[6 Grrrs]

Is that your new engine???

[andrewb70]

Originally Posted by 6 Grrrs

Is that your new engine???

Nahhh....But its a sweet running monster, isn't it?

Andrew

[6 Grrrs]

I thought maybe you were upgrading already...

[andrewb70]

The spring semester has been brutal, but it will all be over in about 3 weeks. My last final is on May 5th. I am still in limbo in regards to a new transmission, but I have also been exploring some other items. I will simply post a couple of pictures and see if you eagle eye techie types can spot what I am trying to show. These are some new adjustable rear upper control arms that I will be installing to replace my current aftermarket control arms. The picture is of the same arm, just at different angles.





Does anyone see what I am looking at?

Andrew

[HWYSTR455]

Difference in angle of the mount to the rear housing....


...

[andrewb70]

Originally Posted by HWYSTR455

Difference in angle of the mount to the rear housing....


...

Hmmmmm....maybe. I am not quite sure what you mean, so please elaborate.

Andrew

[andrewb70]

The bracket that slips over the rear end bushing is offset to the driver's side. Before you all demand the name of the vendor, I would like to point out that this control arm is the only one on the market that is built CORRECTLY. You see, the stock control arms are built with exactly the same offset as these control arms. Every other manufacturer, that I have seen, makes upper rear control arms so that the front and rear bushings are inline. This is INCORRECT! This also explains why the rear end in my car is offset to the passenger side by a good 1/2-3/4" as measured from the wheel to the frame. I have seen posts on various forums where people have complained about a similar problem. I also believe that this improper positioning of the rear end has been contributing the ever present vibration problem that I have been having.

I would like to thank Bret Voelkel and RideTech for making a fine product and paying attention to the little details that can have a big impact on the performance of our cars.

Andrew

[Motornoggin]

Hey buddy!

[HWYSTR455]

Andrew - Are you sure the stock control arms have the offset? When measuring for wheel/tire fitment, in many cases, even with stock components, the offset has been present in all the cars I've dealt with. This, as well as there not being a listing for a left and right side control arm from the factory suggests that the factory ones aren't offset? Finally, I don't believe, or it's my understanding, that any minor offset to one side or the other would cause a vibration issue.

Maybe someone else can chime in, but if, the uppers have the offset as have been built into the ones you had made, AND it's not supposed to be there, won't is cause a wheel hop issue? My thinking: It will load the upper part of the rear to the driver's side, in turn lifting the passenger wheel, and won't load it properly on accelleration.

By the way, f-bodies have the offset as well, from the factory. It was my understanding this is to create a straight line through the pinion gear, and allow the factory to use same size axles on both sides.


.

[andrewb70]

Originally Posted by HWYSTR455

Andrew - Are you sure the stock control arms have the offset? When measuring for wheel/tire fitment, in many cases, even with stock components, the offset has been present in all the cars I've dealt with. This, as well as there not being a listing for a left and right side control arm from the factory suggests that the factory ones aren't offset? Finally, I don't believe, or it's my understanding, that any minor offset to one side or the other would cause a vibration issue.

Maybe someone else can chime in, but if, the uppers have the offset as have been built into the ones you had made, AND it's not supposed to be there, won't is cause a wheel hop issue? My thinking: It will load the upper part of the rear to the driver's side, in turn lifting the passenger wheel, and won't load it properly on accelleration.

By the way, f-bodies have the offset as well, from the factory. It was my understanding this is to create a straight line through the pinion gear, and allow the factory to use same size axles on both sides.


.

I am quite certain that the stock control arms were offset. I have seen several sets and all have this feature. The reason there isn't a left and a right part number is that the stock control arms can only be installed on way: with the U-shaped channel pointing down. In other words, they can't be installed upside down. So there is no need to have a left and a right arm. All arms are built the same way and swapping them left to right makes no difference in relation to the offset.

You are correct in saying that a minor offset may not matter in terms of vibration issues, as long as the pinion shaft and the transmission output shaft are parallel as view from the top (or bottom).

I know that GM 12 bolt rear ends (which is what I have) use same length axles. That means that the pinion gear has to be slightly offset (towards the passenger side) in relationship to the housing. So it makes sense to have the housing slightly offset to the driver's side in order to line up the pinion with the transmission.

When I get back to my car and install these control arms I will be double checking the position of all driveline components.

I am open to all comments and suggestions.

Andrew

[HWYSTR455]

Oh yeah, duh on the different part numbers! Ok, strike one against me!

I'm curious about this latest topic, and really want to hear other's input too. I just disassembled my entire cutlass rear suspension, wish I would have taken all the measurements prior, and compared the uppers with the aftermarket ones. My LeMans has GW uppers I believe, and it doesn't have any vibration issue, and I've topped that thing out many times. I did have a pinion bearing go bad due to a yoke 'nub' being worn, and the u-joint not seating right, which vibrated and took out the bearing. Aside from that, no vibration though.

Explain the vibration? Specific speed range, or above a certain speed? And it's not RPM related?

.

