gojo

This is my first real post on the site, so I just want to say hi to all.

My 1983 RX7 makes a binding sound that vibrates the entire car when coming out of a left hand turn. If I back off on the accelerator while coming out of the turn, the sound will not occur.

Occasionally the sound will occur when going over dips in the road ( I have 175# rear springs so the wheels go flying from time to time), or when starting a right hand turn if my right tire is on gravel, but under these conditions the sound is short lived, and not very loud.

I am suspecting the LSD clutch. I added new limited slip additive with fresh 80-90 gear oil about 50 miles ago, but I am still getting the noise when coming out of left hand turns if I am accelerating.

I am wondering if this is really a problem with the LSD clutch. It is more the just a clatter. It is a binding sound that vibrates the car, and can be felt in the floor. It sounds like it comes from the right rear.

If it is a problem with the LSD clutch, does it need to be fixed, or can I continue to drive the car, and just try to get along with it. Being able to burn both tires has no interest to me. I can pretty much avoid the noise by not accelerating when I come out of my left turn.

Kentetsu

If you don't want the LSD, then you could probably find a forum member who would be willing to swap in an open diff rear in exchange for what you've got.

Some chatter is going to be normal. Even with fresh oil (which claimed no addative was needed) plus a tube of addative, mine will still chatter a bit on tight parking lot style turns. This is more noticeable when the car is cold and first starting out (pulling out of driveway, etc).




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JoeNoble

iTrader: (6)

If the oil says limited slip should I still use a limited slip additive I.e. Trans-x? Sorry about jacking your thread btw.

j9fd3s

iTrader: (3)

its possible the LSD is not happy with the oil, or worn or something. the old break in for an LSD is to go to a parking lot and do figure 8's. note this is figure 8's @like 5-10mph, not the drifting kind!

if you do a few of those and it goes away, it just needed some break in, if it gets worse, or stays the same something might be wrong with it

gojo

Good to know someone may want to trade an open. The car is an electric conversion, so I don't drive it in the winter because the batteries lose their efficiency, and they salt the roads which would rust out the car. With electric cars one pays for fast starts with serious loses in range, plus electric motors can put a lot more torque on the drive train than a gas engine. I have wondered if this is part of the LSD problem.

I would describe what I am hearing as more then clatter. It is a binding sound that vibrates through the floor. However, the heavy duty springs in the rear may be transmitting the sound more efficiently to the cab.

gojo

When I recently drained the old diff oil, it was obvious it had not been changed in many years. I added LSD additive and some 80-90 gear lube, but I have been avoiding driving in a manner that would cause the binding/vibrating sound. I considered maybe I needed bring it on, so to speak, in order to get things working again.

Thanks, and happy trails.

Rogue_Wulff

My car does the same thing. I believe it is a combination of normal LSD action and the 200# rear springs. I only hear/feel the clutch chatter when making a right hand turn while pulling away from a stop. The harder I take off while turning, the more noticeable the chatter.
Since you converted to an electric motor, I'd suspect the chatter is going to be a bit more noticeable, since electric motors create peak torque at near zero RPM. The weight of the batteries, and your stiffer springs, will make the chatter more pronounced.
The LSD clutch chatter occurs from the clutches trying to force both tires to turn at the same speed, which is the opposite of is occuring during a turn.
My thought is, live with the chatter. The added traction of the LSD is far more desireable than that of an open diff, so a little chatter from the clutches is a small price to pay. Of course, I autocross my 83 and rallycross my 84, so there's no way I would give up the LSD in either.

gojo

Thanks for the thoughtful reply. Something else to consider; if heavier springs raise or lower the car, it can change the drive shaft angle. The angle out of my tranny is a couple of degrees more then the angle out of the diff, so I plan on shimming up my motor a little this winter. It may not eliminate the noise but it may allow my drive shaft, and related bearings to last longer.

Question: How would you describe this chatter sound? The sound I get is more of a binding/vibration sound. It happens loudest, and longest on left turns but it can happen other times also. It seems to come from the right rear. I haven't ruled out the watts link, the rear coil spring, or other suspension components. Cars have a tendency to squat when starting, and I would think there is a lot of counter force against the turning wheels going on in the suspension. The car has 28 year old bushings, and they could be making weird noises.

Rogue_Wulff

Mine manifests itself as a vibration-like noise/feeling, most noticable on tight, slow right turns when taking off from a stop. Of course, I also run 205/50-15 Azenia's on that car.
The car is lowered slightly, not sure how much though. Whatever the default is for the Ground Control 200#/in rear Eibach springs that are now discontinued. I have GC coilover front, with 350#/in 2.5" x 7" Eibach racing springs up front. Everything else is stock suspension-wise, and has 28-ish years/223K miles on it.
You are dead on about the old bushings being a good possibility for magnifying the effects of the LSD chatter. Probably as much of a factor as the higher rate springs, now that I think about it.......