Vibration above 40mph

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terrier989

Member
Posts
98
Location
SOUTH WALES
Hi all

old gal starting to show her age Freelander 1 yr 2000 150k miles

Have a vibration at 40mph in 3rd or 4th speeding up does not get rid of it, makes it feel as if frequency of vibration has become faster but not more intense (at speed rear view mirror quite blurred) but usable

If I am doing 30 and come to slight upwards incline a bit more revs for the incline and it starts at 35. going down hill at 50-60 knock it into neutral vibration remains.

My usual mechanic tells me front propshaft cv seems a bit worn, have ordered new front prop.

My main concern is VCU this one has done 50k
Will get garage to do the stick and weight check, it was ok last yr and only done 3k since then.

As I understand it above 40mph VCU is only transmitting 5% to rear wheels and it is at the 40mph point when the vibration starts, could this be the VCU starting to fail?, mech is also going to do a run with front prop off to see if vibration still there , if it is would that indicate possible vcu problems.

cheers

terrier
 
My usual mechanic tells me front propshaft cv seems a bit worn, have ordered new front prop.

How are the tyres? Same make and type all round with least worn on the rear? Are they all pumped up to the same pressure?

The VCU will try to transfer drive from one side to the other, above a pre-set slip rate. So if the propshafts are rotating at the same speed, then it's not going to transfer drive across it. If however there's a difference in rotational speed between front and rear, then it'll start to transfer torque.
As I understand it above 40mph VCU is only transmitting 5% to rear wheels and it is at the 40mph point when the vibration starts, could this be the VCU starting to fail?,
The speed of the vehicle is irrelevant, as long the propshafts are rotating together. The VCU will always try to equalise the rotational speeds of the front and rear propshafts, minus a small slip allowance. If odd tyres are fitted, the rotational speed between front and rear will be different, exceeding the small slip allowance. This normally leads to the VCU transferring torque when it's not needed. This "loads up" the drive train, which causes vibration and damage if allowed to continue unchecked.
 
Nodge, hanks for reply.

yes to all your tyre questions, all good 29psi, newest on rear.

Just remembered it is also noticeable when going round a roundabout to the 270 exit and that is below 40.

Could the suspected worn cv on front shaft cause this imbalance in rotational speeds?

When you could cause damage to where?

terrier
 
yes to all your tyre questions, all good 29psi, newest on rear.
That's good, although the tyres should be at 30 Psi. ;)
Just remembered it is also noticeable when going round a roundabout to the 270 exit and that is below 40
Exiting a roundabout means turning, which would force the VCU to slip. This could point to a UJ or propshaft related issue, which is vibrating under load.

Could the suspected worn cv on front shaft cause this imbalance in rotational speeds?
Outer CVs normally click on full lock. Inboard CVs can cause vibration, but this in normally most noticeable under acceleration from slow speeds.
 
Re CV I am referring to the joint on the front end of the propshaft not the driveshafts to front wheels, mechano=ic and others have described it as a cv joint, iit iis certainly not a UJ

terrier
 
Re CV I am referring to the joint on the front end of the propshaft not the driveshafts to front wheels, mechano=ic and others have described it as a cv joint, iit iis certainly not a UJ

terrier

Ah. Yes that's a type of CV joint, called a tripod joint. It's very similar to the type of joint used on the inboard drive shaft joints.

The front prop CV can give trouble, but not unless it's been overloaded in the past, normally due to incorrect tyres or a failing VCU. This CV is designed to accommodate engine movement while still driving the propshafts smoothly. They don't normally produce much vibration, unless there a lot of radial slop in the joint.

It's not replaceable on its own, as it's part of the front propshaft. So you'll need to replace the front propshafts, to get a new CV joint. However normally they're very long lived, an so seldom need replacing.
 
Ah. Yes that's a type of CV joint, called a tripod joint. It's very similar to the type of joint used on the inboard drive shaft joints.

The front prop CV can give trouble, but not unless it's been overloaded in the past, normally due to incorrect tyres or a failing VCU. This CV is designed to accommodate engine movement while still driving the propshafts smoothly. They don't normally produce much vibration, unless there a lot of radial slop in the joint.

It's not replaceable on its own, as it's part of the front propshaft. So you'll need to replace the front propshafts, to get a new CV joint. However normally they're very long lived, an so seldom need replacing.

Hiya

Is this the joint u mean , only reason I ask is a local engineering company managed to replace it on its own

Think i was lucky as indeed and agree many also said it couldn’t be repaired on its own

Hope I’m not being rude in any way posting this or trying to be a clever clogs

D6D7DBDF-1AE6-4B87-946A-1C1D24554CB9.jpeg
 
Hiya

Is this the joint u mean , only reason I ask is a local engineering company managed to replace it on its own

Think i was lucky as indeed and agree many also said it couldn’t be repaired on its own

Hope I’m not being rude in any way posting this or trying to be a clever clogs

View attachment 172932

I've not found an official replacement Gary. I suspect it's the same as those joints fitted to VAG group vehicles, but couldn't guarantee it without actually comparing the parts.


That's only half the joint. The other part is the component that sufferers the most wear.
 
I've not found an official replacement Gary. I suspect it's the same as those joints fitted to VAG group vehicles, but couldn't guarantee it without actually comparing the parts.



That's only half the joint. The other part is the component that sufferers the most wear.

Many thks, the garage replaced the entire bit that had the tripod joint, explains it now why they did that due to the assembly wearing out

I couldn’t see any part numbers etc on the new parts, bet ur right as i imagine it’s not just the freelander that has the same cv tripod assembly fitted

Imagine it would be a difficult task trying to match the assembly up with fitments on other vehicles

The vibration wasn’t always there, could drive through it, also would make a noise on hill starts

So indeed looks like an entire prop, could feel the movement in the old prop when it was fitted to the landy

Always appreciate ur knowledge and many thks , as every day is a school day
 
update no vibration in 2 wheel drive put new prop on still got vibration they are going to do the VCU test next, if that is ok I assume could be vcu bearings or something aft of that in the drive train

If I drive it in 2 wheel for a while do I need to remove the vcu to prevent it being damaged by rotation of rear wheels.

terrier
 
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being done. tyres yep all same and same pressure least worn on the rear

what abt VCU if I go 2 wheel drive for a while shd I have it removed
 
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what abt VCU if I go 2 wheel drive for a while shd I have it removed

If the VCU is off and it's not vibrating, then it points to something VCU/ propshaft related. Test the VCU as per the Bell Engineering video on YouTube. Also fully articulate the propshaft UJs, checking for stiffness and sticking about the centre point.
 
No vcu is still on, what i am asking is if I just remove the front propshaft can I drive it as a 2 wheel drive for a while or do iI need to remove the rear one and vcu.

I don't know if driving it with the vcu fitted and no front shaft if the rotation from rear wheels will damage vcu

cheers

terrier
 
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