GTV / Giulietta Rod-end watts link

[jimnielsen]

I thought I'd start off the 116 model register off the ground with a note about the new version of the watts link that I made for the car this week.  The old one with the rubber/metal bushes was getting ripped to pieces, especially in the center part - so I decided to whip up a new one with bearings in the center pivot and rod ends at each end of the link arms.

Its pretty straight forwards really - I simply had the existing arms trimmed up and 1/2 inch thread inserts welded in (one left and one righthanded).  The arms are designed to be 530mm long each.  I removed the center rubber/nylon/metal bush and bought 3 sealed bearings that (end on end) fitted into the existing pressed steel center housing. Use bearing retaining compound to secure them.

The rod ends are Aurora Bearing AM-8T's - probably stronger that you really need for this job.. but I wouldn't want it to come apart half way around the sweeper....


Here are two pictures - before and after.. As you can see I have already had the DeDion tube modified to lower the rear roll center of the car (Hugh Harrison did this part last year), but this new watts link will work on a "standard" setup as well.

Cheers, Jim..

[Sam]

Hi Jim
I have a few questions about your Gulietta
1) Where did you get the Vented rotors from, I assume the calipers are non-standard too!?
2) When you lowered the watts link, how did you weld the brackets onto the A-frame? I was told this is high-tensile steel and shouldn't be welded ?
Also, how noticeable is the difference in handling since you lowered it?

Sam

[jimnielsen]

Hi Sam.

1. The vented rotors are from Vin Sharp at Pace Engineering.  The calipers I am currently using are standard 105 calipers. I prefer them because they do not have the handbrake mechanism that causes the pads to have to be manually adjusted all the time. My car does not have a handbrake.

2. The Dedion tube is high tensile steel - but it is very suited to welding onto - this one has been MIG welded - but TIG would be even better. The extention that the watts link center bolts to is just RHS with a crush tube.  Hugh Harrison's Alfpa Repairs made this dedion up for me.  It has 2mm toe-in and 2 degrees of neg camber.  Its put the rear roll center at 90mm.  The problem with this system is that its ground clearance is only 30mm - too low - especially as it is in the centre of the rear.

3. Lowering the roll center of the rear of the car only make sense if you have it in proportion to the front roll center. The front roll center of my car is 65mm.  This is a 'typical' front / rear proportion for this type of vehicle.  On an Alfa that is still equipped with the front tortion bar suspension if you lower it - and still want to get the front roll center to an appropriate height - then you will need to have the bottom of the "uprights" lowered or the top ball joints raised - and probably both!

4. I have been looking at a different method of getting the rear roll centre of the car to 90mm whilst having better ground clearance - its called a mumford link.  Here is a picture of one on a non Alfa car - it should be easy to adapt to a dedion. As you can see the roll center is projected from the long links to a point in space where they would intersect - so the whole system is above the axle. The system attached to the chassis in the center rather than the outside (like a watts) making it simpler to deliver the required amount of rigididy.

5. Having the roll centers at an approriate height makes a huge difference in how these cars handle.

Cheers, Jim