Fitting a Steering Rack

[3litrekiwi]

Slightly off topic. We had our National rally over the weekend. There was a really nice P5B fitted wiith a power rack from a Subaru. The owner paid a fairly significant sum to get the work done but it didn’t look like a difficult job and it didn’t look at all out of place.
The rack was mounted on a tube that fitted between two flanges that attached to the subframe using the mounts for the original steering box and the idler arm. I think the steering column had been shortened and it had an additional mount on the firewall. Really nice job.

[enigmas]

Wow that sounds interesting...especially to an inveterate modifier like me Martin. Now all we need is some photos of the rack in situ and the make and model of the Subaru?

I imagine the forward facing steering arms mounted to the 'uprights' (formerly kingpins) would also have required a bit of massaging with some heat to correct the achermann. As it currently exists on P5s, the ackermann angle is derived from the steering pitman arm and the opposing idler arm. Unless this is done the geometry of the steering would be terrible.

[Mike’S-a-loon]

The original price for the conversion was NZ$12,000, thats around AU$11,000, so presumably there was a lot involved... Its nice to know people are prepared to invest so much in their P5's.

[johnwp5bcoupe]

Mar 28, 2021 12:36:26 GMT enigmas said:

Wow that sounds interesting...especially to an inveterate modifier like me Martin. Now all we need is some photos of the rack in situ and the make and model of the Subaru?

I imagine the forward facing steering arms mounted to the 'uprights' (formerly kingpins) would also have required a bit of massaging with some heat to correct the achermann. As it currently exists on P5s, the ackermann angle is derived from the steering pitman arm and the opposing idler arm. Unless this is done the geometry of the steering would be terrible.

Achermann angle "now there is a can of worms" Vince

[3litrekiwi]

I did think of taking some photos but the car sat a bit lower in front than standard so access without jacking it up was not good. I thought there would be interest here so I will contact the owner and see if I can get more details. The car was also running a 3.9L motor fitted with carbs. I think contact with the shop that did the work would be the best bet as word was that subsequent replacements would be cheaper due to the design work having been done.

From what I could see the placement of the centre line of the rack was where the drag link would have been in the original setup. 

[enigmas]

Sounds good Martin...look forward to your investigations and some pix. No pressure mate.

NB. Another interesting aspect of the setup to consider would be that the rack outer pivots points (for the steering arms.) Ideally these need to be in alignment with the pivot points of the lower suspension arms of the car. If this isn't taken into account...the result is bump steer!

So I'm assuming the Subaru rack is both forward facing (in front of the front cross member...from your description) and has its steering arm pivots at the correct width to align with the Rover's lower suspension arm pivots.

* The only P5 steering rack mod that I'm familiar with is the one 'Nodsmod' (Neale Donahue) expertly fitted, but this car also ran a Jaguar front suspension. The rack being rear mounted.

[3litrekiwi]

Yes, there was a guy in the hot rod club I was breifly a member of back in the 1980's who had a Mk I Hillman Minx with a small block V8 who fitted a rack that was quite a bit out. He drove into the garage one morning when we were watching and when he braked the wheels flopped out about 5 degrees per side! Quite a challenge to drive apparently. Once the rack was shortened and repositioned it was fine. 

[enigmas]

A Rovering friend of mine who is also keen on modifications to improve the driving experience of his P5B was emoting one day about fitting a power steering rack to his car. I asked him whether he had considered the Achermann and the swivel points on the rack in relation to the lower suspension arms of his saloon. He froze for a moment then looked at me in a quizzical, WTF kind of way!