69 F-body - Rear sway + leaf springs?

[anguilla1980]

On my 1969 Firebird I have new Hotchkis everything plus CalTracs and a new Ford 9" based rear axle w/Caltracs perches. Literally, the only things I have left to upgrade suspension wise are adding the Hotchkis handlebars and sway bars. Yes, I know leafs SUCK for handling but I'm doing things in stages as years go on so it's just what I must work with right now. A 4-link and adjustable coil overs will be in my future, but that future is about 3 years off or more

On to my question. It's been suggested to me that adding a rear sway bar to a car with leaf springs can be dangerous and that the twisting of the leafs already acts as a rear sway. This makes a little sense to me, especially with the CalTracs keeping leaf wrap under control which is reducing twist even more due to their mounting plates.



Is that the general consensus here as well? Will I have a dangerous oversteer problem by adding a rear sway? For that matter, will upgrading the stock front sway be too much and cause an understeer condition that's dangerous? I'm looking for a nice balance here of course, a very controllable slight oversteer is my personal preference.

Also, what about adding the Hotchkis upper rear shock brace? Now that I think of it, I don't have that either. Or will that also remove too much flex with the leaf springs?

Sorry, I know leaf springs must be a dirty word on here and this is the first car I've ever had with them so it's a learning experience for me.


EDIT: Upon more research, it looks like the Fays2 watts link is the hot ticket to getting my leaf spring rear to handle better. Can that be used in conjunction with a rear sway? If so, who makes on that will clear it for a 1st gen f-body?


EDIT 2: I've stumbled upon spherical bushings for leafs as well. Specifically the Hotchkis Swivel Max and conical type high articulation shackles, very sweet. Global West sells a similar kits and calls it Cat5 Bearing Kit. Question: With CalTracs, is it OK to use the Swivel Max on the front of the spring instead of the supplied solid aluminum bushing? Seems to me it would still mitgate wheel hop just as much while also providing the deseried increased articulation. Win- win, right?


Thanks!

[F-Body International]

The main thing that causes leaf springs (including the rear end) is rubber in the frame side of your rear suspension shackle. Replacing that with something like a Delalum or delrin bushing will minimize lateral shift. I personally would start there and see how you like it.

Your main issue you will have to observe is whether a spherical spring eye kit will fit those Caltrac springs. Do those accept a standard bushing? You may want to look into something else besides Caltrac if building something other than a drag car.

[stab6902]

My advice is to drive the car and see how it feels before buying any more parts. There are a ton of variables that go into getting the right front/rear roll stiffness balance and everybody's car and preferences are different. If you're running the Hotchkis springs front and rear, some kind of front sway bar, and similar width front/rear tires, you'll be in the ballpark.

After you drive it and tell us how it feels, we'll probably ask for a bunch of details (spring rates, size of front sway bar, tire sizes, corner weights, front roll center height, etc) and then be able to steer you in the right direction.

[David Pozzi]

Hotchkis put a lot of work into their kit. You should run their springs and bars & I doubt you need the caltracs, which I think they would recommend you not use. The hotchkis leaf springs have a traction bar built in to the lowest leaf & we used them that way with great results. The rear sway bar is needed and it's tuned for their spring package so use it. I don't know how much the rear shock brace will help. Didn't have a chance to try it.
Spring twist is not a big deal if you use the Hotchkis leafs as supplied with their rubber front bushings, & polyurethane shackles. The spherical bushings are very harsh riding, we only had to do a very slight sway bar adjustment when we tried them so they don't make a huge difference sway bar wise. I would not use a watts system with leaf springs. The chance of binding and problems is highly increased and I suspect there is only one position close to the leaf spring natural roll center height that would work well but I haven't tested a watts with leaf system.

[CarlC]

I agree with David on all points. For those that figure a leaf spring car is harsh, can't handle, etc. I invite them to come for a ride in mine. With the current Hotchkis spring and shock package it's almost un-naturally good for how simple it is.

[andrewb70]

I know my Cougar is a little different, but I too have the CalTrac split mono leaf springs and ClaTrac bars. The CalTrac springs use a solid bushing in the front and poly in the rear. This car was mostly built as a street/strip car, but I recently got rear tires, added back the front sway bar. The front suspension is all from TCP. I have to say, that this little Cougar rips around corners. I can feel the rear doing some funny stuff if there are bumps mid turn, but nothing that is unpredictable. I think if I added a rear sway bar, it may make it too stiff, as the CalTrac monolwafs are already pretty stiff, but they seem to work well with 500lb/in springs on the front coilers.

Andrew

[anguilla1980]

Thanks everyone for the advice thus far, I really appreciate it.

I am willing to not do the CalTracs with the Hotchkis leafs, but the reason I had planned them was that I am building a car that is a 9.0 sec 1/4 beast, hopefully, 8.9 secs (drag radials,) and I didn't know if just the Hotchkis leafs alone were up to that task.

Secondarily, I want a car that I can also enjoy at the local SCCA track or Willow Springs Raceway. This is why I considered the spherical leaf spring bushings. Ride harshness is not a concern to me, handling is.

My thinking was set pre-load on the CalTracs when at the drag strip, and keep them loose when doing a road course. I understand this will be a compromise in corner handling but I'm OK with that if they help me with my 1/4 ET. Hell, keeping leaf springs is a compromise in road course handling but I can't afford anything more drastic at the moment.

I've also learned that a Panhard bar is not to be used with the spherical leaf spring bushings and that a Watts link would not be needed as the spherical bushings provide a similar effect.

