Classic transmission problem/s

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frog hopper

frog hopper

Well-Known Member
Posts
4,778
Location
france
1988 2.4 Vm. Got a bit of a rubbing sort of noise just started in the last week or so, and what with one thing and another have just got round to doing something about it, which of course has led into a spiral of grief.
The noise is almost like air chuffing through a partly open window, but it isn't that.
Generally coming from underneath, perhaps from the front, and is road speed related, dies out below 15 Mph or so. Cornering/braking makes no difference.
Anyway thought I would grease the prop U/J's just in case, and while I was about it thought I'd check the VCU. That is the back story as you might say, this is what I found, and I don't think I like it.

Grovelled underneath to grease the props and of course the nipples were in the wrong place, though all U/J's seemed to be OK. Jack up the front end and turning one wheel the other wheel rotates in the opposite direction but the prop does not move at all, tried in T'Box neutral and G'Box neutral, no difference.Hand break on/off no difference. All wheel bearings seem to be OK, dropped one wheel onto ground and tried to turn one wheel, solid, no movement at all.

From this I assume 1/. the front half shafts are OK, 2/. there is no drive from front prop through the diff.

What damage will I do in the short term if I drive it in this condition? What if I remove the front prop? ( I never Off-road in this one so don't mind if it's only 2 wheel drive)

Any help greatfully received thanks.
 
Sounds like the VCU is goosed.

A replacement is not too expensive and if it's anything like the P38's Borg Warner t'box it shouldn't be too difficult to replace.

I belive the one wheel up test requires a set 70nm force to turn the wheel..
 
Henry_b said:
Sounds like the VCU is goosed.

A replacement is not too expensive and if it's anything like the P38's Borg Warner t'box it shouldn't be too difficult to replace.

I belive the one wheel up test requires a set 70nm force to turn the wheel..
Click to expand...
Thanks for the reply, I had my torque wrench set at 100Ft Lb, no movement at all, (that's about 140Nm I think).
But why will the prop not turn when the front wheels are off the ground and I turn a wheel?
Just had a thought there, of course if one wheel turns one way and the other turns in the opposite direction the diff is taking all the drive is it? and the prop dosent need to turn, especially if locked up with a duff VCU. Is that right??
Can I drive it a short distance without the front prop?? Like 30/40 miles??
 
frog hopper said:
Thanks for the reply, I had my torque wrench set at 100Ft Lb, no movement at all, (that's about 140Nm I think).
But why will the prop not turn when the front wheels are off the ground and I turn a wheel?
Just had a thought there, of course if one wheel turns one way and the other turns in the opposite direction the diff is taking all the drive is it? and the prop dosent need to turn, especially if locked up with a duff VCU. Is that right??
Can I drive it a short distance without the front prop?? Like 30/40 miles??
Click to expand...

Running it in 2wd will cause undue wear in the Transfer box.

Being the BW transfer box with VCU it will be an expensive lottery. :eek::(

Best to replace the VCU as soon as.. IMO.
 
Last edited:
frog hopper said:
Thanks for the reply, I had my torque wrench set at 100Ft Lb, no movement at all, (that's about 140Nm I think).
But why will the prop not turn when the front wheels are off the ground and I turn a wheel?
Just had a thought there, of course if one wheel turns one way and the other turns in the opposite direction the diff is taking all the drive is it? and the prop dosent need to turn, especially if locked up with a duff VCU. Is that right??
Can I drive it a short distance without the front prop?? Like 30/40 miles??
Click to expand...
if both front wheels are off the ground it will spin the other wheel in opposite direction if you turn one,to turn the prop by turning a wheel you need to have the other on the ground, then it will try and turn prop, if g/box in neutral the wheel should turn with some effort if it wont vc is seized, if seized it puts more strain on drive train ,front diff is usual first failure though output shaft in t/box can shear the splines so drive to rear is lost , if vc is seized you can run around with either prop removed so 2wd, thats ok except its power to one axle so dont over load it
 
jamesmartin said:
if both front wheels are off the ground it will spin the other wheel in opposite direction if you turn one,to turn the prop by turning a wheel you need to have the other on the ground, then it will try and turn prop, if g/box in neutral the wheel should turn with some effort if it wont vc is seized, if seized it puts more strain on drive train ,front diff is usual first failure though output shaft in t/box can shear the splines so drive to rear is lost , if vc is seized you can run around with either prop removed so 2wd, thats ok except its power to one axle so dont over load it
Click to expand...
Thanks James, I think I will remove the front prop just to get me about for tomorrow (and keep a functioning H'brake) and drive like the vicars aunt.
As luck would have it the clutch slave is leaking into the bell housing on my 90 so can't use that till I replace. :mad::(:mad:
Bloody Land Rovers.
 
