2.1 inch lift and CV joint vibration

[BlueRock Junior Member Find all posts View Profile Close BlueRock]

Now that my winch is installed, my front end has dropped a bit. It's now 55 mm over stock (805 mm total). I also installed a diff drop.

Having testing this on the motorway, I'm getting mild vibration between 55 and 62 mph, under heavy acceleration. It becomes light vibration under light acceleration. Outside of this range, it seems to be fine.

Should I be worried?

I'd like to keep this amount of lift. But, it would be good to try to track down and perhaps eliminate the vibration. Initially, I wasn't sure if it was the CV joints or the U joint at the input to the differential. So, I removed to diff drop. That made things worse. Vibration range increased to 50 to 65 mph and became more severe. I could even feel faint vibration when decelerating.

So, the diff drop is definitely helping, and I'll be putting that back on, next weekend. But, because of the way the diff gets angled, it effectively drops the centre of the diff only by 1/2 an inch. So, that would make it equivalent to a 1.6 inch lifted CV angle.

So, I think the problem is definitely in the CVs. But, I'm not sure which one. With the diff drop installed, I can't feel the vibration in the steering wheel. So, my first suspicion would be the inner CVs. But, I'm not really sure. I'm not an auto mechanic!

Ideas?

Can the diff be dropped further? Perhaps, in the rear mounting? Could this be due to aging CVs? Would re-packing or replacing the CVs improve things? Are there better CVs that could be installed? What about installing manual hubs, effectively turning the LC into part-time 4WD? I'm sure that would make the vibration go away.

BlueRock
2001 LC90 (Colorado) D-4D, lifted and ready to winch

[williade Avid PP Poster! Find all posts View Profile Close williade]

AFAIK there aren't any part time kits for 90 series Prados. You could probably get a part-time T-case from Hilux/Surf/4Runner but I don't think there are any free-wheeling hubs that will suit the 90.

Have you had the camber bolts on the LCA adjusted to suite the lift? perhaps the inner CV's are outside their comfort zone or are worn.

[BlueRock Junior Member Find all posts View Profile Close BlueRock]

I got the front end re-aligned. Camber and toe-in is now well within spec, almost spot on. And, this has indeed improved the situation. The vibration has been reduced.

After re-installing the diff drop, I can now barely feel the vibration in 4th gear (overdrive) under acceleration. In 3rd gear (auto), there is still some noticeable vibration under heavy acceleration, between 55 and 62 mph. This is reduced with lower acceleration.

One thing I noticed is that the camber adjustment has effectively increased the front lift by 5 mm. This seems to be due to the change in lever ratio of the lower control arm. My overall front lift is now 2.3 inches!

So, what next? Do I add more weight to the front? Or, are there other tricks I can do?

BlueRock

[BlueRock Junior Member Find all posts View Profile Close BlueRock]

I replaced the batteries with large Optima yellow tops and re-installed the skid/bash plates. So, the front end is now 25-30 kg heavier. Front lift has dropped to 53 mm, so it's pretty much on target, for a 2 inch lift.

Vibration has reduced further. It's now practically unnoticeable in 4th gear (overdrive). Under acceleration, in 3rd gear, it's mild. And, sometimes, it doesn't happen at all. If I push the pedal all the way to the floor, so that it drops into 2nd gear, it's more noticeable. As before, this only happens between 55 and 62 mph.

A mate mentioned that if the CV joint has become worn in the 'normal' position, changing the angle will cause the balls to hit parts of the tracks that have not been worn yet. These 'ridges' between the worn and unworn parts could be causing the vibration. Does that make sense?

Could the vibration somehow damage the transfer case or transmission? Or would it have to be very severe for that to happen?

I'm figuring I will leave it as is, at this point. If the CV vibration gets substantially worse, presumably I could then better track down which CV joint is acting up, and replace it with a new or reconditioned one. Does that make sense?

