I'm so relieved.

[rhipsher]

I've had a vibration problem coming from the rear of my 90 Z for the past 1 1/2 or so and it's bugged the hell outta me as some of you already know. I've tried swapping the tires. No luck. I've replaced the rear wheel bearings. No luck. I've had a four point aligment done. No luck. Checked all of my bushings. Nothing loose. No luck. It's been bad enough that I couldn't even look out my rear view mirror because it shook so bad. I don't care how fast the car is it got to the point where it was no longer fun to drive anymore because above 60mph it felt unsafe. So I decided thats it I'm going to find and fix this problem if it kills me. I've taken this car to 179mph many times and now I can't even take it above 60mph? F that. And I found it and fixed it today damn it. It was my fault all along. A total rookie mistake that I can't believe I made. But it was something I had suspected all along. The last time I replaced my throwout bearing/fidanza and clutch disk I installed my drive shaft 180 degrees out. And let me tell you something! That makes all the difference in the world. When I spun the wheel by hand and watched the drive shaft I swear it looked like it had 1/8 in run out. When I rotated it 180 and bolted it back together and spun it by hand again it ran totally true. The shaft and the ujoint rear diff already had white paint on them to mark proper orientation and I swore I installed it right. I must have been in a rush. But it runs totally smooth now. No vibration or roaring noise. I felt like slapping myself over that one.:cheers:

[HAWAIIZR-1]

Thanks for sharing this valuable info and glad to hear it worked out for you. :handshak:

[flyin ryan]

Simple mistake many have made over the years, don't beat yourself up over it :dontknow:.

[carter200]

Good to hear all is in proper orientation now :thumbsup:

[Paul Workman]

Thanks for sharing!

However, balance is one thing...but runout is another. Runout...:icon_scra Hmmmm.... That surprises me. Unless something was a leeetle bit cockeyed when it was installed, I wouldn't expect you to have runout. (Just curious thinking out loud here.)

Glad you found the problem tho! I hope I marked mine before we (Lee and I) took it apart last August. I guess I've got a 50-50 chance of having the same problem (only w/ my luck, it is more like a 90% chance of getting it wrong!:redface:)

P.

[rhipsher]

Thanks for sharing!

However, balance is one thing...but runout is another. Runout...:icon_scra Hmmmm.... That surprises me. Unless something was a leeetle bit cockeyed when it was installed, I wouldn't expect you to have runout. (Just curious thinking out loud here.)

Glad you found the problem tho! I hope I marked mine before we (Lee and I) took it apart last August. I guess I've got a 50-50 chance of having the same problem (only w/ my luck, it is more like a 90% chance of getting it wrong!:redface:)

P.Runout and balance are the same thing. I deal with it almost every day. I would say in this case it was conical runout . Coming from the transmission it was pretty true but the further down the line towards the differential it got the more it ran out. But if you get it wrong you'll damn sure know it. But only takes a few minutes to switch it around.

[Paul Workman]

Runout and balance are the same thing. I deal with it almost every day. I would say in this case it was conical runout . Coming from the transmission it was pretty true but the further down the line towards the differential it got the more it ran out. But if you get it wrong you'll damn sure know it. But only takes a few minutes to switch it around.

While I don't agree that runout and balance are by strict definition necessarily the same thing, (allowing for variances in driveshaft wall thickness shifting the CG slightly), you're right: runout will result in CG shift due to the eccentricity - no argument thar!. but I always thought the driveline vibration was a function of the centerline of the driveshaft and that of the yoke(s) not necessarily being perfectly aligned. That is OK as long as the error is small and a counter weight can be added to the drive shaft to compensate for the collective (driveshaft & yoke) offset of CG.

Course, if the counterweight is on the opposite side; i.e., the drive shaft is 180º out of position...Um yeah the CG error is doubled. But, my surprise is that the runout would be so bad that you could see it w/ the naked eye...yikes!

P.

[rhipsher]

Well when I get a blueprint of a round part I have to turn and it has several o.d & I.d's and it says diameter A B C & D have to be concentric to eachother within .0015 TIR, that would be the same as the drive shaft not running concentric to the yoke and would cause it to be "Out of balance." Right? Now of course you hear the word balance used more when talking about tires because they can change their shape. Now when machining steel it is what it is. There is no in between. Its either in tolorence or its out.
So I hope that explains it. There's not counter weight that's gonna fix an 1/8" concentricity runout.

