ok back to the steering rack issue , i have a nissan micra rack mounted behind the crossmember on my ute . As you say your car is a racer so moving the inner pivots for the lower arms out 20mm a side to match the width of the pivot balls on the micra rack shouldn't be a problem, thats the bump steer fixed. also it's a power rack so as much caster as you like will be no problem ,any more info pm me for photos

Hey Wards, thanks I'll be PM'ing you asap...

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well, that's bump steer fixed if you were able to fit the rack at the right height (often the sump will be in the way of that) and even then only if you had straight steering arms, which you probably don't, so that the outer pivot matchs the respective inner pivots and the LCA nd tie rod assembly ar ethe same length (most of the time you need the LCA pivot further out than the steering pivot because of the shape of the steering arms).

now what about your ackermann?

not trying to can the idea of a rack conversion, just pointing out it isn't that straightforward. I took the advice of a couple of spaceframe race car builders with over 15 years experience each and stuck with the steering box... if they don't want to take the job on, a novice has little hope of a good outcome.

I agree this project is not for a novice , I have changed my approach many times as i have discovered pluses and minuses in my geometry , as with any motorsport catergory it's a compromise to achieve a workable result . My aim is to build in as much adjustability as possible to try to cover all bases .

Once I have found someone who can point me in the right direction (hopefully with some experience of their own) I plan to get all the info I can (dimensions of their setup) and have the setup "built up" in autocad and all the geometry checked throughout the complete range of movement and "tweeked" before I build it into the car. It could prove to be a costly exercise but it will be one a lot of people could benefit from (I am happy to put my findings on Datsun1200.com)

My brother builds Hot Rods over here in perth and he get steering racks recond and shortend to suit his front end setups. Most hot rods run modified rack setups so as long as your maths are right it should work. i have been keen on this setup for a while and will try to set it up in the next off season. but keep the ideas comming.

that's a good point, if a rack is close to the right length it could be shortened to get things spot on. Height shouldn't be a big problem, and it won't rise at either end of the lock like the old draglink does.

The measurement you want to use for determining the width the rack should be is the distance between the inner rod ends on the drag link, not the lower control arm pivots.

I've see two rack conversions on B110's here and both were pretty old and had been on competition cars for some time. I don't have a great deal of information on either but I have some pictures.

This first setup is currently on a 1200 coupe rally car. The guy who fitted it got the setup complete from a guy who used it on an ex works GX rally car that originally ran in the Lombard RAC rally in 1974 (I think). It certainly never came from Japan with this setup but was used sucessfully for many years with it. I think it was most likely converted in the late 70's or early 80's. Here's the rack and crossmember on the bench. I believe the rack came from a Talbot Horizon and it looks like the lower arm pivots were altered to match the rack...




Here it is in the car...



Unfortunately it was impossible to get a picture from underneath due to the huge skid plate!



The second setup is in an ex-Janspeed race car. This was apparently another race car from Japan originally but was re-shelled at some point and I'd wager there's not much of the original car left. The rack conversion was most likely done by Janspeed who raced these cars in the Dutch touring car championship. Wether the conversion was done before or after that is unknown. The rack used I have been told, is from a Mini. The crossmember is a much more proffesional looking conversion...




Having had a dabble with R7P conversion myself in the past, I'd definately agree it's something a hell of lot more difficult to get right that you'd think. Tiny changes in height and fore-aft positioning have large effects on geometry let along rack with and pivot considerations. It can be done but it a very long road doing it by trial and error.

-Ed

Everyone is talking about how hard it will be to get the geometry right but how many of us run standard struts with standard steering arms, if you have a Stanza struts or 180b then your steering arms are longer and on a slightly different angle. So the steering geometry is already stuffed.

Apparently the good old commodore rack is chosen by the hot roders, easy to get, shortens fairly easy, easy to get parts for.?