Th350 MPG question

[1987 GMC Jimmy]

I wonder how much longevity you’d net out of a non-C versus a C TH350 with the same gearing, engine, tires, topography, and city vs. highway being driven in similar amounts. I’ll tell you what, the locked up 700 in OD with 2.56 gears is a real beauty when the converter is acting up. When it’s working well, it’s not too bad. I need positraction so I may up that a little one day, but the open 10 bolt will never die so what am I talking about...

 

[Rusty Nail]

NEVERRRRRR die !!!!

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@80BrownK10
The th-350 got a lockup trans as part of ever tightening C.A.F.E. standards for emissions levels blah blah mileage stuff.

Across the board in the mid-late 70s everybody got a lockup trans. You can swap em out NP.

 

[ali_c20]

My setup is th350 (with engine oil cooler), np205, 3.08 limited slip and 32" tires behind a ~260hp 350. Everyhing is rebuild. I get 11.5 mpg driving as usual, long highway trips with ~65mph 13.5 mpg and 8 mpg when driving like I like it most . I had 33" tires with the same mpg numbers. I think the lockup won't change much with the 3.08 gearing, maybe a half mpg.

 

[Rusty Nail]

Good post. ^^ @ali_c20 is a pretty good ol boy..
Sounds like you're on target '80!

*edit*

P.S.

wtf is up with that f- truck ridin all wonky lookin like that Cali leanin I see it too what kinda poor boy drop ***** u got goin on in there anyways homeboy?!
Word?

WTH is that little tractor built out of huh? Concrete or??? LoL!
Really though y u no even haz a drop hitch or something I mean geez Louise!
I bet you get all the looks..

No. For reals.
You're like the "I need a drop hitch" Poster Boy. Look!





If I had one layin around I'd give it to you but maybe somebody else will make you a deal. I have zero clue what a 4 or 5 inch drop hitch costs! OR how to pick one for that matter..?
Good Luck!

Hope this helps!

 

[80BrownK10]

I have a different hitch that I use now. It drops a bit more that that one as it sits lower. I use a weight distribution hitch now so it doesn't lean as much.

A side note that blue bar on the bumper is packed with lead and the top pipe is solid steel. There is 200ish pounds right there on that tractor.

 

[80BrownK10]

If we want to post pics of abusing a Square I have those as well. I have pics of around 10,000 pounds of logs on that trailer

 

[80BrownK10]

The weight distribution hitch is on here so it's not as bad as if it wasn't there.

You must be registered for see images attach

 

[bucket]

If we want to post pics of abusing a Square I have those as well. I have pics of around 10,000 pounds of logs on that trailer

We have a thread for that!

https://www.gmsquarebody.com/threads/put-that-square-to-work.849/

 

[Rusty Nail]

Is this a great website or what?!

 

[85 CA SIERRA 1500]

If we want to post pics of abusing a Square I have those as well. I have pics of around 10,000 pounds of logs on that trailer

PLEASE post the log load pic's,,,,would really like to see those. I am going to start doing some local hauling for some extra side $ and some of the loads will be up to 10,000.
BTW, thanks in advance

 

[80BrownK10]

PLEASE post the log load pic's,,,,would really like to see those. I am going to start doing some local hauling for some extra side $ and some of the loads will be up to 10,000.
BTW, thanks in advance

I posted one. That load is about 1.5-1.75 cord of green oak. A cord of green oak weighs around 5700 pounds. So even if it was 1.25 cord your still in the neighborhood of 7000 pounds of wood plus the trailer is 1500 so that's 8500 pounds. But I believe it measured out to about 1.5 so that puts that total load in the 10,000 pound ish range.

 

[clendon1]

As long as you use a load equalizer set up you can get away with a lot.

 

[Goldie Driver]

Still not convinced my lockup is working on the highway, but wonder if maybe it is trying to lock up at low speeds around town.

I am gonna wear that toggle switch out now that I know what it does - or, is supposed to...

That being said, tonight's fillup says 10.69 mpg.

Edited - no idea how I fubarred numbers on the phone calculator, but I did.

TH350C, 3.42 gears, 33 inch tall tires, and I use the odometer reading plus a 12.4 percent correction factor.

Freshly rebuilt tranny, I might add ...

I also did not fill up at the same pump, so it may be a load of

Traffic was light, tho, to and from work- I guess it is possible.

I'll keep track this week.

 

[MikeB]

I had a TH350C in an 81 C10 back in the late 1980s. It tended to lock-up too soon under steady throttle (as low as 35-40 mph) which caused the little 305 to literally shudder. It was especially bad with the 2.56 axle.

I learned to drive around in 2nd gear until I hit the highway, but even at 55-60 mph the 305 wasn't happy in 3rd gear + lock-up. It may have been OK at 70 mph, but that's when the speed limit was 55. I ended up disabling the lock-up and the truck was much nicer to drive. I mean a 2.56 axle with 235-75 tires is already like an overdrive! The factory should have used a 3.08 with that combo.

 

[Goldie Driver]

I had a TH350C in an 81 C10 back in the late 1980s. It tended to lock-up too soon under steady throttle (as low as 35-40 mph) which caused the little 305 to literally shudder. It was especially bad with the 2.56 axle.

I learned to drive around in 2nd gear until I hit the highway, but even at 55-60 mph the 305 wasn't happy in 3rd gear + lock-up. It may have been OK at 70 mph, but that's when the speed limit was 55. I ended up disabling the lock-up and the truck was much nicer to drive. I mean a 2.56 axle with 235-75 tires is already like an overdrive! The factory should have used a 3.08 with that combo.

I think I felt/heard the lockup at 55 on the speedo (67 to 70 ish), but I think I have been feeling some of what you are describing since I have owned her and never knew what it was.

Weird stumbles and shudders at slower speeds in traffic that slows you to say 25 to 35 mph.

I have been working that poor toggle switch like a madman listening and feeling for the lockup, and experimenting at slower speeds.

Kind of fun , actually. Also kind of feels like the tranny is breaking in, and perhaps she is a bit more peppy.

Or, that's my mind making up to justify the expense of a reseal, umm, err, rebuild.

I do see why people suggest the switch for off, though...

Fortunately my PO did it for me.

I just didn't know.