48RE almost didn't start the load

[WoodChuck]

You're wrong. No matter what, with the front and rear axles locked together, there is going to be binding. These Diesels have a lot of torque, and if your tires don't scuff and spin, you're going to break something, plain and simple.



Part time 4wd is NOT for hard surfaces regardless of the direction of motion.

There won't be any binding if you have the same axle ratios and are going in a straight line. When you turn sharply or semi sharply wheel speeds don't match and you build of tons of stress till something has to give (usually the tires will give but these trucks are so heavy they might not).

 

[PatrickCampbell]

Yes, there is a possibility of binding, but if you are smooth, you will be fine. I would use 4 HI not 4 LO though.

 

[DPKetchum]

4 hi wont pull a big load up a 19% incline any better then 2 hi unless I'm missing something. Heck just trounce on it and when convertor hits stall and turbo builds boost it will go. Thats what he did anyway. I had a load on my 93 W250 that was so heavy on a big asphalt incline that it broke the back tires and loose and spun them about three feet and kept a moving. I had a 24 foot long bumper pull oak bed trailer with over a 100 bales of hay and a slide in camper packed to the gills(in the bed of course) with personal items AND 800 lbs of bagged horse feed in it on the floor. (divorce and running away from home). Pouring down rain and got caught in traffic. Had to stop and then start on a fairly large incline. Got into it slow and then tires spun and got going. Truck really threw its shoulders into it.

 

[SMasters]

I figure I would use 4 low for more torque. I didn't have any traction problem.

 

[Swamp Donkey]

I think some of the suggestions are to just put the gear selector in the 1st gear position instead of leaving it in drive. I would try that before getting myself into 4lo in traffic. But I guess sometimes you have no choice. If it won't go it won't go!

 

[BHolm]

The only problem I see with using 4-lo to get started (in a straight line!) is that you are going to have to stop, shift to N, before you can go back to 2-hi. That isn't always very convenient in traffic Gas it and go is my advice. Unless you make 10 starts in a row like that you aren't going to hurt anything. It is just the loose convertor in the trans. An aftermarket one would likely solve the problem completely.

 

[SSage]

Sounds normal to me. If I stop on a steep hill with a loaded trailer it will take WOT to get moving. But once moving I have pulled grades like that with 14K trailers in third at 40 mph plus. I could go faster, but 40 to 45 mph feels right with the 48RE and 4. 10 gear pulling near the GCWR. I select my gears and keep the rpm way up there, 2900 plus. I'm amazed how many times I've passed cars and empty trucks on those hills. If I drop speed it seems to be harder on the truck, engine boggs etc. Keep them rpms up and let her sing.

 

[Tim]

There won't be any binding if you have the same axle ratios and are going in a straight line. When you turn sharply or semi sharply wheel speeds don't match and you build of tons of stress till something has to give (usually the tires will give but these trucks are so heavy they might not).

That is not true. No matter what, no four tires are exactly the same size and they will never travel the exact same distance on the ground. You WILL have binding, even if you drive only straight (been there, done that, I've got four 4wd trucks right now).



On paper your idea is fine, but in reality, there is no way the front and rear axles ever drive the exact same speed with them locked together.



You're putting a LOT of stress on the transfer case chain when you do this. It's not a good idea. I never use 4wd unless the surface is slippery enough that it's hard to travel on in 2wd, unless I'm off road.

 

[JStraw]

Hi Tim, for those of us that 'hotrod', it isn't uncommon to do a hot launch in 4 high. With the extra grip of the fronts, these sleds zip like a rocket. At 60 its an easy shift to 2 high. aside from 'hotroding' I've done the same with 15K where more grip is required. I've eaten a lot of GT's for lunch



I do agree about the chain stretch. As with everything mechanical... . breakage is just a matter of time.

 

[WoodChuck]

No matter what, no four tires are exactly the same size and they will never travel the exact same distance on the ground.

I really don't want to start a war here (god knows too much of that happens on this site) but I rotate my tires every 7,500 miles and I doubt there's much if any difference in diameter.



I maintain that there is no discernable binding happening in a straight ahead driving condition.



Even slight sweeping turns at about 30 mph on dry pavement don't cause enough binding to be a problem.



Tight maneuvers are a huge problem though. Usually tires give before anything else but the undue stresses should be avoided.

 

[WRStrong]

I drove my 03 4x4 a couple hundred yards on dry pavement just the other day inadvertently . I didn't notice it until I made a turn and it bucked like a bronc. Stupid me. It shifted out of 4 hi with ease. I figure if it were bound up I wouldn't get it out of 4 hi without backing up etc. I don't recommend this. I also agree that yes these trucks move out much better in 4 Lo but good luck shifting back to 2Hi on the move under heavy load. I don't like the way the 48RE moves out under the loaded uphill condition either. Sounds like a 58 buick trying to take off.

