Can I drive in FWD only? (BW4405)

[BonesDT]

I'm having a hell of a time trying to diagnose a very bad hum/vibration that kicks in good at 40 mph.

I've tried everything to try to diagnose the rear driveshaft, but I'm still not sure.

Can I drive 40 mph with just the front driveshaft (GKN style CV) in temporarily without the rear driveshaft?

 

[IZwack]

I dont think the transfer case can even do that -- the ball-ramp thing pretty much requires a rear driveshaft to operate. But if it works, technically the manual says you can drive up to 45-ish or whatver MPH in 4wd so you should be fine.

 

[HahnsB2]

Sig says you have a 1354M???

 

[BonesDT]

I was a little ahead of myself. The 1354 is actually sitting on my bedroom floor. I don't have a front driveshaft for it yet. I wanted to solve this vibration issue before I start f'ing with more sh.

Why, could I do it with the 1354? Even the almighty Atlas tells you not to do just FWD, why is that?

 

[IZwack]

I've driven a 1354 manual before with just the front drive shaft (cauz the rear one was too short after SOA and broke in half). But it was only for maybe half a mile to get it back to my house and I was creeping at ~5 mph.

 

[TarHeel085]

i was gonna say, i wouldnt go any faster then 10MPH at the max. i personally wouldnt try it with either one unless absolutely necesary!

 

[IZwack]

i was gonna say, i wouldnt go any faster then 10MPH at the max. i personally wouldnt try it with either one unless absolutely necesary!

Well here's the thought experiment:

If Ford says you can drive the vehicle in 4HI up to ~40 mph, then it would seem logical that the vehicle should be capable of handling the same speed without the rear driveshaft. Of course you're not going to gun the vehicle off the line with just the front driveshaft (poor 1310 u-joint(s)) but it would appear that sustaining 40 mph with just the front driveshaft should be okay. The brakes are still there so braking is out of the picture, only propulsion.

Does anyone see any problems (overlooked factors) in this line of thought?

 

[TarHeel085]

i thought of that too, only problem i see with that with the 4405 is burned clutches, those already weak clutches were never meant to move a 4600# vehicle by themselves.

and with the 1354 i would be worried about undue stress on the bearings for the front output, not to mention it may stretch the chain?

maybe im just paranoid about breaking stuff, but both of the above reasons make sense to me

 

[IZwack]

Oh yeah sorry I forgot to mention in my previous post that I was talking about the manual 1354. But yeah as I mentioned in my first reply, I'm not sure a vehicle with the 4405 can be safely moved w/o the rear driveshaft because the ball-ramp system doesnt have anything to provide the counter rotational force which eventually squeezes the clutch discs together -- but this is just a theory and I'm sure some one will verify that they have moved a 4405 Explorer with just the front driveshaft

 

[kert0307]

FYI, I go 65mph plus in 4x4 high every winter with no problems. Not saying you should go that fast without the rear shaft, but I think it is more of a "how fast to accelerate" verses how fast to drove before damage would occur.

 

[KPT]

the ball-ramp system doesnt have anything to provide the counter rotational force which eventually squeezes the clutch discs together

It should still lock fine. I wouldn't think having the rear driveshaft off would matter.

 

[BonesDT]

I need a really big hill that I can drive to the top of, remove my rear driveshaft, coast down it, picking up 40 mph, hang out the window (I'm coasting, so I don't need to hold the accelerator down) with a mechanic's stethoscope, and then use the front driveshaft when I reach the bottom to hobble off the road, out of traffic so I can reinstall the rear driveshaft.

I'm definitely going to make up for all those bad ideas I had in the past with this one!

 

[IZwack]

You can remove the rear driveshaft, put the front suspension up in the air (jackstands), block off the rear tires, E-brake on, and run the car in 4wd with you in it.