still have a vibration... - Lateral-g Forums

MaxHarvard · #1 05-07-2007, 07:22 AM

... this time is not so bad, just above 65mph+... doesnt matter what gear.. 4th, 5th or 6th... 6th is worse though.

Doesnt matter if i'm on the gas, off it...

i did replace the motor mount, got it aligned, and had the drive shaft rebalanced.

Any other thoughts?? I measured the drive shaft angle to see if that was it, the pinion is pointed 6-8* lower (the correct direction) than the drive shaft.

EDIT: The vibration seems to go in waves, quick waves... shuddering strong to light over and over again.

Clockwork · #2 05-07-2007, 07:37 AM

I replied on the PT forum as well check it out. Check out vibratesoftware.com tons of reading. I believe your pinion should be parallel to the crankshaft/trans angle under load. So if you trans angle is 3* down then your pinion should be 3* up. Also while doing those angles your driveshaft to pinion/trans angles should not be more than 3* and no less than 1/2* for the u joints to work properly.

**Steve Chryssos** · #3 05-09-2007, 08:01 AM

Vibrations come from wierd places including the water pump, fan clutch, flywheel or flexplate and tire balance. Try raising the car a coupla inches off the ground with stout jackstands directly under the rear axle--BE SAFE!!

With the hood open and some frieds standing at strategic places, bring the revs up slowly and in steps. If nothing else, this exercise serves as a great way to rule out the obvious.

**camcojb** · #4 05-09-2007, 08:27 AM

6-8 degrees is too much in my opinion, except for certain drag cars. Get it back to 2-3 degrees down and see how it is.

Jody

MaxHarvard · #5 05-09-2007, 05:26 PM

Thanks guys... i'm currently trying to debug the car as i type this...

From what it looks like, i have a combination of MANY minor problems. I found a tire that was out of balance by 2 oz. Which i was told was ALOT. I also had it aligned, found a broken motor mount and balanced the tires. I'm going to take it for a test drive after i put the tires back on.

My next plan is to tighten up the steering box, there is some play in the steering wheel. If the wheel is pointed at 12 o'clock, i can feel it grab about 11 and 1 o'clock. Yes, all the front end parts have been replaced, so i know that the front end is tight and all that is left is the box.

Then, (if that doesnt work) i am probably going to lower the rear end. The front end has been lowered 2.5-3" and the rear is in the stock location.

If after all that... well... i hope that does it LOL.

**clill** · #6 05-10-2007, 08:23 AM

That is all good but re-read Jodys post above....

ProdigyCustoms · #7 05-10-2007, 09:23 AM

Listen to Jody. I went form 2 degrees negative to 4 degrees in one of my race cars and lost 2/10th of a second and gained vibration. most U Joints are only good for 12 degrees, your past half way to their limit.

MaxHarvard · #8 05-10-2007, 05:51 PM

Yes, this is very true... if i lower the rear end, that should change the driveshaft angle... correct?