4-Link Question
 

I'm most likely not going to do it, but, I was looking at 4-link conversions and I came across the QA1 kit. It looks pretty nice and it is tempting me a little.

My question is about the exhaust. It seems like the factory transverse muffler won't work. So that means two mufflers in front of the rear end. Is there clearance to run the pipes over the rear end ? If so would a kit like Pypes work or would it need to be custom? I've seen some pro-touring cars that run the exhaust under the rear end, maybe this is why?

Thanks.

The back half exhaust on any of the 4 link conversion is going to have to be complete custom. There's nothing over the counter that will fit them. The majority of cars you see with 4 links either dump the exhaust right after the mufflers, or the run the pipes under the axle towards the rear valence.

I hate dumped mufflers, they drone something fierce and make for a more smelly passenger cabin. So for me, I'd have to have tail-pipes added. Whoever is fabricating them just needs to make sure that the pipes clear the axle when it's at full droop. It's not that huge of an issue and doesn't seem to negatively impact ground clearance, even with substantially lowered vehicles.

The torque arm setups have room for over-axel pipes, but you lose the ability to run an x pipe. Some cars can fit an H-pipe, but mostly anything with a torque arm is running a true dual system without any kind of crossover.

Of the systems that will bolt or weld in to place without extensive floor pan and link mount modifications, I believe that the SpeedTech torque arm is the best setup. Because it doesn't need to use upper links and utilizes a panhard bar for lateral axle location, you don't have the issues associated with short upper links.

I'm not saying the available 4 link system are bad (QA1, RideTech, ChassisWorks), but the packaging of the system in a stock car necessitates the need for short upper links. This reduces articulation, increases rear steer and generally creates a fairly lively roll center. Because they are converging 4 links, there's also the tendency to introduce bind that can create the snap oversteer associated with cars like the SN95 mustang that use such systems. You pretty much must run spherical bearings in them to avoid this and when you take that into account, the RideTech offering stands out if for no other reason than the fact that they provide their R-Joints with the kit.

From my personal research, the absolute best live axle suspension system upgrades for these cars right now are the TCI torque arm or the DSE Quadralink. Or, if you can get one a Lateral Dynamics 3 link. All of these are heavily invasive to install. The 3 link and TCI torque arm are invasive enough that you probably don't want to attempt installation on a car that's complete and painted. The DSE 4 link, while requiring cutting and welding in the rear floor pans and trunk divider, can be done on a completed car without much fear of destroying that work.

FWIW if you look at the link setup on the QA1 and Ridetech kits, they are nearly identical. I do like that the QA1 setup has proper double shear shock mounts. It's also slightly cheaper, but most of that is in the difference in shock pricing.

Thanks Jason. Looks like leaf springs are the rear suspension for me.

Sometimes not re-engineering the wheel is the best route.

I looked into all of these systems recently myself. I'm not a welder and I'm not going to practice on these types of parts that hold a lot of load. All in with installation I was looking at costs around 7-8K...before exhaust modifications. My car already handles well with the hotchkis leafs in it. I don't think it's going to handle the better part of 10K better with a packaging constrained link system in it, so I went with the best leaf springs you can get.

If I was a competent welder and I was in the build process on the car, I'd probably have a TCI torque arm in the car. I think Cat 5's are the hot ticket in your situation and my situation.

I should also correct my previous post. The RideTech and QA1 4 link systems are no longer "converging 4 links." They are triangulated, yes, but the newest iteration has the upper links angled outward towards the axle housing ends, while the lower links are still using the factory leaf spring mounts. In this arrangement the roll center is dropped compared to the old arrangement where the upper links angled inward towards the differential. The Chassisworks 4 link still uses a more traditional setup with the upper links canted inward.

As I may have mentioned in your other thread, I went with DSE's Quadralink for my orange '70 Formula, and the Ridetech's 4 link (the first version) for my son's 79 TA. As you probably know, the Quadralink requires a lot of cutting and welding, and the Ridetech stuff is mostly bolt in (and less expensive). We haven't really pushed the '79 yet, so tough to make comparisons. The 70's handling is amazing...far better than I imaged it would be. As the photos show, we went under the rear end with the exhaust on both cars. Could have gone over with the DSE '70 (Pypes used to make a system for this specific application), but it is a crowded in that area with 3" pipe (and given how we ran the brake lines), and it was my HS aged son's first welding project (and he used pie cuts so it would have taken him until college graduation to finish). Things are even more crowded with Ridetech's 4-link system, essentially forcing a below the axle set up. There really isn't a downside though. In fact, one advantage is that we can remove the whole exhaust system in one piece...huge time saver to be able to remove it in 5 min. We haven't run into any ground clearance issues in those ares for either car, and both are really low. I'm getting new headers made for the 70 (to increase ground clearance), and so we'll have to redo the exhaust, and I plan on going under again.

https://forums.maxperformanceinc.com...1&d=1756934841

https://forums.maxperformanceinc.com...1&d=1756934871

Thanks Gator. After my first post I did go back and look at your build thread for the 79. Great stuff there indeed but That's more than I want to get involved in. Thanks again!

Gator, once you can put your sons car with the RideTech 4 link through the paces a bit, I'd be interested to know your thoughts on the handling.

Will do. I'm curious about this as well.

Completely understand...if you went in that direction at some point you'd wonder how much better it would handle with more tire under it...then you'd be contemplating mini-tubs...it never ends!

Hah, you sound like the former owner of SpeedTech. He told me exactly the same thing. Once you start going realistically in that direction, it becomes a game of "as long as you're in there."

To get the most out of these things, you want more tire in the back. Now, the back end is slow and doesn't want to rotate, so you add roll stiffness back there. Now the front is lazy and plowing. Whelp, I guess I need a new subframe and 315's up front.

So on and so on.

There's a point where enough has to be enough, especially for a street car. Shoot a bone stock car with nothing more than a modern set of wheels and tires and a modernized alignment already handles noticeably better then the cars did back in the 60's and 70's.

You and HWYSTR455 both speak highly of the GW cat 5 system. That is not available right now and they have no anticipated date. I'm probably not buying parts until after the New Year, so maybe they'll be available by then.

After driving the car on the new wheels and tires, I was wondering if one had to choose between modern wheels and tires and a stock suspension vs a full on suspension upgrade but with stock wheels and tires, which would be better? I was thinking that it may be the wheels and tires?

I think Ken Crocie once mentioned in a magazine article that modern tires and wheels made up roughly 2 thirds and the suspension mods the last third when it came to handling improvements.

All the suspension mods in the world won’t make a 14” tire on a 6” wheel stick in the corners.

Second-gen F-body cars already have decent stock suspension compared to most other American cars of that era, good wheels and tires make them handle better than most people can drive them.

Yup, especially on a 2nd gen that has some positive updates to the suspension, wheels and tires are the biggest factor.

The tire is what transmits everything to the road. It makes what you're working with better. Updating the suspension and not updating the tires doesn't go as far.

Throwing autocross compound 16" tires made a world of difference in my 78 over even decent 15" tires then throwing road race slicks on it was another jump in handling.

Ridetech is great for minimal cutting and 4 link style like stock GM cars that came with such a set up( a few years back they changed the angle of the upper arms to be like GM a-body and is much better than their original design).

For a serious track or autocross car, Speedtech and TCI is tops. I am just not a fan of the torque arm look (and mount to bottom of rear end housing) and exhaust restrictions etc.