[A26B]

Not to add fuel to the debate about runout vs balance, but they are not necessarily the same thing. Run out most always results in imbalance in rotating mass when all diameters are concentric. However, eccentric imbalance could theroetically be offset by mass, such as increased wall thickness (mass) if it were opposite the runout.

Mass imbalance, such as that which could occur in the driveshaft, can be the result of any or all of the foloowing; (1)tube manufacturing tolerances, i.e. wall thickness variations, (2)tube/yoke welds or (3)yoke forging and machining variations.

Vibration aside, if you had 1/8" runout that was fixed by rotating the driveshaft 180 degrees, it was either an installation issue or some really bad parts.

Just my 2 cents worth...

[rhipsher]

Absolutely Jerry. I think the drive shaft could have a wall thickness variance and they may have purposely welded the end cap out of faze to help compensate for it. Which would explain why at 0 degrees it has runout and at 180 degrees it runs true. That makes sense to me. And I suspect my Z is not the only one that's like that. Some may be worse than others.

[GrayZ]

I've had a vibration problem coming from the rear of my 90 Z for the past 1 1/2 or so and it's bugged the hell outta me as some of you already know. I've tried swapping the tires. No luck. I've replaced the rear wheel bearings. No luck. I've had a four point aligment done. No luck. Checked all of my bushings. Nothing loose. No luck. It's been bad enough that I couldn't even look out my rear view mirror because it shook so bad. I don't care how fast the car is it got to the point where it was no longer fun to drive anymore because above 60mph it felt unsafe. So I decided thats it I'm going to find and fix this problem if it kills me. I've taken this car to 179mph many times and now I can't even take it above 60mph? F that. And I found it and fixed it today damn it. It was my fault all along. A total rookie mistake that I can't believe I made. But it was something I had suspected all along. The last time I replaced my throwout bearing/fidanza and clutch disk I installed my drive shaft 180 degrees out. And let me tell you something! That makes all the difference in the world. When I spun the wheel by hand and watched the drive shaft I swear it looked like it had 1/8 in run out. When I rotated it 180 and bolted it back together and spun it by hand again it ran totally true. The shaft and the ujoint rear diff already had white paint on them to mark proper orientation and I swore I installed it right. I must have been in a rush. But it runs totally smooth now. No vibration or roaring noise. I felt like slapping myself over that one.:cheers:

Glad to hear you found you're problem. I was wondering, What mods have you done to your car?? I'm assuming it's a 415 ?? Not to many of our Z's are able to leg out, much over 166, unless highly modded. Always good to compare notes.

[WVZR-1]

You might need to explain exactly your "rotation"! If you only changed the relationship of the rear joint to the pinion flange you changed "nothing" in relation to the drive-shaft and that seems to be what you imply here.

The only explanation in this case would be that the balance of the pinion flange isn't correct. If your pinion flange is an original it would have a sheetmetal deflector that would have a weight on it. I've heard of the pinion flange being balanced with a drive-shaft assembly but I've never done it or actually seen it done.

NOW if you removed the slip-yoke from the drive-shaft and rotated it 180* you certainly would have effected balance.

It would seem to me that there was more likely an install error the previous install or maybe one of the tangs on the pinion flange has been compromised and allowed the u-joint to be secured off center!

There's one simple remaining fact though, if you "saw what you explain here" the drive-shaft needs to be removed one more time and checked for balance and the run-out you explained.

It certainly shouldn't see "speed" until it's verified!

[rhipsher]

I don't want to over anylize it because it makes perfect sense to me. Its pretty simple. It works one way and not the other. When I ran top speeds in it, it was aligned just like I have it now. As far as ZR-1 not going past 166mph I have to laugh because even the data on this site shows them going between 175 to near 180 factory. My car dyneod at 342rwhp@336ft lbs tq at Coreys. Nothing special and I hit 179mph pretty easily. I have the video to prove it. I posted the video on here a couple of years ago. I thought everbody had seen it but I guess not. My car is no where near a 415. I guess not many guys on this site have tried it.

