VCU Refurbished - Minor Vibrations

Hi all, first time poster here. Hoping to get some assistance if possible.

I picked myself up a 2005 Freelander 1, Manual TD4, earlier this year and set about sorting out a few issues. One of which was replacing the VCU and bearings etc.

After refurbishing the propshaft, (New VCU from Bell engineering, new VCU bearings and new UJ bearings), I have assembled it all back onto the car and found its smooth up until 60mph where I get some vibrations. Admittedly probably not as bad as some have been reporting on the forum, but vibrations nonetheless.

The VCU is straight 90degrees to bearing centerline as per haynes manual, tyres are all OK (all 4 new and balanced correctly) and the IRD seems to be in fairly good health.

The only thing I have noticed is that the rear prop shaft itself does not following the center line of the car if that make sense. From the rear VCU mount it goes off at a slight angle to meet the rear diff flange.

So my question is (as I cannot seem to find any answers/pics to help me) should the whole length of the propshaft follow the center line, or at least be as straight as possible down the length of the car?

And if its not, would this explain the vibration? The only thing I can think of is as and when the rear diff mounts have been replaced, they havent been positioned properly and therefore the rear diff is somewhat twisted?

Hope that makes sense!

Thanks in advanced for any assistance.

The VCU should be straight and the bearings should be perfectly at 90 degrees to the vcu. This is important or the bearings will not last long.
There should be a slight bend or offset to the rear diff but the angle should be in the UJ.
Have you tried pushing the rear propshaft around where it joins the rear diff. Any excess movement means the diff mount needs replacing.
On one car I had a vibration I fixed by rotating the damper on the vcu. It was after a diy refurb of the vcu and I'm not sure why it worked and nobody really believes me but I can assure you that it worked for me.

Give all the propshaft UJs a shake and also check the tripod joint at the front of the front prop. There should be no play in any of them. The front tripod gives vibration if the rollers inside have failed. If it makes a clanking noise when the prop is twisted then have a look inside it.

Just seen you've replaced the UJs but check them again now fitted and run.

Also, was the prop on the car before or have you refitted? In which case a previously tight vcu could have damaged the tripod joint.

Alibro said:

The VCU should be straight and the bearings should be perfectly at 90 degrees to the vcu. This is important or the bearings will not last long.
There should be a slight bend or offset to the rear diff but the angle should be in the UJ.
Have you tried pushing the rear propshaft around where it joins the rear diff. Any excess movement means the diff mount needs replacing.
On one car I had a vibration I fixed by rotating the damper on the vcu. It was after a diy refurb of the vcu and I'm not sure why it worked and nobody really believes me but I can assure you that it worked for me.

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There you go again.

Thanks for the replies all.

I've checked what you mentioned Alibro, and tried rotating the damper and this didn't change much I'm afraid.
Checking the rest of the prop shaft seems to be ok. No movement in UJs etc, and diff mounts are quite new too. The prop was already on the car when I bought it. When I drove it home I didn't really notice anything untoward.

Since my first post, the front CV gaiter has split, so I've had to change that. At the same time I got a good chance to check the tripod bearings and they're all good too, nice and smooth, no notches or play.
I did notice however (before and after this), that the CV joint has a slight angle to it, as if the engine/IRD had dropped slightly. After checking the engine mounts, I found the lower tie rod had a fair bit of play in it. So I suspect this could be causing some problems. I've got a new one on order so will report back in a few days once this has been swapped out.
Cheers again for your help guys.

PS - It's nice to know the whole 4x4 system works after trying it out on the snowy roads we've had recently!

So, I've swapped out the lower engine tie rod and not a lot has changed. I noticed the upper one had some movement in it too so swapped that as well, and again not a lot of difference.

I have however, been driving it a bit over the past week so whilst paying attention to the vibrations a bit more, and have come to the conclusion that the vibrations are actually engine related rather than anything to do with the prop shaft at all. This is because I've noticed a similar vibration when accelerating as the engine revs reach around 2500rpm. Funnily enough, 60mph in 5th gear is around 2500rpm. Hence why I originally thought it was more road speed related. I have confirmed this by getting it up to 70mph, and popping the clutch, letting the revs drop and the car is nice and smooth whilst coasting. If there was any issues with the prop or drive train at all, this would surely still be apparent.

So my next question, if anyone can help at all, is has anyone had any experience with engine vibrations? As I said on my original post, its not horrendous vibrations, its still perfectly drivable, but still noticeable. My thinking is engine mounts? But having changed the upper and lower tie rods, the only ones left to look at are the left hand and the right hand hydromount. If either of these were on their way out, would this cause the engine to transmit vibrations through the car?

Thanks again guys.

TomW1UK said:

If either of these were on their way out, would this cause the engine to transmit vibrations through the car?

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Check the exhaust for excessive rust and off road damage (maybe it's slightly bent), and check all the hangers are taking an even amount of weight.
Exhausts systems that aren't hanging correctly can resonate at different RPMs, which can be felt through the whole vehicle.