manual steering rack question

[unclebob]

got a couple of steering rack questions i hope you fellas can help me out with as im considering changing my eps rack for a non powered rack as ive always felt that its the one point aspect of the car that ive never been happy with, just isnt responsive enough for my liking.

Can you guys with manual steering racks tell me how many turns it is from full lock left to full lock right

if any of you have driven both eps and non eps cars is there significant improvement in steering response in the non eps rack?

finally is the non eps rack very heavy to park or can it be lived with if youre not built like schwarzenegger?

thanks

aijaz

[goldtop]

I've got one of each but at the moment I can only answer the last Q: the non-PAS car does not require Arnie-style biceps. :) But it IS considerably more work at low speed than the other two mid-engined cars I've had: X1/9 and MR2. And that's because of the wider tyres up front.

On the other questions, the move to PAS is what every motoring reviewer said was a significant backwards step for enthusiastic driving. Before that the NSX had won Autocar's handling tests for two years back-to-back, for example. It lost out when PAS came along.

[unclebob]

thanks gold top, yeh i can understand that, seems like you have to turn the eps rack forever, (compared to the dc2 and the dc5 and the s2000 all of which ive owned and all of which are also powered racks), before the car starts moving in the direction you want it to go!

anyone else care to comment?

[sorepaws]

I thought the EPS only worked below about 15mph then it was back to the direct mode - as I understand it the EPS is like an assist "motor" wound around the rack, this is how the assist part works at low speed only.

[TheSebringOne]

The EPS is speed sensitive, but I thought its at much higher speeds than 15 mph when
you lose the assistance?

[markc]

thanks gold top, yeh i can understand that, seems like you have to turn the eps rack forever, (compared to the dc2 and the dc5 and the s2000 all of which ive owned and all of which are also powered racks), before the car starts moving in the direction you want it to go!

anyone else care to comment?

Aijaz, you won't get any less arm twirling with the manual rack over the EPS one, in fact you might get more. The overall ratios are similar 18.6:1 (manual) 18.2-20.8:1 (EPS) so the EPS is slower around the centre but faster as you add more lock. Automatic transmission cars got an EPS system with the fixed 18.6:1 ratio of the manual steering cars.

On the EPS rack I believe assistance reduces gradually above 15mph. I think the system also works in reverse so that deflections at the wheels (kick back) are smoothed out by the "assistance". I'm sure Kaz will be able to provide a proper explanation at some point :)

There were several updates to the EPS system during the life of the NSX. NA2 (>1997) cars got a new controller and assistance program, I think they did away with the steering column angle sensor at this time as well. I think later cars had at least one other tweek.

I've driven both manual rack and EPS versions and personally wouldn't want to be without EPS. At parking speed it's great, who needs feel at 3mph :) Compared to modern cars even the EPS equipped steering gets pretty heavy on lock at speed. On circuit at high speed they are fairly physical cars to drive.

Newer cars, especially mid engined ones, can use "faster" steering ratios because they have stability control systems to keep everything in check when you turn the wheel quickly. The Ferrari 458 has a crazy 11.6:1 ratio but the older 348/355's had much slower 17-18:1 ratios like the NSX. Although not mid engined, TVR's always used to have really fast steering racks but they were very much an acquired taste... and plenty ended up in hedges :)

Cheers

Mark

[Silver Surfer]

I have 2 manual and 1 EPS car and the steering on the EPS is really light and smooth in comparison...smooth meaning there is less kick back on rough road surface.
I have many times nearly over steer the EPS-rack car round a roundabout as the rack does not self centre as quick when I exit a roundabout I had to straighten the wheel with assistance...whereas the manual car self-centres quickly....

It is really what you get use too!
I prefer non-EPS steering....it keeps me in shape ;)

SS

[unclebob]

thanks guys, very informative and yeh silver surfer the slow self centering is one of the things that annoys!