[Paul Workman]

My car dyneod at 342rwhp@336ft lbs tq at Coreys. Nothing special and I hit 179mph pretty easily. I have the video to prove it. I posted the video on here a couple of years ago. I thought everbody had seen it but I guess not. My car is no where near a 415. I guess not many guys on this site have tried it.

I got up to 145 before vibration caused my dash and gear shift to "buzz". (Had to "180" my driveshaft and reinstall it to fix it!;))

So, my friend...I think we're in "violent agreement". :mrgreen: Come shoot some competition rifle matches w/ me and we can talk about concentricity, runout, and match case preparation:thumbsup:.

Dayam! Is it spring yet??

P.

[rhipsher]

I would love to do that Paul. You'd probably kick my but at it.

[GrayZ]

I don't want to over anylize it because it makes perfect sense to me. Its pretty simple. It works one way and not the other. When I ran top speeds in it, it was aligned just like I have it now. As far as ZR-1 not going past 166mph I have to laugh because even the data on this site shows them going between 175 to near 180 factory. My car dyneod at 342rwhp@336ft lbs tq at Coreys. Nothing special and I hit 179mph pretty easily. I have the video to prove it. I posted the video on here a couple of years ago. I thought everbody had seen it but I guess not. My car is no where near a 415. I guess not many guys on this site have tried it.

Rhipsher, to anwser you're question, No, i did not see the video, and i'm not calling you out, although the nonchalant way you stated you've been to 179 mph many times, did make me smile so now that we both have had a nice giggle, WOULD You mind, reposting the video of you going 179mph..cause i'd like to show my friends that make comments at the bar, a video to back up my proud ZR1 boasts,
At the Nellis mile shootout, I went to, most 350 ci ZR1/s ran around 155/160 mph top speed, Demps yellow car, modded exactly like mine at the time, ran 166, ergo the number, my car was modded by m. Haibeck, it dyno'd 424 rwhp. (I have the dyno sheet to prove it).lol.. I have had "Oprah" to 162 mph, Ted Feder's lightly modded car ran 162, all i'm saying is you must of had plenty of room, to get you're car to 179.... in my neck of the woods we don't have the place, to allow us to stretch her legs so to speak. The Morrison world record run, also ran In Texas, was on a test track in Stockton, under controlled environment, with plenty of road to get up to speed. I know that anyone that has a video of themselves running that fast would cherish it forever, I would, so please re-post it, I would really appreciate it.

[rhipsher]

Rhipsher, to anwser you're question, No, i did not see the video, and i'm not calling you out, although the nonchalant way you stated you've been to 179 mph many times, did make me smile so now that we both have had a nice giggle, WOULD You mind, reposting the video of you going 179mph..cause i'd like to show my friends that make comments at the bar, a video to back up my proud ZR1 boasts,
At the Nellis mile shootout, I went to, most 350 ci ZR1/s ran around 155/160 mph top speed, Demps yellow car, modded exactly like mine at the time, ran 166, ergo the number, my car was modded by m. Haibeck, it dyno'd 424 rwhp. (I have the dyno sheet to prove it).lol.. I have had "Oprah" to 162 mph, Ted Feder's lightly modded car ran 162, all i'm saying is you must of had plenty of room, to get you're car to 179.... in my neck of the woods we don't have the place, to allow us to stretch her legs so to speak. The Morrison world record run, also ran In Texas, was on a test track in Stockton, under controlled environment, with plenty of road to get up to speed. I know that anyone that has a video of themselves running that fast would cherish it forever, I would, so please re-post it, I would really appreciate it.No problem. Here you go.http://s301.photobucket.com/albums/nn63/keeno1970/?action=view&current=Reallyfast005.flv:happy1:

[HAWAIIZR-1]

Freakin AWESOME..........you are da man!:cheers:

[Dynomite]

Come shoot some competition rifle matches w/ me and we can talk about concentricity, runout, and match case preparation:thumbsup:.

Dayam! Is it spring yet??

P.