frog hopper said:
Thanks James, I think I will remove the front prop just to get me about for tomorrow (and keep a functioning H'brake) and drive like the vicars aunt.
As luck would have it the clutch slave is leaking into the bell housing on my 90 so can't use that till I replace. :mad::(:mad:
Bloody Land Rovers.
Click to expand...
ive had several that had run for a long time unknowingly on one axle
 
frog hopper said:
Thanks for the reply, I had my torque wrench set at 100Ft Lb, no movement at all, (that's about 140Nm I think).
But why will the prop not turn when the front wheels are off the ground and I turn a wheel?
Just had a thought there, of course if one wheel turns one way and the other turns in the opposite direction the diff is taking all the drive is it? and the prop dosent need to turn, especially if locked up with a duff VCU. Is that right??
Can I drive it a short distance without the front prop?? Like 30/40 miles??
Click to expand...
Yes, as said already continuing to drive on hard surface in the seized condition, (full time 4wd), will deffo break a diff or axle. What we did with my mates, (ex RRC '88 VM + viscous LT77 in an '85 County) we fitted a std transfer box with centre diff lock, easy, and because we had one off an old gearbox, a lot less expensive than replacing the VC, not as "pukka" but does the job.
 
Gazbo said:
Yes, as said already continuing to drive on hard surface in the seized condition, (full time 4wd), will deffo break a diff or axle. What we did with my mates, (ex RRC '88 VM + viscous LT77 in an '85 County) we fitted a std transfer box with centre diff lock, easy, and because we had one off an old gearbox, a lot less expensive than replacing the VC, not as "pukka" but does the job.
Click to expand...
Well, as luck would have it I do have a spare used G'box and std T'box in the store, how the hell do I fit that in place of the T'box I already have??
Do I have to start cutting into the tunnel/making up linkages or anything?
Will the handbrake and rear prop still fit?
 
frog hopper said:
Well, as luck would have it I do have a spare used G'box and std T'box in the store, how the hell do I fit that in place of the T'box I already have??
Do I have to start cutting into the tunnel/making up linkages or anything?
Will the handbrake and rear prop still fit?
Click to expand...
you could just replace vc in situ or fit a lt230 but you need a different rhs t/box mount and front prop with high/low lever diff lock mechanism
 
Henry_b said:
Just replace the VCU it's much simpler than cocking around with other G'boxes :p:D
Click to expand...
Maybe the replacement part is not expensive and obtainable over your side but we couldn't have got one even if we had the money, here parts for those models are like rocking horse do do.
Didn't find it too hard to change the transfer cases, just dropped off the VC transfer case under the floor and working through the tranny opening at top in cabin fitted up all the necessary bits, it was a long while back now so cannot remember all the details. But in labour terms 2X burned out old codgers X 8 hours, and lots of cups of tea.
 
frog hopper said:
1988 2.4 Vm. Got a bit of a rubbing sort of noise just started in the last week or so, and what with one thing and another have just got round to doing something about it, which of course has led into a spiral of grief.
The noise is almost like air chuffing through a partly open window, but it isn't that.
Generally coming from underneath, perhaps from the front, and is road speed related, dies out below 15 Mph or so. Cornering/braking makes no difference.
Anyway thought I would grease the prop U/J's just in case, and while I was about it thought I'd check the VCU. That is the back story as you might say, this is what I found, and I don't think I like it.

Grovelled underneath to grease the props and of course the nipples were in the wrong place, though all U/J's seemed to be OK. Jack up the front end and turning one wheel the other wheel rotates in the opposite direction but the prop does not move at all, tried in T'Box neutral and G'Box neutral, no difference.Hand break on/off no difference. All wheel bearings seem to be OK, dropped one wheel onto ground and tried to turn one wheel, solid, no movement at all.

From this I assume 1/. the front half shafts are OK, 2/. there is no drive from front prop through the diff.

