rear swaybar

[kewpie79]

Just put the front swaybar in from a supercoupe.Noticed a big difference. I looked a the tech sections and it mentions the rear swaybar from the supercoupe and addco. What is the difference, besides the diameter and price. I can get the rear swaybar off of the coupe for $5.00. With replacing the rear swaybar, what kind of difference is there, is it noticeable? All the searches say the coupes rear swaybar is junk or crap, but doens't say why. Any info?

[whitebb]

I too am replacing the front bar, but with a XR7's.(same 33mm bar) I thought the rear bar would work, but it bolts up to the lower arm differently than a M7.(at least on my donor car it did) I ordered the Addco bar, and expect it in tomorrow. I also have done half the rear suspension in poly. (what a pain the the ass!, thats why its half done).
As for difference, search in the archives and you will find the answer.

[Nick]

The rear anti-roll bar off the Thunderbird/Cougar is junk because it doesn't fit and because the attachment method (to the lower control arms instead of the body) isn't as strong and effective. Order the Addco 415 rear bar and you'll be set. I have the upgrade at both ends and it's the best bang for the buck mods you can do.

[Bluegrass]

The replacement bar needs to at least bolt in in place of the original and be a larger diameter than the original to be of any benifit to handling.
I have a different setup that gives very different results but is not for anyone that can't do any fabrication work.
Both my bars are Mustang and require custom fitting and mounting but does a real job in the handling department, in total. ;)

[90LSC]

Buy the Addco! Trust Me!

[Nick]

Bluegrass, if a small piece of stiff steel was welded along its length on a bar, would the heat from the weld create any stress issues with the bar?

[AGE]

I'm a retired mechanical engineer. Welding the small strip on the torsion bar would likely soften up the torsion bar metal and it won't add any appreciable torsional stiffness.

[Nick]

Thanks for the heads up. I've read the recommendation to add a bar from William Mathis' Mustang Performance Handbook 2 or somewhere, but I always wondered about material properties after the heat. What is done to stiffen the bar originally? Is it annealing or cryogenic freezing?

[kewpie79]

Addco it is.

[Bluegrass]

Yes sir, AGE is absolutly correct.
The metal composition is a certain alloy that is soft formed then heat treated.
Doing anything outside of this will deterioate the torsion ability of the bar and likley result in the bar just twisting until it work hardens and breakes at some point along it's length.

[1LapLSC]

Heating comes under the "never heat a spring rule"; after all the sway bay is just that, a torsional spring. Heating will ruin it.

Wiley

[pro-five-oh]

quote:Originally posted by kewpie79:
Addco it is.

Wise choice, you will not regret it. smile.gif

[AGE]

Nick,

Annealing is accomplished by heating steel to a certain temperature (?? maybe 1600 F) and letting it slowly cool. Steel melts at 2600 F so the welded region (and probably the rest of the bar) would have been heated above the annealing temperature. You don't want to anneal it if you want it strong.

Heat treating involves soaking at some elevated temperature for a time (maybe 1400 or so) and quenching in oil to rapidly cool it. Don't try this at home. I'd have to go look for my books (I'm not a metallurgist) if you want specifics. The soft annealed steel probably has a yield strength of 30,000 psi whereas the heat treated material may have a yield strength of 80,000 to 100,000 psi (depending on alloy and heat treatment).

Anyway, a round section is the best shape for torsional stiffness. Adding a local blob of metal along the length wouldn't help the section appreciably and would almost certainly soften the metal.

kewpie79,

Like you already decided go for Addco.

[ November 30, 2005: Message edited by: AGE ]

[Nick]

Thanks for the explanation, AGE. I am in my first materials class now, but it seems I'm forgetting a lot already. :rolleyes:

[84mark]

this 88 xr7 seems to have quite a taut suspension...noticed a different sway rear configuration, including some kind ot extra dampers...

although, it actually seems a little too stiff in the front at times...maybe needs struts....

[Nick]

The extra dampers are there to prevent or reduce axle hop. I was told the longer wheelbase of the VII ensured we wouldn't need them, but I am not exactly sure how. I still wonder about them if Turbo Coupes and XR7s got them.

[AGE]

Nick,

If you're into an engineering education, good luck. I had a most interesting career. I guess I learned most of my materials stuff on the job. I worked awhile for GE in the jet engine business--very interesting.

[JoshMcMadMac]

Hey Al, it's great to see you around. I hope you are doing well, even without Pinkie. ;)

[AGE]

Josh,

Yes, I lurk on the forum quite often to see what is going on. The guy who bought my pink '86 still seems to be trying to sell it. Wonderful cars, but I'm too old to get out and get under anymore and the dealers can't get parts so they don't want to work on them. If Bluegrass lived near me I'd get him under contract to fix my Mark VII and only then would I buy another one. My transportation now consists of a '04 Grand Marquis and a '97 Crown Vic, great cars for fat old guys. Pretty fast, big seats and big enough trunk to carry lots of toys.

Do you need another odometer? I've got another one somewhere.

Al

[Nick]

Al, thanks for the forecast. It's been interesting so far and I bet it'll be light years better in the workforce. I am not sure where in FL you are, but Kit Sullivan, a fellow Floridian, might be able to help you find a good shop/service man. He manages some chain of auto repair centers so he might know something if he can't help you.

[pro-five-oh]

Glad you came by for a chat, Al. smile.gif

quote:Originally posted by 84mark:
this 88 xr7 seems to have quite a taut suspension...noticed a different sway rear configuration, including some kind ot extra dampers...

They use the same rear swaybar as Fox/SN-95 Mustangs. Bolts to the lower control arms, an easier design. Its about 5/8" on the XR7, and the 7/8 Mustang V8 part would be a nice addition. Avoid the 1" unit, its hollow. smile.gif

I need to get off my butt and get one of these for my XR7, its pretty disturbing that this car (with a host of upgrades) feels less balanced than my stock Mark VIII with a Super Coupe rear swaybar.

[ December 03, 2005: Message edited by: pro-five-oh ]

[AGE]

Nick,

I'm near Leesburg, but I think I'm through with Mark VIIs. When I was commuting (almost always by myself) a personal commuter car was a big interest to me. I had a lot of Mustangs and they were just right for that purpose. The Mark VII would have filled that spot well also, but I no longer have that need. Now it's cruising from FL to WV, NY and PA or to the shopping mall (terrible place to leave a neat Mark VII). Also, I do pull a ski boat and have a lot of adult toys to truck around. The GM or CV fills the bill for these burposes.

Pro and Josh,

Nice hearing from you guys. All of you forum folks have a great Christmas and a good new year.