Rear end ratios 3.21 vs 3.92

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You don't say which engine, but I wouldn't recommend anything under 3.92 with any engine less than 5 litres, and I wouldn't recommend the 3.21 for towing even with the hemi.
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Electrician wrote:

My dealer complained the 3.21 9.25" config had considerably higher failure rates than the 3.55 or 3.92. They see a lot of 4.10 failures, but those are likely abuse-based errors from people buying too little truck...
I've got a 318 powered NV3500 (5 spd) 3.21:1 2WD 99 RAM 1500 club cab. 1st is too low of ratio for serious weight and towing - you'll have to play hot-clutch too get moving. I pulled my 92 Explorer XLT on a U-haul 'full' aluminum car trailer behind it, running in 3rd (3000ish RPM) and 4th maintaining 55-60 mph. Two weeks later the transmission failed. *shrug*
Personally I'd get 3.92 or 4.10 gears if I had to do it all over again... The fuel economy hit is small (and may actually be negative overall if you do a lot of city driving, or 45-55 mph back-roading) and the overall drivability of the truck improves so much, especially when towing or hauling.
JS
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JS wrote:

Oh man! Do I need to quote you boasting about how you abused that tranny again?
"I tend to downshift hard with the throttle closed pulling some EXTREME vacuum."
But anyway, you said that the shift lever (inside the cab) on that thing always felt hot. I have the same 318/NV3500/3.21, and mine never gets hot. I think your trans had something wrong from the beginning.
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wrote:

THe lever can get hot for variuos reasons so that is not much of a indicator but a NV3500 with a 3.21 axle is a LD towing setup at best ----------------- The SnoMan www.thesnoman.com
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StickBug wrote:

I think it did too. After the swap I had noticeably less driveline slop (ie - stick it in say 1st gear, e-brake off, push the truck back and forth) which had been there from the beginning.
The "downshift hard" post got blown out of proportion. What I meant by that was "sometimes I close the throttle at like 5000 rpm - that should cause maximal suckage in the intake manifold". One doesn't have to 'abuse' the transmission to do that, at all. The 'hard' part wasn't about grabbing the stick and cooking the synchros. IIRC the original post was concerning intake plenum gasket replacement methods and their longevity...
But, I will say - I have babied this transmission a lot more than the original. I also haven't hauled any Ford Exploders behind it since then either. That combo was about 2200 lbs over the book tow rating for the 1500 w/ 3.21 (the book says "3100*"... the * says "not suggested for towing")... I have a real hard time believing the Dakota weighs that much less, which makes me call BS on a similar driveline in it truely being able to handle 6000# towing.
Now, if you want to discuss me abusing the engine.. well... No argument. Its gutless-wonder-gas-guzzling ass deserves all the whupping it gets and has ever got. I'm certain the new NV3500 will survive a properly driven 360 - just a matter of finding a flywheel (a gasser 360/NV4500 flywheel may work) and getting that junker 318 out of the way. :)
JS
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wrote:

There was a time when the 318 was a good motor and strong running too. It will respond well to the proper tweaking but honselt the biggest thing hurt your combo is axle ratio because if you had a 3.73 or a 3.91 behind it you would have a completely different opinion of it because a 318 lacks torque because of displacement and deeper gear offset this. (even a 3.54 would help) ----------------- The SnoMan www.thesnoman.com
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Out of curiousity, what would it cost, from a shop, to change gearing in a 4x4.
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cab.
to
tranny
EXTREME
thing
That would require a rebuild of both axles and at around $800 a piece (depending on area), it would cost far more than it would be worth.
--
If at first you don't succeed, you're not cut out for skydiving



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Whether it is worth the money or not is completely subjective. You can only say that it wouldn't be worth it for you.
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You are correct, I should have said probably cost more than it would be worth and then you have to add it if the shop actually knows what it is doing here. Changing those gears is not just a slap in thing and if they are not set up properly, you can kiss those new and expensive gears goodbye.
--
If at first you don't succeed, you're not cut out for skydiving



