Getrag & 3.07 gears?

[Doug Czaja]

Is anybody running a Getrag & 3. 07 gears?



I tried a search on this but was unable to find the answer I was looking for, so I apologize if this has already been covered.



The reason I am asking is because I have been running the Dana 60 that came with the truck (318ci/W350) that did not fair well behind the transplanted CTD. I would have bought the Dana 70 w/ 3. 54s if I had been able to find one. I was able to find a Dana 70 w/3. 07 gears this past weekend from a ’89 D350 CTD 3speed auto transmission.



I have done several calculations for rpms at a given speed.



RPM @ 55 MPH w/33" Tire (direct) 1720

RPM @ 70 MPH w/33" Tire (direct) 2189

RPM @ 70 MPH w/33" Tire (O/D) 1686



My truck is rarely used for towing & if it is, it’s less than 7k lbs. The OD would (could) only be used on the highway (65mph +) & no towing. The goal is to increase milage & give me lower rpms on the highway.



So the questions are:

1) Is anybody running this setup?

2) How do you like it?

3) Can the current front Dana 60 (4. 10) be converted to 3. 07 gears?

4) If the current front Dana 60 can’t be converted, does any body know where one is?



Thanks,

Doug

 

[RHancock]

I don't have this setup but have driven trucks that do, Isn't that bad. They work alright if you have it boosted a little,



As for the swap, the axel housings are different and you cant just swap the gears and cariers. You have to swap the whole axels to do the swap.



If you do swap to the 3. 07's you may want to consider going to a 5 or 6 speed with a lower first gear if you ever need to tow somthing.



BTW if you dont do the swap and want to sell the axels let me know I have a freind who was looking for a set.



Also nice looking truck

 

[Doug Czaja]

RHancock,



Thanks for the reply & the compliment on the truck. Makes me feel better about the swap. I have called several places & haven't had any luck with finding the front end.



Looked into the NV4500 & NV5600 transmission swap. Too much $$ for my wallet right now.



As far as selling the Dana 70, I am going to have to put it in the truck. The Dana 60 is howling. Will sell the 60 once its is out of the truck.



Thanks,

Doug

 

[Philip]

I have an auto with the 3:07 rears under my truck. About the only difference would be is the get-rag has a . 77 od where I have the . 69 unit. This means your rpm would be just a little higher than mine at road speed.



I like the gearing mine has. I am normally empty. When I do haul or tow I limit my loads to 10k in the bed or around 8k if it is a trailered load. Running empty I get 20 mpg. With a 8k trailer behind me I get 14 mpg.



The 3:07 axles are their own models very little interchange on these. This axle was built to Dodge spec's. No other mfg used this gear ratio in a truck the size of ours. Which makes it hard to find them. You can't swap the ring and pinion. They are different. The housings are different and the carrier assy the ring and pinion bolts is different.



I don't know where one is eather. Sorry

 

[bgilbert]

Doug, I know Thierry has done the 3. 07 swap in a 2wd. He should be able to fill you in good. BTW its a Dana 71 with 3. 07 and the front is a Dana 61 w/ 3. 07. I know I'd like to do this swap, seems like you'd be able to fly down the highway with low low rpm's. Good luck. Bill

 

[Thierry]

DCzaja

Just saw your post, if you decide to run the 3. 07 rear you will need to change your front gears as well, keep in mind that the 3. 07's that Dodge had installed in the Rear Dana 70 will not interchange with anything else, ie there is no way you can go to 3. 54's down the line, also trying to find 3. 07s for the front good luck. I run these in my 89 D250 with a gear vendor and auto, as well as my 93 with a getrag which I sold and it went to Texas, used to run 1750 at 70 mph.

Email me if you have other questions?



Thierry

 

[Doug Czaja]

Thierry, bgilbert, Philip thanks for the advice,



I was afraid the 3. 07s would not be interchangeable in the front axle. 4wd does get used on a regular basis, guess those situations will have to be avoided until a Dana 61 surfaces. I am looking forward to being able pass some one on the highway.



Thierry – What kind of mileage were you seeing on your 93?



Philip – What rpms are you running @ 70mph with your 518 & 3. 07s?



With my current setup (4. 10 gears) the truck gets around 20mph hwy. I haven’t seen a horsepower / toque graph for a 92 CTD but have heard (don’t have a tach yet) that the “sweet spot” is around 1700-1900 rpm with the max torque being developed at about 1400-1500. At 70mph my calculated rpm should be 1686 with the 33” tires. Do you guys think that the engine will be loaded down too much? Is it safe to run @ this rpm?



P. S. This board has by far been the best investment yet in my truck.



Thanks,

Doug

 

[Philip]

I do not have a tach in my truck. So I can't give rpm's. But the sweet spot on my truck is 80mph. At this speed the rattles and squeaks quite down and the mpg is 17. At 60 the engine rpm is a little low if I want to do a pass of another car or something. It takes forever to get the speed up. If I knock it out of overdrive it passes good at 60. I can do 89 mph flat out against the governors in 3rd.

