nahasapeemapetalon

iTrader: (9)

I just put in 3.70 gears. Now it vibrates at 75 and up. I just had my new driveshaft balanced, still does it.
Any ideas what else would make it vibrate at higher speeds?

nighthawk15

Could it be the u-joints? Probably not the case because they weren't a problem before, but might be worth checking into.

Fotis

iTrader: (2)

warped drive shaft can cause it to

SLP Firehawk

iTrader: (9)

I Have The Same Problem Just Put In 4.10's And I Have A Bad Vibration At 70+ Checked U Joints And Drive Shaft. I Did Notice The Rear Has Very Little Pre Load On It For Some Reason When I Set Up The New Bearings The Preload Was About 55inch Pounds Now There Is Barley Anything On There

JSmee99T/A

iTrader: (15)

welcome to the club, im the president. Ive had one for almost three years after a gear swap. The place that put em in said they couldnt vibrate but i had one. I changed u joints, driveshaft balanced, then the tail shaft housing broke...soo i replaced the entire driveshaft w/ new yoke and u's, got a new converter/tranny, new rims/tires and the brakes have been changed (rotors/pads). I think i have a bent housing or axel shaft....time for a 9" or s60, oh i put subframe connectors on and it helped it but its still there.

nahasapeemapetalon

iTrader: (9)

You are the president!!
I think its something in the rear, but ill check the wheels next in case some weight came off. If its not that, ill try find a shop that can spin a driveshaft faster than 3400rpm and double check it. At that point its time to look into the rear!

BJM

iTrader: (1)

It is hard for the rear to cause a vibration since the diameter of the spinning parts is pretty small and everything is machined as opposed to formed (like a steel wheel). On my car I wound up with a vibration after putting in my 4.10s. I checked the yoke run-out with a dial indicator but found it was true. The driveshaft is perfectly centered by the yoke in the one direction. I found the driveshaft was perfectly true at the transmission, off by about .015" in the middle but the factory plastic locked U-joint is off by .030" from the factory at the axle. It has not moved so I concluded that this was not my problem.

I wound up changing tires and took care of 95% percent of the issue. I suspect that I am now just that bit closer to the shaft whirling speed. With 4.10s I am spinning the shaft 20% faster.

CW00BlackTA

iTrader: (31)

I had a yoke run-out issue which was about half of my problem and the other half was pinion angle. I had to get it to zero to -1/2 degree to eliminate vibration. Also, if your pinion is way off it will eat your u-joints in short order.

nahasapeemapetalon

iTrader: (9)

I may have to look into the yok run-out not sure what that means yet. WHeels were just balanced, still does it, doesnt get all that worse the faster i go.
The driveshaft was only balanced at 3400rpm....maybe i need to check with a higher rpm balancer?

kny3twalker

iTrader: (31)

damn and I thought it was just my car. I bought a 12 bolt last year with 4.10s, kept the stock driveshift, and installed a ES poly mount for the trans. I am at a loss to figure out my car vibrates when out on the highway.... I got some SFC that need to be installed and thicker sway bars as well. Hopefully some of this will help
I have thought about going back to the stock trans mount as well.

nahasapeemapetalon

iTrader: (9)

Adjusted the pinion angle (larger) rearend pointing down more and it remained, didnt improve. I guess I could have tried the other way towards 0. It didnt do it before so that makes me think pinion angle isnt it. THere wasnt any slack in the yoke on the rear. Very slight movement at tranny(yet again nothing there was changed) THe vibration seems more constant than fluctuating. The vibration was pretty equal at the rearend as at tranny(guy checked while car was up)
ANY HELP

CTSmechanic

iTrader: (2)

Yoke run out is common as well as runout in the pinion its self And can cause a vibration... theres many things in the differential that can and do cause vibrations regardless of what was mentioned earler in the thread ... 0.002 0.003 is what I let go anything else time to start changin parts you can clock the yoke differently on the spline and reduce the runout... http://circletrack.automotive.com/10...-handling.html heres the tool used for checking... there expensive... range in price from 300 to 1000 bucks

nahasapeemapetalon

iTrader: (9)

Driveshaft was only about 10 thou total run out. Guy was pretty happy with it that helped me.
NO slack in the pinion at all, still vibrates with tires off.
Its most likely something in the rear.

wht01ws6ta

iTrader: (45)

I started having vibration problems at any and all highway speeds after I broke the stock aluminum DS and went to a chromoly one. As soon as I installed the chromoly DS it vibrated so I figured it was the new DS but then had it checked for balance and it checked out fine. Went back to a stock aluminum DS and it is better, I assume because the aluminum is softer than chromoly steel and "soaks up" or dampens some of the vibration. Played with the pinion angle as well but didn't seem to help much. Ran car on the lift with DS unhooked and can't feel any vibration through just the six speed. Thinking it must be in the rear- maybe I messed up something in there or bent the U-joint on the rear a little before I snapped my DS or the pass right before. Really hoping a new 9 inch will do the trick!

txturbo

I would talk to a driveshaft company. I've heard of driveshafts flexing in the middle at high rpm. It may be that you are spinning the driveshaft faster than it was designed to with the new gears. You could try and verify this by packing a bunch of modeling clay onto the torque arm near the middle of the driveshaft.Build it up until its very nearly touching the shaft.Take it for a spin, make it vibrate and see if you can see where the shaft has made contact with the clay.

nahasapeemapetalon

iTrader: (9)

I took everything apart this weekend. Center section looked great and well within runout tolerances. I know its not the wheels, rotors, axles or driveshaft. Its much better now with a different pinion angle. I am going to make sure the angle is right then if it still does it ill replace the bushing in the output shaft of tranny.
Thats all thats left.
Seems that pinion angle was most the problem.

CTSmechanic

iTrader: (2)

With 3.70's I dont think flexing the driveshaft is the culprit... maybe just maybe in a High HP race car.... with lots of RPM... I have ran AAM Steel 4.5 shafts at close to 10,000 shaft RPM... with no problems... keep in mind once the critical stages are met with a driveshaft they usually dont last...

wht01ws6ta

iTrader: (45)

Glad that worked for you. what angle worked well? -1 or -2?

thebart455

thats what i was going to say the output shaft in the back of the tranny can cause the vibrations your talking about