Ring and pinion / Drive shaft

[slackinoff]

How much drive shaft rotation/slack should you have on these cars (manual car)?

Here is what I am looking at. The wheels are grounded/ebrake and the trans is in neutral. I can rotate my drive shaft about 3/4'' from clockwise to counterclockwise. I am thinking the ring and pinon lash is looser than it should be. I get a pretty good clunk when the car takes up the slack from accelerate to decelerate / less than perfect shifts.

The rotation/slack is coming from the diff. U joints are fine.

Rm

 

[46addict]

All sounds like normal behavior to me. If the ring & pinion lash was loose, you would hear a whine while driving.

 

[Marble]

Sounds normal.

 

[RocketcarX]

normal

 

[slackinoff]

Thanks guys (46addict, Marble, RocketcarX) I purchased a few sqft of dynamat to hopefully quiet the clunking down. I will repost on how that goes. In my searches I found a lot of threads complaining about that noise, so I want to give guys some options instead of being driven insane. My new upper link amplified many sounds. It is not too bad, but annoying.

Rm

 

[46addict]

Is this on a stock driveshaft?

 

[pass1over]

my rear suspension makes all kinds of clunks and rattles

all poly, aftermarket upper and lower arms, 1 piece DS

 

[slackinoff]

Is this on a stock driveshaft?

Yes stock driveshaft. BMR upper link and mount, BMR lower brackets. Car has 180k miles on it......I am thinking I have the world record for miles on a Bullitt.

Rm

 

[07 Boss]

Yes stock driveshaft. BMR upper link and mount, BMR lower brackets. Car has 180k miles on it......I am thinking I have the world record for miles on a Bullitt.

Rm

When you replaced the upper arm did you replace the bushing at the top of the diff?

 

[slackinoff]

When you replaced the upper arm did you replace the bushing at the top of the diff?

Not at the same same time. I did the diff bushing several months back. Got any ideas? I would love to hear them. My thoughts below,

I was curious if I had not torqued the diff bushing side to spec and also the bolt fitment on the diff side. So yesterday I took that bolt out, moved the upper link out of the way, and reinserted the bolt. I was looking for slop between the bolt and bushing. What I found was a good fit, it's not absolutely zero clearance fitment, but (I think) not enough to cause a clunk....maybe I am wrong. Maybe it needs a zero clearance fit? EDIT* (I also put the bolt into the bmr mount alone, it has a very precise fit, practically zero clearance)

The rascal has a good bit of torque on it, and the upper arm fits the AROUND the bushing perfectly. That, combined with the torque of the bolt.....I just don't see how that clunk can come from there. The mount pinches the bushing perfectly is what I am trying to say. It also has a ton of torque....I don't think it relies on the bolt fitment to hold fast. See what I mean?

I reassembled it and re torqued.....but I just now realized I have not pumped any grease into the zerk fitting. That is tonight's project.

Rm

 

[46addict]

It's not so much bolt torque, but the material of the bushing transfers noise into the cabin. If you have a poly bushing back there, greasing it would help prevent bushing bind but the mechanical noises/clunks will still exist. It could be a worn driveshaft CV joint making the noise, which used to be muffled by soft bushings.

 

[slackinoff]

It's not so much bolt torque, but the material of the bushing transfers noise into the cabin. If you have a poly bushing back there, greasing it would help prevent bushing bind but the mechanical noises/clunks will still exist. It could be a worn driveshaft CV joint making the noise, which used to be muffled by soft bushings.

Yes it is poly. Both ends now. You have to be right on transferring noise, just makes sense. When I was testing the driveshaft rotation or should I say ring and pinon lash, it was making the exact noise I hear in the cabin.
I took the rear seats out to listen better and that entire area under the rear seat is bare sheet metal. Its like a damn Jamaican steel drum in there. Putting the seats back in cuts the noise by 50%. Hopefully my dynamat takes care of the rest or most of it. I can live with this, but I want the noise cut down a bit.

Rm

 

[BMR Tech 2]

The driveline on S197s is pretty damn noisy and sloppy. There are lots of clunks that you don't typically notice until you start messing around with the rear suspension, since the factory junk does a great job of hiding all the noises.

The play you have in your driveshaft sounds normal, and my car has always had that. Between 2 gear sets, 2 completely different rear ends, 3 driveshafts, and 2 transmissions, it has always had that little bit of slop.

 

[slackinoff]

The driveline on S197s is pretty damn noisy and sloppy. There are lots of clunks that you don't typically notice until you start messing around with the rear suspension, since the factory junk does a great job of hiding all the noises.

The play you have in your driveshaft sounds normal, and my car has always had that. Between 2 gear sets, 2 completely different rear ends, 3 driveshafts, and 2 transmissions, it has always had that little bit of slop.

Thanks, just knowing what you said will put it out of mind. I do enjoy how much more precise and solid the rear suspension feels and works now. I also appreciate how well the part is constructed. It fits beautifully.
What is your opinion on dynomating the area under the rear seat? I am expecting it to dampen the sound very well since the area is one big bare sheet metal "drum" that looks perfect for resonating sound.

Rm

 

[BMR Tech 2]

I don't think it will help much. I have some raamat in my car (same stuff as dynamat) and all it really did was clean up the exhaust sound some.

 

[BruceH]

IMO most clunking starts after a custom tune. Why? Because of commanded torque in the torque tables. Commanding more torque with the same pedal position makes the car seem more powerful (it isn't, the accelerator pedal is just requesting more power with less input, a common trick used by tuners to fool the buyer into thinking there is more power) but it also starts the clunking due to all the increased torque required at lower accelerator pedal positions.

It makes the accelerator pedal more of an on/off switch than the linear input device it was intended to be. Barely touch the pedal and enough power is commanded to slam the drivetrain, let off and the slammed power is now zero, clunk, clunk, clunk.

 

[slackinoff]

IMO most clunking starts after a custom tune. Why? Because of commanded torque in the torque tables. Commanding more torque with the same pedal position makes the car seem more powerful (it isn't, the accelerator pedal is just requesting more power with less input, a common trick used by tuners to fool the buyer into thinking there is more power) but it also starts the clunking due to all the increased torque required at lower accelerator pedal positions.

It makes the accelerator pedal more of an on/off switch than the linear input device it was intended to be. Barely touch the pedal and enough power is commanded to slam the drivetrain, let off and the slammed power is now zero, clunk, clunk, clunk.

Wow thanks for telling me this. I was just thinking this damn Bama tune is like a light switch even after I asked them several times to make it more progressive.

Rm

 

[wabirch]

Good thread here, I am reminded to relube when it groans a little backing up. Pedal is something I want to cut back on as well.

 

[slackinoff]

Thanks for all the help. All that racket ended up being one of the adjustment lock nuts loose on the upper arm. The car is so smooth and quiet now. I was never able to focus on how much better the suspension felt because of the racket. The drive shaft will still bang when slack is taken up quickly, but no where near the noise level or as often.

Rm