johnf

My FB spun violently after exiting a 180 degree turn at a SOLO II event last weekend. It was as though someone had pulled the road out from under the car. I replaced the four link with Mazda OEM parts & have a Racing Beat suspension complete with sway bars & installed an OEM LSD on the car. This was totally unexpected & I thought something had broken but everything appears to be intact. I'm new to the RX7 but I've been competing in SOLO events for more than ten years. I never managed to embarass myself by spinning while running in a straight line before. There are no clear indications of binding or parts coming together. Anybody know what happened?

CyborgRyu

iTrader: (8)

probably should try and test it out in a deserted area....try to figure out why it did it?

Icemastr

iTrader: (2)

Alignment? I had a similar problem recently except it was doing it almost all the time on hard right turns. My toe was off on the right rear tire making the car want to keep going that direction it would just snap oversteer after a 90 degree or 180.

christaylor

What year is the car?

In late 84 through 85 the rear suspension pickup points were moved ever-so-slightly ( I think I read a mm or two). I'll try to dig around and see if I can re-find the site that had all that information on it, but I'll guess it's linked in some way from the first gen section.

Around here, all the 81-83 guys disconnect their swaybars to keep that from happening. On my car, I prefer the handling characteristics (early 84) but I wouldn't take it off for the world in my dad's car (late 85). With swaybars on both of them the 85 is almost neutral, and the 84 is a handful. It depends on the track, though. A few of the tracks we run on on a regular basis you don't notice it, but it's on turns like you describe where things to go hell in a handbasket. A few years ago a lot of guys described the same scenario as you are, but I've personally never had it happen (haven't run a rear bar on my car much, either! ).

adam c

iTrader: (2)

I agree with disconnecting or removing the rear sway bar. However, that may not be the cause of your spin. I suspect that the new LSD put down all of your power to both wheels coming out of the corner, and broke loose both tires when you accelerated. Since you didn't have it before, you were probably used to having one tire spin as you accelerated out of the corner.

The real fix for this may be a lighter foot coming out of the corners

grantmac

try this:
http://www.pbandjracing.com/rear_suspension.htm
I have the rear bar disconnected on my '85 and I like it, as well I've done the Watts link section of the above write-up. I can still get the rear to step-out but it comes back much faster now; before it was hard to bring back, but I've got the back half of the car pretty much gutted so that might effect things. I've found the swaybar seems to cause oversteer exiting the corner but doesn't do much to stop the understeer on the way in.
Grant

rkcarguy

There is things to do to minimize this, but this is inherant of the 1st gen RX-7 thanks to it's straight axle. Because you can't adjust camber the tire eventually rolls over, you lose traction, and do a loop. Hardcore guys that roadrace these actually tweak their axle housings to get some negative camber on the rear wheels! The axle bearings don't last very long but I guess it's worth it. Stiffer is better if you are stuck with the straight axle. Also make sure when you work on the susp to lower the car down then tighten all the bolts on everything, even swaybars. Having all the bushings in a relaxed position at ride height makes a huge difference.

johnf

Thanks to everyone for all of the advice - I think I managed to find the problem, it's unsprung weight. Upon close inspection on a hoist last weekend I found a bolt that I had installed for the restraint system had come into contact with the driveshaft. It probably bottomed out the suspension prematurely & put excessive load on the rear tires. It's an easy fix, but I think I'll need a new drive shaft. I'm not 100% shure this is the problem but nothing else seems to be out of place.

Rx7carl

You all pretty much covered it. Only thing I would add is to suggest a visit to www.gforceengineering.net. Jim's a real suspension guru on these cars. My fix in the above link is a good bandaid for the price, and is very streeable but Jim's setup is very professional. Of course its alot of work and alot of money, and also not streetable. But in a racecar, his setup kicks butt.

cpa7man

iTrader: (2)

True, for sure. I'm fixin to send Jim my first born son. Jim is the guy. If nothing else buy his book. It's the best $70 I've ever spent.