The V8 Owners Forum -

Hi all, I've got an opportunity to buy a Watts Linkage from an SD1 for not much money (£50).

I'm planning on fitting the Frontline Costello rear 4/5-link kit (well, 4 link with Panhard Rod, but not having the panhard rod makes it £300 cheaper!!) and I've been thinking of replacing the panhard with the watts, to make it full 6-link.

Had a pic of the watts and it looks good, shouldn't cost me a lot to get the links shortened and I can knock up some mounts myself from steel plate.

Anyone done this / sound like an ok idea?

Depending on the bits you need, check Rimmer Bros. They have the linkage on special offer.

DaveEFI wrote:Depending on the bits you need, check Rimmer Bros. They have the linkage on special offer.

you're right! £30! Beast, cheers Dave!

Hi
I am pretty sure this will change the roll centre height at the back compared to the panard rod, not saying it is a bad thing, just be aware.
Best regards
Mike

kiwicar wrote:Hi
I am pretty sure this will change the roll centre height at the back compared to the panard rod, not saying it is a bad thing, just be aware.
Best regards
Mike

No idea what that is, can you explain please?

Hi
Yes, a car, when going round a corner tends to lean over to the outside of the corner. . . it does this rotation about a point in space , normally on the centre line of the car looking for/aft, this is the instant roll centre. How high above the road, or below the road is dictated by suspension design and where various bits of the suspension are attached to the car.
The distance between the instant roll centre and the centre of gravity of the relevent bit of the car dictates how much weight is transfered from one wheel to the other and therefore how much the car rolls less distance less roll. . . however get the instant roll centre too high and the forces on the suspension can cause the suspension on the outside of the car to lift and the wheel to tuck under (the joys of owning a triumph spitfire!).
With a panard rod on a live axel the instant roll centre is, from what I remember always at the point where the rod passes the centre line of the car, on a watts linkage it is always at the attachment point of the linkage to the axel, they are not necessarily the same, however they would/could be close enough to make no odds.
Best regards
Mike

kiwicar wrote:Hi
Yes, a car, when going round a corner tends to lean over to the outside of the corner. . . it does this rotation about a point in space , normally on the centre line of the car looking for/aft, this is the instant roll centre. How high above the road, or below the road is dictated by suspension design and where various bits of the suspension are attached to the car.
The distance between the instant roll centre and the centre of gravity of the relevent bit of the car dictates how much weight is transfered from one wheel to the other and therefore how much the car rolls less distance less roll. . . however get the instant roll centre too high and the forces on the suspension can cause the suspension on the outside of the car to lift and the wheel to tuck under (the joys of owning a triumph spitfire!).
With a panard rod on a live axel the instant roll centre is, from what I remember always at the point where the rod passes the centre line of the car, on a watts linkage it is always at the attachment point of the linkage to the axel, they are not necessarily the same, however they would/could be close enough to make no odds.
Best regards
Mike

Thanks for the explanation Mike. From what I can tell from the pics I've seen, the Watts linkage connects to the centre of the diff plate, and the panhard rod is a wee bit higher but not much!

no reason why a watts cant be mounted flat on the bottom of the diff casing, most of the broadspeed saloons used this system to lower the roll centre and lower the CoG

I was considering this SD1 type system for the back of my TR8 with the same Sailsbury 2HA and the SD1 back diff cover..

After reading a few guides on Race prep ive decied to go the pinhard direction to keep the COG Lower..

I suppose it depends if you are just trying to rectify Axle tramp on a Drag launch or weather you intend to use the car on the Track?

Panhard rods should be as long as possible to prevent body jack caused by the arc that the bar runs when the suspension moves up and down. they should be run as close to parallel with the axle when the car is on the floor at ride height.
When we used to circuit race care with a banjo type axle we often put negative camber into the casing, sometimes by cutting the casing and offsetting the bearing housing or bumping the casing in a flypress, generally there is enough play in the splines to get away with 1deg on each side, the downside is the wear caused to the diff/shafts, tires, we never seemed to notice any problem,

This is modified SD1 (supplied by Ian Stewart !) the solid rods have been replaced by tube, and made adjustable.
(the car is jacked up, thats why the links are not level !)