Question 2. I read somewhere the other day that the ZF steering rack from a VL Commodore can be made to fit into a 116 GTV. It does not look like a straight swap, the mounting points are different for a start, but I am assuming they mean the internals go in the housing.
Anyone heard or tried this one before?
The VB-onwards Commodore was a German Car with a German ZF steering rack, my 33 had a ZF rack, and i purchased a repair kit from ZF Australia, might be worth contacting ZF Australia to see if there is any interchangeability, the housings would be diffferent for the different cars, but the internals may interchange.....interesting subject, when you find out in the auto industry what fits what, Colin.
First of all: What are you trying to achieve?
Is you rack cactus, or get a quicker rack ratio?
This is interesting as I was thinking the same some time ago.
The power steering Commodore racks have a 2.5 turn lock to lock which is about 0.75 turns less than an Alfa power steering rack.
However, if faster steering is your goal, you also have to factor in the length of the steering arms on the upright/strut. The Alfa's arm is quite long, about 150mm from the centre of the stub axle to the centre of the tie rod end hole. What that same distance on a Commodore strut is, I don't know. Tho they do look pretty long.
What I am trying to achieve is a quicker rack ratio. I spent the weekend giving myself a DIY gym workout twirling the wheel from lock to lock. It is a GTV6 gravel rally car, so lots of opposite lock and rear attitude if I drive it properly. On gravel on rally tyres the steering is light enough now. It won't be ideal on tarmac with road tyres, but have to look at what it is meant to do. The common ratio in an Escort set up for gravel and powered by money is 2.4 lock to lock. Quaife make them for instance, but not for a 116.
The other thing that prompted the question is I seem to be suffering from increasing rack rattle, and so looking at what options I have if I pull the rack out for an inspection. What do I put back?
I am sure this has been done and talked about before, could you fit a power rack out of a 75/90?, as power steering has a quicker ratio than a manual rack, and it may bolt straight in, all race cars have power steering, due to less effort and fatique to driver, would need to rig up a pump somewhere, Colin.
Sorry Col. I have to disagree with you on this occasion or at least offer an alternate viewpoint.
Not all race cars have power steering. My particular point about transaxles is that no RACING transaxle being rear wheel drive should have power steering at all.
Driving one around for a shopping basket and parking it 100 times a week is a different story.
On a race car you want maximum steering feedback. Fitting power steering simply decouples the driver from the steering feedback and leaves you in less than optimum knowledge of what the car is doing. Furthermore, power steering can never RESPOND to steering requirements as quickly as a manual one and so for the dual reasons of feedback and reaction speed a manual rack is the go.
Rapid steering response in a rally I would have thought has to be at the top of the list.
Of course if rack ratio is all one needs, it is always possible to simply use the power rack without power assist to use in a manual mode.
Speaking to different people, power steering is a good thing for a race car, as you can run better suspension angles for better grip, but it has heavier steering, and you can drive to this part of the track, because you just steer it there, without power steering it is too much hard work, V-8 Supercars and Formula 1 cars all use power steering as you can turn quicker, downside is more weight, complexity and reliability problems, just look at the Valvoline Volvo Team power steering dramas, and when a V-8 starts to smoke, if it isn't the Albins transaxle about to blow up, then its a power steering issue, Colin.
Without spelling it out when I refer to transaxles I naturally mean Alfa.
Front wheel drive cars are a completely other thing.
I stand by what I said. My Alfetta racer has about as geometry modifications one car can stand and it does not need power steering.
Next time you want to compare power steering with manual steering response, try doing an ELK test in identical cars with and without power steering and see how you go.
To each their own, when the Transaxle V-8 Supercars go back to manual steering, from power steering, we will hear whinging from the drivers, the heavier steering over a race period would be a Health and Occupational issue.
In the UK, some 16 valve 33 drivers have gone from 2-1/4 turns lock to lock power steering to 3-1/2 half turns lock to lock manual steering for better feel and lightening the car, so each one has their own preference.
Is an ELK test anything like a MOOSE test, where the driver of the car has to steer away quickly from a pretend moose, you would need a quick ratio power steering, otherwise you would hit the poor moose or elk, ask Mercedes Benz about it, Colin.
Ummm, MD, my 911 has power steering and it's, ummm, every bit as good as any manual system I've ever used, and I've driven a lot of 116 series cars. Responsive, fast, totally full of feel, all that and more.
If I said it's much, much better on this forum that would be naughty.... ;D
I have no intention of running power steering. More weight and complication and I don't think it is needed. Just looking for something a bit faster and more direct.
I suppose I might keep an eye out on Ebay or somewhere for a $20 Commodore rack and strip it down and compare. Nothing to lose and a fair bit to gain.
Aaahh, the ELK test.
In a power steering set up, do a 10 to 2 O'Clock and back to 10 in a RAPID turn whilst on the move and see how much direction the car has changed. The operation has to be rapid because any steering will eventually change direction if it is done slow enough. Be sure it is in a clear road and don't exceed 30km/hr. (BTW you do this at your own peril)
In the majority of cases there will be little direction change.
Now do the same at the same speed with a manual rack and you could expect go almost from one side of the road to the other.
Unless you have front wheel drive or a big cast iron V8 boat anchor under the bonnet, you don't need power steering.
About the only power assistance I think may work is an electric version that essentially is a manual system with effectively a piggy back help to turn chicken wing arms into Arnold biceps.This would have no oil pump pressure delays.
Flynn, I believe you are on the right track.
anyone got an old Commodore or its rack lying around?
Faaaaark a 911 with power steering thats scaaaary shit right there....... ::) ::)
cheers Paul
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:
QuoteIn 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.
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.
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
Did someone mention Bommodore, i I think I just started vomiting! The rack will only be.....holden together ;D
Rob,
I am holiday this week, might give you a call next week about the Commodore rack. Where are you located?
Great thread here, what did you end up doing Flynn?
I am just about to fit a 75 PS rack into my GTV6.
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?
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.
So what did Greg Carr use in his championship-winning GTV6?
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.
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.
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