What damage will I do in the short term if I drive it in this condition? What if I remove the front prop? ( I never Off-road in this one so don't mind if it's only 2 wheel drive)

Any help greatfully received thanks.
Click to expand...
If both wheels on one axle are off the ground, the prop will not turn as you have found. To turn the props you need one wheel on each axle off the ground, handbrake off and in neutral. Unless I have misread, nothing you have done has tested the VCU.
To test the VCU, it's one front wheel off the ground and with constant pressure it should be possible to very slowly rotate the wheel.
 
Last edited:
As above do the one wheel test first, much easier than maybe unnecessarily removing front prop. Your VCU may be fine, you tend to notice when they are failed when you turn tightly at low speeds and the steering fights against you.
Anyway for the rubbing noise my guess so far is transmission brake :)

Edit: Sorry re-read and saw you did one wheel up
 
Bit more of the story.
Needed the classic to get in the shopping (as the 90 has a clutch problem :mad:) so grovelled underneath and took the front prop off.
A huge difference on the road, steering much lighter, and more stable if anything. Also seemed to roll better.
First off, no strange noises, then as she warmed up I put my foot down a bit - just a bit - and the noise started to come back, backed off the throttle a little and after a mile or so noise went away. Tried this a couple of times, more power and noises start, back off and after a short while noises off.
Something else I noticed on the way back with a fortnights worth of shopping in the back (including a massive case of beer on offer at 40 bottles for €12) there is a small lag between speed and revs, almost as if the clutch is slipping, I guess this is the VCU having a go at doing what it was meant to do, then it's noises on again for a while.

Now looking at Ashcrofts site, think I'm going to have to delay a couple of jobs on her that were going to cost money. Going to cost the thick end of 500 notes.:eek:

Is there anything else I should be replacing at the same time, bearings/seals? The gearbox mounting I shall have to remove looks to be in good order so at least thats something I don't need to replace.
 
frog hopper said:
Bit more of the story.
Needed the classic to get in the shopping (as the 90 has a clutch problem :mad:) so grovelled underneath and took the front prop off.
A huge difference on the road, steering much lighter, and more stable if anything. Also seemed to roll better.
First off, no strange noises, then as she warmed up I put my foot down a bit - just a bit - and the noise started to come back, backed off the throttle a little and after a mile or so noise went away. Tried this a couple of times, more power and noises start, back off and after a short while noises off.
Something else I noticed on the way back with a fortnights worth of shopping in the back (including a massive case of beer on offer at 40 bottles for €12) there is a small lag between speed and revs, almost as if the clutch is slipping, I guess this is the VCU having a go at doing what it was meant to do, then it's noises on again for a while.

Now looking at Ashcrofts site, think I'm going to have to delay a couple of jobs on her that were going to cost money. Going to cost the thick end of 500 notes.:eek:

Is there anything else I should be replacing at the same time, bearings/seals? The gearbox mounting I shall have to remove looks to be in good order so at least thats something I don't need to replace.
Click to expand...
@jamesmartin is the man , I think he worked a while for a company who did a lot of Landy transmission work especially the VCU type.
I remember now, that VM powered RRC of yours is a nice unit and original, be a shame to fiddle with it and spoil originality, VC replacement is a good option, especially seeing as you can get one.
 
frog hopper said:
@jamesmartin a question you might well be able to answer, looks like I am going down the replacement VCU route from Ashcroft, while I have the front casing off to replace it is there any point in trying to change the bearings behind it RTC6015 and RTC6018 ?
Is it even possible to do this? seem to me they are either side of the chain drive gear, is that right?

Thanks in advance. :):)
Click to expand...
no , A you couldnt without splitting the box and they are a tight press fit B they rarely fail the bw is the one lr unit ive rebuilt you dare reusing the bearings apart from the output as they were the 2 bearings lr sourced for the box
a bw from a classic i would remove rear output housing and check the shaft inner splines, you pull housing and shaft out as an assembly
 
Gazbo said:
@jamesmartin is the man , I think he worked a while for a company who did a lot of Landy transmission work especially the VCU type.
I remember now, that VM powered RRC of yours is a nice unit and original, be a shame to fiddle with it and spoil originality, VC replacement is a good option, especially seeing as you can get one.
Click to expand...
the company had the sole official rights for BW box remanufacture in the 90s ,as the engineering dept head i used to go to BW often at the time very decent firm to work with, we did both boxes the classic and p38 types
 
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