It's Gone Too Well...what Have I Missed?

[Bob Tucker]

Guys,

I have the JIGTEC wishbone setup using a Sierra rack, which has over 4 turns lock to lock. The rack with the sliding pillars had about 3.

 

I have searched high & low (Rally design, Burton & Quaife) for a quick rack conversion. Not in production for another few months.

 

So I looked at the power steering rack I had in the garage, with 2.8 turns.

Same width, same bolt fittings, different column connector.

I made up a new steering column, & made the fluid system into a closed loop, leaving enough fluid in for lubrication. It missed the alternator....it missed the exhaust....it even missed the chassis down tube.

 

I've just tried it out & it all seems great. A little heavy at parking, but brilliant on the road.

 

What have I missed? Will the rack lock up for any reason? Is this a safe option?

 

Cheers, Bob.

[Guest daveg]

Bob

 

Usual disclaimer but the only reason it could lock up is if the steering lock engaged...there is no other reason I could think of

 

So IMHO it should be great, thats why I tried to find a power steering donor...without luck :angry:

 

Dave

[Peter Bell]

Just make sure you have a vent in the fluid system to prevent any pressure build ups.

Peter

[Guest Battery Bill]

Dave

thats why I tried to find a power steering donor...without luck

We have all the power steering gubbins out of our Granada you can have if you want, Mind you you would probably fit that at the wrong end as well

[Guest daveg]

Bill

 

Thanks for the offer but I have already fitted the steering and I sure as hell don't want to change it now

 

I want to get on the road before the 2 year mark :boohoo: after sva and a bit of driving I'll know what else needs doing...

 

Dave

[Guest paul thompson]

Hi Bob,

I work for ne of the companies that made the Sierra, and Granada power steering. If you have made the fluid a closed loop and filled it with fluid, you will find that teh damping provided by the fluid makes the steering heavy and will limit your returnability. You do not need to have the thing filled with fluid for it to work, just grease the cylinder bore should do the job. You will need to loop the two sides for the air to get from one side to the other if you decide to take the fluid out but as you have already done this, shouldn't be a problem. The air from the bellows goes through a gun drilling down the rack bar centre. With the Granada rack which you could use you will need to watch thetrack rods as these are longer than Sierra by 18 mm. The ZF gear has a variable ratio and the TRW one does not, so it depends on which year and spec of Power stering you have. The origional ZF Gear (the one we make) is an aluminuim casting in one piece. The TRW or any other patern gear is an Aluminuim casting with a steel tube. The variable ratio will help with steering efforst on centre but they will increase as you approach lock. Later Granada steering has different mounts (Horizontal instead of Vertical) and has Speeed sensitive power assistance, this would be good if used with a pump but does nothing otherwise, it is variable ratio though. If you want to know how come I know so much about all this, I sell these racks to Morgan and Noble, and Farboud, Never heard of it, check this out!

http://www.farboud.com/farboud.htm

[Bob Tucker]

Thanks Paul,

thats set my mind at rest.

Ive done about 300 miles with it fitted & it seems fine.

It does seem a bit heavy, but i'll live with it now until I return from leMans.

Then I'll drain the fluid & see what difference it makes. I already greased the rack (inside the bellows) & it was certainly free enough when I fitted it.

 

Marks out of 10.....

RHE rack.....9

Sierra Manual rack...4 (real twirly)

Sierra Power rack....8 (a bit too heavy)

 

PS just set front pressures to 20 instead of 17...much better now.

Bob.

 

One thought...does the Granada rack have a bigger track, or is that why the TREs are longer?

[Guest paul thompson]

Hi Bob,

Yes the Granada had a wider track, but the mounting of the rack to steering arm on the upright is also different, that's why the Track rods are longer. Don't know what the Track rod ends look like one to the other as I don't supply those. There was a Scorpio EVO rack but I think that was only LHD, that had a much heavier valve characteristic. Can you measure the torque to turn the wheel while stationary and while doing 10 Kph (whatever that is in english money) Do you know if you have a ZF or TRW rack? As stated elsewhere on this board, I intend to fit a steering gear from a Jag X type after SVA and pipe up the origional Sierra pump. (waits for the girly name calling). This is a speed sensitive rack and will give me the heaviest characteristic, about 10 Nm in parking but still has variable ratio. Should make the handling intersting on country roads. This will also allow me to increase the castor to improve returnability which at the moment is crap even with loadsa grease on the rack bar. Current castor is about 3.5 degrees. I think it needs about 6.5. Does anyone else know what tcastor they are running?

[Bob Tucker]

Hi Paul,

It's a TRW rack (ally casting + steel tube)

Just to clarify, I am not using it powered, theres no pump or reservoir.

Ron Champions book recommends 5 degrees caster. The garage where I had the tracking checked reckon I have too much caster from the handling characteristics, but they couldnt measure it. It whips back after cornering, & turning the wheel is heavy at any speed below 30mph, but very heavy at parking. I have 0 camber.

I reckon I'm onto a winner with a bit more fine tuning, but it'll have to wait until after LeMans. I'll make up a camber/caster measuring gauge then.

Cheers, Bob

[Guest paul thompson]

Hi Bob,

Where are you in this fine and green land of ours? I have a castor camber guage for the next few weeks, it is on loan so I'll have to give it back soon. It's dead easy to use. I'm in leamington.

[Peter Bell]

I have about 1.5 to 2° on my Mk1 S7, not a lot of self cetering but weight is fine. I know 5° makes it very heavy, don't know what a standard sierra is but the cortina was 2°. Bigger wheel offsets from the normal Sierra will make the steering heavier too don't forget.

Peter

[Guest paul thompson]

I think you mean smaller off sets, I have 17 mm on my wheels, this sets the centre of the wheel further out from the centre of the car increasing the track. Bigger offsets like 35 mm which is normal for front wheel drive cars, will bring the wheel further in. All offsets are negative these days, there are no cars which have a positive offset so no one bothers with the +/- signs anymore. This DECREASES the effort because the steering roll radius is increased. This is the distance from where the Kingpin would strike the ground if you continued the centreline and the centre of the contact patch of the front wheel. When you increase the roll radius the tyre does not scrub as much. I know this for fact because I have to do steering installation tests measuring the steering effort at full laden conditions. recently I did a test on a double decker bus, once with steel wheels for the European and Hong Kong Market and onece with Alloy wheels with a bigger roll radius for USA, The difference was about 12 mm smaller offset therefore bigger roll radius and the difference in pressure in the system was about 20 bar less than the steel wheels. Handwheel torque was the same it just needed less pressure. Anyone bored yet?Here endeth the lesson.

[Guest MikeD318]

Sorry Paul, I was about half way through when I flaked out and started watching your gyrating lady.

[Bob Tucker]

Hi Paul,

recently in LeMans, but now back in Orpington, a bit of a trek from Leamington.

Many thanks for the offer tho'....

Bob.

 

PS click on the name to get individuals details....

if they filled them in, like wot I did...

 

One funny story about my return for LeMans...

The N138 has many roundabouts, & the locals turn out to cheer "Les Anglais" on their way. So I got used to downchanging early, popping & banging & a quick flick right, left, right round the roundabout, to applause & waves.

I did one, two, three roundabouts like that, then part-way round the fourth, I caught a glimpse of two blue uniforms, carrying a tripod & a speed camera down the road.

 

They waved & shouted too.....!!!

Bob.