mk1 cox and cob

[aaron]

[
   Why that looks so well preserved one would
   think it was built yesterday [:o)]
   [/quote]
   
    The car in the photos is not the real 2532, it was built a couple of years ago.So it is more than a couple of days old.[;)]

[A-Snake]

quote:Originally posted by aaron
    The car in the photos is not the real 2532,
   

   
   That was assumed [:D][:D]

[TLegate]

With all these races, the old cloning machine must be working overtime. (My lawyer says I did not type that)
   
   Reading the history of 2532, it sounds like a lot of its 'originality' was engineered out of it many years ago. It's fascinating just how different one Cobra is to another. I had the experience recently of a long drive in a properly old car with a genuine traceable history and then in a much newer 'old' example. Very different. As confirmed by one multiple-Cobra owner a few years ago, having driven 15 original cars in one day (if you recall, Jim) he said that no two cars were alike. They don't make 'em like that any more (well, not officially)

[A-Snake]

quote:Originally posted by TLegate
   
With all these races, the old cloning machine must be working overtime. (My lawyer says I did not type that)
   
   Reading the history of 2532, it sounds like a lot of its 'originality' was engineered out of it many years ago. It's fascinating just how different one Cobra is to another. I had the experience recently of a long drive in a properly old car with a genuine traceable history and then in a much newer 'old' example. Very different. As confirmed by one multiple-Cobra owner a few years ago, having driven 15 original cars in one day (if you recall, Jim) he said that no two cars were alike. They don't make 'em like that any more (well, not officially)
   

   
   I do recall. He told me that within a very short
   distance he could 'feel' the differences in suspension,
   tires, and drivability of the cars.

[Aceca289]

Good informative thread!
   
   One question I have is why AC designers chose to place the rack in front of the suspension tower in the Cobra rather than aft of the tower as Tojeiro had placed it in the ACE prototype? Many R&P conversions have been successfully made to ACE/Aceca's using Tojeiro's placement of the rack (e.g. Ben Yates design); however, my Aceca (which has a 289) was converted to R&P in the late 60/early 70's by placing the rack in front of the suspension rack a-la-Cobra. Does anyone know where the rack was placed in the conversion of early Cobras that originally had Bishop Cam steering?

[ACOCArch]

quote:Originally posted by Aceca289One question I have is why AC designers chose to place the rack in front of the suspension tower in the Cobra rather than aft of the tower as Tojeiro had placed it in the ACE prototype?

   Not being party to the design process at the time, in order to answer some of Aceca 289's questions I can only present and analise  period evidence to hand.
   
   The first photograph below is from AC Cars. Taken outside the factory, it was attributed to The Light Car magazine. The photo is otherwise unreferenced but is almost certainly the 1953 AC Ace show chassis and clearly has rack and pinion steering.
   
   A number of design details are evident:
   
   a. With the selected steering rack (from a Morris Minor?), the steering column would have to pass through the chassis to reach a front-mounted rack;
   
   b. The rear-mounted rack allows the then necessarily tall radiator to be mounted as far back as possible, with benefits to the styling;
   
   c. The rear-mounted rack is linked to rear-facing steering arms;
   
   
   
   The second photo below is of the 1957 AC Ace-Bristol show chassis fitted with cam and peg steering and disc brakes. Further design details evident are:
   
   a. As with the drum-braked show chassis, the steering arms are rearward facing;
   
   b. The disc brake calipers are 'leading' and so do not foul the steering arms;
   
   
   
   
   
   The third photo below shows a leaf-spring rack & pinion AC Cobra show chassis (probably 1963). Design details include:
   
   a. Front-mounted rack, of a configuration which allows the steering column to pass the chassis;
   
   b. Forward facing steering arms;
   
   c.'Trailing' disc brake calipers.
   
   
   Conclusions:
   
   a. It was probably not feasible to have forward facing steering arms and 'leading' disc brake calipers. Likewise rearward facing steering arms and 'trailing' calipers;
   
   b. A rear mounted rack required rear-facing steering arms, and a forward mounted rack required forward facing steering arms;
   
   c. The simplest conversion of an Ace from cam and peg to rack and pinion would be to have a rear mounted rack connected to the existing rear-facing steering arms. Otherwise new or heavily modified uprights with forward facing steering arms and, where disc brakes are fitted, 'trailing' brake calipers, would be required.
   
   d. A rear-mounted rack conversion would be the closest option to the original Tojeiro concept (photo 1);
   
   e. AC Cars reasoning for having a forward mounted rack on the leaf-spring AC Cobra is not clear from this.
   
   Questions Arising
   a. Can anyone add a photo of an early Cobra cam and peg car?
   
   b.Is there an engineering advantage for 'trailing' brake calipers, which would have forced the designer's hand on the Cobra R&P design?
   
   c. What front upright/steering arm/brake caliper configuration is fitted to 'Aceca 289'?
   
   Hope this helps answer some of Aceca 289's questions

[Aceca289]

quote:c. What front upright/steering arm/brake caliper configuration is fitted to 'Aceca 289'?
   

   
   Thanks for posting the detailed comparison and photos of the ACE prototype and the Cobra layout. To answer your question - my Aceca has drum brakes and the steering arms were custom fabricated and welded directly to the original uprights.
   
   Were there possible clearance problems with the 289 (width of the V8 engine or length where the crank pulley extends vs. the strait 6) preventing routing of the steering column or placement of the rack to the rear? Maybe there was some advantage to making the geometry work better to reduce bump steering with the rack up front. These questions may be hard to answer.
   
   John

[B.P.Bird]

May have been as simple as the desire to reduce the angle which the steering column universal joints had to accommodate.

[MkIV Lux]

quote:Originally posted by ACOCArch
   ..........
   b.Is there an engineering advantage for 'trailing' brake calipers, which would have forced the designer's hand on the Cobra R&P design?
   
   ......
   

   
   I am not an engineer, but I can see an advantage in better anti-dive characteristics under hard braking.
   
   Also, I have always wondered why the AC engineers did not include an upper push rod (or should I call it trailing arm) linking the chassis to the upright (see Brabham BT3 F1 of 1963), triangulating the upper side of the suspension also and solving the problem of torque that the leaf springs have to absorb. Of course for the rear articulation point of such arm they would have had to include each side an additional  suitable vertical frame member at the level of the engine support structure. [?]
   
   Constant

[ACOCArch]

[quote
   
   A number of new posts on the subject of R&P steering appear on "Ace ... Forum BE646 pg5"