Fireball

iTrader: (21)

I have a chassis engineering TA. its solid mounts on the rear and to a x-member that bolts where the g-load brace used to.

I'm having some hellacious vibration at 65+ mph.

Here is what I did to set the angle:

jacked the rear of the car and supported the rear with jackstands (to load the suspension. Partially jacked the car under the engine cradle to almost level the car so the CG was about right. Measured the angle of the output shaft of the tranny (used the engine oilpan...it appeared to be parallel with the output shaft). It was 4 degrees up towards the tranny tunnel. Measured the rear angle (at the yoke...its a 9" ford so its hard to find a level surface). It measured 4 degrees down toward the ground. This makes the 2 centerlines (tranny and rear) parallel with each other (net of zero pinion angle. This is a neutral setting which shouldn't induce vibration I think. But I still get it bad.

I run an A4 OEM steel driveshaft...but it didn't vibrate too bad with the factory torque arm. Is it possible that the factory torque arm with rubber mount dampened most of the vibration of an out of balance Driveshaft?

I've tried all kinds of pinion angles while the car was jacked up and it still vibrated (with the tires in the air) at the same rpm (65+)

Can someone concur that is truly a driveshaft problem (out of balance, bad ujoint, etc)? I'm ready to replace it with a dennys HD driveshaft if this is the problem <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

TIA

Nine Ball

iTrader: (38)

If you have already tried various pinion angles, then its not the pinion angle. Gotta bet on the driveshaft with this one.

I ordered a Denny's Nitrous Ready 1350 setup last monday <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

PS, they prefer not to sell the HD one to F-body owners. They feel this setup isn't adequate enough for 11 second and quicker F-bodies. Denny himself will gladly give you his opinions, he was very helpful and friendly on the phone.

Tony

XtraCajunSS

iTrader: (2)

I've found that for every rubber bushing you change in the driveline, you will start to feel more of what you driveshaft is really doing. I agree with Nineball try a different driveshaft.

As far as setting pinion angle, I really prefer to use a drive on lift so that the body of the car is level this better represents the actual dynamics of the vehicle (i.e. weight distribution)

Hope this helps,
Shane

Fireball

iTrader: (21)

I was gonna dial it in on a drive on lift but I was trying to get it "close" first.

Ok...nitrous ready it is I guess <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

RaceLS1

That torque arm has no provision for fore/aft movement with suspension travel at the front of the torque arm it is solidly mounted. That is the cause of your problem....BIND.

Fireball

iTrader: (21)

even with the car jacked up and suspension loaded...it vibrates....No suspension movement at all and it vibrates....

I doubt bind is the cause <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />

not saying it isn't binding...but I don't think its whats causing this particular vibration <img border="0" alt="[chug]" title="" src="graemlins/gr_chug.gif" />

Furthermore:

From spohns site:

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Unique rotating front torque arm mount, this system allows the torque arm to travel fore/aft which is VERY necessary with a torque arm suspension system. Solidly mounting the front of the torque arm causes the suspension to bind and hurts your car's handling drastically. </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">It don't say anything about vibration <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Rod ended version utilizes a chrome-moly spherical rod end front mount for the ultimate in bind-free performance and strength. </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Mine does have these spherical rod ends though <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

somthing else...someone else local has this same bar and it don't vibrate like I'm getting...but he has an aftermarket DS due to the fact he has a T400 <img border="0" alt="[devil]" title="" src="graemlins/gr_devil.gif" />

<small>[ April 08, 2002, 08:37 AM: Message edited by: Fireball ]</small>

Fireball

iTrader: (21)

sweet...local driveshaft company builds 3.5" steel Driveshafts with 1350 ujoints and hardened tranny yokes for under 300 bucks dynamically balanced (comparable to the Nitrous extreme DS) <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

2 hour turn-around...should have it by tomorrow <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> (taking dimensions tonight)

Fireball

iTrader: (21)

LOL...I was looking at my OEM torque arm the other day...where it bolts the the rear, those holes were SEVERELY egged out <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

As a matter of fact, the rear most hole was so egged out, it actually BROKE <img border="0" alt="[chug]" title="" src="graemlins/gr_chug.gif" />

Guess I'm stuck with this new arm now <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />

Fireball

iTrader: (21)

Woohoo <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

New driveshaft is in...no more vibration <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

rich

Is the new drive shaft shorter than the old one it may have benn bottomed out in the tranny? Glad to see you found the problem!!Rich

Fireball

iTrader: (21)

its about 1/4 inch shorter or so I believe...

but bottoming out isn't an issue...I had this vibration with the suspension fully loaded on jackstands too...this is how I verified that the vib was gone...haven't really tried it out on the street yet...but its DEFINATELY better <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

spun the driveshaft up to 9000 rpm (4500 in 6th gear) and vibration was only starting around there with the new DS <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

No Patience

HoLy ****, 4,500rpm in 6th on jack stands talk about if that thing slips off doing a knight rider imitation thru the back of the garage! <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

Fireball

iTrader: (21)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by A hick from Beaver County:
<strong>HoLy ****, 4,500rpm in 6th on jack stands talk about if that thing slips off doing a knight rider imitation thru the back of the garage! <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Haha..figuring that it was barely throttled in 6th gear...the minute it hit it probably would've stalled <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />

Anyhow, drove it today...its definately gone driveshaft WAS the cure <img border="0" alt="[chug]" title="" src="graemlins/gr_chug.gif" />