Below is an article that I wrote for the Lotus 7 Club magazine, Low Flying, about my winter project of changing from the original Ital axle to a stronger Ford item.

Mechanical sympathy is a strange thing. Some people have it, others don't. I often think that mechanical ignorance would be quite nice sometimes when I see the grief some people give their cars. I know the cars can take it; it's just that I can't bring myself to do the same to my car. I blame my engineering based education personally.

So the question was do I wait for the Ital axle to surcome to my new engine's increased torque and power or do I pre-empt its potential demise and change to a Ford axle and sleep easier at night. These were the long term questions I faced as I performed my engine swap in the winter of 2001.

I had decided to replace the 1.6 X/flow that Q181 ABL had been powered by since I built her in 1996 with a 2.0lt Zetec, knowing that this route would put increased pressure further down the transmission. The gearbox, a standard 5speed, would be up to the job, at least until I got tired of the annoying caravan towing 1st gear. The axle, however, I wasn't so sure of. Increasing the power from 100bhp to around 160bhp, and the torque from 100ft lb to approx 145ft lb was going to be quite a shock for an axle designed for a Morris Marina with about 60bhp and corresponding torque. I coupled this reasoning with the knowledge that a good friend, Simon Ray, had chewed up his LSD equipped Ital axle whilst sprinting with his 155RKE X/flow. His subsequent swap to a Ford axle had taken him off the road for most of that summer so I knew I had to at least have a plan.

My reasoning at the time of the engine change went something like this. The engine change was costing 'enough' so I would run the Ital axle for the next two years, taking it easy, feeding in the power and keeping with my fairly un-sticky Yoko A510's. This should ensure the axle survived until I could afford and justify the change. In the end, I brought this plan forward by a year. The jump in power afforded by the engine was addictive, oh so addictive, but I found I couldn't really enjoy it. Next time you are out in your se7en and you exit a bend, an open road stretching out in front of you, just try exercising restraint and you'll know how I felt all the time! The other useful justification was that an Ital axle in full working condition was probably worth more than a dead one. Thus, a plan was hatched.

I proceeded to carry out as much research as I could, which is where Blatchat and the Se7ens List are invaluable. I was also fortunate in that local meeting attendee and fellow Zetec enthusiast, Brent Chiswick, was also going through the Ford axle route, although his decision was based on an engine upgrade - jealous? Me... You bet!
The general consensus was that whilst the axle would fit, it is tighter in the long cockpit cars compared to the short variety, where Caterham fitted them. The problem hinges around the offset of the diff housing which on the Ford is biased much more over towards the driver's side. Whilst some people confidently told me that they have the axle in with no modifications, I decided that for the sake of a few hours and the annihilation of a few rivets, I would make sure I had the necessary clearance.

Firstly, however, I should go back a couple of steps and mention the axle itself. I wimped out at this stage and bought my axle built up for me. Maybe if I had had more time, a better understanding of the parts required to re-furbish one, and had not been looking at moving house (and importantly the garage) I might have had a go at it myself. This would certainly have been the cost effective, and quite satisfying, route. Another decision influence was that I thought I would try out an LSD and didn't fancy any set-up issues, although it should have been a simple bolt in extra. There are a couple of companies you can talk to regarding having an axle built, the first is SPC in Redditch and the second is HT Racing based right next to Brands Hatch. Both companies are knowledgeable of Caterhams, SPC having built the Ital axles for Caterham and HTR having prepared Dave Edmunds fantastic drag racing 7 featured a few of issues ago in February. Whatever your route to acquiring an axle, it is important to specify/fit a smaller diff flange (the bit that the propshaft bolts onto) than the one it will come with. This is to increase that all important clearance as much as possible and I think that a normal flange would foul on some un-movable chassis rails. The flange required is of the Anglia variety and has an outer diameter of 3 3/8" - this is also important later on when the propshaft has to be modified as the two have to match!
When I was looking to get my axle built, Steve at SPC was just going off on holiday and being an impatient chap I went to HTR who were very helpful and built my axle complete with Tran-X LSD, suspension pick-ups, new bearings, re-furbished brakes and all freshly powder coated. One other thing to consider is whether you want to retain your existing Ital pitch wheels (3.75" PCD for the Ital verses 4.25" for the Ford). I believe both the above firms can modify the Ford axle to have the same pitch as the Ital which would let you keep your current wheels. However, it is worth checking that the wheels will fit over the axles centre boss - I have heard of a case of this being missed and the wheels didn't sit correctly requiring further machining of either the wheels or the drums. Personally I decided to change to Ford centres as the availability of Ford wheels is higher for later wheel buying, or even just borrowing wheels to try out tires, etc. It should be pointed out that the front hubs will also need swapping if you go to Ford pitch but this is easily justified when you compare the weight of a cast iron Ital hub and an Ali Ford version (~1.65kg/pair verses ~4.35kg/pair). With HTR being on the door step of Brands Hatch I was able to drop into Caterham Parts on the same trip and pick up the front hubs - many thanks to Darren for his usual excellent service - he makes spending money all too easy.
(Note: If you want to build up the axle yourself, then I believe Arch can also modify a casing with the suspension pick up points)

