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Can you cruise at 80+mph in your truck?

y5mgisi

y5mgisi

1 ton status
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Aug 11, 2002
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Location
Portland Oregon
Last weekend I drove from Portland to Phoenix and back. I took my '12 gmc. It was comfortable and easy to cruise at 80mph+ for hours on end. After a while I thought, I have never owned a solid axle truck that I would ever want to cruise over about 70mph. Tops. So I was curious, can you comfortably cruise at 80mph or better in your truck for hours on end?

The reason I ask is I have great visions of taking the burb and the 78 on lengthy road trips. But as it is, that drive wouldn't have been fun in either of those trucks. So I'm wondering if I'm spinning my wheels trying to get something to do a job that it simply can't do, and if I need to be looking in a different direction. Particularly an ifs direction.
 
A few months ago I had my burb (91 d60/14 4spd and gear vendor) on the interstate for a couple hours at 80-85. It was surprisingly comfortable and smooth. 11 mpg though. It is maybe an inch or two taller than stock with stock sized tires.
 
What about 85? Engine speed aside, is it comfortable at that 85? Or does it start to get white knuckle over 75?
 
Speed limit around here is 75, and I am old, so I run the speed limits. It will do 80-85. Drives fine. But I have not ran it for any length.

700r4, 3.42:1 and 31's. It just about idles at 65mph.
 
Every year I take the K10 on some long trip around the Southwest someplace for a week of back country travel where it gets rode hard on Interstates for 10 to 15 hours straight to get there. She has no problem doing 80+ and still feels confident and stable without feeling labored at high speed even with an overhead camper on the back. The second look clowns driving diesel trucks give me when I pass them up at 80 MPH is hilarious.

Here we were flying 87 MPH on I40 in the K10 on the AZ/NM border the year we cruised out to Death Valley
8583911755_234c08eace_c.jpg





The Suburban on the other hand, had a difficult doing speed limit (75 MPH) back and forth between here and the COS airport. That problem has been fixed as of last week with the infusion of an extra 2.4L of engine :haha:
 
When It was stock and I daily drove it yes.

Now no.


But I wouldn't mind doing 80 down a dirt road :whistle:
 
It's mostly the stability and level of comfort at that speed. In Idaho and Utah they have 80mph speed limits. I usually do right at 5mph over. Neither of my trucks would feel comfortable at that speed.
 
Mine will do it, but with the TH350 it revs up pretty good....

I think yours would definitely do it, but it doesn't sound like you really want to...and no it wouldn't be as comfortable as a modern vehicle. A big old squarebody at that speed is kind of a constant fight compared to modern trucks...but you drive the old ones for a reason...and I guess comfort isn't one of them.

For trips, I love my Honda Pilot...it is a traveling machine...but I still intend to try to drive my Blazer to Edgartown...but maybe at 65 MPH
 
sweetk30 said:
big key is QUALITY springs / shocks / steering components / alignment / and they be good to go .
Click to expand...

Hate to hijack this for a moment, but you just brought up something I have been agonizing over.

HOW do I know if I need new leaf springs? It's huge expense and I want to be sure I need them before I even think about buying.
Is there a test for leaf springs? :dunno:
 
take some side shot pics of the leafs and post up .

also measure from frame at bump stop bracket to axle tube if I recall. this will get us the info . its been posted before on guys wanting to know how much lift they have .

and if new and quality triangle spring brand has been around for YEARS .
 
If it was a matter of life or death I could beat this ol 350 down the road at 80 but like others have mentioned it wouldnt be comfy.

I was actually thinking about driving the k5 to moab next year which is 18 hours for me. I think with a newer motor and tranny I wouldnt mind it. Although I could probably tow it with my tundra, get similar gas mileage and enjoy AC all the way there.

I would argue that if I never had a newer truck around i would say my k5 rides decent but having a newer truck reminds me of how rough it really is. Rough as in putting power down, suspension, straight line or freeway work to keep it on the road.

Its my hope that one day ill have it riding smooth enough to do long pulls with it. :popcorn:
 
I'm sure my burb would do it, trying to push a lifted brick through the air at those speeds, not fuel mileage friendly. That is my main motivation in my older age and the higher costs of fuel.

I'm actually quite fine with the speed limits around here at between 60-65. The burb does fine at that, Avalanche gets much better mileage running that as well.

Fuel mileage is all its about for me.
 
Chief Brody said:
Mine will do it, but with the TH350 it revs up pretty good....

I think yours would definitely do it, but it doesn't sound like you really want to...and no it wouldn't be as comfortable as a modern vehicle. A big old squarebody at that speed is kind of a constant fight compared to modern trucks...but you drive the old ones for a reason...and I guess comfort isn't one of them.

