Monday, December 24, 2007

Caterham Upright / Hub Kits

Been playing with a Canley supplied kit.

Firstly no instructions supplied.

Which is not ideal, as the hub assembly and fitting proceedure IS NOT AS PER A TRIUMPH.

Instructions are important.

If you do the castle nut up finger tight and back it off to get the pin in and you could damage the stubaxle and suffer leakage of grease and scuffing wear on the spacer/shims and castle nut.... Its hard to describe but looking at the unit assembled its not designed to operate as per normal. Won't bore you with details.

Caterham specify a torque figure of 11mn or 8 ft-lbs for the enlarged nut, not much endfloat! A bit more than finger tight! Back very off slightly if needed to get the pin in.

Not a free castle nut and held by the pin as per normal.

This may help. It certainly helps you assemble them correctly as at £225 its not out of order to print out two sheets of paper to help people do it RIGHT.

There is (in my opinion) a problem to fix with the CC SPORT lower bearing carrier. Having chatted to Caterham the Lower Spherical bearing should be a FIRM fit in the carrier. This is BASIC engineering. A spherical outer case just as with a bearing race must be a tolerance fit in a housing to stop it moving, rotating and eating the carrier/seat area. Any play in such a part will create rapid wear. Lucky the carrier will rust and corrode, as any metal part will and this will take up the slack if you're lucky...Great!

Sadly the Canley supplied housing/carrier is 3.5thou 0.0035" oversized (opinion of two micrometers)the bearing just falls in and out and clonks from side to side when the carrier is perfectly clean and shaken when assembled with the bearing in it (opinion of my ears), the bearing is loose and will be osilating over each bump and the hardened steel outer casing of the bearing will be damaging and increasing the oversized opening on each bump/corner or small stone. So looks like a couple of sets of proper bearing carriers need to made, to correct tolerances, will need to be made to ensure reliable and safe service.

What lead me to find this out was firstly I dismantle EVERYTHING I lay my hands on. But what triggered this, was the unit, upright and carrier, came assembled.

I was wiggling the upright and carrier around as you do, I noticed the stiffeness I'd expect from a lined spherical joint when moving the carrier and upright back and forth etc...I then noticed if you moved it as you would when steering, round and round that there was no friction...This is cause the spherical bearing is rotating freely in the carrier, the outer body of the bearing is free to rotate in the housing. ...the outer of a spherical should never move in a housing and be a press fit and the centre of a two piece spherical does all the work, fore-aft-left-right..

CC Housing bearing opening is 1.91" and the bearing is 1.875" (just a normal Size 10 spherical from NMB or any other supplier with a 0.675" hole and 0.500 thickness - COM10) the housing should be slighty oversize for a PRESSFIT. You cannot have a spherical loose in its housing! You could use loctite bearing seal etc but its bodge.

Interesting to the see (in my opinion) the bearing carrier had been machined again after it had been plated and finished?( possibly, in my opinion) to remedy a design misconception related (I presume, purely opinion of putting two and two together) to the fact the threaded part normally where a trunnion goes on, was presumed to come out straight from the main upright body, but obviously this doesn't come out of the upright body vertically, but at an angle...(castor)...

Carriers were made, with oversized housing (in my opinion), plated and re-machined again account for the angle of the threaded part in relation to the main upright body, so to increase the rake angle of the carrier. As maybe it was presumed the carrier and bearing should be flat and at 90degrees respectively to the wishbone..Where as the stub on the upright required the carrier to be angled upward at its greatest extremity from the wishbone...hense the bare metal showing, done after plating?

Couldn't fault the Caterham parts at all. Bar re-PCD'ed hubs cause of the fitment of standard wheel studs that needed a special tool made (from an old BMW piston pin and a press to remove. Uprated hub kit? Why no uprated studs? No-one uses the normal little studs.

I prefer M12 1.5pitch 67mm long, not 3/8th with a 30mm stud with an alloy wheel (thicker than steel) hanging on a tiny stud with a just a few threads engaged...Best to supply such an item without studs fitted, due to the alloy construction and give the punter a number of options, including an uprated stud and nut kit. Race-Scruts like to see thread poking out the wheel nut. Not that I'd even consider driving a fast road car on the stock studs let alone go racing!

I will get enough flack for posting this basic fact, so I will not add any PERSONAL opinion on this. Purely engineering comment, backed up by my micrometer and plenty of photographs.

This is why the Germans have STRICT - TUV (government product)Testing and Legislation...

This is a not a dig, its a design problem...Someone should have just gone in the original direction!

***Opinions in this post are purely my own and may not resemble those put forward by others, they serve no other reason than no relay my daily experiences in the form of an internet diary. Information put forward here is to the best of my knowledge accurate, however is purely offered as opinion. However any information relayed in the above posting is backed up by the opinion of 2 certified engineers who are happy to write a report on the above items and supply fully documented reports if required.


the_nutter said...

As a "certified engineer", does that make you liable to incarceration in the mad-house?

David Powell said...

Not me personally. I am simply certified!