ALFAGTV6.COM

alfetta27 · Post by **alfetta27** » Thu Feb 17, 2005 3:35 pm

Hello,
was wondering if anyone had any experience with lowering the Watts link pivot on the rear of the tube. from what i understand it will help with the roll center of the front of a lowered car.

i remember seeing it done on a Swedish? alfetta a few years back - they lowered it @30-40mm.

thanks

Micke · Post by **Micke** » Thu Feb 17, 2005 4:41 pm

Yep, this is possible and makes sense.
If you keep the original middle piece it will be a bit lower than the tube and might touch the ground. You DO NOT WANT THIS.

You will get the same outcome as a side-effect when you bend the DeDion for some camber. The middle will drop about 20-40 mm

alfetta27 · Post by **alfetta27** » Thu Feb 17, 2005 4:45 pm

Thanks for the info.

would you happen to have any specs on the camber mod? pics?

Mats · Post by **Mats** » Fri Feb 18, 2005 4:00 am

What do you want to know? We even have a tool for bending tubes in our garage.

Several lowered propellers in the cars in our garage too.

Dennis · Post by **Dennis** » Fri Feb 18, 2005 8:06 am

Hey Mats,

Tell us more about that tool! I always thought that you had to partially cut the axle on both sides and then re-weld it again.

Mats · Post by **Mats** » Fri Feb 18, 2005 8:26 am

Thats the way, we have a tool for getting the angles to what we want them to be.

alfetta27 · Post by **alfetta27** » Fri Feb 18, 2005 9:17 am

do you have pics of this tool?? where do you make the cuts to bend and how degrees are you looking for?

Mats · Post by **Mats** » Fri Feb 18, 2005 12:43 pm

the easiest way is to cut the tube (not all the way through) about 10cm fron the middle and bend the center down.
Angles you will have to work out by ourself but anything between 1 to 4 degrees depending on tires and type of driving.

Look out for toe changes too, they tend to be not so straight fron the factory (or 15 years of driving).

Val · Post by **Val** » Sun Feb 20, 2005 12:03 pm

Hi all,

A picture of my 75 Milano race car. I have not done the mod my self, but I guess the pictures shows the idea. Mail me for more pictures.

Maurizio · Post by **Maurizio** » Mon Feb 21, 2005 3:34 am

I did cut the tube at the outsides. So I could dail in some toe-in ....

Mats · Post by **Mats** » Mon Feb 21, 2005 10:39 am

That is an idéa, but it is more difficult to control the exact angles.
You can also give it some toe-in by put a couple of serieous welds on the pipe, it will pull the pipe crooked as it goes cold.

Pretty difficult to control though so practice first.

Post by **Zamani** » Mon Feb 21, 2005 10:58 am

How big a benefit with a modified dedion (camber and toe)?

Mats,

Does your GT have a modified dedion?

For now I will just go with the modified watts linkage mounts.

AlfaRacer75 · Post by **AlfaRacer75** » Mon Feb 21, 2005 5:46 pm

Can someone explain to me why adding negative camber to the DeDion is beneficial? It seems to me that negative camber shouldn't be needed. The advantage of the DeDion is that it always keep the tires perfectly perpendicular to the road.

The whole point of negative camber is to make the tire flat against the road when the car is leaned over, correct? Are you adding negative camber in the rear just to make up for the tire flexing/distorting?

I can see the advantage of changing toe, but not camber.

Jarle · Post by **Jarle** » Tue Feb 22, 2005 3:22 am

Alfaracer 75: I am no expert at this field. As you say the de-dion is a stiff aksel. But at much pressure the de-dion will flex, so will the sides of the tyre. Normal you make the de-dion camber to about 2deg.... If you compare this to other cars like BMW with no stiff rear aksel they use, (DTC) Danish Touring car champ, as an eksample,6-7 deg neg camber.
I have tested 75s both with an without camber on nurburgring an I can garantee you that the neg camber give better grip.

Jarle

Mats · Post by **Mats** » Tue Feb 22, 2005 10:47 am

The common misconception is that the best grip is when the tire has 0 degrees of camber when loaded, this is not the case... Well, not when turning anyway.

The tire needs to lean a bit to be able to work at it's full potential. I can't explain it logically but it has been known for a long time by those who are quick.

Measure the heat across the tire width and you will see that the outer edge will be much hotter if you have 0 deg. camber.

Z: My GTV (

) has modified angles, very nice behaviour. Does not have the modded watts-link pivot point though. You might wanna think about that modification for a while, at least if you are going to modify your front end...
Watch the roll-axis.

Mods to DeDion tube