Rear Shocks

[Henry 1.9GTi 36]

having the high speed curve go flat is better than nothing! allows slightly higher LS settings to control the car and give good driver feel without completely compromising HS as I'm sure you are aware regressive just makes this effect even greater given the HS damping can actually be reduced rather than just blown off. From the reading I have done it seems very important, and difficult, to get the transition velocity correct per application / track etc.. Although I am sure this is more aiming at fine tune and pro motorsport. Being somewhere in the ball park for us clubman lot would probably still grant gains.

 

Why would you run linear instead of digressive when regressive may not be available? Seems digressive is a logical step forward although been around for yonks and yonks

[EdCherry 34 1 Cars]

To decide what piston to run you first need to decide what attitude you want the car to take.

 

On a FWD car such as a 205 I would run a digressive curve (notice I didn't say piston ) on compression and a linear curve on rebound - on the front of the car anyway.

 

Many reasons, mainly because of what attitude you can achieve with it. Why would you want rebound to 'blow off' its a very powerful tool

[Tom Fenton 1,526]

This is all fascinating stuff if not over most people's heads, however it's not much help for the back of a gravel rally car?

[welshpug 1,627]

given the beating a gravel car gets on the rear end, I'd imagine quite the opposite surely Tom, with your experience of whites on a road rally wouldn't you say it was bloody rough in there?

[Henry 1.9GTi 36]

I understand you can effectively get a car to hug down using rebound damping. NASCAR being an extreme case. But attitude changes are mainly concerned with aero imo. For non-aero you just want maximum tyre grip and good driver feedback. From some papers I have read a few concur that too much mid-highspeed rebound damping has the largest detrimental effect on tyre grip.

[EdCherry 34 1 Cars]

Rebound damping is not exclusive to 'aero' cars at all, it plays just as big a part in saloons.

 

It is one of the first things I would aim to get correct in your situation personally. Im not saying the papers you read are wrong, there is just to varying styles of damping a vehicle and most instantly jump to compression biased damping as it easier to understand a car that you limit/control travel - I certainly fell under this category before I took up my current position.

 

In most cases you gain traction, turn in and driver feel from using more rebound damping. It is easy to spot when you have too much rebound - and the driver will certainly feel it as the steering wheel try's to rip out of his hands.

 

Going back to the OP, when you say to soft what exactly was happening - bottoming, bouncing, harsh?

[welshpug 1,627]

I would imagine in typical rally 205 style that the rear end is being fired up in the air over big bumps, like crossroads or crests.

 

Pretty scary going along and then only seeing the floor in front of you for a bit!!

Edited June 6, 2013 by welshpug

[Rippthrough 98]

 

 

On a FWD car such as a 205 I would run a digressive curve (notice I didn't say piston ) on compression and a linear curve on rebound - on the front of the car anyway.

 

 

Which, as it happens, is the exact thing that's in my Fox prototypes, on a linear piston (albeit a high flow one).

[EdCherry 34 1 Cars]

High Flow is good, you can make it fairly digressive on compression (well on my brand of dampers you can!).

 

Depending on how the rear end is being fired depends on what you change - is it because its bottoming?

[Rippthrough 98]

Usually yes, most bounce off the bumpstops and then fire themselves into the air...

[arwel 43 2 Cars]

Mine was springing up on the initial "take off".. Once it was down.. it was down hard and stayed down. Back to my original question, I have been offered 306 tarmac Billies and 21mm torison bars. Good combo?

[Tom Fenton 1,526]

I have got 306 tar billies and 23mm rear bars in one of mine, it corners on rails, it is very stiff though. its great on smooth Tarmac but I'm not sure how good it would be on anything else.

[arwel 43 2 Cars]

So some 21mm ones may be a good compromise then. Epynt is nice and smooth, Caerwent isn't too bad but can be a bit dirty in places, Pembrey is normally slippy all over the place and a bit rough here n there, Dale and Talbenny are normally slippy and bumpy in places too, Brawdy is quite smooth from what I remember and thats about it really. So Im thinking either 180 lb or 200lb front springs to go on the Billies and then 306 tarmac Billies on the rear with the 21mm torsion bars. Should stiffen it up a bit more than what I have now.