Soooo, what to do now. I decided to compose a couple emails and send them to people who have more experience in this arena than I do. I wrote a couple emails that looked like novels and sent one to Dan at quad4x4. I have had great luck with everything that I have purchased from him but more importantly, I have never been able to stump him with any question I have asked of him. He responded back with some quality information and helpful suggestions. I checked a few of the things out and while I was doing that I got a response from my second email that I had sent to Jess at High Angle Driveline.
Jess' response was basically one sentance stating that he knew what my problem was and that I needed his patented drive flange and a double cardan shaft. He guaranteed that this would solve my problem and while I have no reason to doubt the master, I still wondered why. I gave him a call and he spent a fair bit of time on the phone with me explaining the situation. He said that the problem I am having is called gear rattle. It occurs when the joints operate over eight degress and they create a oscillation in the shaft and the shaft will push the oscillation out into the transfer case or into the ring and pinion. I had not told anybody that the vibration under decel sounded like the ring and pinion was coming apart, but he told me that it was--I was very impressed.
Anyways, I ordered up a 1350 series double cardan shaft assembly and a a week or so later a box showed up. Inside the box was one of these:
I had to change the pinion angle that I had just installed, so out came the new diff. I decided to get new perches so I wouldn't have to cut these off again and re-re-weld them on. I got the new perches tacked on and the axle temporarily re-installed. I installed the output flange on the transfer case and installed the driveshaft. I finalized the pinion angle two degrees down from the driveshaft and welded the perches on and installed new u-bolts. I got the shocks re-installed and hooked the brake lines back up. It was time to go to work and I knew there was no way I was going to be able to get work done efficiently thinking about this thing sitting at home in the driveway, so I decided to take it on a test drive to work--all or nothing.
So I did a quick transfer of all my rain gear from my S10 back into the Suburban (it wasn't needed, but if I didn't have it, it would have poured), grabbed my lunch and jumped in. Now, from the get-go, the biggest pain of the vibration has been that it occurs at 60mph and higher. That means that no matter what I try I have to drive it atleast 60mph. Now, the only place nearby to drive that fast is the freeway and there is no getting on slowly or taking your time getting up to speed. With that in mind, I get on the freeway as gingerly as possible. I get up to speed and merge on and all seems well. I play around in the range that I think it should be in (at this point I have not gotten my speedometer recalibrated for the 3.73's) and all seems well. I get to work and am fairly pleased and I believe the vibration is gone, but I want to be sure so I reserve judgement until the ride home.
I get out of work and and quite anxious to drive the truck for some reason. I get on the freeway and all seems well. I roll into and out of the throttle and it seems good. I run it way past where the vibration should have been and all is good. Then I run it way up and let off abruptly and it coasts down smoooothly and quietly--all is good--life is good!!
Yessir, all it took was a gold-plated driveshaft to fix the problem. Now, there is nothing wrong with my previous driveshaft--nothing at all. It just happens that he length, diameter, angle and any other variable added up against me to create an issue. I have seen drivelines with much more angle run smooth as can be--why did I have a problem?? Basically it came down to bad luck. An identical truck might not have ever had an issue while mine did. One Blazer with a driveline that practically hangs straight down has no isssues while the same setup in an identical Blazer vibrates like all get out--luck of the draw.
So me and my boy head out for an extended test drive. We head about fifty miles east to an antique tractor show and the whole drive is absolutely wonderful. Worth every penny of driveline and 3.73s. It is so nice to drive now.
So the vibration is gone and all is well right?? Well, sort of. I developed a new vibration. Are you getting tired of vibrations?? I sure am.
Near the end of our journey back (on our way to our second destination of the day--still on a freeway) I picked up a
horrible grinding type very deep vibration. WTH now?!? I tried a few things to see if it affected the situation at all. I tried accelereation, braking, swerve right, swerve left and nothing affects it. The wierd thing about
this vibration is it is intermittent--yes it comes and goes. After driving for a couple miles while trying to get on the other side of a mountain to where a good friend lives, the vibration stops--smooth sailing. Huh?? Gone?? Yup, gone. How, why, what...?? I hit a bump--an expansion joint at the leading edge of a bridge--and it is back in full force. Huh?? How?? Then I hit the expansion joint at the far side of the bridge and it is gone--just like that--GONE!! Huh?? How?? It basically repeats this scenario over every bridge/overpass. No worries as there are no mile long bridges or anything, but the problem comes in a single bump that has no partner. The bump kicks in the vibration, but there is no second bump to "turn it off".
Anyways, I get to where I am going and on the way home on surface streets I get no vibration at all. Is all well?? No. On my way
home from work (not to work, but from work) just before I get to my exit, just after hitting a bump it is back in full force. Swell. Same thing the next day, but it came back about a mile sooner, but not enough to diagnose it. Hit one bump and it is on, hit another bump and it is gone. Now I am to the point I do not want ot drive this thing on the freeway or any distance far from home for fear of this thing going crazy, but I have to drive it 10-12 miles to get the vibration to occur.
So, here I am. Everything works fantastic--except whatever is causing the current vibration. I checked my mileage for about 175mi of driving--some highway and some city with a corrected speedometer and netted 19.55mpg without trying--just driving normal. So, with that, I am pleased. I hope to pass twenty soon, but we'll see.
Any guesses on the latest and greatest vibration?? The winner will get a cool prize!!