Live Axle Clunk - where to get it fixed?

[cskip]

Looking for suggestions recommended establishments for having a Shims fitted to a Live Axle. Preferably in the South!

 

Already tried James Whiting, but he doesn't repair them only replace.

 

Any suggestions?

 

Thanks in Advance

 

Clive.

 

Crossflow - Loud and Proud!

 

[ChrisHawkins]

I tend to use Ratrace in barnet(www.ratrace-motorsport.co.uk), They have always been very helpful

I also have a very similar live axle car and would be interested in where you put these shims and what they do and how i could tell if i had a problem

[groutledge]

Hi Clive, it's Graham here thet guy who gave your wheel the clang at Brands.

 

Chris wheeler did mine at the 7 workshop 01992 470480. It depends where you are are in the country, any of the better 7 places should be able to sort you out, James whiting, Caterham Midlands etc.

 

The problem is that the bearing is only pressed onto the half shaft. The shaft itself as a machined face and therefore a step in it which means the shaft can't come out unless it breaks or the bearing colapses.

 

The bearing presses onto this shaft which is then retained in the axle by a plate with 4 bolts. The shaft is tapered and hub then torques onto the taper. this results in a gap betweem the bearing and the hub which when the interference fit goes causes the end float you experience. the shims basically fill this space but should not actually touch the hub or that will stop the hub seating on the taper properly.

 

It's easy to spot just grab the wheel and rock it backwards and forwards if it's gone it will move in and out about 5mm and clang like buggery.

 

I had this problem about 3 times last year in quick succession which is why I had it shimmed. Since them I've had no bother and that's on track using SS32R's and ACB10's

 

The trick with the Ital axle is to:

- shim it DO NOT WELD the bearing on

- jack the back of the car up as high as you can and really overfill the diff with oil

- sort out the A frame bushes. They are crap and when they go the back of the car acts as a slide hammer and knocks the bearings out. You can get powerflex bushes which need to be cut down but I found them to be OK. Chris W can fill you in on this.

 

I actually use the rose jointed A frame which is very good and an ofiicial caterham part

 

Graham

[ashaughnessy]

I thought rose jointing the a-frame wasn't recommended. I thought the a-frame was a crucial component to produce roll stiffness at the rear, and a spherical joint reduced the roll stiffness. So it says in Tony Weale's book, at least. Has something changed since then?

Anthony

[Graham Sewell]

Ratrace sorted my rear axle out - albeit by taking dimensions and ordering the shims from Caterham Midlands.

 

Cheers,

 

Graham

 

Low tech luddite - xflow and proud!

[Casbar]

Took my hub and half shaft out of my axle at the weekend. Had a new half shaft and bearing fitted plus the hub cleaned up yesterday by Steve at SP Components.

 

Great service, turned it around for me in the same day. As to the shim or weld question, it seems to be a bit of a bone of contention. Steve puts a spot weld on the bearing, and didn't agree with shims at all. James W uses Steves axles, plus Steve supplies the axles for the Classic to Caterham. He told me he hasn't had a problem with a modded bearing. So I guess its a personal choice as to which is the best way forward.

 

For my part, Steve did a top job and I will certainly go back if the other side fails.

 

Getting the half shaft out, is a relatively easy job, as long as you use a slide hammer. Re-fitting it, took around 15 mins.

[cskip]

One of the options I am considering is upgrading the Hubs/Brake to use the Fireblade arrangement. It's an expensive option at £700 plus the dreaded for the parts only. Has anyone got experience of this?

 

So looks like the options are:

 

7Workshop

Caterham Midland

Caterham South?

Ratrace

SP Components.

 

Any others?

 

Casbar, Why didn't Steve agree with the Shims approach?

 

Clive.

 

Crossflow - Loud and Proud!

 

[C7JFM]

the fireblade disc conversion sounds interesting. What parts are needed? any one know? does it retain the ital pcd and if so which brake disc is used ?

[Casbar]

Clive, didn't really pick up on his reasoning, but it seemed reasonable, I think he said there had to be some movement. Give him a call, he'll talk to you about it.

 

I can't see how converting to discs is going to have any effect on the bearing, also remember that James W gets his half shafts and bearings from Steve anyway.

 

SPC 01527 894232

[groutledge]

Tack welding the bearing produces a hot spot on the shaft that can lead to stress fractures and failures. If you want to have the wheel drop of go for it!. The Fireblade hub does the same job as shimming as James Whiting expained to me when I wanted to switch to ACB10s. He said that the new hub was done because shimming individual axles is time consuming and not economic, hence the new hub that does them same thing with some sort of grub screw arrangement.

 

As for the rose jointed A frame, it does increase the rear grip as I noticed when I switched to it which may be down to roll stiffnes but I suspect it's down to better location. The Powerflex bush option seems quite good although I only had it on whilst waiting to fit the A-frame. I would not expect the rubber bushes to contribute that much though. In fact I've heard that the A-frame would increase roll stiffnes.

 

Graham

 

 

[Casbar]

Graham,

 

I don't doubt what you have been told about spot welding the bearing. But a couple of facts -

 

1. Steve from SP Components does put a spot weld on the bearing, he is probably one of the most respected gearbox, transmission and axle experts around.

