Help - 4WD issue !!

Hi All, thank you in advance for any help. I’ve recently bought a FL 2 57 plate, never owned one before so didn’t really know what to check on them I thought the all was well as there was no errors when using the TRS, since I have realised there is no drive going to the rear wheels.

I strapped a go pro to the under side and can confirm that the prop shaft is spinning, after reading up found it could be a haldex pump issue, check with a multi meter on the pump and was out of recommend resistance. So I bought a recon full haldex unit which I then cleaned and serviced the filter before use and fitted it, taken the car out to a field and the front wheels are spinning and still no power to the rear wheels,

Does this mean there rear diff is shagged or is there anything else this could be.

Thanks

It is more than likely that the prop is being turned by the back wheels.

My guess is that the PTU that drives the prop has gone.

GrumpyGel said:

It is more than likely that the prop is being turned by the back wheels.

My guess is that the PTU that drives the prop has gone.

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Is there anyway to test this ? Sorry if that’s a stupid question

Kylenx said:

Is there anyway to test this ? Sorry if that’s a stupid question

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If you can get all 4 wheels off the ground and turn each wheel and see which makes the prop turn.

If I recall correctly, the prop will spin all day, untill 4 wheel drive is needed. Only then does it play a role to the rear.

MULDERKE said:

If I recall correctly, the prop will spin all day, untill 4 wheel drive is needed. Only then does it play a role to the rear.

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I see what you mean. If the prop turns when front wheels turned then at least it proves the drive is coming from the front, maybe

J_D said:

If you can get all 4 wheels off the ground and turn each wheel and see which makes the prop turn.

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I'm pretty sure the prop is geared to the front axle - but is only connected to the rear axle with any great force when the Haldex is engaged.

With 4 wheels lifted, the prop may turn with the back axle, due to drag on the Haldex clutches. If it does turn and the front wheels don't, the the PTU is fubar.

However, it should turn with the front axle due to the gearing. If it does not, then the gearing, or splines, in the PTU are shot. Even then there may be some drag on failed splines hiding that they have failed. So I'd say only lift the front, so the back wheels apply some stationary drag to the prop (through Haldex clutches), then turn a front wheel, while somebody else hold the other. Car would need to be in neutral. If the prop doesn't turn, PTU is shot.

Should add that a lot of these 'concepts' are taken over from the F1 setup, but I think apply to F2.

Kylenx said:

Is there anyway to test this ? Sorry if that’s a stupid question

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Yes. With the front wheels stationery (get a helper to stand on the brakes), then try turning the propshaft with force, use a pipe wrench or strap wrench to apply plenty of torque. If the propshaft turns independently of the front wheels, then the PTU is the issue.