Seized Viscous coupling on transfer box Big job ?

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Willos

Active Member
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521
Location
Huntingdon Cambs
After a couple of weeks with the car on ramps replacing cams and top end and bottom end of the engine i know find out Ive a seized coupling.
Im getting a rumbling at around 40mph and theres somrthing not as it should going around corners
Tried handbrake on and gearbox in N. Jacked a wheel at the front and no go from either side, so Im assuming its the coupling.
Its obviously attached to the transfer box. Do you have to drain this to take the coupling off and any tips. Its a thor v8 4.0. If i get a secondhand one will any year and engine fit it
Thanks
 
Had it done recently by my specialist, they didn't charge much for it and apparently not a big deal, but I guess all the right kit helps, ramps lifts etc
 
After a couple of weeks with the car on ramps replacing cams and top end and bottom end of the engine i know find out Ive a seized coupling.
Im getting a rumbling at around 40mph and theres somrthing not as it should going around corners
Tried handbrake on and gearbox in N. Jacked a wheel at the front and no go from either side, so Im assuming its the coupling.
Its obviously attached to the transfer box. Do you have to drain this to take the coupling off and any tips. Its a thor v8 4.0. If i get a secondhand one will any year and engine fit it
Thanks

Rumbling and oddities going round corners makes me think of wheel bearings.
 
I would have thought so.

I've got a manual. Just been out and tried with gearbox in neutral and also gearbox in neutral & transfer box in neutral: same result. With 2' breaker bar on hub-nut it turns slowly with steady pressure.
 
just thought i would ask - coz a mates P38 is in for repair - was told it was a seized VCU - new t-box, having gearbox recon'd @ Ashcrofts and was told from diff might be knackered :eek:
 
just thought i would ask - coz a mates P38 is in for repair - was told it was a seized VCU - new t-box, having gearbox recon'd @ Ashcrofts and was told from diff might be knackered :eek:

Seized VCU will certainly load diff in transfer box can't see it doing much to gearbox itself. Front diff is far more likely to fail before either of the others do because it has to deal with front wheel rotational differences on lock. With VCU seized and no slip in it, diff can't do that without loading the planet wheels. Only relief for it would be wheels skipping.
 
After a couple of weeks with the car on ramps replacing cams and top end and bottom end of the engine i know find out Ive a seized coupling.
Im getting a rumbling at around 40mph and theres somrthing not as it should going around corners
Tried handbrake on and gearbox in N. Jacked a wheel at the front and no go from either side, so Im assuming its the coupling.
Its obviously attached to the transfer box. Do you have to drain this to take the coupling off and any tips. Its a thor v8 4.0. If i get a secondhand one will any year and engine fit it
Thanks

Not a hard job
remove front prop shaft unbolt the VCU bolts and remove the VCU and reverse the procedure for refitting. oil does not have to be drained.
 
Thanks thats what i wanted to hear
Maybe this thread will prompt others to do the test Better buy one quick before the rush for a coupling takes place £300 new . #thought i might do the chain as well until i saw it was £300 as well
 
Thanks thats what i wanted to hear
Maybe this thread will prompt others to do the test Better buy one quick before the rush for a coupling takes place £300 new . #thought i might do the chain as well until i saw it was £300 as well
I test the VCU every 6K miles or every time it's in the barn for work.
Transfer box chain is a big job.
 
Not a hard job
remove front prop shaft unbolt the VCU bolts and remove the VCU and reverse the procedure for refitting. oil does not have to be drained.
Think you will find you do have to drain the oil, I have changed the VCU on mine and even though i drained the oil when I pulled the VCU even more came out so get ready to catch it.
 
Sorry to hijack / dig up but someone on here accredited a pulling left in the steering to 'slight play' in the vcu, would this slight play have been evident in the standard wheel turning test or some other inspection do you think?
 
Sorry to hijack / dig up but someone on here accredited a pulling left in the steering to 'slight play' in the vcu, would this slight play have been evident in the standard wheel turning test or some other inspection do you think?

Can't see that play in the VCU would cause pulling in any direction to be honest. The VCU is there to smooth out small rotational differences front to rear and to lock and give four wheel drive when rotational difference are great. For pulling to left look at steering box cetralisation and steering link problems. Doing the VCU check is a fairly simple process.
 
Sorry to hijack / dig up but someone on here accredited a pulling left in the steering to 'slight play' in the vcu, would this slight play have been evident in the standard wheel turning test or some other inspection do you think?
You cannot get play in a VCU, it either works or it seizes:) The car would work just as well on road with the VCU removed, maybe better.
 
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