Just had Truetrac installed, now feel pulsing vibration when driving?

Just had my Detroit Truetrac installed in my truck yesterday, and on the way to work this morning I felt a sort of pulsing vibration in my truck that I didn't feel before install. Anybody have this issue?

 

I did not notice any difference in feel coming from my truck after my install. No new vibrations. The only slight vibrations I feel at low speed are due to my tire tread. You're likely hyper sensitive to the rear end right now having something new installed and trying to 'feel' it. Call the shop that installed and ask them or shoot ECGS a call with your concerns. I was told there is no break in period per se for the truetrac like new gears have (heat related). It might just be a little tight still and need to loosen up though. As soon as I had mine installed I took it on a 3 hour drive down the highway. Have not had any vibrations specific to the rear end as you state you might have.

 

I would say I was doing 40-50 mph.

 

Yes I saw that it didn't need a traditional breakin per se, but I'm gonna take it easy on it for a while so the new bearings have a chance to breakin, and the truetrac gears can mesh together. As far as I'm concerned any new parts need some sort of time to break in. I also saw they don't recomend sythetic fluid. Anybody know why?

 

I had no choice on the 3 hour drive...had to get home after install, but good break in I suppose.

Apparently the synthetic is too slippery and can affect the torque biasing/gear meshing/limited slip abilities. But maybe you could change the oil weight and compensate. I just plan to stick with regular gear oil that has worked and performed for many miles and just change it every 30-45K or so.

I do know that my rear end felt 'tighter' the first week it seemed (no vibrations though) and it's all good now. It could have all been my imagination though.

 

So I went and checked the alignment marks on the driveshaft, and everything looks right. There's definitely a vibration, I felt it coming back home, but don't seem to feel anything until about 45. Then there's a pulsing vibration in the truck. Maybe my tires lost a weight and are out of balance? I have offroad tires, so I get some vibrations at reall low speeds, but before the truetrac install, it was really smooth. No vibrations

 

Did they do anything to change your driveline angle ?
Was the diff tilted or shimmed . Were the tires rotated ?

 

Nothing that I can tell other then it sliding into itself to take the carrier off. There's no shims, and I don't see what they could have done to change the diff angle. They shouldn't have had to rotate tires, but who knows. I guess I'm gonna have to wait till Monday now. The shops not open on the weekends

 

The TruTrac does not require 'LSD-type' oil, just regular 80/90 gear oil without any additives. What did the mechanics put in?

Make sure the tires on that axle are inflated to the exact same pressure, and are the same diameter.

 

I told him no additives, so he put in whatever is recommended by toyota

 

So I just took a little drive down the highway and around town. There's definitely a bad pulsing vibration(ie, on, off, on, off)about a half second between each pulse), between 45-55 mph. Below that I really don't feel anything out of the norm(which is probably why I didn't notice it on the way home, I didn't go over 40), and once I hit 60 it was barely noticeable. I also noticed a few times today that shifting from reverse to foward was unusually harsh, kind of a thunk feel. Nothing like this was happening before the Truetrac install, so I don't see how it would be related to anything but whatever they did. Called the shop that did my installation, but they're not open on weekends so I left a message and hopefully I get a call back Monday.

 

Things I'm thinking are center bearings or u-joints, although I don't know why it wouldn't do it before install, or some bearings they messed up in my diff. Anything else anybody can think of to bring up to the shop?

 

Only other thing I can think of, is the drive-shaft might not be assembled properly.

The main shaft has two pieces, that are allowed to slip via a male-female spline joint as the axle goes up and down.

The driveshaft assembly has to be disconnected from the diff flange naturally, but if the splines pull completely apart, it needs to be re-assembled exactly the way it was. Usually a mechanic will mark the spline joint on both sides before pulling apart, and line the marks up again when re-assembling. I think its a balancing issue.

 

Ok, I'm pretty sure I know where you're talking about. I'll make sure to mention it. I looked at the flange and you can see a yellow mark that lines up with the mark on the driveshaft, but maybe they put the 2 piece driveshaft together wrong? I gotta figure it out cause it sure is annoying. I was gonna double check my wheel balance today but walmart had a 2 hr wait and I wasn't sticking around that long

 

I did some googling and found this writeup :
http://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml

I don't think it mentions the splines, but its a good tutorial.

 

I never knew there was so much into drive-shafts haha. It is a good read. I will also mention that when I let off the gas while its vibrating, it doesn't stop. I have not tried neutral to see if that makes a difference.

 

One more question, Tan4x4. You ever get into an off camber situation where the truetrac doesn't work, and the diff starts to screech when the one wheel spins? I did it last night to test out the e-brake trick, and I got out fine, but when the 1 tire was spinning it screeched real bad for just a couple seconds before I stopped the tire spin

 

The thunk when shifting between D and R might be the backlash being too loose/sloppy/wide. There shouldn't be much "play" when wiggling the pinion flange back and forth, as backlash is usually set a touch tight to compensate for break-in of the gears (once the settings of a used set of gears has been changed, the gears will need to wear-in again).

 

Shop owner called me this morning and he said to bring it in. I'll be goin Wednesday as that's the earliest I can get there. He's gonna flip the driveshaft 180 and see if that solves the problem. He said usually they mark the driveshaft, but he's wondering if someone forgot to mark it, or missed the alignment marks. Either way, makes me wonder what else they forgot