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I ask since I may be in for a rear end rebuild in the future, therefore I would be committing to that axle anyway. Therefore, an additional axle doesn't sound as bad as just saying both axles at $800.00
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wrote:

Not sure where you are getting this, You do not need to rebuild the axle becuase moct of the time the bearings in it ar fine unless the are subject to neglect. so they can be reused. You can get gears for both axles together for about 300 total on internet and you should be able to get them installed for a total of 400 to 600 bucks because they are not hard axles to work on. The last thing you want to do is get parts from a dealer or have work done there too as you will get scalped. Use a Yukon or Precision gear for axles if you do it and stay away from richmond because they are about a B grade replacement at best. ----------------- The SnoMan www.thesnoman.com
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LOL, you are kidding, right?????? Have you ever done this because from what I'm reading above, I doubt it. Please tell me labor wise, what exactly is the difference between swapping gears and a rebuild. I'll give you a hint, the carrier bearings and if you are working on the DC 9 1/4 rear, you would be an idiot not to replace both the carrier and the pinion bearings anyway and save yourself the grief of having to replace them at around 60,000 when they tend to fail. Otherwise, the labor and steps required are EXACTLY the same and when you replace the pinion (just like in a rebuild), the time required jumps up because now you have to set the pinion depth all over again which can be time consuming when done correctly. If you know someone willing to do it for $300 and who actually knows what they are doing, post the number and address as that really is a bargain.
--
If at first you don't succeed, you're not cut out for skydiving



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Tom, I know this means nothing coming from me but "congratulations" on your promotion. Your spot in the group has been taken by the SnoIdiot. <VBG>
Denny
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LOL
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is
anyway
post
your
I don't know why you would think that as I have nothing against you. My only fear is what exactly I have been promoted to :-)
--
If at first you don't succeed, you're not cut out for skydiving



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wrote:

Most 9.1/4 failure are due to neglect because people think that you do not even need to check or change rear axle lube and if you do this, you may have problem. I messed around with a up 67 charger with a very warm 383 in it and a 4 speed 30 years ago and it had the early 9 1/4 rear axle in it and it took a terible beating without failure. The 9 1/4 is not weak rear end but it is prone to trouble if you never change the fluid in it (which most do not do. Change the fluid after a few K miles when new and then even 15 to 20 K after that if you play hard and it will hold up fine but most seem to think that it never needs changing. ----------------- The SnoMan www.thesnoman.com
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what
is
hint,
would
anyway
when
the
someone
post
I agree that most people never think to check or change the axle lube and because of that they should be built to be able to deal with it. In over 20 vehicles that I have owned I have never changed the oil in a single one of them and never had a rear axle start making noise at all, never mind at 54,000 miles with the exception of my 97 RAM and this truck was babied for the first 70,000 and for the most part, still is. The fact that it is becoming "known" that the 1500 series RAM tends to have rear axle problems at around 60,000 miles pretty much shows it to be a problem with the rear rather than a maintenance issue.

Any assembly is only as strong as its weakest part and in this rear now, that appears to be the bearings. You can change the best design into crap if you use substandard parts in critical areas and while I would say that the bearings in the DC 9 1/4 rear are not junk, they are not exactly the best available either.

I this were required, then the rear should be designed to make this easier such as a drain plug placed in the bottom of the casing. In a severe duty application I would go along with this but contrary to popular belief in this NG, most people do not fall into that category of usage and my truck absolutely did not fall into that category.
--
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TBone wrote:

My 2001 Ram has 80,000 on it. I use it quite a bit for towing and no problems. I have changed the diff oil twice since new.
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problems
rear
Like I said, the bearings are not total crap, just not the best available. Perhaps you got lucky and got a good set. They don't all fail, just an unacceptable number of them do.
--
If at first you don't succeed, you're not cut out for skydiving



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