Ford SD/Excursion 4x4 Driveline Questions
When I bought this truck one of the hubs was slightly hanging out so I knew I would need hubs so I had a shop replace both hubs they found a vacuum line leak that they patched and said 4x4 worked. I p...
Forum Discussion
So just to try to fully answer the questions of the OP
What does the dash switch do? 1. Engages transfer case and allows front driveshaft to spin up to speed so that
2. Vacuum can suck the splines together and engage the wheels to the front differential.
3. Allows you to shift gears in the transfer case to get low range.
What happens in the hubs to engage 4x4? See previous
What else is engaged/turning in the front driveline when in 4wd compared to 2wd? Everything attached to the front diff
Is I harmful to drive with the hubs locked and the dash switch on 2wd? No - see my previous response
What wears or what damage happens if it is driven in 4x4 on dry surfaces? As another poster noted there is difference in distance travelled by the front and rear axles in a curve this also happens due to steering corrections tn a straight line. The front and rear axles are linked by the transfer case and if the front and rear axles travel a different distance on dry pavement this puts a lot of pressure o the transfer case as the tires scrub. This leads to heat and wear and ultimately will destroy your transfer case. This is why all part time systems should only be used when there is some wheel slip available
Does driveline binding only occur in sharp turns? The "hopping" is a function of the universal joints. Binding is worse in sharp turns , but again, should not drive " excessive" distance on dry pavement locked in 4wd.
What does the dash switch do? 1. Engages transfer case and allows front driveshaft to spin up to speed so that
2. Vacuum can suck the splines together and engage the wheels to the front differential.
3. Allows you to shift gears in the transfer case to get low range.
What happens in the hubs to engage 4x4? See previous
What else is engaged/turning in the front driveline when in 4wd compared to 2wd? Everything attached to the front diff
Is I harmful to drive with the hubs locked and the dash switch on 2wd? No - see my previous response
What wears or what damage happens if it is driven in 4x4 on dry surfaces? As another poster noted there is difference in distance travelled by the front and rear axles in a curve this also happens due to steering corrections tn a straight line. The front and rear axles are linked by the transfer case and if the front and rear axles travel a different distance on dry pavement this puts a lot of pressure o the transfer case as the tires scrub. This leads to heat and wear and ultimately will destroy your transfer case. This is why all part time systems should only be used when there is some wheel slip available
Does driveline binding only occur in sharp turns? The "hopping" is a function of the universal joints. Binding is worse in sharp turns , but again, should not drive " excessive" distance on dry pavement locked in 4wd.
