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Discussion Starter · #1 ·
I have an annoying vibration that starts around 20 mph and is gone by 25 mph. The only chnage we have made lately is the springs and shocks on my 97 sw to LR heavy duty springs up front, medium duty springs in the rear, and Bilstein shocks. Is it possible that this change could cause vibration?
We also suspect I may have a weak motor mount and have ordered new mounts to install. I believe this will prove to be the culprit but I thought I had read previous posts that said changing the springs also caused vibration.
Thanks.
 

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crappy motor mounts would cause your shifters to move. there is alotta stuff under your truck that could cause some movement. It could be a u joint vibe due to your new lift, replace the u joints. however I think those vibes were more common at higher speeds.
 

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I would check all the nuts and bolts of the recent suspension work. I use lock tight on all of my suspension componants to try and keep anything from finding its way loose.
 
G

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lift

Hi Rick, did adding the new springs raise your truck at all? If so the vibe could def be related to lift. Basically when you raise the truck, the drive shaft shaft becomes steeper. The rear diff also becomes angled upwards, changing the angle of shaft at diff. When you have LR stock drive lines, the angle on both ends of the shaft should be the same to zero out the vibe. Many folks add rear adjustable control arms to angle the rear diff downwards to an angle that matches the other end of the driveshaft.
To determine if it is a driveline vibe, remove the front driveline from vehicle and test drive.---if yor problem goes away you might consider adding a double cardan shaft to fr.
If the fr produces no results, reinstall fr line --- then remove the rr drive line. If that elliminates vibe you might consider lenghtening your rear control arms to lower the angle at the rr diff.
rock on :afro
 

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Discussion Starter · #6 ·
Yes, the new setup raised the front about 2 " and the rear about 1 1/2". I will check what you suggest. It makes sense to me the angle of the drive shaft, affected by the lift, could be causing this.
Thanks!
 

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Discussion Starter · #8 ·
Dave,

It's not terrible, like violently shaking the steering wheel. It is more like a quiver that you feel through the steering wheel. It starts around 20 mph and is gone by 25 mph. And it increases slightly right before it is gone.

Rick
 

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This is fairly typical with the installation of the lift. Someone here can give a better explanation, but it's basically the changes in the drive line angles you've instituted through the lift. Even if only 2 inches.

I have the same vibe from 30-40 mph, and have isolated it to my front driveshaft.
 

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Discussion Starter · #10 ·
Thanks Dave.
Redrover, what is a double cardan shaft that could be added to the front? Never heard of this.
Thanks.
 

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it is a driveshaft that has 2 u-joint at the output shaft/mount on the t-case and one u joint at the diff. I dont know what or really how they work, they are just designed to help reduce vibrations found with steeper driveshaft angles that result from lifting a truck.
 

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A double cardan shaft is a driveshaft that has a CV joint at one end. The CV is like 2 U-Joints in one allowing for more driveline angle.

That may not solve all of your problems. There are 2 u-joints on your driveshaft, 1 at the Diff and one at the T-case. What is most commonly done is to rotate the front axle so the Pinion points at the T-case. This makes straitens out the U-joint at the Diff end and gets rid of any vibes at that point. This may solve your problem. If not then you put on a double cardan shaft with the CV joint at the T-case end witch would solve any Vibrations at that end.

The first thing I would do would be to remove one driveshaft at a time, then take it for a test drive to see if all the vibes are gone. You will have to put in the Diff lock when you remove the driveshaft. If it turns out to be a driveshaft (most likely the front one) Then I would rotate the diff.

I hope this helps and I’m not too confusing.
 

