Advise regarding rear suspension before EBI

[Jøran Larssen]

My car looks like it is to soft at the rear when launching. I have got original torsion bars and adjustable (60/40, 50/50, 40/60) Carrera shocks.

I am considering replacing the torsion bars with a set of Sway a Way 24 11/16" Lng 26 mm dia that I have got, and a set of red Konis.

Take a look at the two pictures below. Will it make sense to replace the torsion bars, or is it a set of harder shocks that will do the trick?

Or can it be a combination with the ofset of the Ercos?     



 

[richie]

Definately looks to soft there.The torsion controls the down movement,the shock controls the up,the 26mm bars and red konis would be a good combo,see you next week,cheers richie,uk

[Jøran Larssen]

Thanks Richie. I guess I will have to spend the weekend in the garage then. See you at EBI.

Cheers
Jøran

[Rasser]

funny you should post this...

At Bugrun last weekend we talked about your car looked "uneven" running down the track. Looked like the one side was lowered more than the other. Don´t know if you ever noticed that yourself - but it did look a tiny bit scary ;-)

anyway, if you´re changing to new 26mm torsion bars this problem should dissappear as well.

[Jøran Larssen]

I noticed that myself when I looked at some videoclips. It is actually softer and lower on the right rear side 

[richie]

I noticed that myself when I looked at some videoclips. It is actually softer and lower on the right rear side 

Drivers weight     cheers richie,uk

[Roman]

Definately looks to soft there.The torsion controls the down movement,the shock controls the up,the 26mm bars and red konis would be a good combo,see you next week,cheers richie,uk

No, the torsion bars adjust how much you squat and the shocks adjust how fast it will get there. 
Make a simple test:
1: Stand on the rear apron and measure the ride height.
2: Remove the rear shocks and measure again.
You will get the same ride heigt in both examples.

Test #2:
1: Jump up FAST on the rear apron.
2: Remove the rear shocks and do the same as above

Can you see how it goes even under the level of 1: without shocks but goes back to the same level as 1:
This is called Underdamped Oscillator.
Here is a link for those who would like to study more:
http://hyperphysics.phy-astr.gsu.edu/hbase/oscda.html


Yes, I am a math nerd, I have studied math, physics and contol tech at the univeristy...

[richie]

Definately looks to soft there.The torsion controls the down movement,the shock controls the up,the 26mm bars and red konis would be a good combo,see you next week,cheers richie,uk

No, the torsion bars adjust how much you squat and the shocks adjust how fast it will get there. 
Make a simple test:
1: Stand on the rear apron and measure the ride height.
2: Remove the rear shocks and measure again.
You will get the same ride heigt in both examples.

Test #2:
1: Jump up FAST on the rear apron.

Just damaged my rear apron,you going to pay for fixing it? :-)

2: Remove the rear shocks and do the same as above

Can you see how it goes even under the level of 1: without shocks but goes back to the same level as 1:
This is called Underdamped Oscillator.
Here is a link for those who would like to study more:
http://hyperphysics.phy-astr.gsu.edu/hbase/oscda.html


Yes, I am a math nerd, I have studied math, physics and contol tech at the univeristy...

Dont agree,you changed the force by jumping on the apron, but bow to your superior knowledge

cheers richie,uk

[Jøran Larssen]

I noticed that myself when I looked at some videoclips. It is actually softer and lower on the right rear side 

Drivers weight     cheers richie,uk

Only water for me the next week then 

[Russell]

Me too water will help.

However have tried the jumping on the rear apron but cant help but think this is false situation, when you launch off the line the rear wheels are drving forward therfore trying to push the torsin bars down, but at the same time the front of the car is lifting giving an opposite reaction....... If you only push down on the rear valance you will only have one effect !

Im not a maths person but from a practical point of view we have 2 forces on launch and only 1 when jumping....

Could it also be that the rear tracking is out slightly ? or could it just be the way the gearbox is made i.e one sided ?

If all this sound rubbish, please just hummor me !

[richie]

I noticed that myself when I looked at some videoclips. It is actually softer and lower on the right rear side 

Drivers weight     cheers richie,uk

Only water for me the next week then 

Water  = Tea     cheers richie,uk

[lowfastbus]

Not wanting to hi-jack this thread, but on the subject of rear suspension...

Do you pre tension your car with limiter straps? or do you mount them without tension...
How long do they usually have to be?

I'm lowering my car a few cm's for EBI because it has a dangerous positive camber, especially when I lift the pedal.  This should get fixed with the straps...hopefully

[ALIEN]

On my Alien bug i got coilower shoks.. they give the car positive camber.. so i got wire sraps, to hold the car in right posision..

I think it woorks..

or im i wrong?

Alien

[Jøran Larssen]

I ended up with some positive camber after adjusting my car today. It's not exactly what I wanted, but it will stay like this for EBI. As a safety precaurtion, I added a set of limiter straps. Anyway, it is much stiffer at the rear now   

[Gunter]

friends it all makes sence
the only thing I can't figure out now is that I have the distinct idea Chimay is very small for two racers next to each other
what do you think ?

Gunter

[richie]

friends it all makes sence
the only thing I can't figure out now is that I have the distinct idea Chimay is very small for two racers next to each other
what do you think ?

Gunter

It does look narrower than i am used to but we just have to stay in our own lane and it will be fine   cheers nrichie,uk

[Roman]

I have limiter straps. I used to have McKenzies, but I recently changed them to steel wires and wire locks so I can adjust the length.
On a bug 22" usually fits good and they should be so short that you have to put them on AFTER the engine is installed and it is back on the ground. When I lift the rear end with the straps on the axles are almost straight.

If you have stiffer bars there is no need for preload. A 28 mm bar should slip just over the stop when you install them if you have a type 1 trans. If you have a bus tranny you should have about 6 mm of air between the stop and the bar.

[oldbug]

hi guys,
due to the building of a car, could you please give me informations ?
Where to find QA1, red koni shocks, limited straps (summit or other) ?
Models, names and references of this parts ?
regards
Laurent

[Roman]

Look at my recently placed for sale ad, everything you need is there! 

[oldbug]

thanks, look at my question on your ad.

[lowfastbus]

Roman,

I have 8mm and 10mm steel wire and wire locks, would this be any good??

thanks
Jelle