Would gears solve this

[special-K]

Originally Posted by Buffalo Elk

Maybe you don't have third gear at all. That just isn't right for it to be acting like that, even with 4.56 gears in third it shouldn't do that. You better get everything checked out, sounds like something is terribly wrong.

That`s true.Maybe somethings binding.Lift the rear and check for free-spin.Try running it in gear and check what it does with the rear on blocks.I don`t need to tell you how careful to be going about this.

[glock35ipsc]

I personally don't think you can come to any sort of conclusion until you hook up a working tach and see what is really going on at 45 mph, 55 mph, 65 mph, etc. Once you have solid engine speed numbers in hand, than it would be much easier to point at rear end gearing, tire size, clutch slippage, that sort of stuff.

Oh, and try this site. Plug some numbers in and see what you come up with:

http://www.csgnetwork.com/multirpmcalc.html

According to this calculator, with a 29" diameter tire, 3.73 gears, 1:1 final trans gear ratio, at 65 mph you should be turning around 2800 rpm's +/-.

Even with a 4.56 gear, all other numbers the same, it shows 3434 rpm's.

Of course these are just averages, but using the numbers from my 68, they are pretty dern close!

[Longhorn Man]

forget the 4.56 gears, he has a 1/2 ton.
a 3.73 gear (standard with the 3 speed) WILL slow down fairly quick when you lift... pretty much any gear in these trucks will, even the 3.07.

the prob is the truck is wound out doing 45,

Most of us see 'wound out' as redline, or as far as it'll go... etc.

[glock35ipsc]

Originally Posted by Longhorn Man

forget the 4.56 gears, he has a 1/2 ton.

Yeah I know. I was just trying to use that as an example to show the differences. My 68 originally had a 6 with 3 speed manual, and it had 3.73's.

[Fmspeed]

put it on a hill, put it in neutral, see if it rolls, or push it on level ground, sounds like u got somthing hanging up, check the e-brake.

[Longhorn Man]

I was pondering this as I was screaming down the road in the truck today.. (I hit...4000 RPM... 4.10 gears, 37 inch tall tires, TH350, do the math ) and was thinking a few ppl have mentioned something binding...
However, if something was holding it back, say a hung up brake, the RPM's woulnd't be sky high as indicated. The only way the RPMs can be hich, is if there is slippage in the tranny/clutch, or tire smoke... that's it.

[wibilly]

andy you got 37" tires on the longhorn?

[Longhorn Man]

Oops, that was supposed to say 31 inch. LT235/85 16

[motocrosschump]

well going off Longhorn's theory of loud exhaust. I have 3.73 and dual exhaust. I previously took out the carpet and what not, and I thought my truck was going to BLOW UP going down the interstate. I put some sound deadner in the cab. Now it sounds normal inside cab. Just a thought.

[1LoC10]

ok, well after reading everyones posts, I think its a mix of both........ for one yes it rolls in neutral, and it shifts into all 3 gears just fine..
so I'm going to assume its a little of both, that it has to much of a gear in the rear (for towing), and that Its also my first vehicle without overdrive, so some of it might be normal but just not use to... either way, im not satisfied with the 3 speed so ill be looking for a tranny first, then see about gears... Thanks for all the replys

[Gray Ghost]

That explains a bit....without OD you'll n o doubt think it's winding hgiher than it is. I would not go to an OD tranny unless you get a 4L80E or something newer. Best idea [albeit expensive] is a TH-350 with a Gear Vendor OD unit behind it.

[Ole Blue 68]

Originally Posted by 1LoC10

ok, well after reading everyones posts, I think its a mix of both........ for one yes it rolls in neutral, and it shifts into all 3 gears just fine..
so I'm going to assume its a little of both, that it has to much of a gear in the rear (for towing), and that Its also my first vehicle without overdrive, so some of it might be normal but just not use to... either way, im not satisfied with the 3 speed so ill be looking for a tranny first, then see about gears... Thanks for all the replys

I've had similar experiences 1lo. I'm currently running a 350 with 3 speed manual and I still don't like pushing it past 60 or 65 on the freeway cause it sounds like i'm gonna blow it up. I know that's not the same as 45mph but I know the feeling. Just gotta get used to not having OD or drop an OD trans in it.