--------------

So, with all of that in mind, what should I do? Not do either the CalTracs or the spherical bushings, just do the spherical leaf spring bushings, or go ahead and do both to achieve the goals I mention above?

Thanks!!!!

[andrewb70]

Is the car on the road? If so, do nothing and see how it all works, then adjust accordingly.

[anguilla1980]

Is the car on the road? If so, do nothing and see how it all works, then adjust accordingly.

I'm replacing the factory rear end with a Ford 9" and thus just doing all the rear suspension at the same time. I have all of the parts ready to go in except I have not ordered the spherical leaf spring bushings.

[andrewb70]

I'm replacing the factory rear end with a Ford 9" and thus just doing all the rear suspension at the same time. I have all of the parts ready to go in except I have not ordered the spherical leaf spring bushings.

I'd order the bushings and drive it...lol

[anguilla1980]

I'd order the bushings and drive it...lol

Agreed. That's what I'm leaning towards. The Caltracs are easy enough to throw on anytime I want to try them at the drag strip. The spherical bushings, on the other hand, need to be pressed in and welded and they seem like they could only possibly help. So now would be the time do them.

I think that's what I'll do unless anyone can provide an objection why the spherical bushings should not be used, but they seem like a win-win.

Thanks. I'll hold off on the CalTracs and just do the spherical bushings and test. In the end tho I'm pretty sure they will be needed for a high 8-second car, I just can't see the Hotchkis so-called built-in traction bar in their leafs cutting it at that level of traction on a prepped track with a trans-brake and slicks.

[c4racer2]

Hmm. I have hotchkis front and rear springs plus F and R swaybars on a 71 with bilstein shocks and Caltracs. Works pretty good. Car has run mid 11s with this setup. And is more of a handling car. Handles very good considering the old technology.

[anguilla1980]

Hmm. I have hotchkis front and rear springs plus F and R swaybars on a 71 with bilstein shocks and Caltracs. Works pretty good. Car has run mid 11s with this setup. And is more of a handling car. Handles very good considering the old technology.

Thanks very much for the feedback!

[c4racer2]

Thanks very much for the feedback!

yup - not exactly the same but similar set-up between 1st and 2nd gens.

Picture of the car for reference:

[David Pozzi]

Thanks everyone for the advice thus far, I really appreciate it.

I am willing to not do the CalTracs with the Hotchkis leafs, but the reason I had planned them was that I am building a car that is a 9.0 sec 1/4 beast, hopefully, 8.9 secs (drag radials,) and I didn't know if just the Hotchkis leafs alone were up to that task.

Secondarily, I want a car that I can also enjoy at the local SCCA track or Willow Springs Raceway. This is why I considered the spherical leaf spring bushings. Ride harshness is not a concern to me, handling is.

My thinking was set pre-load on the CalTracs when at the drag strip, and keep them loose when doing a road course. I understand this will be a compromise in corner handling but I'm OK with that if they help me with my 1/4 ET. Hell, keeping leaf springs is a compromise in road course handling but I can't afford anything more drastic at the moment.

I've also learned that a Panhard bar is not to be used with the spherical leaf spring bushings and that a Watts link would not be needed as the spherical bushings provide a similar effect.

--------------

So, with all of that in mind, what should I do? Not do either the CalTracs or the spherical bushings, just do the spherical leaf spring bushings, or go ahead and do both to achieve the goals I mention above?

Thanks!!!!

In that case, you will most likely need the cal tracs but you may also need stiffer leaf springs. For drag use they go much softer, but for autocross or track a stiffer leaf package works better.
Look at the Global West Cat5 with spherical bearings. Hotchkis is around 175 lb, cat5 is 225 lb. But the spherical bearings will transmit more road shocks which hurt ride quality.

For anyone who is doing Minitubs, that is the point where I think you need to move away from leaf springs.

[anguilla1980]

Thanks for the additional response!

I'll take note on the beefier leafs springs. I'll see how far the Hotchkis springs get me and go from there.

[andrewb70]

For what it's worth, the Caltrac split mono leaf springs are pretty stiff!

Andrew

[David Pozzi]

Thanks for the additional response!

I'll take note on the beefier leafs springs. I'll see how far the Hotchkis springs get me and go from there.

Just for your information: Hotchkis does not approve of additional traction devices. I did see one report of a guy breaking a leaf spring with Caltracs & Hotchkis leaf springs. I think he was trying to jack up ride height with very high preload, which is a crazy idea. I do think you will need some kind of added traction device to stabilize the leaf springs with slicks and that much horsepower.

[c4racer2]

Well maybe so. But the setup on my car has been in place for over 10 years and it works great. Not using much if any preload btw.

[Sleeper68]

I agree with David on all points. For those that figure a leaf spring car is harsh, can't handle, etc. I invite them to come for a ride in mine. With the current Hotchkis spring and shock package it's almost un-naturally good for how simple it is.

Carl,

Are you using the box stock Hotchkiss springs and ARBs fr/rr? I found them to be a little softer than the DSE spring package, which I am currently using (before they sold out and moved production to China ~550lb/in fr ~175 lb/in rr progressive).

I'm looking for an even stiffer package if possible to be more competitive in SCCA CAMT autox and since I'm moving to 275/35R18s square, not sure if Hotchkiss has more options than I'm not aware of.

Thank you in advance.

I hope this info helps the you, anguilla1980 as well. I advise not using cal-tracs if you plan on doing any "spirited" street driving or autocross/track duty. They tend to bind in roll and cause abrupt oversteer.

Ryan