Custom Suspension

[Batfink 201]

The spec of my custom suspension is being finalised now

 

its basically a lightweight autograss double wishbone setup with turrets to run leda coilovers on the rear! The track width will match the 309 gti at the rear. Brake wise depending on costs will possibly be 4 pot honda fireblade calipers but I dont think I will need such powerful brakes so will be looking at others.

For the front. Some custom tubular 309 wishbones on fully adjustable 405 hubs and some ledas.

 

it should be a very lightweight setup

[Sam 4]

Whens this happening then

[Adi 0]

its basically a lightweight autograss double wishbone setup with turrets to run leda coilovers on the rear!

 

How is this being made to fit the 205?? I have heard a few times of the 205 using double wishbones on the rear......but this has been done by fitting a space frame.

[Batfink 201]

Adi,

I think the rear suspension will have a frame that sits under the floorpan where the beam is currently

[Adi 0]

When are you getting full details? Could you let me know cos this will be of interest.

Do you know if the boot area is going to be chopped into?? With the double wishbone set up....there has to quite a bit room inside the wheel for the lateral links. On the rear of any Pug using the beam axle.......there is very little room inside the rear wheel.

[Batfink 201]

I'll see if he has pictures etc of his old car

[zeolite 0]

Batfink. As I am building an autocross car i would be most interested in what you are doing. Will you set the car up with stagger as in a stock car?

[Batfink 201]

::runs to read up on stagger:::

 

 

hmm seems that stagger is only any use for oval racing so I dont think I will be having that

[zeolite 0]

I thought you autograss guys only turned in one direction?

 

Guess I got that wrong

[Sam 4]

Its a road/track car, why sbc phase 1/2 won't do i dunno, guess we'll see how it performs eh

[Batfink 201]

cos at the end of the day SB phase 1/2 kits are developed for road cars with a lot of comprimises. Torsion bars are great if you want to put your shoping in the boot but it can be improved! So i'll bin that and try something a bit better designed. There are so many flaws in using torsion beams that I cant see the point in trying to develop something around them. Its a bit of an expensive experiment but if it works it will be worth it.

My brother is building a group a shell with a rear beam on turreted suspension and he is very interested in seeing how the two different systems will compare

[Adi 0]

why sbc phase 1/2 won't do i dunno

 

If a double wishbone set up can be used at the rear......the ride/handling of the car will be transformed. It will be a lot of work/money to design and fit that type of set up.......but if someone is prepared to do it......the difference is well worth it.

[Batfink 201]

The guy who is going to build it had the system fitted to his rallycar. He said corners that you would usually back off for - you could drive flat out like a 4wd.

[DrSeuss 0]

Sounds mint, be sure to get plenty of pictures and schematics, measurements would be good.

[base-1 17]

There are so many flaws in using torsion beams that I cant see the point in trying to develop something around them.

give me 5

[M3Evo 0]

give me 5

Well one fundamental flaw is that camber is directly related to body angle so the harder you try to corner, the more grip you lose!

 

It's a high stress system which may be one reason why they used the heavy cross beam to negate the need to make strong mounts on the body.

 

It's difficult to make static camber changes without major mods so setting up for different events is a pain

 

The effect of applying brakes causes the ride height to change depending on brake effort.

 

Um....... well that's four

 

EDIT: Oh yeah, you can't make any adjustment to the roll centre.

 

There ya go, 5 reasons!

Edited March 10, 2004 by M3Evo

[zeolite 0]

6. Difficult to dial in stagger.

 

 

gets his coat.

[Snowman 0]

7. Slow job to change Ride Height.

[Sam 4]

Bah it takes 30 mins to do mine now and most of that is jacking it up and preparing and lettign down again etc

[Batfink 201]

add the crap damping abilities due to the shock position

[Sam 4]

They are in a decent position? inline with wheel movement ?

[Adi 0]

the crap damping abilities due to the shock position

 

They are in a decent position? inline with wheel movement ?

 

 

One of the fundamental problems with the rear beam axle/torsion bar set up is the damper movement is 1/4 that of the wheel movement. For the best ride/handling results, you really want that movement ratio the other way round. On a F1 car the damper movement will be 4-5 times greater than the wheel movement. That way you get the most control possible.

 

As far as ride.....and especially handling terms......any trailing arm suspension at the rear of a car is not a good design.......unless maybe the engine is either mid or rear located.

As I've explained in part of the suspension thread......weight transfer is a major ingredient in making a car handle well. Weight transfer needs to be either greater or faster at the rear of the car to help steering the vehicle in and out of corners.

Roll centre placement plays a great part in weight transfer. The higher the roll centre......the quicker the weight transfer. For FWD especially......the rear roll centre needs to be higher than the front roll centre to allow that greater weight transfer at the rear. With any trailing arm suspension.......the roll centre is at gound level. With McPherson strut suspension......the roll centre will usually be about 1-2 inches above ground level.

So, on any Peugeot with a strut suspension at the front......and a beam axle using trailing arm suspension at the rear.......the rear roll centre will be LOWER than the front roll centre. This means the weight transfer will be greater/quicker at the front of the car than at the rear. This is a basic ingredient for UNDERSTEER.

 

By incorporating a double wishbone set up on the rear.......the rear roll centre will be raised above ground level.......and in fact if set up correctly......will be higher than the roll centre at the front. This means the weight transfer will be quicker at the rear than at the front and encourage the front end to turn in sharper/better in and out of corners.

Also the damper/wheel movement ratio will be more like 1:1 so providing greater damping of the rear wheels. This makes the rear end far more stable under braking and cornering.

[Batfink 201]

I blame Adi. If I had never read any of his technical explanations I would never have decided to do anything like this lol

[Adi 0]

I blame Adi

 

 

[GtiMad 1]

Well one fundamental flaw is that camber is directly related to body angle so the harder you try to corner, the more grip you lose!

 

Surely that's a good thing, lol

 

 

Batfink, did you see Deans rear double wishbone setup on his Rally car or was that not there when you picked up your Drysump?

 

PS Still on for Sat morning if you are.........