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Rear end questions


Exile
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She just turned 21 and i want to get her a new rear end.

The truck, so get your minds out of the gutter. 

Three questions-

1.  How hard to change?  Third axle doesn’t look too bad, kinda scared of power divider axle.  And what about that input yoke, does it need torqued to preload that bearing?  My skills and tools are moderate to good, i have pulled pickup xmissions, disassembled them, put them back together and it still worked.   Local quote was for 650 per axle for labor

2.  What are the pitfalls ordering it?  I understand the axle spline count, i have eaton dd405, and should be able to install ds405, ds404, 402, but I don’t know about the input shaft spline count and the yoke.

3.  Can i run a locker axle with a non locking axle if the ratios match?

Bonus question- should i just drive it to Rickeieio’s and get him to help/supervise me?

Thank you for your advice and opinions.  

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3 hours ago, Exile said:

Bonus question- should i just drive it to Rickeieio’s and get him to help/supervise me?

Advise is worth what you paid.  Bring it on over and I'll watch.

Have you checked truck salvage yards for a set of diff's with the ratio you want?  Might be a lot simpler.

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The yokes torque to 600.  Not fun.  Haven't met one yet that would come out without a puller.  Will also have to cut out a half moon shape in the axle housing flanges to clear the new difflock part.

DD405 is already difflock.  Does the truck just need to be plumbed?  Double check!  The whole carrier family for 404/405 is going to be 44 spline fwd and 39 spline rear.  Then just match yokes from that group to whatever your driveline is.  4 bag suspension probably has a high angle yoke on the rear rear.  You'll probably need to get a "thick flange" bolt kit since your truck is '90s.  New carrier castings will look a bit different and take longer bolts.  Will need to buy two of the long axle shafts with the longer spline on them for the difflock collars.

You can do a single locker, trucks are built that way all the time.  Most common on the fwd, but can be done either way.

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6 hours ago, Scrap said:

The yokes torque to 600.  Not fun.  Haven't met one yet that would come out without a puller.  Will also have to cut out a half moon shape in the axle housing flanges to clear the new difflock part.

DD405 is already difflock.  Does the truck just need to be plumbed?  Double check!  The whole carrier family for 404/405 is going to be 44 spline fwd and 39 spline rear.  Then just match yokes from that group to whatever your driveline is.  4 bag suspension probably has a high angle yoke on the rear rear.  You'll probably need to get a "thick flange" bolt kit since your truck is '90s.  New carrier castings will look a bit different and take longer bolts.  Will need to buy two of the long axle shafts with the longer spline on them for the difflock collars.

You can do a single locker, trucks are built that way all the time.  Most common on the fwd, but can be done either way.

My apologies for the confusion, thank you for the replies.  I have dd405s with 4.88s and all the locking stuff is attached and works so far as i can tell. I go 60 mph at about 2000 rpm with a .76 OD xmission.

i would like to go a little faster so I don’t get run over. I agree this would be painfully stupid to change just a few rpm.

Rickeieio, looking at all the junk connected to the axles, it looks easier to change the gears, but that is just my observation .

Axles would cost more than just the gears, from my research at the local LQT.  I don’t have good access to a loader, so handling weight of an axle would be difficult

my understanding is that my axles have long splines, and i can use a locking or non locking diff with no problem.

The truck has four air bags, with springs supporting the other end of the lever arm, “air spring?” Is maybe the name of it. 

so, I understand that i could have only one locking axle, so long as i have matched ratios.

i understand that yoke removal and retorquing could be difficult, possibly involving a trip to local truck shop to have them pull it and torque it. 

I understand all the gear sets discussed should have compatible input splines  

And i will need longer bolts, i had not considered this.

Thank you. Btw, anyone know what the diff set would weigh?  I’m assuming 1000 lbs ish or less for each axle.

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1 hour ago, Exile said:

My apologies for the confusion, thank you for the replies.  I have dd405s with 4.88s and all the locking stuff is attached and works so far as i can tell. I go 60 mph at about 2000 rpm with a .76 OD xmission.

i would like to go a little faster so I don’t get run over. I agree this would be painfully stupid to change just a few rpm.

Rickeieio, looking at all the junk connected to the axles, it looks easier to change the gears, but that is just my observation .

Axles would cost more than just the gears, from my research at the local LQT.  I don’t have good access to a loader, so handling weight of an axle would be difficult

my understanding is that my axles have long splines, and i can use a locking or non locking diff with no problem.

The truck has four air bags, with springs supporting the other end of the lever arm, “air spring?” Is maybe the name of it. 

so, I understand that i could have only one locking axle, so long as i have matched ratios.

i understand that yoke removal and retorquing could be difficult, possibly involving a trip to local truck shop to have them pull it and torque it. 

I understand all the gear sets discussed should have compatible input splines  

And i will need longer bolts, i had not considered this.

Thank you. Btw, anyone know what the diff set would weigh?  I’m assuming 1000 lbs ish or less for each axle.

 Two healthy men can carry, though not comfortably, a complete single speed drop in gear head.

 I just sent a text to the guy that bought my 3.36:1 eaton 40ks. They have a rear locker, and were in excellent condition, out of my 96' Pete 377. No rust. I asked if he would sell them. I'll let you know when he gets back to me. They're in western Oregon, but easy nuff to ship.

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36 minutes ago, Deezl Smoke said:

 Two healthy men can carry, though not comfortably, a complete single speed drop in gear head.

 I just sent a text to the guy that bought my 3.36:1 eaton 40ks. They have a rear locker, and were in excellent condition, out of my 96' Pete 377. No rust. I asked if he would sell them. I'll let you know when he gets back to me. They're in western Oregon, but easy nuff to ship.

