hey ,

i seem to be having trouble getting into 4x4 at higher speeds.

if i seem to recall correctly - i used to be able to pull into 4H while travelling around 60-70kmh (35-45 mph) or maybe even higher.

this year i can't get it in 'nicely' unless i am under 30 kmh (18 mph).

is my memory bad and this is normal, or should it slide in at higher speeds?

TIA!

 

I often shift mine in and out of 4H at 80kph on the Whitemud freeway. I would look for a vacuum leak to the front axle disconnect.

 

Mine is harder to shift into
4X4 when its cold out and if it has been sitting for a while.

 

Does fluid level have to do anything with it? Maybe check/change it

 

There's a synchronizer in the transfer case that spins up the driveshaft to meet the drive speed. I've heard of this wearing out and causing engaging problems if the trucks speed is to fast. Maybe you should check the transfer case lube.

 

the one in front is the old syncronizer, the new one is in the back. I dont think it is wise to be engauging the transfer at those speeds.i bet the owners manual dont advise it.

 

With all due respect to those of you that are shifting into 4-whell at those speeds...you are pretty much answering your own question.

Slow to a crawl before rippin' it into gear. Can't imagine a scenario where you have to have 4-wheel at high speed...

 

I agree..... As much as I think there's plenty of scenarios which would involve driving in 4wd at around 45 mph, I dont see the reason why anyone would try and engage 4wd at anything above around 10 mph. Not only is it dangerous since you'd better be on slippery ground to need 4wd in the first place but if you are then simply the process of engaging in 4wd could cause an accident.

 

I believe the owners manual says up to 80 KPH. I have always maintained there is absolutely no point in engaging 4X4 after the accident or hitting the ditch. If the gears are turning the same speed that is the tires are the same circumference, the gears will just slide in just don't force it give the CAD time to engage and spin up the gears. The worn synchros could be from CAD not engaging fast enough, low fluid level, tires not the same circumference or just plain incorrect shifting, it can't be from shifting at too high a speed if it was 5th gear synchros would be worn out also. It's not about vehicle speed it's about the difference in speed between the gears that are trying to mesh.

 

No Busboy. You're confusing CAD axles with non-CAD axles. On a non-CAD axle truck (usually '01.5-'02 on up) the driveshaft is full time which means its always spinning at road speed, so when you pull the transfercase lever into 4hi then there's no synchronization necessary between the front driveshaft and the front axle since they're already spinning at the same speed. They just fall into place unless the front and rear tires or gears are different. BUT.....on a CAD axle the front drive shaft is part time which means its NOT spinning at road speed, so when you pull the transfercase lever into 4hi, the syncro has to spin the driveshaft up to match road speed so that the CAD unit can engage. The CAD will not and cannot engage until the front driveshaft matches the road speed. The reason the syncro wears out is because the driveshaft is heavy and guys are trying to force it into 4wd at unnecessary speeds. You cant compare abuse the transfercase syncro has to sometimes endure to the manual tranny syncros.....unless you dont like to use the clutch and aren't good at matching RPM's to road speed.

 

The live front axle was in late '02, just before the third gens came along.

 

That was the idea but you'll see some '01.5's with some '02 parts (like the non-CAD axle) because they stopped supplying the assembly lines with '01 parts and had to pull from the '02 supply. Thats where the '01.5 comes from. Some '01.5's had rear disc's, but no inner fenders, no rear cup holders, no under hood insulation, etc.....

 

I'm looking at the operating manual that came with the truck. On page 133 it states that..... "shifts between 2H and 4H can be made while the vehicle is moving or stopped. If the vehicle is moving shifts can be made at any speed up to 55MPH. The shift will be easier if you momentarily release the accelerator pedal. Apply a constant force while shifting the transfer case."

 

I do release throttle when shifting into 4H every time.

 

Make sure you have a good not to heavy gear oil in the front axle. A few years ago when I was doing the diffs I added synthetic 75w140 the same oil I run in the rear into the front. Bad choice and poor 4 x 4 shifting. I changed to a synthetic 75w90 and no more issues. I can easily shift at any speed.