Dana 70 survival

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freak007

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Dec 25, 2009
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What are you guys doing to get your D70s to survive?

I am currently running a '92 with a VE pump and the following mods:

  • ISSPRO Boost, fuel pressure, pyro gauges
  • South Bend Con O clutch
  • 5 x .014 injectors
  • HTT 62/65/13
  • Source Automotive (Diamond Eye) 4" turbo back, straight pipe exhaust
  • BHAF
  • Piston Lift pump, 3/8" feed line, 5/16" return
  • A1 studs with OEM gasket
  • 3600 RPM governor spring
  • Turned full fuel screw several (6?) turns (on the edge of runaway)
  • Timing bumped 3/8"
  • KSB hotwired
  • Starwheel is up 4 turns from bottom, pin is shallow side forward, smoke screw all the way out (When I did this the smoke was greatly reduced and spool-up was noticeably faster)


I made 353Hp and 747 Tq in this configuration.


I am removing the head in the next couple of weeks for porting and o-ringing. I am also adding titanium retainers, a M&H M2 pin, and timing spacer. I will be pulling the base timing back to stock or 1/8" bump to boost low end and turbo spool...

I am hoping to get close to 400/850 with these mods. Next spring I will be adding compounds...


Now that D70 is already getting kinda sloppy... I do not expect it to survive another year, so I am already planing on an upgrade of some sort... What can I do to make it live?
 
Short of replacing it, not much.
Many guys have welded the spider shaft to the case, which helps in that aspect, but backlash is hard to tighten up and still have the gears live.

I see a Dana 80 or a GM 14 bolt in your near future.

Mark.
 
yep when the 70 goes i would get dana 80. Stronger pinion

I think the 14 bolt is becoming more popular because it's less expensive/parts less expensive? About equal strength to I believe.
 
Mine is doing fine at 550+hp/1300ftlbs. Adult driven with no sled pulling it will last forever at a VE hp level IMO.
 
I have a 93 that had alot less done then you do on my gfs ve truck (fueling air wise)went to three pulls and the spider gears and pinion are done for....... now im hunting for an 80
 
freak007 said:
Is there a dana 80 that would be a direct swap?
Click to expand...

Few minor tweaks.............. Emerg cable is different and shock mounts in my case had to be redone.
you have to pay careful attention to the u bolts , Because the size different in the new axle
The spring perches are wide on the newer axle no biggy and you more than likely have to shorten your drive shaft
 
What year of D80 did you use? What needed to be done to the shock mounts? What about the emergency brake cable? Is the overall length the same as a 1st gen?


What are the weak points on the D70?
 
freak007 said:
What year of D80 did you use? What needed to be done to the shock mounts? What about the emergency brake cable? Is the overall length the same as a 1st gen?


What are the weak points on the D70?
Click to expand...

Its usually the pinion i believe. I broke a 70 daily driving at 450ish hp. I drive generous. wiped everything out
 
Freak007,
The Dana 80 SRW is considerably wider than a 1st Gen D-70, but the center distance on the spring pads is the same between the 2 generations.
The 2nd gen rear in a 1st gen will have the tires running just even with the wheel openings on a 1st Gen.
Normally they sit back away from the wheel openings @ 2 inches.

You'll need the Dana 80's lower spring mount "cups", plus the 2nd Gens have a wider spring pad, so you need to shim the side of the springs.

As far as shock mounts, a simple piece of heavy angle iron welded to the back of the lower spring cup, with a shock bolt/stud welded to it works well.
Look at the old Dana 70 lower spring mounts and you'll get the idea.

Mark.
 
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Are DRW axles wider or narrower than the SRW axles?

I do not have 35x12.5 tires, they fit perfect with the rims I have now, so a wider track width is not an option :(

What about the "other brand" of trucks, any of them have a similar track width? I am not worried about spring perches... I can weld those wherever I want ;).

Or did Dodge use the 70HD or 80 in any of the 72-93 trucks?
 
My D70 started leaking at the pinion seal at 220k after a very heavy 500miles tow, had quite abit of slop. New bearing kit for less then $100 and it was good to go. Gears looked great, but I'm sure if I let it go longer then that might have been different. I was told by quad4x4.com that they usually need to be rebuilt by 110k. All the diff. bearing were worn and sloppy. I had plenty of 12.5 sec q/m's and 20,000lbs tows in it's life before that. I was looking for a excuse to get a disc D80, but I couldn't touch one for that price.
 
I like the 14 bolt because it super easy to work on, you dont have to pull the carrier out to work on the pinion, just dont get a mid 80s chevy, they got a stupid small and expensive pinion bearing(the caged bearing most rear of the axle) yes, they have 3 pinion bearings.
 
freak007 said:
Are DRW axles wider or narrower than the SRW axles?

I do not have 35x12.5 tires, they fit perfect with the rims I have now, so a wider track width is not an option :(

What about the "other brand" of trucks, any of them have a similar track width? I am not worried about spring perches... I can weld those wherever I want ;).

Or did Dodge use the 70HD or 80 in any of the 72-93 trucks?
Click to expand...

IIRC, the '94-'02 Dodge Dana 80 1 ton Cab & Chassis axles are actually slightly narrower than their comparable 3/4 ton axle.

The earlier Dodge 1 tons, '72-'88, did in fact come with Dana 70s, and those also had a Cab & Chassis, narrower than a pick-up dually, version 1 ton axle available.

As far as I can figure, Ford was the first to utilize the Dana 80, but I'm uncertain of the exact year they started showing up, I believe it was 1988 or 1989.
The '94-'02 Dodge 3/4 ton is actually the most common for a SRW Dana 80 application.

Mark.
 
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the SRW D80 was found behind trucks with manual transmissions
 
nrose07 said:
My D70 started leaking at the pinion seal at 220k after a very heavy 500miles tow, had quite abit of slop. New bearing kit for less then $100 and it was good to go. Gears looked great, but I'm sure if I let it go longer then that might have been different. I was told by quad4x4.com that they usually need to be rebuilt by 110k. All the diff. bearing were worn and sloppy. I had plenty of 12.5 sec q/m's and 20,000lbs tows in it's life before that. I was looking for a excuse to get a disc D80, but I couldn't touch one for that price.
Click to expand...

Was this on a 1st or 2nd gen truck? The 2nd gen d70 has a heavier pinion bearing than the d70u that was used in the 1st gen trucks...
 
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