Changing gear ratios: opinions/suggestions wanted!!

[bucket]

I don't understand why everyone says they can't keep up with modern traffic. Why the heck not? Just get on the skinny pedal and let it eat. If it's keeping temp and not floating valves, don't worry about it and just drive it.

 

[Grit dog]

Exactly which has me thinking of buying a drivetrain parts beat up old truck that has LS and trans i want in it.

You have a 2wd so options are much cheaper/easier/more numerous than 4wd.
The swap I’ve been thinking about but can’t wouldn’t do due to time and space required to make it happen is gmt 800 Tahoe/yukon full chassis under shortbed square body. The wheelbases are within 3/4” iirc so that solves one hurdle. Of course there are plenty of other things to consider but sleeper AWD LS on 21st century chassis that looks like a C10. Except you pull up to the stoplight drag and just leave. No tire spin. But you got 2wd for the rest of the time or 4wd for snow.

 

[Grit dog]

I don't understand why everyone says they can't keep up with modern traffic. Why the heck not? Just get on the skinny pedal and let it eat. If it's keeping temp and not floating valves, don't worry about it and just drive it.

Can’t keep up is not what I was insinuating. Moreso don’t want to try to keep up on the freeway with a deep geared non od setup.
Sure my C10 with 3.5x gears can run relatively comfortably at 70mph. Does ok in Seattle urban freeways where the avg speed is like 20mph lower than than most cities. But it would not be so awesome in Denver or Dallas say, where 70mph is getting run over, 80 is getting passed or your parked in the right lane with the turban Suburbans and 90 is keeping up with the general flow.
Now WA is differnet. Even the open highway interstate 70mph is pretty acceptable. WA is weirdly slow and the po po keep it that way. I could run the K20 all the way to tri cities or Spokane and not get run over at 70. It would still not be a great experience.
You understand. You drive a lot for work from what I’ve gathered. You ain’t running your k30 dually 300 mi a day. You have a newer vehicle.

 

[bucket]

Can’t keep up is not what I was insinuating. Moreso don’t want to try to keep up on the freeway with a deep geared non od setup.
Sure my C10 with 3.5x gears can run relatively comfortably at 70mph. Does ok in Seattle urban freeways where the avg speed is like 20mph lower than than most cities. But it would not be so awesome in Denver or Dallas say, where 70mph is getting run over, 80 is getting passed or your parked in the right lane with the turban Suburbans and 90 is keeping up with the general flow.
Now WA is differnet. Even the open highway interstate 70mph is pretty acceptable. WA is weirdly slow and the po po keep it that way. I could run the K20 all the way to tri cities or Spokane and not get run over at 70. It would still not be a great experience.
You understand. You drive a lot for work from what I’ve gathered. You ain’t running your k30 dually 300 mi a day. You have a newer vehicle.

For whatever it may be worth, I wasn't focusing just on your comment, but really the general opinion of many recently. But you did bring up a couple points that I'd like to talk about.

So you can keep up with traffic, but you just don't want to try. Why not? Just because of the higher than normal rpm's, compared to modern trucks? RPM is just a number. If the engine is happy, then the engine is happy. Is it because you are worried about wear on the engine? That seems to be the biggest concern for many. But for many of those people, the alternative is an LS drivetrain swap in which they are ditching the current engine anyway. So why not run the thing for all it's worth and then when/if it expires, do the drivetrain swap then? Many people probably would never even kill their engine running down the interstate with no OD.

And as far as the driving I do for work. I most definitely would drive my old K30 everywhere if the owner would allow it. Lol, and pay for the maintenance like he does for the company trucks. But do to insurance reasons and the fact that he doesn't want his business relying on a 40+ year old truck (understandably), I can only use it for doing local work.

Occasionally I can slip something by though. Last summer I managed to use my 454 SS as a supervisor truck for a couple months on a somewhat local job. Also early this year I used my '00 Express van on a quick job in Texas, because I trusted it more than any of the work trucks I had available to me at the time.

