D70 3.07 value

[MMiller]

FWIW as far as I know, 3. 73 was the highest gear you could get in a full floating 14 bolt rear diff. There is another 14 bolt, that is a nonfull float, or a semi floater rear diff that was available with 3. 42 gears. Also for what its worth, a semi float 14 bolt can be broken with a very mild 350 hooked to a sled.



The full floater 14 bolt is tough, and readily available. The only options that hold up are open, detroit locker and spool. The factory limited slip or "gov lok" is a grenade ready to go off at any time. Not many were equipped that way. I've got one in the back of my 90 because it was cheep to get and lock up. I've got one in the back of my pulling truck also. I did go ahead and cut off the spring perches, because IMHO they are far enough off to cause spring bindage problems. I prefer my suspension to work as its designed, not all pinched together and bound up. I do know that lots have put chevy axles under dodges with no mods, but I prefer not to do it that way.



Edit, I learned the other day that the "14" bolt means the number of bolts that hold on the ring gear to the carrier, not actually the bolts that hold the cover on... .....



Michael

 

[therabbittree]

Well I run the 3. 07 gears in my w350 with a getrag ,and it feels good and drives nice. But I haven't gotten the fuel mileage that I'd like too . . I think its the stop and go and short trips and the big injectors (PODS) Out of the 6 tanks I've run in it over the last year I've gotten 15mpg, 11mpg, 12mpg, 17. 5mpg, 14. 5mpg, And 16 mpg averages those and its 14. 3 mpg average. . now this a is a part time truck. I have a take home car for work, so I don't drive this much and if I do drive maybe 3 times a week its in the 20 mile range if that. So the 5 mile trip etc is about average for the truck ( Hardware Store, Fire response calls Vol. Fireman etc). . I run all sythetic fluids . . engine oil, trans, transfer, and axles. I fill each tank till the foam stops and I see clear diesel in the neck and its all hand calculated and I have the records since I built the truck last year. I run 285 truxus mud terrain tires and the front hubs are unlocked unless I'm stuck or plowing etc. . no lift just a stock w350 . . pod injectors, fuel pin is ground and set to kill, turned up pump timing bumped etc valves adjusted, 65psi in the tires, 5 " exhaust, and stock turbo with 21cm housing still haven't swapped it out . . ha. . oh and reg cab too etc. I rarely tow anything and empty 99 % of the time etc.

The truck likes 3-4th gear around town . . if I shift to 5th I can actrually lug it at 50 mph with the tires flexing and boucing from the lug. . so 5th is normally for 65and up speeds. it pulls awesome 100 mph comes real fast!!! I can really slip the stock clutch. . I haven't swapped the south bend fe in it yet. . my '89 had the 727 and the same axles. . and same mpg ha. . but not as nice sounding etc ha... oh well thats my experience with 3. 07s... I like em but iIhaven't gotten over 20mpg ever. . any ideas or tips?

thanks,

Deo

 

[Don Tanklage]

anyone ever try a gv od or taller tires?



i wouldnt put a general motors anything in any of my trucks



don

 

[pepecat]

Sure, one could fit some real tall tires in the back, like 255/85 r16 and yes there have been some folk here with GV Od's as well. Highway speed is an issue with stock 727 non od auto and 3. 07's and no Gov spring... However you can always remove the high idle screw even! I spent 1500 on my getrag conversion and did labor myself. New clutch and all the rest used/rebuilt parts. GV will cost over 3K to do bottom line. Even then you'll still have a slushbox with no lockup! The cummins likes to be locked up to the road no slip IMHO, that's where the torque is really utilized.

 

[dpuckett]

Deo- you can improve your MPGs by getting a tach and not letting the RPMs get below 1500. I dont go into 5th til 55+ with my 3. 54s, preferrably more like 60-65. If i know I wont be going over 55-58, I keep it in 4th. I keep it in 3rd til about 40mph in town (2200 or so RPM). The trucks will get their best cruise MPG at 1600-1800rpm, but the vaired stuff needs to be a little higher up the scale.



Daniel

 

[MMiller]

i wouldnt put a general motors anything in any of my trucks



don

A 14 bolt was built by AAM the same manufacturer that makes the axles for the brandy new Dodge trucks powered by our faithful Cummins engine. Both my Dodges needed something heavier then a dana 60 rear. The options were Dana 70's at $4-500 for just the axle, then $750 for the Detroit Lockers to make them work right, or free 14 bolts, and $450 for a detroit locker. Poor people have poor ways. Heck its cheaper to buy a dead 70's or 80's chevy for the rear end then it is to buy a dana 70 rear diff by itself. I'm not sure that a 14 bolt will stand up to what a dana 80 does though. I've seen alot of 14 bolts break behind a 650-800 hp big block pulling trucks.



I will say that there will be no small block Chevies in my dodges, no turbo whatever transmissions, or duramax's either... ... ... just big block Mopars, and Cummins power for me!



I gotta agree with Daniel that it sounds likes your grunting your truck a little much for good economy there Deo. Also sounds like that will be a good truck for those 10 hour trips across country at 75 mph. There will not be much economy difference in town driving, between a truck with 3. 07's, 3. 55's, and 4. 10s when speeds are 55 and below. My truck on 3. 55's like 70 mph a whole bunch, but it will eat up 55 in OD all day long too, empty.



Michael

 

[pepecat]

yes and also you guys are bombing it right? Deo I know you have an aftercooler and a bombed p-pump right? I think that that may have a 'lil something to do with your mileage!

 

[therabbittree]

Yeah i don't have the p pump in yet so its just pods and a turned up pump... . i have a autometer diesel tach 1000-1400 is 4th gear just crusiing. . i have figured i may have to rev it higher to get better mileage. . i will have to try it. . i normally drive slow and easy but stomp on it every now and then. . the pods and the 21cm turbine housing make for a really good mosquito killer. . its bad . . LOTS of smoke till its spooled up. . i want to swap the turbine down to a 16 i have. . i hope that helps its a little much if i drove with out looking in the mirror it would be a large cloud hanging every where... ha. . looks like the "Thing" from the show Lost is chasing me haha

Later

Deo