Offroad Trailblazers and Envoys

Front end shake in 4WD after 3" suspension lift

G80, GU6, GT4, GT5, WTF? This section is for gearing and driveline stuff.

by SMT59 » Tue Sep 20, 2016 8:50 pm

I had a 3" suspension lift(MarkMC) installed recently and all is good, even got the alignment within spec without flipping the UCA's. So today I decided to check out the 4WD which worked fine but when I started getting up to speed limit I noticed a front end shake which was not there prior to the lift, I was in rush hour traffic so could not check higher speeds but at start it is good then as I get it going it starts to shake then goes away, if I get on it I really feel it.

Any ideas as to what this may be or something not done during lift install?

Conditions were dry and hot driving on asphalt surface.
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by mason10198 » Wed Sep 21, 2016 10:33 am

If you haven't thoroughly checked out your 4x4 components it could be alot of things. First thing I would guess is bad bearings/seals in the disconnect on the passenger side. That can cause your passenger CV shaft to flop around (also dangerous because this is usually what causes the pin on the shift fork inside the disconnect to shear off).

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by mason10198 » Wed Sep 21, 2016 10:36 am

Whoops, gave my 2¢ but no help!
Check for play in the bearing by gripping the passenger CV shaft and pushing/pulling it back and forth. Watch how much it wiggles in the disconnect. Try that both in and out of 4wd. I beleive we have a few videos of "bad play" on here somewhere...

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by Rickalicka18 » Wed Sep 21, 2016 12:12 pm

Flip and the UCAs! I had mine not flipped for atleast 10 months with the 3" lift and 87s springs and went through 5 cv shafts on my drivers side and always had a shake when driving down the road. It was most noticable in 1st on initial acceleration since it was the gear with the most torque, but there always was a lingering wobble it had. Then I flipped the UCAs and EVERYTHING smoothed back out.

So I highly recommend flipping the UCAs, I flipped mine in 2 hours. Remove both front tires, remove fender liner, Used a sawzall to cut the metal that is in the way of getting a wrench on the bolt, I believe the bolt size is 7/16 and a open end racheting wrench worked the best for me, then there's one more bolt where the UCA and balljoint meet and I forget the size of that bolt. Disconnect the abs wire from the UCA then you take the passenger UCA, flip it, and put it on the drivers side and zip tie the abs wire back on the UCA and vice versa.
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by Rickalicka18 » Wed Sep 21, 2016 12:16 pm

Edit: I didn't see the 4wd part but I still think its the UCAs.
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by SMT59 » Wed Sep 21, 2016 4:52 pm

Hey guys thanks for the quick replies, looks like I'm flipping the UCA's . I checked the play on the passenger side shaft and it seems minimal but not sure what is acceptable so I will try and find the videos on the site.
Thanks again and will keep all posted on what I find out.
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by ErikSS » Wed Sep 21, 2016 10:58 pm

Do not drive on bare asphalt in 4 wheel drive. Problem resolved.
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by KingBird » Thu Sep 22, 2016 12:55 am

I think Erik nailed this one.
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by SMT59 » Thu Sep 22, 2016 5:07 pm

Yes I know I'm a bad guy for that but I was checking the 4WD system out after the lift, I do this occasionally to make sure everything is working. It never shook prior.
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by KingBird » Fri Sep 23, 2016 8:52 pm

I do it too, from time to time I throw it in 4 wheel while going down the road.

I instantly feel a difference in the road manners when I do this though.

You don't run "slime" in your tires do you?
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by hilljb » Sat Sep 24, 2016 1:08 pm

When I first installed the suspension lift, I had a horrible shake under acceleration. It turned out to be a bad CV axle in combination with a slightly off alignment.

Under torque (rotational acceleration), a worn CV axle will be much more noticeable with the suspension lift, just due to the angle it now sits at. As others have pointed out, you want to avoid putting the CV axles under too much stress due to bindup from the transfer case on grippy surfaces.. Here in Colorado, I can't help but have 4lo engaged on rocky/grippy surfaces, and I pretty much accept that I'm going to go through CV axles once a year or so. They're not too expensive and once you've done them once, they're pretty easy. I've replaced them twice so far, and the shake is starting to come back under acceleration again. I hear that the Detroit CVs are better, so I may go that route soon.
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by larryk » Thu Oct 20, 2016 8:43 am

Rickalicka18 wrote:....I believe the bolt size is 7/16 and a open end racheting wrench worked the best for me, then there's one more bolt where the UCA and balljoint meet and I forget the size of that bolt. .


The bolts holding the UCA to the frame are 21mm (and yes, a ratcheting box wrench works great), and the pinch bolt holding the arm to the upper ball joint is 15mm
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by Rickalicka18 » Thu Oct 20, 2016 3:11 pm

larryk wrote:
Rickalicka18 wrote:....I believe the bolt size is 7/16 and a open end racheting wrench worked the best for me, then there's one more bolt where the UCA and balljoint meet and I forget the size of that bolt. .


The bolts holding the UCA to the frame are 21mm (and yes, a ratcheting box wrench works great), and the pinch bolt holding the arm to the upper ball joint is 15mm


Thankyou for the clarification :cheers:. I knew 7/16 didn't sound right lol
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by GreatLakes » Mon Aug 14, 2017 10:15 pm

you mention you were in rush hour traffic. would that imply you were on paved roads? were the roads dry? I understand you wanting to test your 4wd but I personally would've tested it the next time I was out wheeling, cruising down the logging roads or on some other "soft" surface.
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by djthumper » Mon Aug 14, 2017 10:26 pm

GreatLakes wrote:you mention you were in rush hour traffic. would that imply you were on paved roads? were the roads dry? I understand you wanting to test your 4wd but I personally would've tested it the next time I was out wheeling, cruising down the logging roads or on some other "soft" surface.

Who are you talking to? This thread has been dormant for almost a year. Your comment has added no value to this thread.
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