I can press the rear end down with my arms and touch the fender to the rear tires with little effort (their 55s). It's difficult to have 2 people in the car without the rear end constantly dipping and rubbing the tires. The question is I want to tow a single dirt bike trailer on the back. What can I do to stiffen the rear end?

1989 Iroc-Z

 

Moog CC635

 

Could you please elaborate a bit as I am not too familiar with suspension. Are these stiffer than the stock springs? Is there anything else I would need or just throw these puppies on for a stiffer suspension? Thanks

 

Moog is the brand, CC635 is the part number, and the CC means Cargo carry or some such. These were original equipment on some third-gens, possibly convertibles, according to my research. Similar with Moog 5665s. Specs are similar for both part numbers. Maybe one or the other is progressive-rate? I'm considering ordering a 30% higher-rate rear spring than either of these.

 

CC635 is variable-rate, 5665 is constant rate.

There's pluses & minuses to each, but for a street-driven car, esp given the trailer and load type of concern, the var-rate is the way to go.

They're "stock replacement", but AHELLUVALOT stiffer than any old wore-out flattened sagging stockers. Stiffer than NEW stockers were for that matter. Yes you just jam em on. Takes longer to jack the car up and let it back down, than to change em out. In fact, if you've got an extra 10 minutes or so to spend on it, I'd HIGHLY recommend changing out the shocks, sway bar bushings, and end links, at the same time. Beats jacking up the car 2 or 3 times.

 

Thanks guys, very informative.

 

I had experienced much the same problem (although I certainly couldn't push the rear suspension down to the tires!). At one time I actually HAD a trailer hitch and would haul the slicks and tools to the track. On other occasions I had the car loaded with luggage, golf clubs and a passenger and the lowered suspension made for a rough ride (as in hitting the bump stops in the rear in a worst case situation).
I made a move to Air Lift Drag Bags, primarily for the tunability at the drag strip but the advantage of being to add a little air when I might be fully loaded has made the move one of my better decisions.
This is not meant to dismiss your need for new springs however as a supplement, its's an inexpensive upgrade.

http://www.jegs.com/i/Air-Lift/022/6...oductId=743887

 

My tires are pretty wide at 55s and they don't go up inside the fender well so it's only a few inches of travel until they touch the outside of the fender. Those air bags looks a lot easier to install too.

 

What I like about them is that when they're not needed they can be kept at their recommended minimum pressure (4 psi) and the car still maintains it's intended stance (with my choice of spring). When they're needed, the pressure goes up to maybe 10 psi and there's the increased capacity.
Yes, installation is pretty simple. The most difficult part is deciding where to put the two schraeder valves. I made the mistake of installing them under the car (near the bumper) and it's a pain to work with. I intend to relocate them to behind the license plate.

 

Takes longer to install the air bags than the springs... you have to do all of the exact same work (R&R the spring), PLUS, put the air bag up inside it. Might DOUBLE the install time; might even add as much as 5 minutes to it or something.

Plus, springs are only like $50 a set. They cost ALOT less than air bags.