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TR2/3/3A Rack and Pinion Conversion for Tr's

colbtr

Freshman Member
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Hi
I thought it is worth a comment on the forum of the trials I have had in getting my rack and pinion conversion certified for registration. I am located in Australia and in order to get a order to get a vehicle registered (MOT in UK I think and not sure what they call it in the US) any modifications need to be signed off by a qualified automotive engineer. I bought a rack and pinion conversion from Rimmer Brothers some time ago when they were on sale. After receiving the kit with the one page of instruction which told me very little I contacted Rimmers and complained and consequently was sent 11 pages of instructions for a Moss Motors kit. My guess is that they are supplied by the same suppliers as the design was identical.

I have installed the conversion and contacted an engineering company that specialises in steering engineering. He came and inspected the conversion, he had asked me to remove a spring from one side of the suspension to check bump steer so all that was done before he arrived. Mounting bracket was checked and bump steer was good so the actual rack conversion passed no problems. I had purchased a steering column with the rack as I was keen to use the control head on the wheel so I needed a hollow steering shaft. The engineer requested that I remove the shaft to check its integrity and lo and behold the shaft is joined about 3" above the lower spline. To get certification the change must meet the Australian Design Rules for vehicles which categorically states that a weld cannot be used as the main method for the transfer of torque in a steering system. Steering shafts are welded but as a back up to a mechanical press fit or other mechanical join. As I worked as a steering column engineer for a good part of my life designing columns for GM, Ford Toyota and Nissan I actually knew a bit about this. To add insult to injury the quality of the weld was pretty poor and the linishing to buff the weld had actually cut into the core diameter. This is a 19mm shaft with a 12mm bore so there was not a great deal of metal in the wall thickness to start with let alone having some bloke taking chunks out of it.

I contacted Rimmer Brothers stating the obvious that I had paid for something that could not be used without further modification and expense. After a few weeks I rang the guy up looking for an answer and was told that a welded shaft is acceptable in the UK (and I presume this also means all markets they sold to) which is incorrect as the Australian Design rules for steering are remarkably similar to the design rules everywhere else and all cars imported to Australia must meet our design rules. Essentially all the designs for steering columns are similar with regard to the steering shafts. I have visited factories producing steering columns all over the world including the UK, US, Europe, Japan and Korea and all design manufacturing of the shaft is essentially the same

I was also told that the shaft had been tested and was considered safe. Having been intimately involved in the manufacture of steering columns I know the extent of the safeguards used to ensure 100% compliance because anything less would require a recall. I am certain that the supplier for Rimmer has no idea about any of this.

Finally I was told that they spoke to the supplier and was told that that was the only way they could make the shaft. I have looked at the shaft and recognise the issue that was the cause of their thinking and have sent back a design that will make the shaft compliant to rules around the world as well as reducing the cost of manufacture.

The long and short of this is that a good engineer should not certify the Rimmer (and supposedly the Moss Motors) conversion. However the rules apply to original equipment and I am aware that some engineers will either turn a blind eye or not be across the Design Rule. I am not sure what happens elsewhere but the big thing to remember is the bigger issue is whether you are happy to have some guy weld the 3.5mm wall of the tube and then undercut the weld knowing that this is the only thing connecting you with the the bits that make the car point in the direction you want.

As a qualified engineer experienced in the design and manufacture of steering systems I do not recommend that you purchase the steering column offered with this kit.

I happen to have a friend who worked for me in the steering column business who has set up his own workshop and specialises in steering column issues. We have devised a repair that will meet the engineering requirements so it will get registered (without seat belts which is another issue if anyone wishes to know!) but I don't want others to get caught on this.
 
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