I just did 4.10 install and I was nervous I messed up till I read about all the driveshaft issues after 80mph. I have a steel driveshaft, but the vibration wasn't there before the gear install, is this because the 4.10s make the driveshaft spin alot faster compared to 2.73s? Finally got my gears broken in and first highway run I get this horrible vibration EVERYWHERE, especially in the brake pedal. Only after install though, i have a aluminum driveshaft sitting in the driveway so I might spend 10 bucks on u joins and throw it in and try it, what do u guys think?

 

That can play a significant role in this new found vibration. Is it the stock steel driveshaft? They were notorious for vibration to the point of a GM implementing a technical service bulletin. I would definitely put the aluminum DS in place of the steel one.

 

I sure hope so, and yes stock steel from my auto, kept it cause i thought it was stronger. But my other one, I assume it's aluminum because it's from the parts car that I got my t56 from. The lt1 t56 came with aluminum right? Not just ls1 cars?
Thanks for the quick reply

 

The gm aluminum DS was only available in the 1LE package from the factory, IIRC. The TSB stated to replace steel DS with 1LE if there was a vibration. I had this done with my car when it was under warranty and still had to fight them on it even when I had the TSB number and printout in my hand. I could only feel it at 75+mph and they were saying I shouldn't drive that fast anyway. Once they finally caved they told me I was lucky to have it done because they would only do it for SS models. Retards.

 

4:10 will get you higher drive shaft rpm vs the 2:73. The aluminum DS may help but still you may see vibes at higher MPH. You would then need to find a drive line shop who could balance it. Also if the dust cover for the pinion yoke on the rear end has a small weight tac welded to it..that was for the stock DS assembly and you would need to remove that for the Aluminum one if you do experience any vibes with it.

 

Have had the 20 year old 1LE on the road course up to 115 sustained in the last month and no issues.
Switch to the alumn and be happy.

For drag racing, steel will be better, but you won't need to worry about that with the gears you put in. The 10 bolt with 4.10s will puke pretty soon if you get on sticky tires.
Compare the meat on the old gears vs the new to see what I am talking about.

 

I have 4:10's and the same issue. Mine starts around 75-85 and anything after it smooths out. I have a Denny's Nitrous Ready DS...Its annoying as hell, Ive been trying to track it down. At first I thought it was pinion angle since my car is lowered and I chased that around for a while. Pinion angle was always good, so I dunno

 

Bent wheel? Bent axle? Perhaps the DS is out of balance? Tire(s) out of round?

 

checked it all, Going to put some new rubber on the wheels and then a fresh re-balance. I'm thinking about taking the DS to a different shop and see if it is out of balance again. The last DL shop I took it too around 6 years ago said they could find nothing wrong with it.

 

Dennys is regarded as being one of the best DS. They are one of a few drive-line shops with a balancer big enough to spin the DS to 10k rpm.

Not saying it isn't the Dennys DS but more likely DL angle, tires,axle or even bent rim

 

Also have 4:10's, brand new Spohn steel ds, new wheels and tires and pinion angle is correct and have same issue. Is it possible to install a rear sway bar upside down? Just noticed it looks like it's on wrong.

 

Pinion Angle is fine, and within Specs. I went as far as starting at the front of the car and working my way back, I'm going back to square one and starting with a fresh tire balance and alignment. Checked my Axles when I took out my full spool and installed my Detroit TrueTrac. Went as far as to check them 3 times before I reinstalled them. I'm not a weekend warrior when it comes to turning wrenches and am currently working my way up to my ASE Master Tech Cert. I do this for a living, but anyone can be fooled by the simplest of things. Come Monday I'm shooting out an email to Denny's and see what they'll charge to check the DL. Going to have to break down and make my own flow chart for this Vibration issue! hahha


EDIT: I read someplace, that someone had a similar issue and it was internal the 5th/6th cluster gear became sloppy on the back of the main shaft in the tranny. Rebuilt it and solved the issue. Also someone else did all of this and fixed a similar issue at the same speed.


"-wheel bearings (not damaged)
-carrage bearings (damaged)
-pinion bearings (not damaged)
-pinion gears (some play 5degrees each way)
-drive shaft (straightend and balanced (damaged))
-corrected pinion gear angle( way out of spec)"

 

I finally fixed my issue, after installing 4 different driveshafts, 2 steel lt1 shafts and 2 ls1 aluminum shafts ALL had the same vibration.

i bought a new one, .125 walll aluminum with Spicer yoke, vibration is gone! I figured it was because all the driveshafts were tested and balanced the same way from the factory, so even though i tried difference aluminum ones, it made no difference because they were made to thesame specifications....its been a great day gentlemen, finally fixed my issue.

 

Im glad you got it sorted out. I have a Denny's Nitrous DS with a 1350 U Joint and Yoke. I was hoping mine was the DS but the DS shop I took mine to said it was balanced perfect. So it wasn't the issue in my case, I was hoping it was as that would have been a quick fix to the issue.

 

My vibration ended up being shitty Mickey Thompson tires i bought from Summit.

 

Id also like to note that after installing the shaft, i had the car in the air still and bround it up to speed and STILL got the vibration, i kept going to about 140 and the car seemed as if it was going to detonate, i had jackstands under the rear frame and the rear end was hanging...so originally after putting the new shaft in i was pretty pissed off and used plenty of colorful language, but on my drive home i went up to 120 and it was smooth as butter...very pleased..

saying all of this i believe that pinion angle has alot to do with vibrations, also be sure to set your u joint bearings (hit the housing with a hammer where the u joint is pressed into). I cant explain it but my father and his friend who owns a custom shop swears by it that it fixes alot of u joint vibration

i have dealt with this vibration for a long time. Definetly the most annoying issue i have had to date

 

I was fighting a similar issue after my moser 12 bolt install. I checked everything from Pinion Angle to my Dennys Nitrous Ready DS...took me s couple years. But it ended up being the 5-6 year cluster had worked lose on the shaft. They are pressed on from the factory and I guess it was a common thing for a while that they can work lose. Sent the shaft and cluster off to be fixed. The person doing it plates the shaft then machines it to 1.5 they are 1.46 from the factory I believe. It should fix my issue

 

Im sorry it had to be the most expensive part of the system there, that sucks! But im a little unsure of what u meant, im working in a machine shop makeing tools for aerospace, and its not easy or cheap to machine something "larger" they may open up the gear inner diameter and press a sleeve in there. Im not too sure as this isnt my specific field. But im pretty certain they cant make that shaft bigger.

however after further testing my vibration has changed....it seems to be most prominent at the top of 4th gear, going away as i shift, which is alarming, however when i approach 115 to 120, it comes back but not nearly as bad as before...my trans came from a beat to **** 4th gen trans am, was told there was upgraded shift forks in there and the trans was "freshened" either way i was told by a few mechanics thats the trans shifted very well, i feel it still shifts great, but i may be missing something other than the vibration, maybe it comes strong on the top of 4th because the ratio is 1:1 so the driveshaft is spinning the same as my rpms? Is that correct?

 

Id like to add that the vibration is much more bearable and certainly am satisfied with the progress in the right direction.. sometimes i wonder if i expect too much from these old fbodys...can they really drive as smooth as i want!