Engine/Transmission (1998.5 - 2002) "Heads-up" about gear ratio changes.

[badams1]

I recently ordered a 7:73 ring&pinion set from West Coast Differential because I read an article about them in TDR. The gears were installed in my 2001. 5 2500 auto, diesel, w/ tow pkg. and the L/S 3:54 ring&pinion were changed out by Houston Drivetrain here in Houston Tex. I went through the 500 mile break in period just as perscribed in their literature. I took it easy but noticed my temps would get up to 200F empty just driving around town. Thinking that 200F is normal for break-in I dismissed it and changed the fluid to Amsoil 75/90w,after 500 mi. expecting to see some improvement. Not so! At 950miles after the gear change I hooked up my 1000 lb 10ft flat trailer to haul my lawn mower to my ranch in Austin. The temp went to 250F driving 65 MPH. I have the dana 70 w/Mag-Hytec w/Westach temp etc. When I called Houston Drivetrain, they told me to come in for a look see. They called Dana and the tech person"sherl", told them that the gear set was not rated for my truck and that the 3:73 was for older less powerful trucks that did not have the towing package. The newer trucks use shot peened HD gear sets for towing and that there is a significant strength difference from my OEM 3:54 and the 3:73 that WCD had sold me. Dana does not make a 3:73 HD shot peened gear set for my truck. I had given all the exact #'s from the OEM Tab's to Ed at WCD who sold me the gear but they did not think that it made any difference about the quality of the gear set and they told me to run it. Dana said no way and now I am out $600 for R&R on my end. Now does anybody out there pull heavy trailers and have upped their HP& Torque on their trucks? I don't know why it ran hot yet? Will tear down Friday at (H D T). "But" picture this! I would have ended up at Ratan pass or somewhere with a broke truck if I had not found out these facts. By the way WCD is going to refund for the gear set but assumes no responsability for selling me the wrong part and the cost that I have incurred. A $600. lesson guy's and nobody cares including Jerry, the owner of WCD. It ain't right and we all know it now! I am going back to my OEM 3:54 with the tear down. Ain't life great! -- email address removed --

 

[Seed Guy]

7. 73!!!!!!!!!!!!!!!! What?!?!?!?!? My truck runs high enough revs with 4. 10, what are are describing is a like a crawl ratio.

 

[badams1]

oops

:--) sorry I ment 3:73. To mad to type.

 

[tarussell]

badams1 Did the tech person from Spicer say all the diesel trucks had the hardend gears. I am wondering if it is only for the Dana 70 or does it include the 80 as well. Thanks, Thomas

 

[M Evan]

2003 models will use 3. 73 ratio, will this be complete different axles or still Dana 70 and 80 ?

M

 

[MikeR]

I would have ended up at Ratan pass or somewhere with a broke truck if I had not found out these facts. By the way WCD is going to refund for the gear set but assumes no responsability for selling me the wrong part and the cost that I have incurred.

The are two things coing on here that don't seem right.



1) How in the world can something like this be wrong? Something here doesn't sound right to me... gears and axles aren't rated by the engine your spinning in your truck, gears and axles are built and rated by the weight and duty it needs to carry. Ford diesel duallys use 3. 73's in Dana axles, and the new Dodge diesels come standard with 3. 73 gears, so how can this 'tech desk' person say a 3. 73 is not rated for a diesel pickup?? For one thing, this chick is covering the company's butt by saying your not using a original spec gearset.

That is just like if you called Cummins and told them you had installed 275rv injectors in your 235hp Ram. They'd give you the incorrect spec speech also.



2) The biggie... . I do not think the 'incorrect' gearset is creating your higher temps. It has to be the installation job that is creating that... something set way too tight? I'd say find out first what is creating your higher temps.



-Mike

 

[rubberneck]

Check the backlash. If the ring and pinion were set up with with either the incorrect pinion depth or back lash, temps will get hot fast. Ive seen rearends that were set up incorrectly turn the gears and bearings blue in only a few miles. I too am a little sceptical about this so called rating system they are describing. Shot peening relieves stress risers which will help reduce the chance of cracks, but i dont see how it is going to do anything for temperature. drain the oil and look for filings. Smell the oil see if is burned. Before you let them rip it out, do a little more homework. I know there are members on here who have gone to the 3. 73's hopefully they will chime in. Call dana and skip the tech person and ask to talk to one of their engineers. Just a few ideas.

