75's on ice - Page 2

peelaaa · 8th December 2010, 18:48

Quote:

Originally Posted by -Joe

I have put the Spitfire away for the winter and have been driving my 75 again. The FBH is working beautifully! none of this de-icing nonsence for me! I have noticed that whilst driving over ice patches the 75's rear wheels will push out which feels odd at the controls.

Anyone else experiance this? I'm sure there is nothing wrong with the car. I think it's caused by the passive rear steer Z-axle getting out of shape.

The Spitfire has some element of passive rear steer in the way the rear suspension works but doesn't do this because it's rear wheels can't move outward, only up&down and slightly forward and back.

I've never driven a rear wheel drive Z-axle equipped car so I don't know if phenonemon effects V8's or B*Ws. I just think it may be a disadvantage in icy conditions but an advantage in most other driving conditions.

My cdti tourer does exactly the same, it feels as if the back is about to lose traction then gains traction.

Villa Villan · 8th December 2010, 23:13

http://www.autozine.org/Graveyard/html/Rover/75.html

Note the updates.

Cheers
Tony

-Joe · 11th December 2010, 01:04

The passive rear steer function is controlled by the "give" in the rubber bushes used to connect the wishbones. It will allow a small forward and back motion of the rear wheels.

In the Spitfire this maybe 1/2 centimeter at maximum. In the 75 it might be 1cm or so I guess.

With modern small cars they use trailing arms mounted solidly to the wheels center axle but with a rubbery mount to the body well forward of the center of the wheel. Which I feel is a bit uncivilised and takes getting used to but it does make these hot hatches handle really well.

The pivot point on 75 is closer to the center of the wheels so that the small rear steer characteristic is harder to detect.

The outward push is to do with the wishbones design for up and down suspension movement.

I guess the garage guy just doesnt understand suspension geometry in the same way as a car designer. If the rear wheels can independantly move back and forward even a little bit, that will help steer the car.

8th December 2010, 23:13	#12
Villa Villan I really should get out more....... ZT-T 160 1.8T Join Date: Jan 2008 Location: West Sussex Posts: 2,664 Thanks: 46 Thanked 64 Times in 42 Posts	http://www.autozine.org/Graveyard/html/Rover/75.html Note the updates. Cheers Tony __________________ [SIGPIC][/SIGPIC] Last edited by Villa Villan; 8th December 2010 at 23:18..

11th December 2010, 01:04	#13
-Joe Avid contributor Rover 75 Classic SE 1.8T Join Date: Dec 2008 Location: wink Posts: 135 Thanks: 0 Thanked 20 Times in 15 Posts	rear suspension The passive rear steer function is controlled by the "give" in the rubber bushes used to connect the wishbones. It will allow a small forward and back motion of the rear wheels. In the Spitfire this maybe 1/2 centimeter at maximum. In the 75 it might be 1cm or so I guess. With modern small cars they use trailing arms mounted solidly to the wheels center axle but with a rubbery mount to the body well forward of the center of the wheel. Which I feel is a bit uncivilised and takes getting used to but it does make these hot hatches handle really well. The pivot point on 75 is closer to the center of the wheels so that the small rear steer characteristic is harder to detect. The outward push is to do with the wishbones design for up and down suspension movement. I guess the garage guy just doesnt understand suspension geometry in the same way as a car designer. If the rear wheels can independantly move back and forward even a little bit, that will help steer the car. Last edited by -Joe; 11th December 2010 at 01:06..