 

[BHolm]

Well Tim, if it is a "contest" I have 7 4x4s right now. There is NO WAY you are going to hurt anything by starting out in 4wd in a straight line on dry pavement. I think you are the one using theory here. You are correct that binding may occur. It certainly isn't going to occur in the 100yds or 200yds required to get the truck moving. There is plenty of tire scrub especially if the fronts are lightly loaded, heavy trailer, going uphill.



I think your point is well taken that running 4x4 on dry roads is not a good idea but, it is FAR from the problem you seem to be presenting it as. I have read stories here about guys who have inadvertantly run in 4x4 on pavement for 20-30 miles. I don't believe for a second that it really hurt the trucks, the components are a lot tougher than you give them credit for.

 

[CLAYTON]

This happend to my father in-law last fall. We were stopped at a stop light on a steep grade with about 14k behind us. I put it to the floor and I started moving. He said he pushed the the go pedel but there was no go. Guess he just didn't hit his stall. Could the clutches be slipping in this case and not doing their job?

 

[c-hawk]

I don't run 4wd on dry roads for no reason... but i have over 100 launches at the drag strip in 4wd, and who knows how many i've done other places.



At times i've turned on dry roads while in 4wd. You can definitely feel it binding then.



Still through all this, my transfer case, axles and all have held up fine and i'm at just under 100,000miles.



I'm not saying it's good for it, but these trucks are tough. I can't see any damage occuring from going straight ahead for a short distance in 4wd.



Heck lots of us do it at over 100mph on a regular basis. (at the track)



Just my opinion,



Chris

 

[DPKetchum]

Just didn't hit stall. I have known a V10 auto truck that the owner had a STEEP drive(paved)pulling his HOUSE(some huge bumper pull travel trailer) if he stopped at the base of drive it would NOT pull it up the hill. Had to be moving some and it did fine. His problem was a DIP before the steep part and if he was moving the hitch and front of trailer hit and gouged bad. He wanted to know what WE were going to do about it(warranty)we even went to his house and saw what he went through. It was like O WELL. We tried it in a diesel 4. 10 gear auto. Same deal. He needed a smaller load or smaller trailer OR a contractor!

 

[WoodChuck]

How about a good aftermarket torque converter? That oughta do it.

 

[DPKetchum]

YEP. Thats the ticket.

 

[WRStrong]

Has anyone installed an aftermarket TC in their 48RE? Why are they so loose from the factory? There's usually a reason for everything, even the bad stuff. Most often smooth, quiet, longevity and drivability.



I know this was a 48RE thread originally but humor me a bit.



I have an ex brother in law who drove his 79 (or so) Blazer around in 4Hi in Phoenix for like 6 or 8 months. It was almost new at the time and had those always-locked hubs. He thought that weird rocking (bucking) motion going around corners was just a 4x4 quirk. No mechanical genius here. Finally he asked a more knowledgeable friend what the problem might be. The friend sat in the truck and saw the problem immediately. I don't know if Dan ever lived that one down. Anyway, there was no noticable damage. Not even excessive driveline lash. Probably the tires (33-inch!) were giving it up and relieving the stress.

 

[DPKetchum]

Actually the 48re convertor is tighter then the previous years.

 

[pwerwagn]

Just to add to the debate about driving in 4-wheel, and talk a little about the 48RE/47RElaunching:

I have driven home from the lake, about 130 miles to my house, in 4-high, at 80mph on the freeway, with 40" super swampers in my 74 power wagon. (basically, just to prove it could be done ) I used to pull a 10,000lb trailer every sunday with the same truck, and the 360 wasnt to happy turning 40's with a 10K trailer, so I used 4-low. The truck didnt have hubs at the time so it was in full four wheel drive (they were 3/4 ton chevy axles in the dodge, 44/14 bolt). I've launched quite a few times in 4-wheel in my cummins. I dont think it is a huge problem.

My grandpa has a 02 CTD 3500, and hauls an 11. 5' lance, and tows a car hauler with a jeep (probably 10K between the camper/trailer). He regularly uses 4-low in colo on the hills. He has now rigged up a vaccuum switch to disengage the front end, but didnt always do it that way. He always puts his truck in low BEFORE he stops on a large hill, or in a steep campground, etc. Usually his wont go into low if it is stopped (normal). He has actually had to have another truck pull him out of a campground once because his truck wont untrack. His truck also wont go over curbs for crap. his truck was my inspriation to get a 5-speed. :-laf He is havin ATS do the torque convertor and valvebody next month to cure the problem. It is pretty dissapointing to me about the torque convertor chrysler chose to use. Some people, (like my grandpa) feel like the bought a truck and didnt get a transmission. the trans is a good unit, but the torque convertor sucks, plain and simple.

Also, there is always going to be a difference in tire height though. no matter how you rotate them, no two tires are the same. We are sorta in the tire business, and I have personally seen goodyear tires that were bought the same time, marked the same size, and were right at one inch difference in height. that is an extreme case, but it goes to show that no two are alike.

FWIW

-Jeff