brand tap and die.

both tap and die cleaned up the studs (anodized finish) and nuts.

It would seem mass produced studs and nuts aren't really precision machined items.

and wear is another factor.

torqued them up  to standard spec- magic.

[RallyRed]

Agree mate...the cost of preparing a car, entry fees, accomodation etc etc, means we need to turn up at the track with everything "right".

[Balfizar]

Agree mate...the cost of preparing a car, entry fees, accomodation etc etc, means we need to turn up at the track with everything "right".

Will sell my VH SS Group III later this year, I can't wait for the "its been thrashed and trashed"
Little do they know that as you say (we need to turn up at the track with everything "right".)

any weakness, wear or failure will be obvious and can ruin your day.

in 15 track days I have only ever had  a power steering belt throw off and a mushy front right tyre, none of which stopped the track day.

Edited by Balfizar, 03 June 2021 - 11:55 AM.