Jumper K Balls
Jumper K Balls PowerDork
5/17/18 4:39 p.m.

I have had the extreme pleasure of working with Ransom to do a complete suspension redesign for the Fiat 600 chassis. Major changes and one of those is switching to rack and pinion steering. The owner of this car for some reason wanted to use the Triumph Spitfire steering rack. It was inexpensive and easy to get so that is what we used.

Susprog3d guided us to locating it and after having to relocate it a few times so as to not occupy the same space as other immovable objects we wound up with bump steer and Ackerman numbers ranging from awesome to acceptable.

But the length of the steering rack needed to be radically altered as well. It needed to be 162.6mm shorter than it was.

So here is the patient

I centered the rack and measured both sides to be sure.

Then blew it apart

Cut 162mm off the end.

Chucked it into the lathe and cut the shoulder down and threaded to match the tie rod. In this case M14X1.5

Then I karate chopped the housing until I knocked the same chunk out of the center.

Trued both ends up in the lathe and sanded off the powder coat

and welded it up.

Reassembled and tested for function. Yeah it is SHORT! the car is narrow and we had to push the rack position so far forward that the tie rods will be quite long.  Bump steer is quite good in the software model and Ackerman is better than a stock Fiat 600 but not 100%

Then after setting the subframe at the proper angle and bolting it securely to the fab table we were able to make fixtures to hold the rack precisely where it needs to be for fabricating the mounts.

BTW these Certiflat tables are worth every penny. If you have the means I highly recommend picking one up, it is so choice.

 


Also what I learned more than anything on this job is that you probably shouldn't go screwing around with modifying and relocating steering racks.  It was really eye opening having Susprog3d show exactly how much change in bump and ackerman and necessary lengths was happening with very small movements. I am confident we got this as correct as the software told us to, but with out that software it would have been a trial and error crapshoot.

wheelsmithy
wheelsmithy Dork
5/17/18 5:09 p.m.

Jumper K, You're my hero.

Is this YOUR Fiat, or a customer's? Awesome work either way.

 

Jumper K Balls
Jumper K Balls PowerDork
5/17/18 5:17 p.m.

Not mine. I mean if I accidentally make an extra set of everything no one is gonna get upset laugh

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