[andrewb70]

Originally Posted by HWYSTR455

Oh yeah, duh on the different part numbers! Ok, strike one against me!

I'm curious about this latest topic, and really want to hear other's input too. I just disassembled my entire cutlass rear suspension, wish I would have taken all the measurements prior, and compared the uppers with the aftermarket ones. My LeMans has GW uppers I believe, and it doesn't have any vibration issue, and I've topped that thing out many times. I did have a pinion bearing go bad due to a yoke 'nub' being worn, and the u-joint not seating right, which vibrated and took out the bearing. Aside from that, no vibration though.

Explain the vibration? Specific speed range, or above a certain speed? And it's not RPM related?

.

I am open to hearing from anyone that wants to comment on this issue. The vibration occurs at high speed. It starts at about 75 mph and down not go away as you go faster. It is dependent on the driveline speed, not engine speed. In other words it will occur in any gear that will go to that speed and is also present if you pop it into neutral. By those symptoms the vibration is in the driveline, most likely the driveshaft. This vibration has been present with two engines, two sets of tires, three driveshafts, two pinion yokes (the latest pinion yoke made it a little better), two front brake systems, and two rear end assemblies. The other clue that tells me that it is related to the driveshaft speed is the fact that the vibration moved in the MPH range when I switched rear ends. The first rear had a 3.31 gear and now it has a 3.73 gear. When I went to the 3.73 gear the vibration started to occur at a lower MPH (but same driveshaft speed) as before.

I had a lengthy conversation about this with Frank at the Driveshaft Shop. He is a good guy and I have dealt with him on some custom axles for my RX7. He just got a new high speed balancing machine and has been doing a lot of work with several NASCAR teams. He seems to believe that a material change is in order to bring the weight of the driveshaft down. Stock a-body driveshafts are about 2.5" in diameter and are fairly light. Even though I have gone through three different driveshafts they have all been 3.5" mild steel, and pretty heavy. Frank believes that going to an aluminum shaft will solve the problem and a carbon shaft would be even better.

As I said, I am all ears if anyone else has comments or suggestions.

Andrew

[HWYSTR455]

Well, by the sound of it, it's certainly behind the transmission. Did you change slip yokes when you did the driveshafts? An out of balance driveshaft can eat up a pinion bearing pretty quick, fyi. You tried new pinion yokes, correct? And how does the yoke center the u-joint, with 'nubs'? And the u-joints are centered in the nubs correctly?

When you changed the rears, did you change the axles and rotors? Maybe a axle flange isn't true? And/or the rotor doesn't sit flush/true? Have you had it on a frame rack? 4 wheel alignments?

I have never heard of a driveshaft's weight being an issue when it comes to balance, and used a several different ones in the LeMans as I went from a Th400 to a Th2004R, then a 4L80E, none had a vibration or balance issue, and all were mild steel. I run 373s, and have had it over 150 mph more times than I can count, no vibrations. Did the same guy balance all your driveshafts? Maybe just for sake of elimination, try someone else?

.

[andrewb70]

Originally Posted by HWYSTR455

Well, by the sound of it, it's certainly behind the transmission. Did you change slip yokes when you did the driveshafts? An out of balance driveshaft can eat up a pinion bearing pretty quick, fyi. You tried new pinion yokes, correct? And how does the yoke center the u-joint, with 'nubs'? And the u-joints are centered in the nubs correctly?

When you changed the rears, did you change the axles and rotors? Maybe a axle flange isn't true? And/or the rotor doesn't sit flush/true? Have you had it on a frame rack? 4 wheel alignments?

I have never heard of a driveshaft's weight being an issue when it comes to balance, and used a several different ones in the LeMans as I went from a Th400 to a Th2004R, then a 4L80E, none had a vibration or balance issue, and all were mild steel. I run 373s, and have had it over 150 mph more times than I can count, no vibrations. Did the same guy balance all your driveshafts? Maybe just for sake of elimination, try someone else?

.

Each driveshaft was built by different people and I've had two different slip yokes. One was a Spicer yoke the other was a Strange Engineering billet yoke. The second rear end got Moser axles and I've installed new rotors. If it was an axle flange I suspect it would result in some serious, visible wobble at the wheel. I've run the car up on jack stands and have never noticed any wobble. I can easily double check this by checking the run-out, but I don't think that is the problem. If you look through some previous pages in this thread I discuss some other issues like driveline angles.

I have a new pinion yoke which uses 1330 u-joints and has tabs which position the u-joint. The u-joint fits snugly between the tabs. I am planning on getting a Mark Williams billet yoke.

Before I started building the car the frame was on a rack and there were no issues that were found at the time. It was straight, true, and square. I did have a 4 wheel alignment done at one time and they did mention something about the rear being slightly off. I don't recall if they said the rear was cocked or just shifted laterally. The lateral shift can be explained by the upper control arms being built wrong. If the rear was cocked, that would indicate either a frame that was out or lower control arms that were not the same length. I am using the GW lowers with heim joints at the frame and delrin at the rear housing.

Andrew

Is your Lemans lowered significantly?

[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.

.

[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.