911R Steering

[chris_seven]

The 911R Driver's Manual say the steering was 2.07 Truns lock to lock.

The Spare Parts Maqnual say use parts from 911/911S.

I think the early rack and pinion was 2.7 turns.

Is it possible the the 2.07 is a typo or were they 2.07 turns?

[Mr9146]

It's been my understanding that the 911 steering racks were all roughly 3 turns from lock to lock.

The 930 rack is slightly less from lock to lock. I would suspect the 914 racks to be different as well.

That said, however, they are all interchangable but will yeild different results in turning circle, tire to body clearance, etc.

[Flieger]

Someone on Pelican was asking about the 930 racks for an autcross car. Do you know how much quicker the ratio is? I suppose the total travel is the same as a 911?

Bending the steering arms on the spindle part of the strut as a method to correct for bad bump-steer geometry and tie-rod angularity on a lowerd car will shorten their effective length and quicken the steering ratio but also increase total angular displacement.

[chris_seven]

Early racks with the housing to fit a steering damper are 2.7 turns and I am not sure when the changed but later racks are about 31/2 turns.

It is possible to buy rack and pinion components for the later 'flexible rack' that are 2.4 turns and work well but don't fit the early rack bodies.

[mike curnow]

What is a flexiable rack. Where can you buy the parts for a 2.4 system?

Early racks with the housing to fit a steering damper are 2.7 turns and I am not sure when the changed but later racks are about 31/2 turns.

It is possible to buy rack and pinion components for the later 'flexible rack' that are 2.4 turns and work well but don't fit the early rack bodies.

[Flieger]

I think the "flexible rack" started with the LWB. The puck would press on the rack and the rack would bend to keep proper backlash between rack and pinion. The earlier racks floated in connections to the tie-rod end outputs and did not bend. It was first used in the 914 and soon fitted to the 911s.

[chris_seven]

I agree, the change was 1969 and the rack parts, which used to be 2.4 turns, but now seem to be 2.5 turns are available from Quaife

They list an RHD and LHD but as it is a centre rack I guess they are the same part.

http://www.quaife.co.uk/catalogue/se...40%2C331%2C333

[Flieger]

What is the quickest rack that can be fitted to a 911?

[chris_seven]

If the 911R did use 2.07 I would certainly look at having some made at this ratio but I do think 2.7 is most likely.

To determine the quickest rack would need some calculation of the tooth loadings to see how to change the ratios due to the fixed centres or I imagne that it may be possible to fit a powered Woodward or similar centre rack without too much difficulty.

I would think that a 2.4/2.5 would be quite good without power assistance.
Most Rally Cars seem to be fitted with this approximate ratio as they still need to maintain a decent turning circle. Many 'quick' single seater racks have very poor turning circle capability so the absolute ratio isn't quite what it seems.

I drove an Ex-Works Alpine A110 once and it had 1.75 Turns but it was a very light car and very twitchy in the wet on wide TB15's.

[Flieger]

I thought all 911s had the same amount of total rack displacement and that the fewer number of steering wheel turns indicated a higher/quicker steering ratio. I would not want to limit steering travel.

So 2.4 turns is the fewest and therefore gives the quickest response between steering wheel movement and road wheel rotation. This is what the normal flexible rack is? My car has a 1971 rack so it should be the 2.4 turns?

I think I will just stick with that then. More steering wheel turns per angle of front wheel can give more precision, if one chooses to look at it like that.

I see how the quick racks could be useful on rally stages and tight racetracks. Sometimes while shuffle-steering in the heat of battle , I think a quicker steering ratio would be nice to control the tail's swinging momentum with a flick of the wrist, rotating the car around the most twisty curves.