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<-- wiki clickyQuote:Ackermann

Oh... now you have made me more curious, can you elaborate on what the differences are? The internet doesn't seem to be providing much info so it looks like I'll have to go to my local tech book shop.

Carol smith's book " Engineer to win " has a good explination on ackerman. it seems that street car and race car ackerman are very different .

Cheers for all the pick ratdat_uk. I have been researching ackerman and so far I can find plenty of definitions but nothing that tells me if there is a desirable amount and what its true affects are... As far as I can see the difference in the angles of the front wheels at full lock would result in a bit of tire scrub and possible loss of traction (?). Can anyone tell me/us more...

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.?

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

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.

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.

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.

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)