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Check for wear in the drive shafts. The lift is probably only about an inch if you used the rear springs at the front and shouldn't cause problems:grin
 
G

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follow up

Hi rick, getting alot of info I see. Just want to clerify a few things for you. Also I would recommend talking with a drive shaft specialist company like "six states" or "Tom Woods" to fully under stand why there are basically two different options on how to solve your problem.
The first option , if we are dealing with the rear shaft and a stock drive line is to tilt the rear diff closer to level, so its angle is similar to the angle on the other end of shaft near rear output from transfercase. With stock shaft, you DO NOT want to tilt the diff up to match driveshaft, if this worked it is the exception rather than the rule. The rear diff angle can be manipulated with adjustable rear links. Here are few companys that make these--rovertracks, rovertym, safari guard,maybe rockware.
The second option, if we are dealing with rear shaft and a double cardan driveline is to tilt the rear diff upwards to be inline with driveshaft. This also requires adjustable control arms. Although I have moved the frame ear bushing to the opposite side of ear to accomplish same thing as shorter control arms and saved a few bucks.

As far as the front goes I went with a double cardan shaft. It is more difficult to mess with diff angles in front if you are not using a 3- link susp. But in my experience, just installing the double cardan was enough. As my lifts got larger 3", I would hear a vibrating/clashing noise when letting off the gas at highway speeds. After a few calls ,GBR bet that the sound was from the front drive. So I installed a front double cardan and noise/vibe be gone. I do now run a 3-link and with the diff angled upwards there is no improvement over what the double cardan accomplished.

My point is I bet your vibe is related to the rear drive, because as you raised truck, the short shaft gets steep fast even with small lift. The cheepest fix with stock drive line is to lenghten your control arms and return the diff to a matching angle of opposite end. This works great for lifts under 2". Also many of these adjustable control arms are stronger for offroad and some have bends to reduce hangups.
ROCKON
 

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Discussion Starter · #15 ·
Ok guys. I have a pretty good idea of what to check for, as does my mechanic. I brought him to my computer and we reviewed the info you furnished.
Next week, we are taking the D-90 in for Borla, plus motor and transmission mounts (old issue you may remember regarding knocking from underneath). When we do this, we will run the diagnostics you have suggested. I will follow back up to let people know what we found.
By the way, my mechanic, who has worked on Rovers for many years, was impressed at the input/knowledge from this group.
Thanks!
 

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Rick,

It also could be as simple as a bad u-joint. You can check it by removeing one of the drive shafts and locking the t-case and go for a short drive. If the vibes are gone you know there's something wrong with that shaft.

Rick if you put the larger tires on it could be the swivel pre-loads and steering lash. This happened to my dad's 110, at first the steering wheel a wobbled little at about 30-40mph, then quickly got real bad. It's easy to fix/reset, just a lot of people forget about it and blame the shaking on the tires.

Also going with that lift you shouldn't need CV driveshafts, unless you put 4.10 in, then your shafts will spin faster, which causes a noise from the t-case when you are coasting.

Rick, I hope to see you at the Fall Rally

Matt
 

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Discussion Starter · #17 ·
Hey Matt. Thanks for the input. Rick Sanders and I will look at all of these when we get the truck in his shop next week.
I saw your D-90 on the ECR site. Looks really nice. And I bet it runs even better. One day you can tell me how much you spent on the 4.6 change out, plus the other things you did. That may be a change in my D-90's future as well.
Unfortunately, I have to travel to Cape Cod the end of next week and will not be going to the Fall Rally. I am very disappointed as this was going to be my first one. I'll be at the next one.
See you around.
Rick
 

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Rick,

What was the source of the problem? I recently had the same thing happen to my truck and my technician was able to pinpoint to a catalytic converter that need to be replaced. I hope that helps.

Brian
 

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Discussion Starter · #19 ·
Sorry Brian. I missed your question.

I still have some vibration that is a result of the lift I installed. The suggestion, which I have not done, was a double cardon shaft. I was going to do that but haven't as yet. My other problems were related to a crushed motor mount but it did not take away all of the vibration when we replaced it.
 

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Also try pumping the prop shaft sliders and their u-joints full of fresh grease. They like to be nice and greasy.
 
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