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Aerospace bolts


Pierre Gillet

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I have just finished replacing the bolts below the flare wings by aerospace anodised mushrom bolts( in red, my car is in pearlescent ruby). It improves quite a lot the look because, at first sight, one cannot really see the bolts anymore , and if one does insist, they look great. I wonder if the racing anodised ali nuts proposed by Compomotive can be used for the minilite wheels of the Seven.They have some in anodised red which look great and you can spare 400g in weight!

Cheers,

 

Pierre

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Where can I get COmpomotive alloy wheel nuts??

 

If we need to machine the seat angle I can arrnage this en mass.

 

This has to be a significant weight saving - 1.5 - 2 kilo's for the car, off the unsprung weight???

 

Arnie Webb

The Fat Bloke blush.gif in a Slow Old Vauxhall wink.gif

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Arnie,

the 16 nuts of my Seven weigh 900g. Assuming that alloy nuts are 60% lighter, you may save half a kilo of unsprung weight! Not bad!

I don't know where we can buy some . I assume by calling Compomotive.They must have a web site.

The Compomotive racing nuts that I saw in the CCC ad are very attractive because they seem to be anodised in blue or red.

Pas mal!

Cheers,

 

 

Pierre

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What colours do they do? Not keen on blue or red. Gold, silver or black would be ideal...

 

I considered getting some Ti ones but believe these ones are even lighter still (AMMO, can you confirm? Where did you get yours from?). The other benefit would be not seeing them get that mottled rust effect, so I'd be interested...

 

C7 AJM

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I think the ones Compomotive sell only come in blue and red - and I think they're matched to the thread size / seat angle, i.e. Ford, etc. ones with 60 degree seat and M10 thread are blue and the other options (Jap stuff ?) are in red.

 

Could be wrong of course, but they list different car makes for each colour nut which suggests you don't get a choice if you have Ford, etc. thread / seat pattern - blue or nothing.

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As an aside, and going back to the initial point of this thread, be a little cautious using anodised alloy bolts - they are not all "aerospace" grade alloy and cannot take high tension or shear loads as they snap very easily.

 

Some are better than others but I'd really only use them in stress free, cosmetic applications.

 

I'm sure everyone knows that so apologies for any egg-sucking lessons.

 

Nick

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OK I've spoken with them:

 

They are 7000 grade aerospace alloy.

The red and blue are ex stock, but the can anodise to order in other colours.

They are only available in metric sizes so will only fit Didion Ford PCD cars.

I have secured a price of £3 per nut plus VAT and shipping. Retail is £5.95 inc.

 

Arnie

 

 

 

Arnie Webb

The Fat Bloke blush.gif in a Slow Old Vauxhall wink.gif

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The 7000 Series of Aluminium Alloys is an entire family of alloys that have a wide range of properies depending on detailed chemical composition and heat treatment.

 

The family breaks up into 7010, 7020, 7030,7040, 7050, 7075 and there are even further sub-divisions.

 

There are several heat treament categoies from T0 to T7 but T6 is the most common temper that is commercially available.

 

Even the heat treated alloys can vary in strength from a 7020T6 at 380MPa to 7075T6 at 570MPa. Obviously 50% is quite a strength range.

 

The real problem is that the higher strength types of this series of alloys tend to have poor atmospheric and salt water corrosion properites. The anodising may help but again high strength versions of this alloy don't anodise very well.

 

It is quite common in Motorsport that people talk about "Aerospace" material but we all need to be aware that you can buy Mild Steel certified for use in aircraft, it doesn't change the material only the inspection.

 

I did send Compomotive an e-mail and asked them the maximum recommended torque for these nuts, which is really the point, but they never answered !!!!

 

Hope they have good Public Liabilty Cover!

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I don't really have titanium nuts. I am considering making some wheel nuts in 6AL4V Titanium. I have used both ali and ti fasteners on racing motorcycles before but only use aluminium fasteners in non-stressed areas. Titanium ones will not be as light as 7000 series aluminium but would be a lot stronger. Basically I'm really paranoid about safety and would rather pay the weight penalty. I'm sure Compomotive have done their homework. Maybe it's worth checking what kind of life the nuts have in time or mileage and if they are only for competition use or if they can be also used in high mileage road use. Also my car is a porky one not one of these stripped down road missiles so my requirement may be different.

 

AMMO

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Chris,

 

They put them or rally cars and they are one form of 7020. Thats good enought for me.

 

Regarding Ordering I suggest we create a list in this here posting.

 

4 column format as follows - as you add to the list please cut and paste this into your posting (i.e so the last posting contains everyones order) Then I'll get a bulk order made.

 

Name: Qty: Colour: Email Address:

Arnie Webb 20 Red arnie@the-webbs.com

 

 

 

 

 

 

Arnie Webb

The Fat Bloke blush.gif in a Slow Old Vauxhall wink.gif

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Nick,

For my flare wings, only the small bolts( M5) that are in rivnuts are alloy. The 2 main bolts ( 12MM heads I think) that are fitted to the chassis tubes remain the original steel ones on which I have fitted anodised ali caps matching the color of my car to keep them looking neat and less visible. So I think it should be OK. I shall check often though.

Cheers,

 

 

Pierre

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I have used aluminium fastners in nearly all of the unstressed areas of my car without any problem.

 

I worry more about wheel nuts though. I like the idea and the reduction in unsprung weight but I do worry about the potential problems.

 

The 7020 alloy that Arnie tell us is used for these nuts is probably a good idea because it has good corrosion resistance compared to the stronger 7000 Series materials, which I think is vital on a road car.

 

I guess that my concern is that how much of the ultimate tensile strength of the material is used to torque up the pre-load on the stud compared to the working stress in the stud/nut arrangement when driving.

 

It's quite interesting to see the wheel stud failures on trucks (About 3% of total fleet according to the DOT). It is ususally the nearside rear that suffers the first stud failures and this is thought to be due to the combined effects of driving/braking torque combined with road camber effects causing a relatively high mean stress within the studs.

 

It is normal to design a bolting arrangment so that the stud/bolt will fail befor the internal thread stips out and I can't see anyway of doing this with an aluminium wheel nut. Studs are commonly 8.8 Grade material with some competition studs being 10.9 or 12.9.

 

The nut strength recommended for these studs is Grade 8, 12 and 12 (not a misprint).

 

The Aluminium nut would be equivalent to a steel nut of grade 4, this is 50% of the usual strength.

 

This could cause a problem of wheels working lose because of the nut yielding during a high working stress excursion and losing preload. Once the nut starts to work lose it will just keep getting worse.

 

On a typical stsge rally car the wheels are changed virtually every stage and the wheel tightness checked very hour or so, much more than on road cars.

 

I will try to find some "real" figures for the working stress developed in a stud and see what it all looks like from the stresses.

 

Let me know how you get on in practice.

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The formatting of my message above got knackered by the server!

 

If you want me to order you some nuts drop me an email and we'll order off lien. I anticipate ordering by the end of next week!

 

 

 

Arnie Webb

The Fat Bloke blush.gif in a Slow Old Vauxhall wink.gif

 

Arnie Webb

The Fat Bloke blush.gif in a Slow Old Vauxhall wink.gif

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