For trips, I love my Honda Pilot...it is a traveling machine...but I still intend to try to drive my Blazer to Edgartown...but maybe at 65 MPH
Click to expand...

I know what your getting at. Im good with having to actually DRIVE the truck. The '12 practically drives it self. The old trucks just get to a point of being difficult to keep in their own lane. Being between two cars in a corner at 70+ in the burb is terrifying! The 78, oddly, is the better driving of the two. I think i could do 75 all day long in it pretty easy if it had proper gears. But still, the 12 will do a 100mpg straight as an arrow. Neither of the other trucks would bother staying on the road, much less its own lane at 100! Not that i do 100 very often, but the level of stability at that speed approaches zero.

sweetk30 said:
search this huys build thread . he has had his burb well past the 80 mph mark :whistle: http://coloradok5.com/forums/member.php?u=56292

big key is QUALITY springs / shocks / steering components / alignment / and they be good to go .
Click to expand...

I think you might be right. I think all the things listed will produce a truck that is reasonably stable at 80.

Chief Brody said:
Hate to hijack this for a moment, but you just brought up something I have been agonizing over.

HOW do I know if I need new leaf springs? It's huge expense and I want to be sure I need them before I even think about buying.
Is there a test for leaf springs? :dunno:
Click to expand...

Acceptable question. I am pretty sure i need new springs. I just havent been able to afford them yet.

sweetk30 said:
take some side shot pics of the leafs and post up .

also measure from frame at bump stop bracket to axle tube if I recall. this will get us the info . its been posted before on guys wanting to know how much lift they have .

and if new and quality triangle spring brand has been around for YEARS .
Click to expand...

Yep.

wetoolowdingbangow said:
If it was a matter of life or death I could beat this ol 350 down the road at 80 but like others have mentioned it wouldnt be comfy.

I was actually thinking about driving the k5 to moab next year which is 18 hours for me. I think with a newer motor and tranny I wouldnt mind it. Although I could probably tow it with my tundra, get similar gas mileage and enjoy AC all the way there.

I would argue that if I never had a newer truck around i would say my k5 rides decent but having a newer truck reminds me of how rough it really is. Rough as in putting power down, suspension, straight line or freeway work to keep it on the road.

Its my hope that one day ill have it riding smooth enough to do long pulls with it. :popcorn:
Click to expand...

I am mostly just trying to get a feel for if i am off base or not. I might be in the same boat as you but i cant tell!
 
Yeah I think you and I are on the same page. In 1985 doing 80 mph im sure was way more than what most people would drive. Our new trucks will do 120mph all day but I can guarantee id be picking up connecting rods off the freeway with my k5 :haha:
 
The Jimmy did 101mph for 3 miles on a dry lake bed once. That 6" high pucker bush was aptly named. I think I tore some vinyl off of the seat.
 
I agree with SweetK30 said, QUALITY springs / shocks / steering components / alignment help drastically in keeping driver fatigue at bay. To expound on that, quality tires and wheels make a big difference as well. I noticed a huge increase in the level of highway stability moving from load range D tires on cheap Summit Racing house brand steel “Rock Crawler” wheels to load range E tires on aluminum wheels. That coupled with the heavy weight of the truck and camper (it actually has a low center of gravity if you see the way the camper is built and loaded) really keep it glued to the ground on the trail or cruising at highway speeds. The only thing that creates any sense of paved road pucker is the stinking rear Detroit Locker that gives the sensation of having rear steering under hard acceleration or quick decel or downshift. Wet or icy roads are flat out scary even as heavy as the truck is thanks to that damn Detroit. I am so looking forward to the day the Detroit is yanked and replaced with a selectable locker.

If you think about it, trucks really aren’t that much different today than they have been for the past 50 years…shaped like a brick, ladder frames, recirculation ball steering gears (okay, rec ball gears are only used on today’s HD trucks but still…), tires are round, etc. so when you really get down to it, adding OD, modern power plant (something with more power than 180HP engines of the 70’s), using quality tires/wheels and renewing all of the old worn steering and suspension components you can actually get a really a decent highway experience in an old rig. The only thing you will practically never get rid of is the wind noise old truck technology is notorious for, especially on our old GM trucks with vent wing windows….and the faster you go, the more wind noise you hear. I guess they never figured wind noise would be a concern with those old trucks engineered in the days of 55 MPH speed limits. I get more fatigue from noise than actually driving the K10 80 MPH after 10 hours on the highway. The seats are even comfortable and the ergonomics of the old rig are second nature to me. I’ve driven $200,000 RV’s for much less distances with much greater driver fatigue at 70 MPH than 1000 miles in a 37 year old 4x4 :haha:
 
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