So, with the new axle back home all I had to do was come up with a plan of attack. Obviously, the first thing I had to do was remove the old axle. A top tip at this stage for anyone with a modern single garage (you know, the ones too small to house modern cars!) is to a) get the car at far over to one side as possible and b) remove 1, if not both, rear wings. I had failed to do the later the previous year and managed to get my axle wedged hard up against the wall. Removing the wing not only gives better access to the dampers/radius arm fixings and reduces the risk of damage but also allows a greater angle of withdrawal.
With the Ital axle out of the way I could assess the weight penalty that the Ford axle was costing me. I was quite pleased to find that it was only 5kg heavier, not as much as I had feared (for the record, the Ital was ~45kg, the Ford ~50kg). Those 5kg would surely be out-weighted by the fact that I would be able to use all of the throttle's travel. As Dave Edmunds stated in his article, if you have the funds, there are lots of ways to reduce the weight of the Ford axle.
After a couple of very helpful phone calls to Bruce at Arch Motors (chassis builders) and Pete at Raceline Engineering I felt I had a good enough understanding of what modification was required on the transmission tunnel. You have to remove the carpets to gain access, although in my case I had used poppers to hold down the lower edges so they just folded back out of the way. With the axle out of the way, it was also a simple job to remove the fuel tank out of the side gap, and this gives lots more access from below. With the car raised as high as the axle stands would go it was easily possible to sit in the fuel tank void and get good access to the back of the tunnel.

Chassis Modification:
So, to the actual tunnel modifications required. No doubt how I describe them, they will sound worse than they are, but they really are quite straightforward and it only took me an evening to do. The objective is to move the rear tunnel edge on the driver's side over by approx. 1". This means that the tunnel needs to be bent out, the bulkhead trimmed back with some tin-snips and then the whole lot riveted back together again. See, nothing to it.
The first thing to do was to undo any cable ties holding wiring for the last 9" of the tunnel, and move any cables out of the way so that I could drill the rivets without risking damage to them. At this stage I could see that the rear of the tunnel is made up of several sections: The tunnel itself which is obvious, the bulkhead which is again obvious, the saddle which is the kind of domed section which links the full radius top section of the tunnel to the bulkhead, and finally 2 'L' shaped brackets which tie in the straight sides of the tunnel to the bulkhead. As I was only concerned with the driver's side, I ignored the passenger 'L' bracket. I started to de-rivet the area I was going to work on next, making sure I had the right sized drill (4mm) and that it was sharp. Of course, some of the rivets decided to spin and for these I clamped a pair of mole grips on the rear part to held them still. I removed the saddle and the drivers 'L' bracket and removed the rivets holding the side panel to the 'U' shaped support piece - this was also done on the passenger side.
The rear of the tunnel was now free to move and being as careful as possible, I worked out the last 100mm so that it sat approx. 25mm further out at the base, tapering up to the normal bend at the top. With the tunnel bent out to the right position, I could mark and remove the surplus bulkhead material. This is quite awkward and good pair of tin snips were essential.
To enable saddle to sit correctly at the side, the radius of the saddle needed to be modified slightly. To allow the saddle to be bent without a kink forming, a small dart shaped piece had to be cut out at about mid-bend of the flange. Once this was done, it could be eased out to suit the modified side position/angle.
The next task was to climb under the car and move the 'U' shaped support that the tunnel sits on. This was moved where it fixes to the chassis bracket so that it sat against the other side/face of the chassis bracket. This gives more clearance at the diff flange area. To get enough movement can be tricky, and is why the rivets on the opposite side and the top needed to be removed.
With the tunnel moved out and the bulkhead trimmed back it was time to start riveting everything back in place. Starting with the saddle piece, I could ease the shape to fit, riveting as I worked around. I fixed the support hoop next and I riveted from the inside where it had been moved as this meant only the head of the rivet protruded into the tunnel. The rivet gun limited how high I could rivet in this way due to access, but I only needed to worry about the area of the propshaft. I fixed the lower edge of the tunnel and then offered up the 'L' piece. Thinking back it was obvious, but I found this was no longer big enough to bridge the gap from the bulkhead to the tunnel side. Doh! However, it was very easy to fabricate a larger replacement from some Ali sheet, and fix this in place. I lastly used some silicone sealant to fill in a couple of small gaps.
Easy huh!

