Ital Axles

[R2D2]

The subject of Ital axles seems to be occupying a great deal of time and energy and is obviously causing a lot of anxiety.

 

There are obviously a large number of Sevens fitted with this axle (mine included) and changing to a Ford unit certainly causes headaches for people with long cockpit cars.

 

I have been reading about failures and weaknesse for months but I can't seem to identify a clear trend.

 

Is the problem diff wear? Half shaft Failure? Wheel Bearing Collapse? beacuse if we can identify a common trend we might be able to engineer a solution, which may not be any cheaper than changing axles but may be a lot easier.

 

I was also interested to read that fitting an LSD helps to solve these problems and I have been trying to fathom ou why this should be the case.

 

If crown wheel and pinions are wearing our too quickly because of the power they are transmitting it is ccertainly worth looking at the tooth loading to see if some improvements can be made and judging by the number of people with problems we could manage to have a batch of parts manufactured.

 

It could be that the diff housing cannot accept the loading and that excessive deformation may be damaging the side gears and I guess that this would be fairly terminal unless there is a stronger unit that could be fitted to the existing casing.

 

If half shafts are breaking I am sure it is realtively easy to have a batch of stronger half shafts manufactured because the steel that was used in the Marina days was not very highly specified. (Maybe the Ital used stronger steels, but I some how doubt it)

 

If the wheel bearings are breaking up it is almost certain that higher specification bearings would be available.

 

Fitting an LSD could certainly help solve side gear wear as they would be completely removed but I am not sure how it would help with crown wheel and pinion wear, half shaft failure or bearing collapse.

 

How can we find out the predominant cause of failure and try to find a fix???

 

 

[flick]

One of the common problems is that the bearing on the half shaft is just located by a press fit (Interferance).I think it might be possible to re engineer this area.

You know if you have this problem because when you jack the rear off of the ground you can pull a rear wheel out and push it back in by approx 10mm.

 

The half shaft/wheel ass will not fall out as there are inbuilt measures to stop this happening.If a rear bearing was to let go then you could loose the assembly.

 

 

 

 

[I.Mupferit]

From what I've read over the last couple of years, I would say half shaft breakage appears to be the dominant but, by no means, exclusive problem with the Ital axle. I understand it was/is possible to buy stronger half shafts from Caterham which are used by the live axle racers but, in any case, it should be possible to spec. a better grade material relatively cheaply given that the shafts are relatively easy to make. The diff. assembly is a whole different problem and would, I imagine, be very expensive to have specially built in a higher grade material, you would need to be talking about a large build run to make it economically viable. The difficulty with making one component stronger is that you simply move the problem on to the next weakest component and so on. The whole crux of the matter is that the Ital axle was never designed to be stressed to the levels that we impose upon it in our cars.

Rather than re-designing or re-speccing the Ital axle, both of which could be hideously expensive, should we not as a group investigate a basically stronger existing axle which could be adapted to our cars? The Toyota axle has been suggested as one possibility although I know nothing of it's potential myself. I would be happy to assist, where time permits, to talk to a few people who might be able to help. The axle issue is a very real problem for me as I am loathe to use the full potential of my engine at the moment, mind you it does make my driving somewhat smoother!

 

Brent

[Graham Perry]

It might be worth looking into what other people do in motorsport where live axles are the norm. For example national hot-rods still use a live axle and run big horsepower and sticky tyres. They may use an axle that is more appropriate or have solved the problem. There could be other motorsport users as well to consider.

[tgracing]

You could try giving Classic Carriage (01455 841616) a call. They did the work on the uprated Ital axles for the Scholarship/Academy/Graduates race cars. (I think the half shafts were uprated and the bearings were welded.)

 

As the Academy is moving to De Dion cars from now and Ital axles are in short supply I suspect there won't be a lot more research done.

 

Oh and by the way, try telling the Scholarship competitor who saw his wheel sailing past him a couple of years ago that the wheels don't become detached.teeth.gif

Cheers,

 

Davebo

C7 CAR

[R2D2]

I agree that re-engineering a complete diff assembly may be too expensive but some of the parts may be affordable.

The real problem that I have is that the Ford axle was never designed for high power outputs either. I have rallied Escorts for years and the only way to get good reliability once you exceed 160BHP is to fit a Atlas axle. I feel that these are just a bit too heavy for a Seven although I know some people have used them to be confident in not experiencing failures.

 

I agree that the Toyota axle is probably the best bet as it is used in th Birkin and the Frazer.

 

I have seen them used on Hot Rods for several years and they tend to run 190BHP MAS engines and they run without too much trouble. I think some of the factory Toyota Rally cars produced about 240BHP and didn't suffer too many diff problems. It looks very similar to an English Ford unit and I suspect that it will be a similar weight.

