brianmurfy

New Member
Since I've had my FL1 IT'S always been 2WD a previous owner apparently removed the drive shaft as he noticed the VCU perishing and was afraid it would damage the dif.(APPARENTLY)

It runs great as 2WD but given the winter that's predicted I'd prefer 4WD i have 2 full prop shafts including VCU's that I can send off to a prop shaft company to be checked and reconditioned.

My question is this, Am I mad to put back in the 4WD and risk the previous owner lying and destroying the hippo? If something did go wrong can I simply remove the prop shaft again and go back to 2WD or will I have a huge repair bill?

Any advise is appreciated
 
test the vcu first ,if its too stiff dont fit it ,if ujs and cv feels ok props wont need sending anywhere
 
I would suggest fitting each of the propshafts and carrying out the test on each of the ones you have.

You dont need to drive the vehicle to do the test so no chance of causing damage to the gearbox / IRD.

If you find that they are too stiff / tight you can always remove them and then get one of the VCU's overhauled by Bell or buy in a replacement.

I am in the same situation myself and will be doing this over the next week or two also.

And yes you can damage the IRD and / or gearbox by driving with a VCU that is too stiff / tight.

Good Luck
 
First thing to do is check for play on the pinions coming out of the IRD & rear diff. If there's quite a bit, its shagged.

You could install a set of props and do a 1 wheel up test. Will tell you the condition of the VCU. If its been lying around for a bit, give it a few goes. As said, before installing, check the bendy bits on the props.

Hopefully you're on the flat. Then deflate 1 rear (or front I suppose) tire quite a bit, and give it a push for a few yards. This will put some stress on the IRD - but not as much as from the engine. If it makes any noises, the IRD (or possibly rear diff) is shagged.

If all's OK, pump the tyre back up, check all tires are same make & model and pressures are the same. Take some Dutch Courage and gingerly try it under power!

If the previous owner is telling the truth and spotted the problem before serious damage you may be lucky. Maybe I'm a doubting tom, but I think you'll find there are problems.

Good luck though :)
 
Thank you MHM

....... could you please help me find the information as all I have been able to find so far is related to testing the VCU on the vehicle.
 
The man of many hats has told you all you need to know - given his response, I found the answer about 30 sends after I found the SEARCH button.

Testing it off the car though is pointless in your situation.
 
The man of many hats has told you all you need to know - given his response, I found the answer about 30 sends after I found the SEARCH button.

Testing it off the car though is pointless in your situation.

why, only a fool would fit a vcu to test it
 
Thanks Grumpy Gel,

I must have misunderstood what I had read here on the forum about the bench tests not having meaningfull / repeatable test figures.

I guess I have a little work to do, as I intend to remove the VCU and carry out the bench test from Bells site as a base line.

Then I'll be refitting the VCU to the prop and carrying out the "one wheel up test" for further info before I contemplate driving with the thing in situ, subject to the figures being ok.
 
Thanks Grumpy Gel,

I must have misunderstood what I had read here on the forum about the bench tests not having meaningfull / repeatable test figures.

I guess I have a little work to do, as I intend to remove the VCU and carry out the bench test from Bells site as a base line.

Then I'll be refitting the VCU to the prop and carrying out the "one wheel up test" for further info before I contemplate driving with the thing in situ, subject to the figures being ok.

you allways check a vc before fitting as well as ujs and cvs, do the same with diff and ird flanges with a wheel jacked up to allow you to rotate the flanges, nothing wrong with checking after and regularly
 
I've already checked the CV's and prop uj's and they are ok.

I need to check the rear diff and IRD output flange for excess play / movement.

Just something else to add to the list of checks & repairs :biggrin1:
 
since both flanges are supported by taper bearings there should be no end float at all, there will be backlash, but should turn without any notchines
 
since both flanges are supported by taper bearings there should be no end float at all, there will be backlash, but should turn without any notchines

Just been out and checked very little backlash in the IRD output and smooth as silk rotationally.

Rear diff has a minimal amount of backlash ( approx 10mm on the flange od ) and no notchiness or roughness at all.

Thanks for the pointers on what to check and look for.
 
Thanks Grumpy Gel,

I must have misunderstood what I had read here on the forum about the bench tests not having meaningfull / repeatable test figures.

I guess I have a little work to do, as I intend to remove the VCU and carry out the bench test from Bells site as a base line.

Then I'll be refitting the VCU to the prop and carrying out the "one wheel up test" for further info before I contemplate driving with the thing in situ, subject to the figures being ok.

No probs. TBH whether there's play in the pinions will probably give you a good understanding of the condition of the IRD & diff. When the trans is damaged, I'm pretty sure they go first. This then screwes the tollerances on the crown & pinion gears, then teeth start slipping and breaking off. At that point the props are removed and the car works fine as 2WD because the remaining gears usually remain intact.

I'd also suggest changing the oil (in IRD & diff) and see what colour it is. A greyish metalicy colour indicates wear. Of course the oil may have been changed after removing props - so might look 'fresh'. Make sure the fill bolt on IRD comes off before emptying :)

My point is the VCU is the 'cheap' bit - its the bits t either end that will tell you how expensive it will be to put back to 4WD.
 

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