Propshaft:
With the chassis modifications done, the axle could now be heaved into place. It is wise to get a second pair of hands to avoid removing powder coat from the chassis rails and to lay an old rag over those that are exposed. With the axle in the right place I bolted up the radius arms, the dampers and the A-frame, although in the best build manual tradition, I didn't torque anything fully up until the car was down on its wheels later on. The next job was to swap the axle stands over so that the new axle was supported. This meant that the weight of the car was now taken on the dampers and that the length of the propshaft could be measured. I had read a recommendation for a company called the Propshaft Clinic and can totally endorse them. Not only was Peter very patient when dealing with my questions regarding where to measure to and from, but the service was very quick, and I considered very reasonable. He told me to measure from the rear face of the gearbox seal (which can be seen as the black rubber ring set slightly back from the Alloy casing) to the diff flange on the axle. I duly did this and found that the angle of the gearbox relative to the diff flange gave me two readings, 662mm and 666mm depending if you measured top to top or bottom to bottom. I e-mailed both these dimensions to be on the safe side and sent off my propshaft. It should again be noted that you need to specify the change to the correct/matching Anglia flange. Low and behold, 5 days later it arrived back, shortened, correct flange fitted, balanced and re-power coated. Very impressive. Being a '96 car, my tunnel is open at the bottom, so I was able to feed the new propshaft up, over the axle, slide it forward to engage in the gearbox and then align and bolt it up to the diff flange using some 12.9 grade M8x25 cap head bolts and nylocs - although this is a fiddly job with little space.

Brakes:
The Handbrake cable is re-used and was a simple job to bolt back into place, the balance method of the bar is retained and mine came supplied with the new axle, although I am sure the Ital one could be adapted to suit if required.
This just left the normal brake lines to sort out. I contemplated the copper pipe arrangement as used on the Ital axle, but the memory of both my father and I cursing over them when we built the car put me off this. I therefore decided to use braided hose for all the brakes from the bulkhead fitting back. You can buy these made up from most good m/sport suppliers. I, however, decided that I would make mine up myself as I already had experience when I upgraded to Hi-Spec 4-pot front brakes the previous year. I measured up and bought a length of braided hose from my local m/sport factors, Autocross in Binfield, along with the necessary fittings. To give a quick overview of attaching a fitting to the hose, use a small flat bladed screwdriver and splay out the braiding until the brass olive can be fitted over the PTFE liner and it sits fully home against the end of the PTFE. Then curse the fact that you have forgotten to put the clamping nut on the hose first. Put the nut on the hose. Fit the main part of the fitting so that the spigot slides down into the PTFE tube and then rests against the olive. Pull the nut up and as it squashes the braiding back down over the olive, screw it onto the main body part. Do this nut up until it butts up against the main part and hey presto, all done. It probably takes long to explain that to do. With hindsight, I should have bought at least one swivel fitting as using fixed fittings to link each fixed side meant that I had to remove one of the wheel cylinders to allow for the twist. Doh! Lesson learnt. Bleed the brakes in the same way as the Ital, adjust the handbrake, and operate it a few times to get the self adjusters to take up and slack and the job is done.

All that was left was to swap the front hubs over (fit bearings, swap brake discs over and repack the bearings), fill the axle with oil and bolt on my new wheels. These just happened to have some nearly new 032's fitted - shame huh, I would just have to put up with them I guess. Castrol B3 oil was recommended to me for the Tran-x LSD, but boy did it take an age to dribble in (will try warming it next time), and it smells horrible, like all gear oils.

So, a sunny summer later, and do I think it was all worth it? Well, it isn't cheap, and an argument can certainly be put for treating the Ital as a disposable item, replacing if or when it breaks. However, I don't think I could live with that hanging over me and what happens if you can't track down a replacement? You risk losing a large chunk of our all too short summers. The Ford axle also means I can now consider upping the power of my car, run stickier tyres without the Ital end-float bearing problem but best of all, floor it with confidence again.
So in answer to the question, yes, for me it was worth it. It means that when you exit that bend, see that open road clear in front of you, I too can put my foot down, not worry about it, and sometimes, even keep up.

Useful contacts:
HTR - 01474 872888
SPC - 01527 894232
Raceline - 10483 811978
Propshaft Clinic - 01274 305399

 
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