 

I have some good contacts for manufacturing splined shafts and all of the geared components that would be needed so I am inclined to persevere wwith the Ital unit and see what happens. If any one has any broken parts that I could have so that I can see what the original materials are it would be helpful. I wouls gladly pay postage or carriage.

 

I have been trying to find a used AE86 axle for a few weeks but I haven't looked to hard.

[Barry H]

I may be talking out of the back of my head but it occurs to me that the stress caused by 160 bhp to an axle on an Escort weghing, say, 800 kg could be somewhat less than to a Caterham weighing 500 kg.

 

If nothing else the Caterham is more likely to experience wheelspin thus reducing component loadings.

 

Am I barking up the wrong tree or just barking mad?

[R2D2]

I think I agree a 160BHP Escort on racing tyres could cause more trouble for the axle than a Caterham but the Ital was quite heavy as well and some versions did produce similar power to Mexico's and RS2000s.

 

The point I was trying to make was that spending a great deal of time and trouble in fitting 30 year old Escort axles with half shafts and diffs that have been well used doesn't seem particularly rewarding and maybe there are better solutions.

 

I agree that finding a modern live axle that will do the job properly would be ideal. The only option I know of is to buy new axles from Birkin (They bought tools from Toyota and are making the AE86 axle) if they will sell them. I imagine if there were enough enquiries they may even be prepared to bracket them up to suit but I haven't asked.

[Graeme Smith]

AS Davebo said earlier in the thread, Classic Carriage Co and Caterham did some work on the shearing half-shaft problem last year and tried a number of solutions. An initial idea of welding the (already uprated) half-shaft at another point (sorry, a bit hazy on the details) didn't work (I had this done and parted company with a wheel at Donington, but to be fair I had been warned there was a recall). The subsequent solution involves copper shims (I think) to take up any play in the axle, and the number of wheels falling off in Grads races seems to have dramatically reduced (I'd say stopped but...).

It seems that its only a problem on cars used hard on the track - I doubt most trackdayers abuse their cars as much/as regularly as racers.

 

Edited by - Graeme Smith on 16 Feb 2001 19:39:50

[Richard Gibson]

I am going to drop this same statement I dropped before which got no response. So maybe my sources are bad.

 

I have had 2 separate people tell me that the TR7 used an Ital axle. And it had a better grade of steel/or better build quality.

 

Also some or all the automatic cars were fitted with a LSD.

 

This is the TR7 not the TR8. It seems to good to be true as far as finding a LSD. Can someone shed some light?

 

Richard Gibson

[I.Mupferit]

Richard

Don't know anything about the TR7 axle, I will try to find out but in any case the chances of finding one are slim to non-existent I would think. It may, however, shed some light on whether or not the Ital axle can be sufficiently strengthened. As an aside does anybody know what axle the TR8 used? This should be strong enough as it was transmitting power from a 3.5L V8!

 

Brent

[elie boone]

Is it not possible that the axle housing is to flexible, Caterham did reinforce the English axle, but if you weld a tube from the top of the axle to a spot as close as possible to the wheels. This on the top,bottom and back would strenghten the housing with not to much extra weight,or go for a five link set up this gives a lot less strain on the axle.

 

 

 

[mark.hall]

I seem to recall saying this before too......

I thought that ALL TR7's were designed with V8 power in mind, and only got the Dolomite engine (or whatever it is) when Austin Rover ran out of money/engines/enthusiasm. Therefore,I am led to believe, all TR7's have drivetrain parts capable of dealing with Rover V8 power and torque.

 

[I.Mupferit]

I have just found out from thr TR Register that the TR7 used a "lightly modified Marina axle which was very similar to the Dolomite axle. The diff. on this is practically the same as the Herald/Spitfire, and it's not very strong"

He goes on to say "The Marina derived axle was pretty marginal on the TR7 2-Litre 8 valve engine, there was no way it was going to take the V8'torque. So for the TR8 and later TR7s they used a modified Rover SD1 axle, along with the SD1 gearbox. The TR7/8 has a wider track than the Marina, though narrower than the SD1 so the question remains as to whether this late axle could meet your needs"

I would imagine the SD1 axle would be quite heavy and probably too big anyway but don't know without seeing one and measuring up.

[Richard Gibson]

Well, at least over there you have the resources to figure this whole TR7 axle thing will work or not. I still did not see anyone address the LSD on Automatic equipped cars. If this is truly the case, a deal may be found. I was told the drive axels themselves are stronger and could be used in a 7 as well as the diff, but how much modification??? Here in the USA almost all British cars are split up and I know in my local area where I could locate 5-6 axles immediately. I would figure that the TR7 Axles would still be around in the UK.

 

Richard Gibson

Washington DC

[R2D2]

The factory TR8 rally cars were fitted with a Salisbury 4HA axle. This unit was used on Mk2 Jaguars, Sunbeam Tigers and is massively heavy. I am not sure about road going TR8s