Jag XJ6 IFS - sway bar questions

We're putting in a Jaguar XJ6 IFS in my buddy's '50 Fleetline, and it the stock XJ6 sway bar seems really skinny and dinky to me. For instance, I'm doing up my '52 Plymouth, and a common upgrade is to chuck the stock pencil-thin sway bar in favor of a Jeep Grand Cherokee bar. The stock Jag sway bar seems every bit as flimsy as the stock Plymouth bar, and it seems it could use an upgrade.
So, has anyone fit in any other heftier sway bar onto this front end with success?

 

The stock bar is kind of weeny, only 3/4". I understand the xjs, the two door coupe, has a larger bar. Same chassis. I think it's either 7/8 or 1". When I find one at the pull and pay I'll do the swap. You can get aftermarket bars for jags if you don't mind spending some money.

 

Yeah, Jaguar doesn't really know much about suspension/chassis design and tuning.......


Ray

 

This seems to be putting the cart before the horse. Get it together, THEN see if it handles badly. This will save money and be a proper method of diagnosis.

FWIW, center of gravity will play a large part, the Plymouth IS higher, but spring rates and what you do with them play a (n arguably larger) part as well.

Cosmo

 

Yep make sure it doesn't work to suit you before you start making changes.

 

Like said try it first. I think if it rides and drives like a XJ6 you will be happyer than a punk in boys town.

 

Figured I'd ask first while we were hacking away at the front of this Fleetline, since it seems a lot of folks have done the XJ6 swap and might know better right off the bat.
And yes, I did check out the Jag forums, seems a lot of folks say the XJ6 sway bar definitely needs an upgrade. I mean, why bother seeing how the stock one will be, if someone who did this swap might chime in and tell me that yes, indeed, the stock sway bar is pretty weak and one from a _____ will work better, right?

 

I have the stock bar on my '57 and it's fine. Even if you plan in upgrading you have to do the same mounts for it. And swapping a thicker one in afterwards is pretty easy. I'd roll with the stock one first.

 

Putting a lot of the roll stiffness in the front with a big bar there can make a car pretty clumsy feeling.
Front and rear bars were a big part of why 442s and Studebaker Hawks were considered such good handlers in their day.

 

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OTOH, having NO sway bars can give a rather nice ride. I had a Citroën 2CV for years - no roll bars, soft, long-travel suspension, low CG, and it rode like on a cloud.

Also, drove for years (step-van deliveries) in Chicago. Roll bar bracket broke, talked the mechanic into leaving it off. Rode great (true, no high speed). Super came by, insisted the trucks be "stock", so mech put it back on. I was right, it rode better without. BTW, it was Wonder Bread, you see where thousands of decisions like THAT got it.

Cosmo

 

Anti-roll bar stiffness is a factor of the bar arm length and the length of the center-section of the bar, not just the diameter. The shorter the bar and the shorter the arms the stiffer it's going to be. Also consider where the bar mounts on the arm and the motion ratio of the bar end vs the wheel at that point.

The effective arm length of the Jag bar is fairly short IIRC, and the end links are WAY out at the wheel, both of which will tend to make a small-diameter bar more effective.

Suspension tuning (for most purposes, at least) is about balance - front to rear, springs vs sway bar, and getting the shock damping right.

I agree with those who say not to change it until you've run what's on there first.

 

The XJS has a 7/8" bar which makes a good upgrade to the stock XJ6. I can tell you for sure that an XJS without a bar at all rolls like a boat. I added a 1" front and 3/4" rear bar and it handles very nicely now.

 

...check out a thread Titus did on here, think he used a different bar on it.