Rack and Pinion Steering in an Amazon?
 

Spotted in the piece on the Swiss Aston Martin engined P1800 in Octane this month that they fitted a TR4 steering rack to the car. Has anyone else got any further experience of trying to fit rack and pinion to an Amazon or thoughts to add? Might make for even nicer steering feel and parts to do the conversion are quite reasonable.

Harvey

Interesting idea. Won't the rack have to be quite far forward, in which case its position & also the angle / length of the steering arms (custom ones will probably be required) will be critical for it to be a worthwhile conversion. If Amazon's have Ackermann steering geometry, then the postion of the rack etc can be calculated rather than being a case of trial & error.

Thanks Paul, unfortunately the article didn't include photos of the rack in situ so its difficult to know what they had to modify or how they chose geometry without getting some bits and making some measurements...

Ackerman was new to me, if any of you would like to know about it there is a clear, concise description on Wikipedia:
http://en.wikipedia.org/wiki/Ackerma...ering_geometry

There are basically two places the rack can go - behind the engine or in front of it. If behind (Morris-Minor-stylee), that will involve extensive bulkhead / inner wing mods, so that can be ruled out unless the front end is being spaceframed.

So that just leaves in front of the engine. It's been a while since I've had to look under the front end of my heap, but isn't there a transverse steering link (with steering box drop link & idler at each end) around there? If a rack is being fitted, that is presumably redundant so the rack can go there.

The issue is the steering arms - not just the angle but also clearance thoughout the steering lock, especially as long arms may be required with correspondingly greater arc of movement. I'll have a look under my car tomorrow & let you know my thoughts :)

If a TR4 rack is used I think it would have to go infront of the axle, as if it went behind the steering would work in reverse!

Indeed, unless a LHD rack is used. E.g. RHD Spridgets use an upside down LHD Moggy Minor steering rack mounted in front of (instead of behind) the axle line :)

BTW, are the front chassis structure & suspension mounts etc on P1800s & Amazons basically the same? I.e. can whatever was done to the 1800 be swapped straight over to an Amazon?

It might also be worth asking over on http://retrorides.proboards86.com/ They are very much in favour of uprating old cars & there are also quite a few technical / car engineering gurus who post regularly on there & who would know far more about how to carry out such a conversion :D

There is indeed such a transverse link and it certainly seems logical to remove it and fit a steering rack in its place. However it would affect the steering geometry, as the transverse link is a rigid rod hung directly between the two idler/droplink arms and not otherwise constrained, whereas the rack is a rod that can only move transversely relative to the body and connected to the idler/droplink by two hinged bits on the end. The straight-line distance between the moving ends of the idler/droplink would vary with the position of the steering, being shorter on full lock than in the straight-ahead position. This effect could be minimised by using as short a rack as possible, but I'd still want to draw it all out and work out how much of an effect it is before doing the job.

Most steering and suspension parts are sg=hared with both P1800 and amazon.

Personlay I would not bother fitting a rack as in good nick the steering box gives very poitive steering.

Steering boxes are still used in new cars today!

Steering boxes also give less of a "shock" though the steering wheel, say if you hit a pothole for example.

122/Amazon - Steering conversion to Rack and Pinion
 

I have free play on my steering and I have change the steering box with slight improvements.

I am very keen to have the whole steering system change to a Rack and Pinion and would like the advise of the club members on how to..

Thank you in advance for your advise.