Javelin wheels/tyres and powder coating

[David Morris]

Hi there,

Our Javelin has just come up for its annual MoT and while checking round, I noticed that the Avon Tourist cross-ply tyres fitted to the car were starting to show signs of the side walls perishing. They have been on the car for 15 years and have only done about 12000 miles. However, there have been articles recently in the magazines about the dangers of using tyres on classics that are ‘time-expired’, let alone ones that are starting to obviously get perished.

So, it was time to bite the bullet and get some new rubber!

I thought that, whilst the tyres are off the rims, it is also the time to have a good look at the steel rims themselves. I have heard about the rims cracking, but don’t know which parts of the rims should be examined closely. I would welcome any advice on this safety issue.

Also, I would like to investigate the possibility of having the rims powder coated, as this would be the ideal opportunity. Has anyone had good/bad experiences of doing this?

I have spoken to two local companies doing powder coating and one was advising caution, as he thought that the sand used for the grit blasting process before powder coating begins can get into the riveted joints in the wheel and then cause rapid rusting, as well as blistering when the whhel is heated during the curing process. Has anyone heard of these problems?

Best regards,

David

[ian Howell]

David: -

I cannot comment on the pro's and con's of powder coating, but I DO have direct experience of a split rim!

The split was circumferential and fairly close the inner edge of the wheel roughly along the line of the edge of the tyre in the rim.

The effect was that the piece of metal stayed attached to the rim but moved under pressure from the tube so that it rubbed the track rod end (there must be very little clearance here).

My wife was driving at the time and noticed the 'graunch' but a succession of would-be helpers could find no fault. So, on she went, SLOWLY, with the steering being 'pulled' to the nearside with every revolution, until at last the tube burst.

When I eventually caught up with them, at first there appeared to be only the puncture, but of course, when I took the wheel off, there was a VERY neat milled groove across the track rod knuckle, and a highly polished bit of displaced wheel rim!

I have heard of Jupiter wheels cracking from the 'ventilation' holes, but as I have never owned a Jupiter I don't know for sure.

Hope this helps.

[David Morris]

Hi Ian,

Thanks for this advice. I guess the split was not readily noticable until the rim started to become detached?

It will be one of the areas well worth checking when the tyres are off the wheels.

As our Javelin, DCB 246, was previously owned by Ken Lees, who was once the Competition Secretary of the Club in the 1960's and who I believe was very active then in the rally era, I suspect the wheels may have seen a rather hard life - hence my concern!

Many thanks,

David

[Forumadmin]

The rally boys have had many experiences of cracking rims. The only occasion where the wheel needed to be changed when on a journey was in the Dolomites. Jupiter wheels are more prone to cracks; but Javelins also suffer.

Cracks occur mainly around the posts for the hub caps, stud holes and any other holes there might be. I have successfully stopped cracking by welding around all the holes and putting some cross pattern lines of weld in other areas. Such heat treatment relieves the stresses and strengthens the areas.

For the desert Marathon I had special wheels made out of steel twice as thick. Wide sticky tyres and a 1000 hairpins take the rims over there design limits; plus 50 years of stress!

[Leo Bolter]

Hello "Team Jowett".

In all possibility our wheels were never "Normalised" after the forming process of pressing them to shape.

Subsequent stressing from the forces of the tyre inflation pressure and from cornering would eventually manifest itself as splitting around the perimeter of the wheel rim where the tyre fits, simply because the area there already has stress forces "built in" from new.

Of course the forces of cornering are also concentrated, particularly at the wheel mounting points of the hub disk, i.e. the stud holes, and cracking is even more likely at this point as the metal has been "upset" by the pressing in of the seats for the wheel nuts right at the most stressed region.

I have experience with both of these areas of failing.

A Caravan rim split exactly as was described by Ian Howell.

Caravan tyres are usually pressurised to a somewhat higher value than would be the case of the tyres supporting a 4 wheeled vehicle of similar weight and of course the wheel is subjected to the swaying effects too.

In this case the displaced rim section cut through the brake line as the fracture line increased until the tube burst . . . a most frightening experience as it occurred on New Zealand’s Highway 1 in a road cutting and in heavy holiday traffic . . . we were very lucky! The caravan “onlyâ€

[ian Howell]

This all seemed to be going so well, until Leo mentioned leaving things out in the sun to get warm!

There must be more reliable methods = like move to Spain or take the car on the Sahara Raly?!

[David Morris]

Hi there,

Many thanks to everyone for your help on crack detection in the wheels. I plan to have the wheels grit blasted, with a fairly large grit if possible, to avoid it getting between the two layers within the wheel and then applying Leo's crack detection technique. However, I may have to wait for the sun!

I plan to follow this, if all proves OK, with the powder coating process.

It seems as though cracks can develop almost anywhere, but the favourite sites from the advice I have received look like around the wheel nut holes and particularily by the studs holding the hub caps. A time for careful examination!

Many thanks to you all. I shall let you know how it goes. I should say that I have checked three wheels so far visually with no sign of cracking yet, but this may be hidden under the existing paint. Who knows what lurks below!

Many thanks,

David

[vicboddy]

Hello Dave. FYI and to compare prices, I have just had 6 Jupiter wheals sanded, galvanized, and powder coated (in black, for what that is worth) here where I live in France. After sandblasting the wheals were washed with very high pressure water to dislodge any remaining grit, and I was able to check for cracks --and found none. End result is great. I was charged 219 Euro for the 6, which I thought was very reasonable.

For anybody interested, I had the Jupiter chassis similarly treated for a cost of 400 Euro.

regards Vic

[Robin Fairservice]

If there is a firm that does non destructive testing in your area, ask about "Magna Flux" examinations. This process useds an oil containing fine magnetic particles. The particles tend to collect in any fine cracks and show up under a UV light. The wheels would have to be sand blasted first. This is similar to the earlier sugestiin