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Detroit Locker Vibration?

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kpanza

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Ok, here's a question that has to do with the dreaded driveline vibration! I went from a 4" lift to a 6" lift last December. This was done with 6" Superlift Superride front springs and an ORD 4" shackle flip + 2.5" Superrides out back. At the same I swapped in a 14bff with a Detroit Locker rear and converted to 8 lug 10 bolt with ARB up front. Upon driving the thing for the first time, it vibrated horribly! So, we lowered the t-case by turning the stock spacers over underneath the frame. That helped a bit, but didn't get rid of the vibes. Then I installed some 3 degree shims under the rear springs, that again helped, but didn't stop the vibes. It doesn't vibrate very bad except when in that "zone" between on the gas and off the gas, you know, when you let off suddenly and then as you get back into the throttle. So, then I tried some 4 degree shims, same effect - a little better but still no cigar. So, last night I swapped in some 6 degree shims - this brought the angles of the rear diff and t-case output to 1 degree up (rear axle) and 1 degree down (t-case) - keep in mind that this was done on an unlevel driveway so my main concern is that the angles are damn close to one another, that is the key! So, I go drive it and it is still doing the vibe thing when off the gas/on the gas.

So, I am wondering, do any of you guys with Detroits have a similar vibration? Is this something that I should just put up with? I have broken u-joints in the past at speed and I don't want any more of that, so that is why I keep trying to fix the vibes. Thanks for any ideas/help. I am getting ready to just say to hell with it all and get a CV shaft and turn the axle up, but I would much rather spend that big $$$ on something else if I can!
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And if that didn't cure it would be pissed!
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Oh, and by the way, this IS a brand new driveshaft with brand new u-joints (I munched the old one on some rocks two weeks ago), and the vibes have been present ever since the lift last year. If it is just the Detroit doing its thing with its built-in "slop", I guess I can put up with it, but whatever it is it really drives me crazy!!
 
Maybe....................hummmmmmmmmmmm........................mufler bearings..........J/K

I wouldn't have a clue. Sorry.

The CV shafts from High Angle Driveline are very nice thou, I can vouch for that.

See Ya,
Keith

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<font color=green>Born to Drive My K5</font color=green>
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In the past I have replaced worn out u-joints with new u-joints that were not that much better than the worn out ones. From what you describe, it sounds like a u-joint to me. I have a 14FF w/detroit locker and 4" lift superlift springs, and I have no problems like that.
 
Nope, keith, I KNOW it isn't the muffler bearings, as I change those out every month! ha,ha
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And that is right after I adjust the "double kickback reverberator" and top off the ol' blinker fluid! But seriously, does anyone have any ideas?
 
Are you still running the stock case? For an '86 I am guessing a 208 w/ a slip yoke output. (Side note: see what happens when you fill out your profile, even though he didn't say so I know he has an '86. Makes it much easier to comment. I'll get off my soapbax now.) That might be at least part of the problem. My '80 (slip yoke) has some vibes inspite of the shims &amp; case drop. Not as bad as before I made the corrections, but still there. My '73 (fixed yoke) does not viberate, even with the old u-joints &amp; the case where it belongs. Both have 4" lifts.
Also make sure you keep the joints greased. I do mine at every oil change. Sometimes in between, too, if I run through a lot of water.

Jim '80 GMC & '73 Blazer
Tread Lightly!
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Keith, put a 4" TC all spring lift on three months ago..........they come with some degree shim which I do not know what %, while adding a Detroit-equipped Wes special 14BFF.........no vibrations ever. Very rarely do I even hear/feel the Detroit doing its thing. Transfer case (NP 203) is dropped the 1" spacer width..........and I actually never even have checked the degree difference front ujoint to back.

Q - was the driveshaft new when you did the lift? Might have been improperly balanced?

Anyway, we have all heard of this vibration thing with the shackle flip, which was a major reason I went with a rear spring lift. Let us know what the solution is............
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Good point about the slip yoke, you are probably right. That is kinda why I would like to swap a dodge 208 in there. As for greasing the joints, most of you will think I'm extremely anal (or nuts), I grease them every 2 weeks or every 4x4 trip (whichever comes first!) I have a very black underside where the extra grease flings up after each greasing!
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So, I can always rule out the un-greased u-joint problem (I blew one out one time towing a trailer and it was due to being dry + an uncorrected angle problem, so I learned my lesson about the grease!)

I might have to really look into that fixed yoke Dodge 208...unless Drivelineman can hurry up with the SYE kit (and make it affordable)

Thanks for the responses, if anyone else can shed some light on this I would really appreciate it!
 
I am in the process of gettin my 208 converted...it should be done at the end of the day today...some of the mods required were to machine down the speedo gear housing to fit in the dodge housing, cut off move and reweld bracket that holds the bar inside to move the shifter on the back side of the T case..(keep in mind i had to use the back half of a 208 for a dodge since the Chevy's oil return goin into the tail shaft dident line up and the case half is not thick enough to redrill the holes. I am thinkin i would have been better off to give advance adapters a call and get a adapter to get a 700r4 and 205 adapter...would have made life alot easier and posibly cheeper...as of right now the bill for the 208 converson sits at 600...and i still need to get a drive shaft built....but its only money...cant take it with ya!

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You could go with the Tom Woods shaft with the CV slip yoke style. This would give you a new slip yoke and it would give you the CV to help eliminate the vibes. Captcrunch got one and says it rocks. he's running a 6" lift too If I remember correctly. Adn the shaft was $325 delivered to his door.

What is and what should never be....
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I am thinking about the CV shaft, but I think if I am going to spend money on this, I would want to get rid of the weak link once and for all - the slip yoke.

As for the driveshaft, it was not new at the time I did the lift (I only went from 4" to 6" lift, so it was still fine). But the shaft that is in there now is BRAND new as of last weekend! It's got a new slip yoke and new Spicer joints, brand new everything, professionally balanced, etc. And this vibration has been present since last December, so it has stuck around for both driveshafts, so I think I can rul out the u-joints, shaft, etc - but the slip yoke could be the ultimate culprit here...I'll let you know if I EVER figure it out!
 
Keith,
I would bet on it being the slip yoke also. My Blazer did the exact same thing after I lifted it. It would vibrate on decelleration and nothing that I did would get rid of it. It went away when I put the Doubler in with the fixed yoke.
Russ
 
Keith,

I am experiencing the same thing. I have the 6 inch lift. And uhh, yeah that is a 4 degree wedge i thought...uh, yeah...Anyway, When Mike and I rewelded the perches my vibes totally went away. Then I raised my T-case back and I have a small amount of Vibe, I think when I get wedges under I will be able to run it vibe free and t-case up. Even now it isn't that bad..

The only thing is that I cannpt keep my t-case from leaking...Such a pain in the ass...



Surfing is Life...
 
Yeah, I put in the 6 degree shims and it is pretty good now, especially if I have weight in the back. I went up to Big Bear last weekend and with all my tools and coolers, etc it didn't vibrate at all, so I think it may finally be fixed. But I hear you on the t-case leak!! Mine has leaked since I got the damn thing! I have resealed it and resealed it, but it is a mess! I am seriously thinking about swapping to a fixed yoke 241 when/if I do the Klune V swap!
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Try a new yoke for the leak. Thats what it took to fix mine. It was Spicer and not enpensive.

Jim '80 GMC & '73 Blazer
Tread Lightly!
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