Rear end

[fnny6770]

I'm just curious as to what type of rear end my 1980 GMC 4x4 dually truck has, I haven't torn into it yet but soon I will to change the gears to a different ratio, it came from the factory with either 410 or 411, my brother changed the th400 automatic to a 3-speed standard, so the gearing isn't correct but I don't know if it's limited slip or a posi, maybe someone can tell by the picture of the cover? It's a 10 bolt cover.

 

[Rumbledawg]

Dana70

 

[bucket]

In addition, it should be a Dana 70 HD. I'm not sure if that makes a difference with bearings.


How is the gearing not correct, do to a transmission swap? Both transmissions are 1:1 ratio in top gear.

 

[Ricko1966]

Before I'd do a gear swap I'd do a 700r4 or 4l80 transmission on 4x4 if you switch rear gears,you also have to do front gears. A 700r4 will get you more 1st gear and overdrive. A 4l80 is tougher and will get you overdrive. If you want to stay standard it's going to get harder and more expensive to get overdrive.

 

[bucket]

Oh yeah, as far as I know, GM never offered a locker of any kind for that axle. So it is an open rear.

 

[bucket]

Before I'd do a gear swap I'd do a 700r4 or 4l80 transmission

I'd do bigger tires, lol.

 

[Ricko1966]

I'd do bigger tires, lol.

There's something strange about this site I'll be typing and it just freezes and won't let me type until I hit post,then edit then start typing again. O.P in case you didn't know bigger tires has the same effect as a different gear. There are online gear ratio tire diameter calculators.

 

[bucket]

There's something strange about this site I'll be typing and it just freezes and won't let me type until I hit post,then edit then start typing again. O.P in case you didn't know bigger tires has the same effect as a different gear. There are online gear ratio tire diameter calculators.

That's happened to me a few times, where you can't scroll down in the text box to continue typing. I think every time it's happened, it was right after I had scrolled up to read a previous post again. I don't remember what I had to do to make it work right again, but I didn't have to post prematurely.

 

[bucket]

You must be registered for see images attach

 

[fnny6770]

Wow that's some pretty good information! Originally it had a th400 my brother wanted to put a standard in it and it seems like the tachometer is a little higher than it should be doing 55 miles an hour, in addition he changed the steering column to a tilt non-automatic column, I asked about overdrives in a previous thread and they mentioned doing a 700R but I think somebody mentioned that that 700R would not survive very long in this truck, I would have rather be left an automatic because I'm tired of shifting gears all the time! I'll have to go reread what they warned me about going to a 700 r4 transmission but I really would like an automatic which means I'd have to replace the steering column again, I could leave the brake pedals the way they are that's not a problem.

 

[fnny6770]

I found a set of 17 inch rims for so that should help a little bit

 

[Ricko1966]

Wow that's some pretty good information! Originally it had a th400 my brother wanted to put a standard in it and it seems like the tachometer is a little higher than it should be doing 55 miles an hour, in addition he changed the steering column to a tilt non-automatic column, I asked about overdrives in a previous thread and they mentioned doing a 700R but I think somebody mentioned that that 700R would not survive very long in this truck, I would have rather be left an automatic because I'm tired of shifting gears all the time! I'll have to go reread what they warned me about going to a 700 r4 transmission but I really would like an automatic which means I'd have to replace the steering column again, I could leave the brake pedals the way they are that's not a problem.

You won't have to replace the column or the pedals. Use a springbto hold the clutch pedal up and put in floor shifter. If you use something like a B&M unimatic or Hurst unimatic it will look like a four speed truck,but be automatic. A 4l80 is more durable than a 700r4 but GM used 700r4s in 4wd trucks don't abuse it it and don't get very big tires. The shifter that says th350. Would work on 4l80,700r4 or th400 with easy mods.

 

[fnny6770]

I like the way those four shifters look, I'll look into what it would take to change this transmission over so I'd rather have an automatic

 

[fnny6770]

But all I find is a 4L80E transmissions are they the same?

 

[Ricko1966]

Yes 4l80 is 4l80e. It's going to be a harder install than 700r4,th350 or th400, due to the fact it is electronically controlled. There are several work arounds but wanted to let you know it will be the most difficult. I think it's the best of those,but you will have to control the transmission. Stand alone controller from diesel 4l80 vehicle. Home made controller,good (expensive)aftermarket controller, transgo 48mod and modified electric shift,48 mod and cheap aftermarket controller. All would be okay. Not okay in my opinion,would be electric shift or cheap after market controller,without 48 mod or modified pump/valve body.