Which live axle?

[Morls]

Soon I'll have to choose my back axle specification, and hence will be able to fix my front hub and wheel choices.

 

The car so far;

Apologies to purists for the unethical transplant of a 2 year old heart into a 40 year old classic. And no, it's not the one that's been for sale before. I'm rebuilding / uprating it after years in bits and it will look exactly as an SII should, but will go / stop / steer better (I hope).

 

Lotus 7 SII chassis, Short Cockpit, (So Ford or Ital should fit OK).

Lowish power, About 130BHP from a standard 919cc Fireblade unit on carbs.

Very light, thanks to power unit / lack of seperate box etc.

Narrow wheel arches, 9.5", as it's an SII.

Long final drive needed, over 3.54 would be ideal.

 

I would prefer to buy a ready built / bracketed axle if possible.

It came with a horrid flimsy Standard axle, these are apparently poo.

My current front hubs are triumph pattern.

 

So....given the above, can anyone pass on the benefit of their hard gained wisdomquestion.gif

 

Does anyone have either a cheap example of either cluttering up their garagequestion.gif

 

All comments gratefully recieved, thanks in advance.

 

 

Mark

[I.Mupferit]

Mark,

 

Think we may have discussed this before but what is your timescale/deadline for a complete axle? Looking at changing my Ital axle for a Ford next October(ish)

 

Brent

[Morls]

Brent,

 

The plan was for completion prior to May's Curbrough but I need to sell my bike / other 7 to raise cash before buying the remaining bits. If things sell soon then I'm still hoping for May / early June.

 

Ideally I need to make a decision on axle type soon in case a cheap set of the right wheels or hubs come up.

 

Have you costed the Ford route yet?

 

Mark

[allen]

I recon a bike engine should be OK with the ital, especially if you can stretch to an LSD.

 

Torque is the killer and shouldn't be a problem.

 

Like your thinking, S11 has less chassis bracing, but should be OK with the lightweight bike engine.

 

Regards

 

allen

[Morls]

Allen,

I've added a little bracing where it seems neccesary, and where it would have been added in period.

Diagonal braces in the sides at leg and hip levels, extra reinforcement to the Radius arm pick up points and corner diagonals in the base of the engine bay. The engine was designed as a stressed member in the bike so this has also been solidly mounted to add to the chassis stiffness.

The mods have added very little weight but plenty of thoretical stiffness.

 

Looking forward to testing the theory.

 

Mark

[allen]

Sounds very interesting and sod the purists.

 

I am of the opinion that Mr Chapman would approve (though he'd probably want to try it without the extra bracing to see if it fell appart).

 

Having lived through the 50s 60s & 70s, there is no holy writ of originality, if you want an investment keep it original, if you want to drive an authentic piece of motoring history, and be frequently remined that it is a piece of history, keep it original.(Actually if you realy want to drive motoring history, buy a Morgan!)

 

If you want fun, update, modify and give it some, in the Lotus 7s heyday it was very rare to see a stock example!

 

Question, will the ital axle (I guess with narrow wheels & tyres) fit under the SII narrow rear arches? If so it should be adequate and the same PCD as the front hubs, though I understand there is not the choice of final drive ratios there would be for the ford axle.

 

What is the final drive ration from the standard, as you describe it, piece of poo?

 

allen

[Morls]

"Mr Chapman would approve"

 

Exactlythumbsup.gif, that's why I decided to carry out the mods. Rather than showing a heathen lack of purity I am following the true faithsmile.gif.

 

I've been measuring wheelarches/ clearance in the garage and...

 

On my Ital axled Caterham, the 11.5" arches are only about 1" horizontally clear of the side of the (185) tyres, (on 6" KN rims). But the clearance vertically, (and at the front and back) is nearer 3".

 

I cannot believe that a live axle has 3" of movementquestion.gif, from a comfort point of veiw it feels more like 1".

 

If I fitted my 9.5" arches to an Ital/185s combo then on 3" bump the tyres would hit the arches, BUGGERsad.gif

 

Is the english axle narrower?

 

Will it ever use 3" of bump?

 

The old diff is, I think, a 4.1:1 or some similarly short geared unit, the halfshafts are also apparently made of cheese on the standard axles.

 

So...I may have to fit later, wider, back arches as I think the 3" Herald wheels and narrow crossplies might be a bit scary with 130BHP.

 

Mark

[cdg]

Mark,

 

I would use a Ford axle. The crown wheel and pinion on the Ital are quite weak, and the teeth are prone to breaking when subjected to harsh treatment. The half shafts are also stronger on the Ford timken axle.

 

The rear track on the Escort Mk2 is 51" when using 13" wheels (4.5" width I think),I don't know how this compares to the Ital.

 

The main drawback of using the Ford axle is that the diff carrier is a heavy lump of cast iron, whereas the Ital is alloy. Alloy Ford items are available from Flowtech Racing, but they're not exactly cheap at about £300.

 

Sorry for confusing the issue!

Chris.

 

 

[Nigel Riches]

With regards to the axle width problem, the axle could possibly be cut and narrowed to the appropriate dimensions by one of the outfits that modify axles for drag and funny cars, a look through some magazines with those types of machines in mind may be of assistance, hope this is of some help. Nigel.

[Barry H]

Yes, the Escort axle is slightly narrower than the Ital - from memory, about 3/4 inch.

 

Barry

[allen]

What profile tyres are you going to run - lower profile obviously reduces ground clearance, but has same effect on vertical clearance to rear wing, Adjustable spring platforms can be wound up to give more clearance, and a second bump stop can also be fitted.

 

The return lip on the rear wings can be reduced too, you can also get non-standard offset wheels.

 

Always more than one way of skinning a cat, and a combination of things may give the desired result.

 

I still think the ital axle (with lsd) is man enough but others may know more - I have a ford axle! (Anyone know what width an anglia axle is? I can only find overall widths of vehicle, anglia 57.1, escort 62.8).

 

allen

[Morls]

Thanks all for the comments thumbsup.gif, keep em' coming.

 

I'll be running fuller profile tyres to help the gearing on the road so that's another thing that will exacerbate the wheelarch clearance problemsad.gif.

 

Wheels with a lesser offset sounds a simple option but then, unless I go for different front/rear, the front track will be reduced, presumably a bad thing.

 

As the overall weight will be so low the axle weight will be an issue, particularly as I expect the distribution will be biased to the rear anyway, (65Kg engine/box/clutch against 17stone fatbloke driver).

 

Money unfortunatly will also play it's part, meaning a £300 diff nose is hard to justify, and a "funny car" narrowed axle may be beyond my meanssad.gif.

 

Given the above I may have talked myself into wider rear arches, maybe Caterham or sIII type.

 

Does anyone know the width and offset of the weller steels fitted to some classics? These appear to fill the arches less well on some Caterhams and so might give a little more clearance allowing the 9.5 inchers to stay.

 

 

Mark