What driveshaft for vibrations?
 

Hey all. I have been having driveline vibrations for a while. 70 theyre ok but annoying, 80 they start getting bad and anything 90+ feels like im going to break something. Im really at wits end with this problem and it makes the car way less enjoyable and I have been finding that Ill make excuses NOT to drive it which sucks because it used to be a lot of fun to drive. Before anyone asks, the vibes have gotten progressively worse the more Ive modded the car. I think these cars have vibe problems from the factory and they use all that soft stamped steel shit to mask it and once you start adding these stiffer parts it just amplifies stuff you couldn't feel before. My suspension setup is bilsteins, Hotchkiss springs, UMI adjustable torque arm, lower control arms, UMI rear sway Spohn front sway. My question is, what is the best driveshaft for vibe reduction? I would assume carbon fiber but that's out of my price range, so I would be between steel, chromoly, or aluminum. My other option is adding a double cardan which apparently acts as a CV joint and eliminates the need for the front and rear joint angles to be exactly the same. Some input from you specialty driveline guys would be appreciated. I really want to start enjoying this car again. I want to be able to take it on long highway trips and sip an open cup macchiato like Jean Gerard from Talladega nights...not really but you get the idea. Thanks in advance.

My stock WS6 is dead smooth even at 120 mph. I'd say if your vibrations started when you started modding it things are not setup properly. Ya know the factory doesn't just toss a bunch of parts together and sell it as a car.

Yeah mine was smooth as can be stock as well. I know they don't just toss parts together, but everyone I know with an fbody has driveline vibrations no matter their setup after they start taking out the weak stock components so it seems to me as the vibes are there they just aren't apparent until you take out the give of all the stock crap. I have played around with the pinion angle a bunch of times and it never made a difference. Sometimes it got a little better or worse but never went away.

You need to make sure your pinion angle is correct seeing how you put aftermarket parts on your car.

What kind of trans mount are you running? I've been down this road before and the oem trans mount is the only one to use. Your much less likely to break it with polyurethane motor mounts anyway.

^^^ this right here.

I installed my new Strange Drive shaft and transmission yoke on mine and below 70 no issues go higher and I swore something was vibrating lose.

Called Strange and they had me recheck the pinon angle, I was out by 4*.

Made my adjustments on my adjustable torque arm and several test drives later smooth as glass.

Thanks for the responses guys. I know my pinion angle is off but no matter what i do or how I measure it I just can't seem to get it right. Probably doesn't help I don't have a drive on lift but I do put the car on 4 ramps. Either way it's hard to get it right with the exhaust resting on my face. I had the poly trans mount and it was terrible I went back to stock. So you're all saying it's angle related and just go regular shaft?

Get 2 angle finders, Place one on the drive shaft the other on the pinon.

You need to adjust them to where they zero each other out. For example if the driveshaft is -2* the pinon should be -2*.

that would be the first thing to check. Have you had the balance on your driveshaft checked? U-joints in good shape? Your LCA's, do they have bushings or are they heim joints?

ive never tried that method but that sounds simple and pretty easy I'll try it thank you!

Well my driveshaft was in good shape it was a strange 3" chromoly to link up to my Dana 60 long story short I cut it to weld in what I thought was a double cardan turns out it wasn't the right type so now it's a paper weight and I need a new one but before that it was only a couple years old with maybe 10k on it. I'm now wondering about the balance of the shaft though. It came with tiny little thin weights welded on, but when I shortened it (took 3" off) and got it balanced they put these much bigger thicker weights on. So I'm wondering if it wasn't balanced that great from strange. Also my lower control arms have bushings and

You're using a double cardan joint on one end of the shaft?

I was thinking about trying to run one this way my angle problems won't be as apparent at least in theory

Exhaust efforts to solve the issue using a conventional driveshaft, because other options get expensive and may make the issue no better, or worse. There also harmonics, balancer, and wheel balance issues that can contribute to vibration.

To eliminate the driveline as a cause though, I'd get my angles opposite but equal in side view, and use a long straight edge down the casting marks of the transmission and diff to find out if my driveline components are parallel, or on the center line with each other in top view.

I'd be leery of doing a double cardan joint, unless both ends of the shaft are using them, or I know for sure the output shaft and input shaft are on the center line in top view with each other.

When using a double cardan on one side, the single u joint side cannot have any angle between the shaft and the yoke, in either plane. If you have an angle on the single u-joint side of the shaft you'll end up with vibrations, among other things like worn bearings and leaky seals.

If you have to go with constant velocity joints, because of unsolvable angle issues, Driveshaft Shop makes shafts with rzeppa CV joints on both ends of the shaft. Double cardan joints, unlike actual constant velocity joints, split the difference in angles, but still have variations in velocity when at an angle. Additionally, Driveshaft shop can make, slip yokes, and flanges to make them work in many applications.

Thanks for the informative responses sir. Unfortunately not only is that driveshaft from DSS out of my price range I also am not a huge fan of DSS from past issues. I think I'm going to go with an aluminum shaft from Midwest chassis as in theory the lighter shaft will transmit less vibes? I will also try to get my angles setup correctly somehow.

Hey, I thought I was the one that said you should check pinion angle LOL. j/k

OP - Check this out The crankshaft and pinion should be aligned for smoothest operation. The angle between the pinion & driveshaft doesn't mean much.

I read the early post about using the driveshaft as a guide for setting pinion angle and wanted to find that video. Good stuff there

I usually put the digital angle finder on the crank pulley, zero it out and then just zero out the pinion. This makes the engine and pinion angles the same but opposite cancelling each other. In an f body I'm not sure I go crazy on pinion angle since under power the diff might not move much upward, but my 4 link chassis I'll set my pinion down 1-1/2 degrees or so

Once pinion angle matches the engine/tranny, this is when you find the working angle of the joint by placing it on the driveshaft and measuring the balancer again if you have already set negative preload

Ride hieght, affect angle a lot and if the working angle is more than 3*, you can shim the tranny up or down, or vary ride hieght to get it working

Having an issue myself. After installing the tubular torque arm, panhard, LCAs, sub frames and trans urethane mount, I was fine. Abandon my stock aluminum drive shaft for a stock steel unit because I wanted to launch the car at the track on slicks and I ended up with a vibration that starts at 70 and gets worse at 80, then even worse from there.

Had a custom built steel drive shaft made. Even worse.

Back to stock aluminum, the problem is gone.

Going to have a aftermarket aluminum DS shortened and see how that works. Supposed to be good for 600 HP.

Best DS for reduced vibrations is carbon fiber. Yeah it's expensive but how about compared to three different iterations of driveshafts?

I'll stick with the hope that 180$ to shorten this aftermarket piece and it will not only fix it but not break should I run at the track. Unlike most normal people that have 1-2 vehicles, I have 7. The extra cash I'll save will go to my 89 coupe I'm building at the moment. It is more of a racecar so it would get a carbon DS well before the 02 SS would.

i purchased an aluminum driveshaft from Midwest chassis. I'm going to install it, adjust the pinion angle a little and take it for a rip on the highway tomorrow. Hopefully ill be pleasantly surprised.