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Discussion Starter · #1 ·
So I have had the rear end replaced twice now in 1500 miles and its ready for a third. All I do is tow with the truck, it gets driven very little otherwise. I have put a larger cover on to hold more oil and that didn't help. When I tow I can smell the fluid burning up and if I throw water of the diff it boils off. Obviously it is getting so hot that the fluid fails and the gears go because of the heat. Chrysler is unconcerned with whats causing it they just keep replacing it. My question is what is causing the heat build up? Can someone explain how the axle and rear end work together and what would produce the excessive heat? I would like to go in for the third swap out prepared and get to the bottom of this. Thanks.
 

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Discussion Starter · #3 ·
They havent really told me....just said the gears were destroyed.
 

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Besides you just knowing its getting hot what other symtoms makes you check/think somethings wrong???(are you hearing noises or feeling grinding??)
How much weight are you towing?? (is it a backhoe?? or more then 7500 lbs??)
What gear ratio does your truck have???
A little more info is needed because just towing wont destroy gears.
 

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Discussion Starter · #5 ·
Basically when I can smell the diff oil and the smell keeps getting worse the gears are about to go. Last time it go so hot that it fried the parking break sensor, an abs sensor and a sensor that had to do with the speedo since it went out. All of those things I was told are in the rear end. The first time I didnt smell the oil at all I could hear a whining noise that kept getting worse. Right now the only symptom is the smell of the oil breaking down an the abnormally hot case. I am towing a tow hauler so the weight varies between 7-8000lbs, I make sure not to go over the 8100 listed limit. The ratio is 3.92. I just took it on a trip with lots of hills and that was the first trip on the new rear end. I am going to the dunes this weekend and its mostly flat the whole way. I was gonna change the fluid and see how it did.

Thanks for your responses.
 

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You should have got a 2500 or 3500.

These 1500's are not meant to pull that much weight up hills.

They keep replacing it is because their papers say it can, but it can't.

If you are towing 7000+, get a diesel. That's what they are meant for.
 

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I agree that even though Dodge says the 1500 vehicles can handle a certain payload towing capacity that they are NOT designed to do this day in and day out without troubles........the larger the ring gear and pinion the more abuse they can take as well as heat. This is why 2500 and 3500 trucks have upwards of 11.5 ring gears and very large rear diffs to help in cooling.Once the fluid starts breaking down the trouble starts.

I towed a 7500 lb travel trailer on ocassion and never had any troubles BUT I bet you if I were to use it strictly for towing that alone I would have had problems.I had 4.56 gears too.
 

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Sleeper in The Making
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I would think Maybe if you have not been using synthetic that would help. And maybe stopping sometimes and letting the rear diff cool down ?
 

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Discussion Starter · #9 ·
My problems is that i bought a truck with a tow package that said it could tow 8100 lbs. The truck is paid off and now I have a trailer payment....thus I cant afford a diesel or trust me I wouldnt be posting. I am beginning to think that the 9 1/4 rear end isnt meant to move anything more than the weight of the truck. I have a big problem with being sold something that wont perform like it says it should. What are my options with chrysler, where can I go from here?
 

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Sleeper in The Making
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Ouch Dont really know what to tell you then.
 

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Trade the 1500 in on a used 2500 Diesel or keep replacing rearends .
 

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Is swapping out the entire axle assembly with one from a 2500 an option? If so, you would probably have to change the gears in the front diff also.
 

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jordanp123 said:
I would think Maybe if you have not been using synthetic that would help. And maybe stopping sometimes and letting the rear diff cool down ?
they come from the factory with Synthetic so that rules out what you said.
no Punt intended;)

I agree with you guys on the 2500 or 3500.
 

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I dont see why the rearend would keep going because of the weight. if it was too heavy i'd say the brakes would fail first.. Maybe the gear oil isnt lubing like its suppose to so its not cooling the gears etc... i pulled a 6500 to 7000 lb wake setter for 55000 miles with my 02 1/2 ton 4.7 and never a problem.. maybe get a whole new rearend, housing and all and see what happens..
 

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Discussion Starter · #15 ·
The Juice said:
The truck is paid off and now I have a trailer payment....thus I cant afford a diesel or trust me I wouldnt be posting.QUOTE]
.......

I would love the larger rear end thats in the 25/3500's, is that even something that can be done?

I just got back from a trip to the sand dunes. Its mostly flat so there were no hills to pull. Prior to the trip I changed out the burned up oil which was amsoil, and put in the mopar gear oil. Never smelled anything and had no trouble. I have never used amsoil diff oil before, could it possibly have something to do with it?....and yes I used the right weight and everything.
 