 

[Doug Czaja]

Dana 70 w/3.07 gears LSD?

One more quick question pertaining to the Dana 70 w/3. 07 gears. Is there a traction control device (LSD) available for this axle. I don’t need a Detroit Locker or anything that heavy duty, just something to get out of the mud holes. Would love to have a ARB air locker, but since my bank account balance has more zeros in the front than the back it looks like a LSD some day. So what’s out there for this axle?



Thanks,

Doug

 

[Philip]

There is one made for the 3:07 carrier. The only place I have found a listing is at a dealer. All aftermarket places I have checked do not list the LS in their books. I think dodge had a clause in the contract with Dana that the carrier could only be sold by Dodge.



As of about 4 months ago it was $550 for it.



The 3:07's were not an option in the 94 and up series of trucks.

 

[Doug Czaja]

Thanks Philip!

 

[OnlyCummins]

Originally posted by DCzaja

... With my current setup (4. 10 gears) the truck gets around 20mph hwy. I haven’t seen a horsepower / toque graph for a 92 CTD but have heard (don’t have a tach yet) that the “sweet spot” is around 1700-1900 rpm with the max torque being developed at about 1400-1500. At 70mph my calculated rpm should be 1686 with the 33” tires. Do you guys think that the engine will be loaded down too much? Is it safe to run @ this rpm?



P. S. This board has by far been the best investment yet in my truck.



Thanks,

Doug

Here's a link to HP/TQ curve graph:

http://dodgeram.org/tech/dsl/Facts/92specs.html

The TQ & HP labels are reversed so keep that in mind. TQ is the red curve on the graph not the purple one. Also, the horizontal axis rpm #'s don't appear to be properly 'aligned'. If the leftmost vertical is 500 rpm then peak torque is at ~1700 rpm which agrees with my Chilton's. From all I've read, the fuel mileage sweet spot is considered to be at or just above peak torque so you'd be a little overgeared in OD ... but ... since I suspect your 33" tire diameter figure might be nominal (not actual) then you might be ok. If the actual tire diameter was 32" then your rpm's in OD & at 70 mph would be ~1737, just above peak torque.



As far as the 3. 07 gearing, have you considered an auxiliary OD instead? They can be bought used & would allow you to retain your current gearing plus give you a 10 spd. The Gear Vendors OD has 0. 78 OD so the rpm's would be ~1810 instead. Higher than with the 3. 07's but IMO close enuf to torque peak. Bought mine used for $900 complete & delivered but I'll need to buy a different tailshaft bc it currently has a C6 tailshaft.



Good luck.

 

[Doug Czaja]

Onlycummins,



Your are correct sir, the nominal tire size was used in my calculations. Not sure of the actual tire size but think it is around 32. 7” or 32. 8” which would place the rpm @ 1701 (32. 7”) or 1696 (32. 8”) @ 70mph with a . 77 overdrive gear. So if speed is kept @ 71mph or 72mph the engine should be real close to the sweet spot & I’ll get there a little sooner.



Yea, a ten speed is very appealing & I would have liked to have gone with that option but needed to upgrade to a Dana 70 rear axle anyway. That’s a great price on the Gear Vendors, where did you find it?



Thanks,

Doug

 

[OnlyCummins]

Sir ... ? Puhleeze don't do that to me. I'm neither an officer (or a gentlemen, but that's for another time) or thaaat old. OTOH, Sir Charles does have a nice ring to it .



I think you might be a little surprised at the actual tire diameter. I believe tire manufacturers are allowed up to 10% variance from nominal to actual so you might want to double check the actual, on the vehicle, diameter. Here's an example from specs I have on the Dayton Timberline A/T LT255/85R16D: "Overall Diameter"=33. 1" but "Static Load Radius"=14. 6" which multiplied by 2 -> 29. 2" & is no where near 33"!



Believe it or not, I found the GV OD on a Ford Diesel website. I lucked out bc I was a little slow in making up my mind & someone else initially beat me to it but lucky for me the deal fell thru & since I was next in line I got it. Now if only I could make up my mind on a replacement vehicle I'd finally be able to put it to good use!



FWIW, before I lucked out, I made a habit of 'surfing' classified sections of sites where I thought I might find one for sale. It took a while before I found what I wanted at the right price. I did find quite a few on eBay Motors but none in a condition I was willing to pay for. YMMV. Another site that I've found a couple on was at recycler.com but just keep in mind it's California based.



Good luck.

 

[Doug Czaja]

OnlyCummins,



Sorry about the "Sir" thing, kinda sounded like a game show host







Your are probably correct about the 10% of tire size. I was unable to find the actual tire size & it does seems like I've heard something about that in the past.



BTW, thanks for the link to the engine hp / torque chart . I had been looking for that.



Later,

Doug