Vacuum Hubs
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From: NE Ohio
Vacuum Hubs
There was 28" of snow at the jobsite today. I was driving up and down the driveway (3,000 ft) to make it easier for the crew...... when I would sit at idle for a few minutes the front hubs would not engage, until the rear spun, then the front would jerk into gear and everything was great. This is my first truck with the vacuum hubs, is there a leak? Is this normal? Should I just lock my hubs (manually) for the winter months like I have on all my previous trucks?
Thanks
Thanks
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From: Long Island USA
That doesn't sound right - the vacuum is only a 40 second pulse to lock it - it doesn't require constant vacuum to stay locked.
If they are unlocking on their own (without touching the switch), they are mechanically suspect.
If they are unlocking on their own (without touching the switch), they are mechanically suspect.
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From: NE Ohio
Originally Posted by krewat
That doesn't sound right - the vacuum is only a 40 second pulse to lock it - it doesn't require constant vacuum to stay locked.
If they are unlocking on their own (without touching the switch), they are mechanically suspect.
If they are unlocking on their own (without touching the switch), they are mechanically suspect.
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From: Mason, Ohio
Mine was doing the same thing. I thought it was a vacuum leak too. I'll have to check into this some more. I know I need to replace my vacuum lines as they are starting to dry rot.
If anyone out there has covered this, please chime in.
If anyone out there has covered this, please chime in.
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From: Long Island USA
Originally Posted by fomoconut
Thanks, I jacked it up and spun the wheel. There is a clicking sound.
Your inner spindle bearing might be bad and it's locking up to the axle making it feel like the hub is locked.
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From: So.Ca./ N.E. UT
Were you putting in 4 lo or 4 hi? If 4 hi some movement is required for it to engage (1 mph? per the manual). 4 lo however requires no movement to engage and should happen within 40 seconds.
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From: Wake Forest, NC
AFAIK, the movement is required to get the splines to line up then the hub will lock.Most all locking hubs work this way. I would assume it should be the same in 4 lo. Does it actually say different somewhere?
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From: Long Island USA
The transfer case goes right into 4LOW.
Whether or not the hubs lock is a different story - the splines do need to line up in the hubs for them to lock, and it has to happen during the initial 40 second vacuum pulse otherwise they won't lock.
Which is why there's a manual handle on the hub.
Whether or not the hubs lock is a different story - the splines do need to line up in the hubs for them to lock, and it has to happen during the initial 40 second vacuum pulse otherwise they won't lock.
Which is why there's a manual handle on the hub.
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From: NE Ohio
I had it in 4 high the whole time. It only happened when I would sit at idle in park, then put it in drive / the rear would spin then the front would clunk and grab. I never took it out of 4 high, in fact the truck was in 4 high for 3 days straight, we were slammed with a bunch of snow (20" to 30" inches).
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From: SE Wisco
Originally Posted by fomoconut
There was 28" of snow at the jobsite today. I was driving up and down the driveway (3,000 ft) to make it easier for the crew...... when I would sit at idle for a few minutes the front hubs would not engage, until the rear spun, then the front would jerk into gear and everything was great. This is my first truck with the vacuum hubs, is there a leak? Is this normal? Should I just lock my hubs (manually) for the winter months like I have on all my previous trucks?
Thanks
Thanks
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From: Stephensville WI
Yes, replace them with a good set of aftermarket manual hubs, like Warn or Mile Marker. See link below. This is a very common modification because of the poor track record fo the vacuum hubs. It is also very easy.
https://www.ford-trucks.com/forums/4...-complete.html
https://www.ford-trucks.com/forums/4...-complete.html