vibration from rear above 60

-
thrust angle is off less than 1/4 inch. Took u joints apart at the driveshaft shop (all good) Installed new u joints (no help) While on the ground level the yoke is out of the tail shaft 3/4".
 
Hey Sam, sorry I missed you at the Mopar show, I seen you signed the banner!

You said you have a snubber? Is it adjustable, If so what setting do you have it in? My car had the same vibration at 60 mph, but it went away at 65-up. Not real bad but enough to bother me. All engine internals were balanced, rebuilt 4-speed trans and new driveshaft, rebuilt 8 3/4 rear with new SS Mopar springs, new MP drag shocks with a MP adjustable snubber.

Had driveshaft balanced (at 2 different shops) and it was spot on, u-joints were like new too. Still had a vibration. My rims are not bent and tires are balanced perfect. For the hell of it I dropped the snubber down (I had it on the top setting) and the vibration is almost gone!! I think it was making constant contact with the floor on the top setting and the vibes were transferring from the road through the car. But on the top setting is the only way to prevent wheel hop on my car. I never checked pinion angle when I put it together but probably should. But by just adjusting the setting on the snubber it helped alot with the vibes. Not sure if this helps but thought I would pass this on...good luck!!!
 
Lot of names on the banner already. Took the snubber off last night. same issue
 
Eventually they'll listen.... i've only been doing this forever.

Many many driveline shops use a hines balancer, great for shafts for street cars that are dd, not performance stuff, those machines have limitations and the operators 98% of the time just suck...
the shops here local to me all have the hines machine and i constantly fix there shortcomings.

66340 has the same problem, that pin snubber is not your 5 mph area vibration....

You both need balancing... a new shaft isn't the answer, and if you do get a new shaft, do it in AL not stl...

You'll thank me later
.

1350 series isn't going to make anything better, is it stronger? yes is it needed? no

.

If the shaft you have now isn't right, what makes you thing the new one will be better... try another local shop
 
Since I have been fighting the same battle as you i am down to the pinion angle being the problem. i measured today and noticed I have a nose up of 3-4 degrees. Cant remember if you took your measurements. I am starting to think that since I am nose up at the pinion that when I apply some torque it is forcing my ujoint to slop. Any luck adjusting your pinion angle?
 
emnestor said:
Since I have been fighting the same battle as you i am down to the pinion angle being the problem. i measured today and noticed I have a nose up of 3-4 degrees. Cant remember if you took your measurements. I am starting to think that since I am nose up at the pinion that when I apply some torque it is forcing my ujoint to slop. Any luck adjusting your pinion angle?
Click to expand...
you should be 3-4 down you mite be binding your U joints..........Artie
 
You know you guys have 2 of the most smartest mopar guys anywhere telling you your shaft wasn't balanced properly ,so why are you still talking about pinion angle etc... find a shop that has the machine and expertise to balance your shaft at the RPM it will be used at and a little beyond and be done with it already .
 
The problem I'm having is I don't want to spend a bunch of cash having a stock shaft shipped somewhere to get balanced correctly. I am to the point were I would like to have one built that I wont ever have to worry about. I know 1350 joints are over kill but if I break a shaft there is a lot of things to take apart and check (trans sprag, rear end, etc) Also something about being a mopar guy that more power is always needed! So how much $ is it going to cost to have one of you or a shop you recommend build me a aluminum shaft with 1350's? By the way I tried swapping leaf springs just for kicks and took it up to 90 mph on jack stands and the vibration went away. so 60 bad, 70 worse, 80 holy crap, 90 smooth.
 
Wow Skep, you've done just about everything you can do. As long as it's not in the carrier it must be harmonics in the shaft. Alum. would be nice and chromoly would be a option also for a new shaft. Been many years since i had one built, but today you're probably talkin' 3 to 400 large. Man i hope you get this worked out soon so you can spend time on the street and track and not worrying about this crap.
 
In my case...my new drive shaft may still need to be balanced on a machine capable of higher rpms but with the pinion nose up 4 degrees its still gonna cause me problems.
 
godfatherofchry said:
you should be 3-4 down you mite be binding your U joints..........Artie
Click to expand...

emnestor said:
In my case...my new drive shaft may still need to be balanced on a machine capable of higher rpms but with the pinion nose up 4 degrees its still gonna cause me problems.
Click to expand...

If your 4* up at rest, under launch conditions your approaching the "breakin' something" range....imo.
 
Before going and spending a ton of money. check your pinion bearings. If the chrome has come off the bearings. It can give you a nasty vibration with out the noise. check both races and were the bearing rides on. clean well with brake cleaner so its more visible.
 
swapped 3rd members last night to the 741 3.23 open. Vibration GONE!!!!
Brought 742 3.91 sure grip in to work today to take apart. Took it up to 100 with no vibration.
 
Interesting! I also have a 742- with 3:91 sure grip. Please let us know what ya find.
 
skep419 said:
swapped 3rd members last night to the 741 3.23 open. Vibration GONE!!!!
Brought 742 3.91 sure grip in to work today to take apart. Took it up to 100 with no vibration.
Click to expand...

Hopefully you fixed it but keep this in mind. With the 3.23 gearset your rpm was A LOT less than the 3.91's were so you just may not have been spinning the shaft fast enough to get it up to the rpm where it vibrated. You might try putting it back on stands and spinning it up to as fast as it'll go and see if the vibration ever comes in. If it don't vibrate at top rpm that's great. Tear that 742 apart and let us know what you find.
 
Took 3rd member apart all good. Took pinion to victory engines. .003 run out. Put it up on stands shakes like a bioaach. Evidently on my 100 mph blast I shot past the shake zone like a cheetah on cocaine. Driveshaft! Who would of thought. Note to self don't get your hopes up on inexpensive fixes.
 
.003 run out on the pin gear ? at the front pin bearing ground hub surface there was .003 run out ? and with the end yoke bolted to the pin the run out at the ground hub surface of the end yoke the run out was .___ ?
 
.003 run out on the pinion at the front pin bearing ground hub surface. never measured it with the end yoke bolted up.
 
Very important how it was checked, the bearing centers the pin, so using the bearing surface to check the ground hub surface at the end yoke would tell you if there was an effect at the shaft
 
the threaded side was locked in a lathe. used the hole in the center of the gear side to hold it in place while spinning by hand.
 
You must log in or register to reply here.
-

Back
Top