tracking on rear of modern vehicles???

[Peter.N.]

I think the one big drawback on the older hydropneumatic Citroens was the fact tha tthey couldn't use rubber bushes. The forces generated by the hydraulic rams were way too big. On the plus side, you got excellent control over the suspension geometry and never had to replace rubber bushes, but on the other, whilst amazingly good at absorbing big bumps and potholes, I always felt they lacked refinement over small disturbances like white lines and cats' eyes. They tried to improve refinement and road noise on the CX bi putting the body on to the "chassis" with lots of rubber pads in between, but I always felt they lacked the refinement of the big German saloons.

I have always observed that but until now didn't realise why - thanks. The choice of tyres can make a considerable difference to the low speed ride, you need ones with a really soft tread and the only way you can find them is to go to your local friendly tyres supplier (I have one, my son went to school with him) and feel the stiffness of the tread, there can be a considerable difference, push your thumbs hard into the middle tread, some wont budge others will give considerably and they not only improve the ride but make the steering lighter.

As Avoset says 'if the tyres are worn evenly its unlikely that the tracking is out. The problem with rear wheel tracking is that although the toe in may be correct they may not be parallel with the front wheels but you will notice that because it will offset the steering wheel.

Peter

 

[Avocet]

Yes, for some reason, the pushrods between the suspension arms and the cylinders just "rest" in their sockets, so if the wheel drops into a pothole, the cylinder has to keep a load on the pushrood no matter how fast the wheel moves downwards or it will just pop out. That means having a colossal leverage ratio (something like 8:1 or 10:1 from memory), such that if the wheel moves 1" the hydraulic piston only moves about 1/10". That's all great, and it keeps the space requred for the suspension nice and compact, but the loads on the pivots are massive so any rubber bush would be absolutely "mullered" in pretty short order. The great thing, though, is that you can get into a 20 year old DS and the handling will be as sharp as the day it left the factory (not that the bar was set especially high when it came to "sharp" handling)! That said, I alays thought the DS was actually quite good if you grabbed it by the scruff of the neck and ignored the body roll!

Interesting about tyres. I think also the modern trend towards lower and lower profiles makes a big difference too. Stick a DS on 40-profile tyres and I think it would feel really horrible over cobbles and rumble strips!

 

[Peter.N.]

Right I see that, I have often thought about ways of damping out that vibration, the only way I have found is by fitting accumulator spheres in place of the regular ones - you don't feel a thing, rolls a bit though.

I would go for comfort over handling every time, I don't drive fast enough to need handling

 

[Peter.N.]

Just a note to anyone who takes on the job of changing the rear tie rods on a 406. I fitted another rod of a different make yesterday, a Delphi and it now tracks up, so if you attempt the job make sure you have a matching pair of a reputable manufacture.

Peter