P38A VC test

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plumbfisher

plumbfisher

Active Member
Posts
523
Location
Berwickshire
'Morning all,
Having on going probs after replacing a front propshaft uj.
As ever, being full of doubt:confused:, thought perhaps I should test the VC.
I've jacked up one front wheel, put it in neutral and tried to turn the raised wheel by means of bar and socket on wheel nut. It does turns but takes some effort. Does this mean my VC is okay?
Also would it be safe enough to drive about for a few days with no front prop shaft?
thanks
Saint, if you are still there, I believe you know all about this:)
 
Lift one front wheel put gearbox in neutral. Wheel should turn slowly with around 70 lb ft pressure turning force on hub nut.
 
Thanks Wammers. Yup, it did turn with a lot of effort.
Would it be safe to drive with no front prop shaft?
It seems that I might need to get it balanced after all. (see my post on 'What did you do today..)
 
wammers said:
If there was no viscous coupling to lockup. If you removed the front prop the front output shaft would just spin backwards and there would be no rear drive.
Click to expand...
Learn something new every day, I was always under the impression that the drive to the rear was direct and the VCU would start to lock up if it saw the front shaft rotating more slowly than the rear. Never had one apart so didn't question it.
 
Wazzajnr said:
Learn something new every day, I was always under the impression that the drive to the rear was direct and the VCU would start to lock up if it saw the front shaft rotating more slowly than the rear. Never had one apart so didn't question it.
Click to expand...
The VCU sits across the front output shaft and a concentric extension of the rear output shaft, it locks up when there is a speed differential between the two shafts.
 
Some times (and I am not saying this is the case with yours, but worth checking) the UJ can get stuck when you fit it, and you have to hammer it to shock it, then it will move freely
 
I had no idea thats how it worked, I was the same as Wazzajnr. Very interesting as they used to say on some telly programme
 
wammers said:
Lift one front wheel put gearbox in neutral. Wheel should turn slowly with around 70 lb ft pressure turning force on hub nut.
Click to expand...

Shouldn't the hand-brake be applied as well?
Long time since I had a VCU equipped RR, my last three classics have all been the old style 'boxes (LT230?) with diff lock … less to go wrong ;)
 
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