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Are you breaking in the gears? I dont know why the first set failed, but you are NOT supposed to tow with new gears for the first 500 miles. Youve had the diff replaced twice in 1500 miles with towing in the middle, obviously you arent letting the gears break in. You need to run them for ~20 miles or so the first time out and then stop and let them completely cool. Then take it easy the first 500 miles with no hard starts, etc and dont go over 60mph in the first 100 miles. Then when you tow you are only supposed to tow for 15 miles or so at a time and then stop and let the gears cool for the first 50-100 miles of towing.

You fried your gears by not breaking them in, I am suprised the dealer keeps replacing them. The site below explains the break in procedure and also details what happens when you dont do that. Crazy thing is...... it matches what you are decribing.

http://www.ringpinion.com/content/technicalhelp/default.asp?pid=122
 

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When I had my gears put in by a race shop, I brought the mopar synthetic with the additive with me.

He told me no. The way to go is use regular 75w80 and no additive unless it chatters on tight turns, then add a tenth of the bottle at a time until it goes away.

I now have regular 80w/90 in the rear with no additive. No problem, no chatter.

My bud, a motorhead told me that the synthetic had already made the lsd clutches slippery and it would give me a problem when I launch if I stayed with it.

That synthetic is not all that its crapped up to be.

My buds that run 8 and 9 second 1/4 cars use regular Pennzoil in their engines, not any synthetic stuff.
 

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Discussion Starter · #18 ·
biglowt said:
Are you breaking in the gears? I dont know why the first set failed, but you are NOT supposed to tow with new gears for the first 500 miles. Youve had the diff replaced twice in 1500 miles with towing in the middle, obviously you arent letting the gears break in. You need to run them for ~20 miles or so the first time out and then stop and let them completely cool. Then take it easy the first 500 miles with no hard starts, etc and dont go over 60mph in the first 100 miles. Then when you tow you are only supposed to tow for 15 miles or so at a time and then stop and let the gears cool for the first 50-100 miles of towing.

You fried your gears by not breaking them in, I am suprised the dealer keeps replacing them. The site below explains the break in procedure and also details what happens when you dont do that. Crazy thing is...... it matches what you are decribing.

http://www.ringpinion.com/content/technicalhelp/default.asp?pid=122
The first time they went the truck had 50,000 miles on it, obviously broken in. The next time they went there was 400 miles in between the change out. I dont think 100 miles will make a difference. I believe it went because they used the wrong weight oil and also whatever the underlying problem is. The dealer that installed them said there was no break in.....the dealer that replaced them said there was so because they didnt tell me they covered it. Now I followed the break in to a "t" and I'm still boiling oil. Got a nother trip this weekend so i will see what happens.

Thanks for everyones input.
 

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kenihemi said:
When I had my gears put in by a race shop, I brought the mopar synthetic with the additive with me.

He told me no. The way to go is use regular 75w80 and no additive unless it chatters on tight turns, then add a tenth of the bottle at a time until it goes away.

I now have regular 80w/90 in the rear with no additive. No problem, no chatter.

My bud, a motorhead told me that the synthetic had already made the lsd clutches slippery and it would give me a problem when I launch if I stayed with it.

That synthetic is not all that its crapped up to be.

My buds that run 8 and 9 second 1/4 cars use regular Pennzoil in their engines, not any synthetic stuff.

I agree with you by not adding the friction modifier at first. If chatter occurs then just add enough modifier to eliminate the chatter.

But as far as you running the regular gear lube with no modifier and not getting any chatter, maybe your lsd is wearing out???

The condition of the lsd is determined by the amount of torque it takes to break the friction between the discs. It seems the friction between the discs on yours is very low thus allowing for smooth operation with regular lube and no modifier.

I changed my original lube out at 15,000 miles to synthetic and didn't add any friction modifier and after about 40 miles of constant city driving I had to add the full 4 oz of modifier to get rid of the chatter.

When I changed the oil at the 30,000 mile interval I had to add the full 4oz of modifier again to the new synthetic lube to eliminate all the chatter.
 

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I know what you are saying bucci and I appreciate it.

I have the stock 20's with the stock 33" tires on it and did a little showoff kinda burnout the other day and both marks were even. That means the clutches are fine or one or both would have slipped.

I'm making good power and I need all the help I can get. Just thought it could help others with what I learn.
 
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