BlueRock

[BlueRock Junior Member Find all posts View Profile Close BlueRock]

With more driving, I'm noticing it's not a single vibration, but several. Around 55 mph, the vibration is lower frequency, perhaps 20 Hz. This goes away before I hit 60 mph. Around 63 mph, I hear a light hum, perhaps 50 or 60 Hz, which goes away at 65 mph. I think there might be a third vibration or hum, somewhere in there.

Usually, this is all too faint to be able to distinguish from all the other hums and vibrations caused by the engine, tyres, and road. So, I have to listen carefully. But sometimes, often in 3rd gear, the lower frequency vibration can be more pronounced. I rarely feel it in the steering wheel, but on a couple of occasions, I have. The front wheels are also slightly out of balance, which I can feel around 70 mph.

Here are the current CV angles, with the lift, extra weight, and diff drop installed...




I will continue to monitor this. I am open to more suggestions, of course.

BlueRock

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

Maybe try switching your tyres around - front tyres to rear, and vise versa.

[MDSimpson Advanced Member Find all posts View Profile Close MDSimpson]

I'm no expert either, but the CV joints seem like a logical place to start, the bearing would wear in at their original angle, and changing this would cause issues. As for the variations in actual vibrations, it could also come down to the CV's..

[BlueRock Junior Member Find all posts View Profile Close BlueRock]

Bluerock, MickL has got a kit he is selling that will bring those outer shafts down straight. PM him or have a look on the for sale side of this website. You have to remember that IFS is a lot more maintenance to keep everything in alignment then a live axle. It probably is your CVs on the way out if there is no noises coming from your driveline. Your friend is right because by changing the angle, the CVs will wear differently.
The Roo.

Is this a diff drop kit? Or something else?
I already have the diff drop kit from Sonoran Steel installed.
BlueRock

[MDST Member Find all posts View Profile Close MDST]

Hello!!

I think the front 882 OME coil are too much for your Prado. 882 are for winch + bumper + double battery + etc. You have winch and 2 batteries but you don't have a front bumper and that's are 40 kg minimun of weight to add. But too much weight is less performance. Nothing is perfect!

880= 365mm, 881= 375mm and 882= 395mm. The ome front coils have the same spring rate! The difference is the high.

More higher front coils, more angle for CVs.

If you don`t put a front bumper, I think 881 is the best for you!

Cheers

[Schaffer Addicted PP Member Find all posts View Profile Close Schaffer]

Yep, MickL is doing a diff drop kit.

[andycook Lurker Find all posts View Profile Close andycook]

I had same issue with the 882 springs
after changing prop-shaft U-joints, trying diff drop kits

I swapped the springs for 881 and lost 3-4cm of lift (but still about 2-3cm above original springs), but solved the vibration issue - which I reckon was CV's

I also have twin battery, TBR hidden winch mount, warn 9.5 winch - but not a full-on steel winch bumper...

[BlueRock Junior Member Find all posts View Profile Close BlueRock]

A full kangaroo bumper, whilst weaving through London traffic, would be pretty cool. He he. But, there are some legal complications with that, here in Europe. So, for now, I've stayed with the conservative look. Besides, there aren't any kangaroos here!

Regarding the extra weight, I think I'm pretty close. The two batteries I have are extra-heavy, and the winch mount alone is 20 kg. So, I think I'm less then 20 kg from target. The thing I'm not sure about is the D-4D engine vs. the standard TD.

I swapped the springs for 881 and lost 3-4cm of lift...

Wow! This is exactly why I didn't want to go for the 881 springs.

The vibration continues to be very minor. After 2,000 miles, it hasn't gotten any worse. In fact, it might have gotten slightly better. Or, maybe, I'm just getting used to it.

A mate jokingly suggested I do a 'spectrum analysis' of the noise. I might just do that, when I have time.

BlueRock

[BlueRock Junior Member Find all posts View Profile Close BlueRock]

After 7000+ miles, including a long cross-European trip (where I managed to reach 170 km/h on the autobahn), I haven’t seen any indication that the CV joints are deteriorating. In fact, I hardly notice any vibration at all, now.

So, I think my CV angles are probably fine and the original vibration was due to the wear pattern on the inside of the CV joints.