FORD ZD 351

Have been chasing a minor vibration in my ZD 351 since I bought the old girl a few years back. Just had new tailshaft built with new uni joints. still there at 65-70 mph. 9" limo only drives one wheel when pushed hard (ie: smokin'). All new tyres and balanced last week. Problem in the diff ??

northey

pinion snout not bent? where yoke attaches. If pinion has been bent no matter what you did elsewhere it would have vibration.
bent axle?
They are rare possibilities but when you can't find problem everything has to be looked at.
dial gauge may be needed to check both items.

atec77

Does it vibrate at the same revs in all gears ?
if not then you might have a bent diff housing ( but I doubt it) a bent pimion or a bent output housing/pinion on the box , other possibility would be a wheel or stub but thats beyond the scope of this forum and will need some careful inspection , can you swap the wheels off another car just in case ?
sounds like you might need an lsd or locker if your wqanting not to spin the open

lukeh

Try taking the tyres to get rebalanced somewhere else and see if anything changes.I once had a car with a vibration at about 60-65 MPH,and I found the tyres were'nt balanced correctly...rebalancing fixed problem.

eon

Driveline vibrations seemed to be built into many of those early Fords, especially if you exceed the speed limit. I chased the vibrations on an XC and ZH, then gave up. Just stayed on 110kph.

FORD ZD 351

Thanks guys for the comments.

New Tyres have just been fitted and balanced. Problem did not change.

After a weekend run on Motorway I have more clues which will probably mean I need to speak with someone who can diagnose diff faults.

Cruising at any speed 40 to 80mph, mild vibration, full throttle vibe gone no matter what speed, zero throttle (speed coming down) no vibe, as you start to apply throttle to cruise speed I see biggest vibration - back to gentle vibration at cruise speed. Seems to have a lot to do with the load on drivetrain. Accel/Decel give no vibe - cruise gives vibration, hmmmm ... that's gotta give someone the clues to point me in the right direction.

atec77

I would be starting with the uni joints and check the prop shaft is straight to begine

FORD ZD 351

Thanks Atec. Agree, good place to start .. so I had a new shaft made (after recently getting orig re-balanced), new unis. Problem still there. Such a shame cause she's a dream to drive. Fitted 3 baby seats this weekend and left the family cruiser (BA Wagon) parked .. even got the wife to drive the old girl to church !!

ToddZC

My brother's ZD had similar vibration problems until he replaced the rear brake drums with new items. Now no more vibes. Maybe worth considering?

FORD ZD 351

Thanks. Will check that out.