blownzed

There's a few scrambled threads on the subject of the Rancho Challenger GT-III suspension kit available in the 80's. Rancho dropped the product line and since it was before the internet there's no info available on their website.

In the mid to late 80's I worked at a shop that sold Rancho equipment and I bought the kit for my 84 Z28. I've been running it ever since although the front struts were recently replaced with adjustable KYB's.

Overall I'd say the kit is a great upgrade from stock but it does have a few idiosyncrasies so I'll go over what I know from my experience.

The kit came in four stages numbered I, II, III and IV.

Series I included front struts and rear shocks.
Series II included adjustable front and rear sway bars with spherical rod ends and polyurethane bushings, plus steering stops and rear shock braces.
Series III added front and rear coil springs, polyurethane bump stops and limiting straps on the rear.

Series IV got serious with an adjustable panhard rod p/n 909102, adjustable strut tower brace p/n 909103, boxed rear trailing arms with polyurethane bushings p/n 909106, a polyurethane transmission mount p/n 909105 which didn't work at all for my 700-R4 and a torque tube brace p/n 909104.

Oddly, Rancho lists the order of assembly as Series 3 first, Series 2 second and series 1 installed last. They don't mention series 4 but presumably that'd be last last....

From my own experience I recall the kit was pretty straight forward to install with the exception of the strut tower brace. The add-on steering stops intended to keep the tires from rubbing the front sway bar at full lock didn't seem to serve that purpose and there was a bit of metal that needed bending and massaging to keep the front bar out of contact with the pinch welds and subframe.

The front bar does tend to slide through the bushings side to side a bit and the ends of the bar wind up contacting the front sub-frame where the bulge for the springs is. The short Z-bends in the bar beside where the bushings are located are meant to limit this but the bar still slides up to an inch in either direction. It's difficult to get any sort of clamp in beside the bushings to stop the movement due to the bends being close to the bushings-just not close enough.

If you have a Wonderbar- the sway bar comes very close to contacting it because it protrudes forward due to the short Z-bend meant to keep the bar from sliding sideways through the bushings. You may need to fab some spacers (1/4 steel plates should do) to space the sway bar mounts down in order to provide clearance there.

The system works quite well overall. I've since replaced the front struts with adjustable KYBs. I think the original Rancho struts had better valving for ride and handling but I like being able to back off the KYBs for the drag strip. Konis or Bilsteins would be a fine substitute.

The springs lower the front of the car about 1". Rancho made an adjustable panhard rod as part of the full kit to re-center the rear end. Without it the rear moves over a noticeable amount after the springs are installed.

The strut tower brace was part of the 3rd stage. It was a good idea in theory but they must have rushed it into production still half thought out and poorly executed. From day one it didn't fit- firstly because one of the ends did not quite fit under the master cylinder so some grinding was required. 2nd it sat too far back so it wouldn't work with a stock air cleaner. Rancho recommended a 12" or smaller aftermarket air cleaner. I believe they also said it wouldn't work with fuel injected models. (the kit I bought was for 82-84 models and I don't recall any fuel injected models those years.) I wound up making spacers and using longer bolts to move the bar forward and replacing the stock metal air cleaner snorkel with one that angled down under the bar. That set up lasted a few years until I bolted on a Weiand supercharger then the thing didn't fit again and it was off the car for maybe 10 years before I took another crack at it this year. I bent the bar slightly to gain more clearance without shortening the bar too much. That fit properly for about 10 minutes until I converted to hydroboost- then the bar was too far back again so I had to grind the end bracket mounts off, fab and weld an extension onto the u-bracket that mounts to the strut tower and re-weld the end brackets to that piece moving the whole setup forward. It finally works but I'd probably have been better off making one from scratch!

The rear setup includes 12" braces that snake from the sub-frame up to the top of the shock to stiffen the rear. They claim, with the full kit, body flex is reduced to near zero. Limiting straps are included to keep the rear springs in place. The rear bar is slightly too long and the ends of the bar contact the stiffening bracing ever so slightly, so you need to remove a smidge from the ends of the rear bar.

The initial setting for the front bar is the clamps 3" from the end on the front and 1.5" on the rear. I found the initial settings made the car a bit tail happy but it remained virtually flat. I tuned the rear bar a bit and wound up with perfectly neutral handling. What settings you use will depend on your tires/wheels and spring rates. This is why I think you should use both bars together. They do caution against extremes (Max 4" from bar end minimum 1". And don't set one bar at max one way (4") and the other at max the other way (1").

There's also boxed rear control arms with poly bushings- not adjustable, but stiff. No grease fittings and probably heavier than stock. A pain in the pattoo when it comes time to re-grease the poly bushings.

There's supposed to be a torque tube brace but I don't have it and in fact I've never seen the Rancho one. Back then it was all the rage to get a second torque arm from a wrecker spoon them together and bolt both to the car thus doubling stiffness. boxing the stock panhard rod and trailing arms with a bit of steel plate and some welds was also a thing.

They also have their own recommended alignment specs: Street 3 degrees (+) of caster, 0-.5 degrees negative camber and 1/16" toe in for the street. For the track: 3.5-4 degrees (+) caster, 1-1.5 degrees (-) camber and 1/16" toe in.
They claim 1g on a skid pad with the full kit which they say is equivalent to an 86 Corvette.

Recommended wheels are 15x8 with 4 3/8 to 4 1/2 inch backspacing. Tires 245/60-15 all round for the street.

There's no mention of these parts on Rancho's current website. They also had kits for 2nd gen F bodies and *kack* Mustangs.

I've attached the installation booklet that came with the kit. It has lots more info including engineering notes and tuning tips.

QwkTrip

iTrader: (22)

Maybe I'll make a review about the Firestone tires that were on my car in 1992.

scooter

iTrader: (11)

Yeah, for real, he keeps bumping old threads that don't need bumping just to link this one

QwkTrip

iTrader: (22)

Exactly, how do you think I found this thread? He's got the search tool working overtime.

scooter

iTrader: (11)

DynoDave43

iTrader: (11)

I had never heard of this kit.

I wish more of these parts that were once available, were still available.

Several interesting ideas here. Like the rear shock mount reinforcement. I don't recall reading anywhere in the past that there was an issue with the strength of the rear shock's top mount.

Dokken10

iTrader: (18)

Great info and thank you

I have the front, rear sway bars and all the hardware. I removed it from a 84Z about 14 years ago.

It is stamped Rancho but I never knew its model name or number.

It is a very nice setup but more than I need or want. I might be willing to sell it.