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Jon Grainger
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Discussion Starter · #1 ·
Hi guys,

Over the past few weeks, I've been noticing that the grub screws in my NSR wheels, are starting to cut another thread in the alluminium, resulting in a hole that is two wide for the screw, meaning the wheel wont 'lock' onto the axle, rendering them useless.

I thought this maybe because they are older wheels, and thus the thread is starting the wear after being used. However, I recently bought some NSR wheels from a UK supplier and after the second time of tightening them onto the axle, the one had cut itself a new thread! I recently bought an NSR Corvette, from Italy, when the car first came out. And after a few times of use (setting the wheels up), I had the same problem. So I doubt it's a dodgy batch here in the UK.

I'm using NSR's own allen key for the job (the silver one), and not putting any real force into it. But it does seem that the metal used for the grub screw is harder than the alluminium wheels, and cutting a new thread in them.

So, the long way around the question, but has anyone else noticed this, and is there a solution, apart from buying more wheels?

Cheers,
Jon
 

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The solution is to drill the hole out, rethread it and use a larger screw, but if you can't do this your self it's probably cheaper to buy a new wheel, you could investigate helicoils, but I doubt if they come in small enough sizes and probably will cost more than a new wheel.

BTW the screw is made of steel and the wheel alloy, therefore the screw will always be harder metal than the wheel.

When you're taking the wheels off are you taking the grub screw right out, you should only need to undo it by quarter of a turn for the wheel to slide off the axle.
 

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Ey Up John.

NSR grub-screws are quite coarse thread, with a "knurled" end.. The hubs are quite small. So there is not a lot of "engagement" before the screw meets the axle.

Next NSR wheels you get, take the screw right out, then grind the grub-screw tip flat with the coarse disc in your dremel.

That will maximise thread engagement in the hub.


In fact do that to all your NSR wheels, now !!

vbr Chris A.
 

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Jon Grainger
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3,825 Posts
Hi Julian,

I've thought about re-drilling the hole, but because NSR put the holes close to the edge of the wheel, and especially now they have been made bigger, it wouldn't be possible to drill through, without going through the alluminium on the one side.

I very rarely remove the screw completely, only if I have to file the inside to get them to fit on a slightly larger axle.

Thanks Chris, I'll give it a go
 

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Hey John,

Our posts overcrossed there, hope you read mine !!.

In addition, I have on occasion replaced the large size NSR screw with the smaller 2mm Slot-it size.

You do need a pillar drill, and a screw tap, to achieve this consistently.

That mod also allows the boss to be slightly shortened and therefore get wider tyres in a given set-up.

Your comment re "filing out the wheel" gave me the screaming hab dabs !!.

What you should use, of course, is a 3/32 reamer, available at your local tool supplier !!.

VBR Chris A.
 

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Jon Grainger
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3,825 Posts
Discussion Starter · #6 ·
Hi Chris,

Yep, I did see your post, and the second one as well. My problem, is that I dont own a pillar drill, making it difficult to drill accuratly, to cut another screw hole.

I seem to remember NSR used to tap a hole on both sides of the wheel boss, but my recent purchases have not had these features. Would two holes have caused the wheel to not be as stong?
 

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QUOTE (ferraif40 @ 7 Nov 2011, 14:44) <{POST_SNAPBACK}>Would two holes have caused the wheel to not be as stong?

Yes, but I don't think a slot car puts enough stress through it's wheels for it to be an issue.

I've held plastic wheels on with Araldite when the hole has got worn, when I've needed to remove them twisting the wheel on the axle sharply has been enough to crack the Araldite.
 

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Lee Green
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1,995 Posts
To find the thread instead of creating your own screw the screw in backwards untill it falls into the thread , then tighten , or simply dont take the screw out of course
 

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Premium Member
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Hi Jon,
Several issues here.
First NSR wheels do seem to be made from quite soft aluminium.
Second the bosses are very small diameter, so not much thread depth.
Third, as Chris says, the grub screws do have a taper and a knurled bit on the end.
You can't do anything about the first two, except maybe buy a different make of wheel, but for the third problem, again as Chris says, grind off the taper and the knurled bit so your screw has a flat end and threads along its full length. Be very careful putting the screw back in or you will damage the thread in the wheel.

I have drilled and tapped several NSR wheels right through the boss but the metal is so soft that they rarely run true afterwards.
Mind you if you're opening out the centre hole with a file the aren't going to run true anyway.
A 3/32 hand reamer isn't cheap but will save you money in the long run.

Cheers.
****.
PS. Did you know that Slot.It now make air wheels? I don't like the 2mm screws but at least they don't strip the threads so easily.
 

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Nobby Berkshire
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2,015 Posts
Myabe the wheels are fine and the grub has a bad thread?

Just glue the wheel on with araldite epoxy. You can get it off just by dipping it in near-boiling water.

Or take the faulty stock back to where you bought it and get a refund. use your consumer rights rather than fiddling around bad manufacturing.
 

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Eddie Grice
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2,307 Posts
QUOTE (**** Kerr @ 8 Nov 2011, 00:21) <{POST_SNAPBACK}>I have drilled and tapped several NSR wheels right through the boss but the metal is so soft that they rarely run true afterwards.
Ah, I had aways assumed it was my ham fistedness

ABS sells 4/40 taps, he used to do drill & tap as a set but I don't see that listed now? He also does 3/32 hand reamers.
See the green bit on this page, http://www.abslotsport.biz/page19.html
Eddie
 

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A little while back I bought a job lot of old Parma hubs the grub screw was the same as NSR only slightly longer (really like the idea of putting a flat on it) but marginaly less course and being a bit longer would lend to the mod. I wonder if this in conjunction with a slight flat on the axle might help resolve the problem.
 

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rob Wallader
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785 Posts
Hi Jon,
Bring the hubs along to Wolves next meeting. I have a drill & M2 tap, I can sort these out for you.
You will spot me a week on Sunday, Im the good looking bloke on race control.

Rob
 

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rob Wallader
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785 Posts
I suspect that Ninco & NSR by their Aluminium from the same place, It must get mixed in with some playdough!
Ive had several pairs on NSR & Ninco alloys with damaged threads.

Rob
 
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