[HWYSTR455]

Yeah, it's lowered about 2", ATS spindles, GW stuff, front uppers & lowers, springs, rear uppers & lowers, same as yours for the most part.

Has it been the same trans the whole time? And it's getting freshened up now? Had an issue with that? Might have been the output shaft causing it, since you had a prob there? Guess you'll know on that soon, so you will see.

Can look into the diag tools, there are certain harmonics that can indicate where the virbation is coming from, and also laser ones that can be used to measure. Believe there's one that has a transmitter you place on the balancer and pinion yoke, includes the entire driveline.

http://www.quartermidget.biz/products.asp?cat=58

http://dodgeram.info/tsb/1998/18-49-98.htm (look at the graph)

http://cgi.ebay.com/ebaymotors/Elect...-/250806120453

I know it can be frustrating, but stick with it, you'll ID it and get it corrected. If you end up tossing your arms in the air, try contacting a chassis builder/shop and have it looked at. A lot of the roundy-round guys deal with this stuff every day, and it's cake to them. Maybe even Schwartz, he could prob do it in his sleep. The rock crawler guys too, the are angle magicians.

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[andrewb70]

Originally Posted by HWYSTR455

Yeah, it's lowered about 2", ATS spindles, GW stuff, front uppers & lowers, springs, rear uppers & lowers, same as yours for the most part.

Has it been the same trans the whole time? And it's getting freshened up now? Had an issue with that? Might have been the output shaft causing it, since you had a prob there? Guess you'll know on that soon, so you will see.

Can look into the diag tools, there are certain harmonics that can indicate where the virbation is coming from, and also laser ones that can be used to measure. Believe there's one that has a transmitter you place on the balancer and pinion yoke, includes the entire driveline.

http://www.quartermidget.biz/products.asp?cat=58

http://dodgeram.info/tsb/1998/18-49-98.htm (look at the graph)

http://cgi.ebay.com/ebaymotors/Elect...-/250806120453

I know it can be frustrating, but stick with it, you'll ID it and get it corrected. If you end up tossing your arms in the air, try contacting a chassis builder/shop and have it looked at. A lot of the roundy-round guys deal with this stuff every day, and it's cake to them. Maybe even Schwartz, he could prob do it in his sleep. The rock crawler guys too, the are angle magicians.

.

Thanks for the links. I really dig the True laser Track driveline alignment tool. I think that is exactly what I need to get. It will help to align the rear end both laterally and pinion angle wise.

Yes, the same transmission was installed in the car the whole time, so it could have been the cause. I did check the output shaft runout and it was barely detected on the dial indicator, so I doubt that the trans was the problem.

I am definitely going to keep working at it. There is a solution to this problem.

Andrew

[gearbanger]

When I had my GTO off the frame, I was doing alot of measuring and checking, because I was really thinking about raising my trans tunnel so I could get the tailshaft up a bunch. I could only get my driveline angles within about 4 degrees. In other words 3 deg down on the trans, 1 deg up on the drive shaft and 3 deg up on the pinion. Like this \/\.

While I was looking I noticed that the pinion was 5/8" off centerline of the frame of the car. This is with Hotchkis uppers not stock. I do not believe this was caused by the uppers though becuase my backspacing puts the tires so close to the frame, that an offset of 5/8" would put one tire against the frame, and the other tire 1-1/4" off the frame. Everything is nearly perfectly centered on my setup. And my control ares are set equal length.

I was thinking about making my driveline in a perfectly straight line, and using the 5/8" offset as my working angle to keep the needles movign in the u-joints since 5/8" over the length of my driveshaft figured out to be right at a .5 deg if memory serves. But it all seemed like alot of work for a little benefit. I have the similar vibrations the Andrew has, and would love to figure it out as well.

So Andrew, are you saying both of your arms are offset in the same direction? I am just thinking out loud, but I am not sure that that is going to scoot the rear end over any, because they are still the same length, and that is going to force the rear end to the center. If the arms were parallel, obviously the rear would scoot over by the amount of the offset, but the triangulation seems to me like it would still pull the rear to a center location if both arms are the same length.

[gearbanger]

Okay, so I just came home and got out my old 67 model upper control arms, and the best I can measure, these have no offset at all. So maybe 70 is different?

[andrewb70]

Originally Posted by gearbanger

Okay, so I just came home and got out my old 67 model upper control arms, and the best I can measure, these have no offset at all. So maybe 70 is different?

