Steering Racks for 116 Cars

[LukeC]

The real answer to this is providing a source for a higher ratio (2.5 turns lock to lock for the same linear rack travel), cost effective rack that can be easily adapted into a GTV6. And being a gravel rally car, I agree from my limited knowledge of rally cars, that you do not need or want power steering.

However, I know this is a little off topic but:

In the majority of cases there will be little direction change.

Not wanting to get into a debate here, but.... Oh why not!

See image I have posted to show the basic priciples of power steering (ZF) and pretty much used in older Alfas (75s etc.. even though the image is for Servo-tronic with road speed weighting variation the main priciple is identical). Looking at the pinion/valve body, you can see two of the most important parts of the power steering. These are the input shaft (dark grey), and the torsion rod (white). The torsion rod is always directly connected to the input shaft and the pinion by upper and lower pins. This allows road feel to always be fed back up to the steering wheel. As this torsion rod flexes, there is a small loss in steering feel. However, at some point the torsional flex will be overcome and the drive is actually done by the input shaft turning the pinion by two drive keys. These keys are not a close fit (to allow for the torsion rod to do its thing). This all allows the hydraulics to do its thing (I am not even going to attemp to try to explain the complex hydro-mechanics here). I will say though that people who run a 75 PS rack without PS pump functioning (and not having modified the internals of the rack valve body), will suffer from pretty woolly steering. Don't do it! 

So the only real loss with a properly functioning PS rack to a manual rack is if the hydraulic supply can't keep up with the rack's requirements and you use up this torsional flex in the torsion rod. I am not sure what it is (in degrees), but am sure it will be less than the increase in rack and pinion ratio.
I am running a 75 rack (was 3 weeks old, as in brand new) when I bought the 75 with modified 164 PS pump. The feel at all speeds is as good as any 105, but much more direct. I think there is a little mismatch between the pump and the rack, as when I throw the car through tight roundabouts I feel the pump is not quite keeping up with the demands of the rack and am using my arms to compensate. The 164 pump and the 75 pump are also rated to different pressures (164 pump pressure is lower). I am considering going back to the 75 pump as I can't ever remember this being an issue in any 75 I have driven or had before.

Try the Elk test with two near identical GTVs: One with PS, and one without. Oops, not fair... one will have 3.3 lock to lock, and the other will have 3.7.

[Duk]

From what I found, the Commodore racks have a variable ratio around centre. That is, they use different angle of the rack teeth around centre.
The power steering rack in the Alfa's are 3.25 turns, but have constant rack teeth angle, so are constant rate.
Be aware that I am talking about a gear ratio change with steering lock, not changes in hydraulic effort from the power steering.

Again, you will need to know how long the steering arms of the Commodore struts are, in order to make valid comparisons. Just quoting "Lock to lock" numbers doesn't say enough.

[alfarally]

Flynn

I think i have an old commodore rack you can have. Give me a call and I will see if I can dig it out for you.

I currently have 2 classic rally cars in the workshop for 'steering rectification' (one is an R100 getting a rack and pinion conversion) and there are a number of options you could take to achieve your outcome.
If you do find that the steering is a little heavy after the ratio is changed, a great mod is to add electric assistance to the actual column and it's light and simple. Don't underestimate the ability of a good PAS setup to lower your stage times.

Rob. 0414 864120

[VeeSix]

Did someone mention Bommodore, i I think I just started vomiting! The rack will only be.....holden together 

[Fylnn]

Rob,

I am holiday this week, might give you a call next week about the Commodore rack.  Where are you located?

[Nicolas]

Great thread here, what did you end up doing Flynn?

I am just about to fit a 75 PS rack into my GTV6.

[Fylnn]

Well the short answer here is nothing to date.  I was Deputy Clerk of Course for the recently completed International Rally of Qld, and so have not been down the shed lately.  But having now created lots of fun for other people I am dead keen to get back out there and have some myself.

I just pulled a spare rack and steering column from a wreck.  My plan is to build a new steering column with a 1.5:1 steering quickener built into it.  That would give me 2.4 turns lock to lock, which is the same as the gun Escorts do.  Not sure how the steering effort will end up.  Probably tiring at low speed on road tyres on bitumen, but hoping it is fine on dirt and rally tyres.  At present it is not a problem at all.

Interestingly one of the classic Datsun's on Rally Qld, had 2 offs in short order.  He had just fitted an electric power steering system and he is now blaming that, saying he did not even feel the car let go.

But drivers always say that don't they?

[Fylnn]

Well the steering quickener and parts have arrived, so just drawing up the new steering column mounts on CAD.  Then got someone who will make up new mounting brackets and will then cut, shut and weld steering shaft from wreck and mount the whole thing back into the car.  I will lose the steering lock and ignition key, so will go to just ignition key and starter button in center console.  Not a problem for a rally car.  Also safety measure given recent experience of guy in Gemini whose ignition key barrel was worn and on the dirt road the key vibrated out and the steering column locked.  Fortunately at low speed, but scary at the time.

So this ratio is 1.5:1 which will give 2.4 turns lock to lock with standard rack.  Hopefully not too heavy otherwise got to investigate power steering options. 

[Beatle]

So what did Greg Carr use in his championship-winning GTV6?

[Fylnn]

Not entirely sure what Greg Carr used, there was stuff available in the day.  There is still a guy in Finland who makes them but on for Spica racks and only LHD.  Which is why i came back to this idea.  It is drawn in CAD, just got to make some parts and see.  Either the best thing i ever did or the dumbest.  Time will tell. 

[Paul Newby]

Peter Hollinger made a number of Alfetta quick-racks for Nigel Bolling's Autodelta (Sydney) business back in the 1990s. They went on a few Alfetta GTV based sports sedans up here. Not sure how much they cost but I understand that they were not cheap...

I did look at trying to source a quick rack for my Alfetta GT racer a few years back (the steering is waaay too slow) and I think there were a crowd in the UK that were making them, but I never followed through.

[Nicolas]

I sent Quaife UK an email, they can produce a quicker rack and pinion to fit the GTV6 Rack Body. Minimum is 30 and they will have to see an example to quote.

Maybe someone in the UK could get a manual GTV6 rack to Geoff Booth so we can get a quote. If it's $$ reasonable I would take 2 so that leaves us with 28 more to sell.

Nico