 

[Scooby]

I agree... . it doesn't pass the smell test... .

 

[Shooter]

She doesn;t know her #$%^*@ ( ) from a hole in the ground #@$%!



Incorrect install. They did not set it up correctly. To tight somewhere.



Stress relieving will just keep the teeth attached to the ring or pinion under higher pressures but will not effect temp.

Did they booger the sending unit ???

 

[Un-Hemi]

M Evan, the axles in the 2003s are made by American Axle. Up until 2003, they were made by Dana. Long live Dana Axle.



I agree: there's something not right about the install.

 

[Bigramguy]

Bad install

There are different types of aftermarket gearsets available. Racing gearsets tend to be a little softer so they can absorb drivetrain shock without shattering the gearset. This will have little or no effect on temps if set up correctly.



There are a lot of things which could be set up incorrectly,and should be checked when it is disassebled.



-backlash

-diff bearing preload

-pinion bearing preload

-pinion depth adjustment

-ring gear runout (could be a bad gearset,but unlikely)



I have seen a lot of installers just ram the pinion nut on with an impact gun and not pay attention to the torque and preload specs. Diff temps will skyrocket if the pinion is tight. You can check it right on the truck. If the driveshaft is tough to turn,it's too tight. It should have just a small amount of drag.

 

[badams1]

Heads-up Guys

To answer some questions... I did not ask about the Dana 80 so I don't know, but the tech Phone # is 1 419 866 3955. I agree about the temp problem probably being an install issue. My best guess is a bearing pre-load being set to tight so I am going back in to HDT for a tear down Monday, to find out what is causing the excessive temperature. A preliminary check of the gear run out and back-lash was checked out ok from pulling the inspection cover, but thats not the only issue here. I would have never known about the problem if I had not had the temperature issue. Ignorance is bliss? Maybe? I called Dana again today to speak to their product development engineer. He will call me tomorrow. (busy guy) hey! I AM JUST AS CONFUSED AS YOU HERE BUT I AM DIGGING. I would rather keep the 3:73 in there because it is just perfect for my application RPM wise. It gives you an extra 100 RPM at 65MPH. Man, I love it and I hope that the gear is good enough but I don't know anything about Fords and don't plan to either. Keep talking I am listening.

 

[badams1]

The "heads up" guy

I got the call this morning from Dana about the 3:73 ring & pinion set that I bought from West Coast Differential. The"head product design engineer" researched the part # and relayed this information to Shirl the tech person to relay to me. Remember he is a busy guy! The 3:73 gear is "OK" to run in my truck under any condition that is within the intended design parameters. That is to say that the shot peening process is an extra step that Dana is doing now on later model applications to help prevent possible stress cracks that could possibly occur, but is not to say that they will occur. This is just an extra step that is known to help in the event that something could cause a stress crack. Engineering stuff!. But the good news is that the gears are the same metalurgy and that there is not a strength difference. The 3:73 Dana OEM gear set is warrenty good for all of the aforementioned applications. I don't know about Ford's but I would assume that these are the same gears that are used in their applications too but like I said I don't know. The heat 250F, is probably an install issue and will be worked. I will apolagize to the West Coast Differential people for the bad thoughts that have been generated by lack of detailed knowledge from myself and the Dana tech. She did do a good job of getting to the answer after specific questions were asked. She's a good person so don't be hard on her. The good news is I can keep my 3:73 with out fear and be confident that it will perform as good as my old 3:54 strength wise. Dana did like the fact that I am running synthetic GL5. She did not blink when I said Amsoil 75/90W. They liked the fact that I am using synthetic! Thanks guys for all the input and I hope that we can all benifit from this ordeal. Pardon me while I go eat crow.

 

[Motorhead]

badams1, Good info as I have a friend that wants to go the other way with his truck, 4:10 to 3:73. His is an auto but also a 4X4 so he has to do it twice.

 

[Huff N Puff]

MikeR is right

Sounds like Pinion preload or carrier preload are too tight. Its easy to check the preload,remove the axles remove the drive shaft,spin the pinion it should spin with just a little resistance. If preload OK then it might take a little longer to brake in. It can take thousands of miles to brake in a set of bearings,especially if the preload is on the tighter end of the tolerance. Merv