 

[Grit dog]

Nah, not worried about blowing up a motor. If it’s good it’s good if it’s not it’ll blow anyways.
Chevy 350s were the gold standard for tow boat motors (tow = ski/ wake / surf boat) for years. Mine is low hours but 1500-2000hrs +/- is avg life for a wake/surf boat running 3000-4500 rpm’s under full load.
Which is more than your avg freeway drive. More like towing a trailer up a grade. Constantly.
It’s just different strokes for different folks which I recognized earlier.
Not a chance I’d want to make my daily commute or frequent trips around the state in an old pickup. NVH, comfort, reliability all factor in.
If one likes living in the past on a daily basis, great. But it’s a unique outlook.
If budget dictates an “old” truck then there are better options to achieve a more relaxing drive. IE 90s and 2000s models.
But it’s really a mostly non issue, as the rust belt parts of the country, you’re not finding local 70s-80s trucks that are in great shape and if you do have or find or import one, it doesn’t make much sense to pound it thru the snow and salt months as it will be a pile of rust sooner than newer trucks. But to be fair anything driven all year in the rust belt is beginning to turn to junk if it’s mid 2010s or older anyways.
Whatever. All friendly discussion and largely off topic for the thread.

 

[CountKrunk]

Pretty sure my truck cant go 70 haha. 3k has me hitting 55-60.

 

[DoubleDingo]

Pretty sure my truck cant go 70 haha......

Not with that attitude

 

[Bloodhound1981]

Using a gear ratio calculator, my C10 tops out at 194mph, but I'm pretty sure that ain't happening.

 

[Ricko1966]

Pretty sure my truck cant go 70 haha. 3k has me hitting 55-60.

You could if you wanted, even as steep as 5.13s you could go 70 even with 235/70r/15s this charts fun to play with

https://tremec.com/calculadora.php

 

[3 Ton]

We went from 4:11s to 3:08s, sure nice going over 50 now.

 

[MikeB]

FWIW, I think changing axle ratios is a lot simpler than a transmission swap. The 700R4/4L60 can be a PITA to set up properly, and reliability can be marginal, depending on the year of manufacture. And the electronic versions (60E/80E) are much more expensive, especially when you add aftermarket controllers.

Your TH400 is probably stronger than all but the the 4L80E and has proven to be very reliable. As for the new ratio, 3.73 would be my choice. The 4.10 ratio would drop RPMs by only 10%, hardly worth the cost of parts and labor, IMO.

 

[BigT]

I'm really liking the discussion, lotsa food for thought!! Thanks all!

 

[chris3353]

My 78 K20 4x4 has factory 4:56 gears in it and a TH400 transmission. These are great when off-road or pulling something, but poor on the highway. I grew up with a 75 half ton 4x4 with 3:73 gears and a 4 speed manual, which was very versatile for both off-road and highway, but that was partly due to the 4 speed manual transmission. I'd like to switch out my low gears for something more versatile, but I can't decide on 3:73s or 4:10s, as I don't have an experience with either ratio in combination with the TH400, since I just bought the truck a few weeks ago. I'm leaning toward 4:10s, as I used to have a 74 F150 with something close to that combo, and I liked it. But, the 3:73 is the more common one and gets better mileage, etc. We've touched on this in another thread, but I'd really like some more thoughts from other folks who have experience with either. Thanks!

I run 4.56s, 37 Falkens and a 4l80. The 37s make the 456 feel like ~3.73-3.91s. Without OD it sucks. The converter lock up is a added bonus.

Before swapping the gears,, look into a 4l80,, a lot of donors available. I use the MSD atomic controller and it has been flawless for 10 years now.

 

[jwroblesk]

I have a 1974 C20 with 410 gears and not happy at all with them. Too much RPM on the hiway. I can only imagine What 456 gears are doing on the hiway. I’m considering the 700r4 but not sure who to take it to for the work. I live in MN.

 

[chris3353]

I run 4.56s, 37 Falkens and a 4l80. The 37s make the 456 feel like ~3.73-3.91s. Without OD it sucks. The converter lock up is a added bonus.

Before swapping the gears,, look into a 4l80,, a lot of donors available. I use the MSD atomic controller and it has been flawless for 10 years now.

Forgot to add,,, I run 411s in my dentside with a C6 and 38s, it is OK on the highway ~60mph but i don't drive it a lot of miles,,, Before the motor rebuild I went 488s and had gear remorse.

New motor has a lot more HP, went back to 411s. Still wish i had OD in the truck.