That would certainly make the truck go faster, i might need to forgo that last gear!

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Oh, yea, don't need all that stuff for a regear.  Just a ring & pinion kit, but while it's all apart might as well do bearings, side gears, input shaft, I/A diff, new yoke to seal on and....  For non-lockers I just do the Dana exchange, but the locker ones still go to the gear guy.  Don't think I've done a R&P since 2004, so not much help there anymore.  We bought the diff adapter for our trans jack a long time ago as well, so no help there either.  Just unbolt it and pull.... ;)  To get it out from under the truck just raise the truck on the mobile column lifts and roll it out.... :D

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My 635 is single, just did a pumpkin change on a non-locker. Had 3.73's, went a little too far w/ 3.08's. But w/ a .74 OD, it will run 55-65 in 9th & it's cool to pass someone at 65 & hit another gear alongside..............

I get hi 8's on reasonably flat road, rig weighs 38K.

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Having the wrong gear is a pain.  Our truck will run all day in 10th, up hill or down, as long as your at about 68 mph or higher.  Try to stay in the right lane and run with the trucks and it will go back and forth from 9th to 10th, unless you lock it in manual mode.  Then it gets embarrassing when you roll into the rest area and forget to shift down.......

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Howdy All,

My Freightliner had a 10 speed auto-shift and 3.55 gears in the diff, 470 HP 12.7 DD.  1,350 RPM in 10th at 62 MPH.  I hated the 10 speed, the gap between 9th and 10th was enough to when in the mountains it just seemed like it was never in the right gear.

My Pete, has the 550 HP C-15 Cat, 18 speed auto-shift and 3.55 gears in the diff's, 1,500 RPM at 72 MPH and that seems to be it's sweet spot, it just pulls.  Having the 18 speed is WONDERFUL, being able to split gears it's always possible to have it in the right gear no matter what the road situation.  I love it.

Dave

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20 hours ago, mr. cob said:

My Pete, has the 550 HP C-15 Cat, 18 speed auto-shift and 3.55 gears in the diff's, 1,500 RPM at 72 MPH and that seems to be it's sweet spot, it just pulls.  Having the 18 speed is WONDERFUL, being able to split gears it's always possible to have it in the right gear no matter what the road situation.  I love it.

A little off topic, but does your transmission shift through all 18 in normal operation or does it skip up and down if conditions don't need all 18?

 

 

On topic - I'm following this because I do not have a locker in my truck at this time and this is the one option that I would like to add to the chassis.  Is it possible that I could use the existing pneumatic plumbing for the power divider to run the locker?  (No additional switches or computer programming needed) Since I'm singled the PD is no longer there and I use that switched air currently for the hitch.  I plan to change my hitch air to a constant source rather than switched.

Edited by Av8r3400
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21 hours ago, GlennWest said:

Mine still has the govenor set at 65. Keep intending to change that.

When you go to get it reset, have the tech go over ALL the things that can be changed same time, like time to shut down after idle, etc. Same cost, lots of stuff you might not know can be changed. Usually 1 hr shop time.

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The Eaton Fuller automated 18 speeds will skip speeds as terrain, weight, throttle dictate. The driver can also ask for skip/progressive shifts by double clicks in the selector switch. You can ask for higher gear starts at a downhill intersection. You can upshift/downshift in reverse. You can operate the trans in full manual mode. You can select low at 60mph and impress the bystanders with full jake brake deceleration in every gear down to 1st. You can make julienne fries.

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3 hours ago, Av8r3400 said:Is it possible that I could use the existing pneumatic plumbing for the power divider to run the locker?  (No additional switches or computer programming needed) Since I'm singled the PD is no longer there and I use that switched air currently for the hitch.  I plan to change my hitch air to a constant source rather than switched.

Yes you could repurpose the power divider plumbing. The only reason they are on separate switches to begin with, is that if you are fully locked with moderate traction, you cannot steer the truck.

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4 hours ago, Av8r3400 said:

A little off topic, but does your transmission shift through all 18 in normal operation or does it skip up and down if conditions don't need all 18?

 

 

On topic - I'm following this because I do not have a locker in my truck at this time and this is the one option that I would like to add to the chassis.  Is it possible that I could use the existing pneumatic plumbing for the power divider to run the locker?  (No additional switches or computer programming needed) Since I'm singled the PD is no longer there and I use that switched air currently for the hitch.  I plan to change my hitch air to a constant source rather than switched.

Howdy Av8r3400,

My 18 speed auto-shift will skip shift up and down depending on road and load conditions.  I really like this transmission.

Dave

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1 hour ago, noteven said:

The Eaton Fuller automated 18 speeds will skip speeds as terrain, weight, throttle dictate. The driver can also ask for skip/progressive shifts by double clicks in the selector switch. You can ask for higher gear starts at a downhill intersection. You can upshift/downshift in reverse. You can operate the trans in full manual mode. You can select low at 60mph and impress the bystanders with full jake brake deceleration in every gear down to 1st. You can make julienne fries.

Yup it will do all that 😀

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The interaxle dash switch for 2000's+ trucks is fine (maybe change out the switch or it would drive me nuts).  The interaxle actuator is gonna be on the opposite side of the rail from the difflock but I'm sure that can be easily overcome.  The 80's and 90's trucks like the 379 of this thread have to be careful if they use the old shift bottle that you have to put the ATF into as they use too much air for the dash switch to exhaust fast enough.  You have to put a QR valve in the line or it'll nick all the actuator teeth when releasing.  404's might not have used that bottle and it was just the bigger axles though, I don't remember.

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