View Full Version : vibration, your thoughts??


rpmauto
06-28-2009, 08:35 AM
I guess i just am curious what some of you think is going on. Last monday nite i switched my 3.73s for a set of strange 4.11s in my strange 12 bolt. Before the switch i had no issues. I made a short drive the next day and had no issues. That nite i took it out for a longer drive and it started grinding going into 5th on the upshift, no problems on the downshift from 6th. I also have developed a vibration ONLY IN 6TH ABOVE 65MPH. It isnt a bad vibration, i can tell it is there and it pisses me off. I does not do it in any other gear at any rpm or mph. So i am thinking it is the tranny. I know the tranny will have to come out to get the 5th taken care of. I pulled the cover on the rear, backlash is still perfect, gear contact is just the way it should be. (i made damn sure i set the rear up just right.) Has anybody else had this issue?? I dont want to beleive it is the rear. I think i need to get more miles on the gears, and get the tranny fixed before i condemn them. Let me know what you think.

Gen414
06-28-2009, 10:30 AM
Have you checked your tq arm bolts? Known to loosen up sometimes,and since you jsut did the install, maybe did not tighten them? Driveshaft problem possibly. And yes, it could be a problem inside teh tranny, but kind of weird that your tranny shifted fine BEFORE the gear install, and now it shifts bad AFTER :confused: I would think it would be more rear end/driveshaft/tq arm.
Is your tranny due for a service? If so, go ahead and drain teh fluid to check for contaminents. If not, I would start out back...tq arm driveshaft rear end.

Once you make sure tqarm is bolted up and tightened correctly, maybe you can borrow another driveshaft from someone? Also, did you check pinion depth when you did teh gears? Or did you jsut check backlash on ring gear during install? Did you reuse the shim from teh 3.73 pinion on teh 4.11 pinion? What pinion spacer did you use? Steel or crush?

rpmauto
06-28-2009, 12:27 PM
well, the t/a bolts are tight, installed the 12 bolt 3 years ago and have never had an issue. The driveshaft is new this year a pst from epp. Had no problems with it before. I drained the fluid from the tranny and it was like new. No chunks of blockers or anything. As far as pinion depth goes, i took the shims from under the rear bearing on the 373s and used that on the 4.11s. Everything looks to be meshing well. And yes i thought it was strange that everything was fine before, then after the gears i have problems, but It has to be coincidence(spelling) at least with 5th gear grinding. That is a tranny issue and i would assume in no way related to the rear end. Would a bad blocker on 5th make a vibration in 6th though?? Ohh, i used a new crush sleeve with this ring and pinion. The 3.73s has a two peice solid spacer from strange, but the install kit did not have any shims for that and i had my hoist tied up and could not wait a couple days for the correct shims for pinion preload.

solocus
06-28-2009, 05:47 PM
I seem to have a small vibration in 5th gear on my S60. It is very minor and almost not noticable. My pinion aggle is at -4 so I'm hoping that it might make a difference when I adjust it to -2, but since it is only a 5th gear thing I'm doubtful. I noticed my slight vibration with the new rear end install and trans crossmember TA relocation. I also put in a new Driveshaft. It is something I can live with as all other gears feel great with stock like smoothness. I have no issues shifting into any gears as well. Good luck and I hope you find your problem.