I wish I had my stock arms around so I could compare. It's also interesting that you have a vibration. What kind of driveshaft are you running? Material and diameter wise.

What are your front and rear working angles? Is it a high speed vibration, similar to what I have described?

I do plan on getting one of those laser driveline alignment tools. I think it will work very well in determining exactly the exact alignment of my driveline components.

I have also explore the possibility of having a dirveshaft made using CV joints instead of u-joints. I don't mean the cardon style CV joints that are used on 4x4. I mean true CV joints that are used for halfshafts on front wheel drive cars and cars with independent rear suspension. BMW rear ends are setup with pinion yoke that take Porsche 930 style CV joints.

The Driveshaft Shop has been building driveshafts with CV joints for various applications. Thus far they have focused on IRS applications, but their latest is for 2005-2011 MUstangs that have a live axle setup. It seems that some of these cars have high speed vibrations as well. The problem is that nobody makes pinion yokes or transmission yokes, that accommodate CV joints, for domestic rear and and transmissions. Maybe The Driveshaft Shop will step up top the plate and offer something unique. Using CV joints at both ends of the driveshaft will render any sort of driveline alignment issues, mute. CVs can operate at high angles and the relationship of the front and rear angles is irrelevant.

Andrew

[gearbanger]

Andrew, I had my driveshaft made by inland empire driveline when I did the TKO swap. Then when I had it off the frame I switch my pinion yoke to a 1350 U-joint so I had to shortn the driveshaft 1/2". I found a driveshaft shop in Glasgow KY call precision driveline. As soon as I walked into his shop I knew he was the guy I wanted to work on my car. Everything was so organized and clean. He had a driveshaft spin balancer and he checked it for runout in three places and he actually said it was kind of bad. It seems like he said it was about .005 out at one end or something? Its been a while so don't quate me on that. He said what the tolerance was and I remember that it was just outside the tolerance. But most vehicles are not beind made to run at 100+ mph. At any rate, it took him about 30 minutes and he was done, fixed my runout problem, shortened it .5", and balanced it for $40! I though that was awesome.

So anyway, I am hoping that was the problem. I havent had it out at any speed yet to see bu I will report back as soon as I can.

[gearbanger]

Also, mine is 3.5" steel. If you do an aluminum, I would have it sized smaller in the last 12" or so if you can, because mine wants to hit right at the back of the back seat tray, right where the rear seat bottom catch is in a hard bump like right on the bumpstops. The stock driveshafts were stepped in the back this way. Again, 70 may be different. I did not do aluminum because usually you have to go a size bigger in aluminum to keep the strength and I knew I did not want any more clearance issues.

[andrewb70]

Originally Posted by gearbanger

Andrew, I had my driveshaft made by inland empire driveline when I did the TKO swap. Then when I had it off the frame I switch my pinion yoke to a 1350 U-joint so I had to shortn the driveshaft 1/2". I found a driveshaft shop in Glasgow KY call precision driveline. As soon as I walked into his shop I knew he was the guy I wanted to work on my car. Everything was so organized and clean. He had a driveshaft spin balancer and he checked it for runout in three places and he actually said it was kind of bad. It seems like he said it was about .005 out at one end or something? Its been a while so don't quate me on that. He said what the tolerance was and I remember that it was just outside the tolerance. But most vehicles are not beind made to run at 100+ mph. At any rate, it took him about 30 minutes and he was done, fixed my runout problem, shortened it .5", and balanced it for $40! I though that was awesome.

So anyway, I am hoping that was the problem. I havent had it out at any speed yet to see bu I will report back as soon as I can.

Look at post #156 in this thread. Do the pictures look familiar? LOL

Keep me posted. I am curious to see how you do with your vibration issue.

Andrew

[HWYSTR455]

You know, that's a very good point, many shops balance using the 60 mph sweet spot, and in many case that isn't even close. I know there are some cheaper balance machines that don't have as good a tolerance either, and I had to scout around to find one that will balance to my liking.

I think you may be over-engineering this issue, (something I'm guilty of regularly!), and is probably simpler than all this. Call Denny's or Inline, or Dutchman, any should be able to give you a lot of info. I would also stick with 1350s by the way.

I still say that diag tool that uses the harmonic freq to point you in the right direction is the ticket. That gets away from looking at it from a just angles point of view.

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