 

2. Steve, as already stated, supplies all the live axles to Caterham for the classic. If you speak to James W, you will also find he supplies the half shafts and bearings made up for James as well.

 

So does, he only spot weld the bearing for his own customers and not the ones he's supplying to others - Wouldn't seem to be good practice!

 

So you have clear evidence of the wheels falling off if the bearing is spot welded, there must be a lot of live axles cars out there, with missing wheels then!

 

I am a little concerned about the wheels falling off issue, so I'm going to phone SPC today, and let him know that your telling people that his mods are unsafe, as I wouldn't want to be driving anything that is possibly dangerous.

 

 

[Graeme Smith]

Had my half-shafts spot welded. Wheel fell of a week later at Donington. Had shims put in instead. Wheels still attached two years later.

 

To Caterham's credit there was a re-call on race cars that had had the spot welding done in that period.

[Violet Elizabeth]

Would be VERY interested in any possible saftey issues, as I have an SPC spotwelded diff as well. Bit of a worry.

[R2D2]

I must say that I agree with Graham. Using welds on comonents that were designed to use interference fits is not always a good idea without fully understanding the metallurgy.

 

The debate about welded bearing tracks has gone on for a couple of years now and it is just not good practice and can't really be justified. There is potential for cracks to initiate in the welds region due to the materials being used and the results of wheels falling off in high speed corners just doesn't bear thinking about, let alone the liability implications.

 

 

Bearing tracks are made from a very high carbon alloy steel and are just not suitable for welding. The post weld structure of a steel of this type of steel would be almost 100% maretnsitic unless it was heat treated to allow transformation.

 

A Marina/Ital half shaft uesd to be manufactured from EN8, which is a medium carbon steel with a Carbon Equivalent of about 0.43%.

 

It is ususal to recommend either pre- or post weld heat treatment to any steel with a CE of greater than 0.4% other wise heat Affected zone structres may be brittle.

 

EN8 is marginal but if fatigue failures do initiate in HAZ regions wheels will fall off.

 

I am sure that a couple of years ago several Academy cars (?) suffered form wheels falling off Ital axles when racing. I beleiev that Caterham supplied these cars complete with axles but I never saw a failure so this is only hearsay but I am sure that someone may know what happened.

 

I have an Ital axled car and I would never fit a half shaft with a tack weld it would worry me far too much and I have been bothered about this practice for some time it can be potentially dangerous.

 

I am sure this debate will go on and on but my vote is to use spacers.

 

Just an additional note, the term "spot welded" os incorrrect. Spot welding is a low energy solid phase welding process.

 

The mods carried out to Ital axles ues a "tack weld" with a TIG or MIG welder.

 

Edited by - chris flavell on 3 May 2002 09:27:52

[Casbar]

Just spoken to SPC, facts are:

 

1. SPC put a 10mm tig weld on, as per Caterhams instructions, and have been doing for years. All Caterham live axle half shafts are done this way, as is James's.

 

2. Steve at SPC did say that there was a problem with the race cars, he doesn't know where the shafts failed, but all Caterham did, was have new half shafts manufactured, with exactly the same design as the old ones, and, they were all tig welded by Steve as they are today.

 

3. He mentioned that at one point, on Caterham's instructions, he tried using shims, but all that did, was push the hub out, with the the result that the drum brake shoes could be seen. Caterham then told him to go back to the tig weld.

 

He did mention that some others that have provided axles for Catherham and they used to weld all the way around the bearing, which is different to his single small weld.

 

As already stated, this debate will go on, so I don't know which is the best way, I supposed many things could cause a half shaft to fail, if there was a major safety issue, wouldn't Catherham of instructed SPC to stop the practice?

 

 

[R2D2]

Casbar,

 

I think you need to make your own decision.

 

It is impossible to guess the reason for the instructions of Caterham without being party to their rationale and engineering judgements and it isn't sensible to speak on behalf of Caterham as why they have continued the practice.

 

The real problem here is that no-one seems to have published the reason for failures that have occured and no-one seems to want to be responsible for the engineering decisions. Its all a bit cloudy and indistinct.

 

The basic decisison is whether or not welding bearing tracks to half shafts is good practice or not and without a great deal more information I would consider it as very risky.

 

Good luck.

 

 

 

 

[groutledge]

Chris Flavell is a very experienced engineer who makes very high load rolling roads and torque meters so he knows a thing or too about metallurgy and i respects his opinion on the matter, in fact I think it was his posting that prevented me having the bearings welded.

 

As for shimming the shims should only fill the gap between the bearing and hub ( witha smal clearance),as the hub is torqued onto a taper which is then used to transer the drive ( not the woodruff key ). Is the shims are the wrong size you will be relying on the key and not the taper fit.

 

Chris Wheeler had to make my shims up on his lathe after much measuring.

 

Graham

[Casbar]

I agree, with Chris, you pay's your money and takes your chances. Its a bit late as I've already fitted the said half shafts. So, I'll keep you updated.

 

I have no doubt of Chris's engineering abilities and experience, but the same could be said of Dave of SP Components, he is also an experienced engineer.

 

I can only make judgements on recommendations of people with more experience than myself.

[cskip]

Oppps! Opened a big can of worms. Very interesting though.

 

I will contact Caterham and ask their advice, maybe they can clear this up.

 

 

 

Clive.

 

Crossflow - Loud and Proud!