You sound serious....I am just a jack of all and master of none when it comes to the Z mechanics or loading ammuniton. I do get 3/8 inch groups shooting 55 gr sp with 35 grains of 748 in my 22-250 Savage model 12 :mrgreen:

Chronographed at 3,500 fps :thumbsup:

[USAFPILOT]

It does take more than a mile to get to 180!

[rhipsher]

It does take more than a mile to get to 180!Absolutely. My car would probably hit in the 155mph range in the Texas mile. But as you can see with plenty of road they will all run in the 180mph range all day long. And that video was taken before the top end porting/Fidanza flywheel/headers and a master tune by Corey H. I don't know what it would do now. I'm not sure my balls are big enough to see. I'd like to live to the ripe old age of Glenn B. hehehe!

[flyin ryan]

I'm not sure my balls are big enough to see. My money says they are ;)

[GrayZ]

rhipsher
thanks for re-posting. u must of been on a lonely stretch of texas blacktop, it would really have been cool if you had a harness mounted camera, like used in dave's obession's salt flat run, kudo's to you, i'd love to be able to see exactly what my z "oprah" could do, but am afraid of the consequences of explaining to Missouri state patrolman, exactly what i was doing

[TFENT]

We have 3 ZR1's. 1 completely stock and was good for 169mph. The other 2 in Germany have Geoff Jeal built motors (650+ hp). Here is a link of the red one at 316kph or 197mph on the Autobahn at 1:30am. It's a beautiful thing to see a ZR1 travel 100 YARDS PER SECOND!


http://movit.de/images/316.wmv


http://i100.photobucket.com/albums/m16/tf-ent/MovIt%20Brakes/MovIt%20ZR1%20Pics/corvgall01.jpg

http://i100.photobucket.com/albums/m16/tf-ent/MovIt%20Brakes/MovIt%20ZR1%20Pics/corvgrs.jpg

http://i100.photobucket.com/albums/m16/tf-ent/MovIt%20Brakes/MovIt%20ZR1%20Pics/corvgbac.jpg

http://i100.photobucket.com/albums/m16/tf-ent/MovIt%20Brakes/MovIt%20ZR1%20Pics/zr1engg.jpg

[rhipsher]

The only mods at the time were the ram air on the front of the car with the open air temp sensor routed right in the middle of it along with all of the bugs that went to heaven splattered on it.
http://i301.photobucket.com/albums/nn63/keeno1970/Picture068.jpg
http://i301.photobucket.com/albums/nn63/keeno1970/Picture067.jpg
Also thick finalic plenum spacers that keep the plenum luke warm after a drive not frying pan hot. And adjustable camber rods on the rear. That stuff was already on the car when I bought it. And then of course the top end porting I did myself and had it powder coated. I'm waiting for Corey to make me the Jeal copy headers with high flow bullet cats. Then I'll have him tune it. Like I said, I don't know what it will do after that.
http://i301.photobucket.com/albums/nn63/keeno1970/9.jpg
http://i301.photobucket.com/albums/nn63/keeno1970/7.jpg
http://i301.photobucket.com/albums/nn63/keeno1970/finished1.jpg

[gbrtng]

I'd like to live to the ripe old age of Glenn B. hehehe!

I'm surprised I got this far ...

[rhipsher]

I'm surprised I got this far ...
Hehe! I heard that. I gave up rice rockets for corvettes. In 1993 I said fair well to the last GSXR 1100 as I was recovering in the hospital. I got tired of taking spills on bikes.:thumbsdo:

[Dynomite]

Hehe! I heard that. I gave up rice rockets for corvettes. In 1993 I said fair well to the last GSXR 1100 as I was recovering in the hospital. I got tired of taking spills on bikes.:thumbsdo:

I went to ATVs (Raptor 700s)....at least they have 4 wheels and the spills are usually on sand vice asphalt :mrgreen:

[rhipsher]

I went to ATVs (Raptor 700s)....at least they have 4 wheels and the spills are usually on sand vice asphalt :mrgreen:Yep. Hitting the asphalt at 120 around a corner because somebody spilled some sand in the road is just way to painful. I was 23 years old getting ready to turn 40 and knock on wood I don't have any aches and pains from it.