gear's?

[TCASON]

I'm looking at getting my grandfathers 68 1/2 ton with a 307 2wd auto, from an older brother who has let it sit for 10 yrs. Was going over some ?s with him on the condition, and he mentioned that when he had last driven it, it sounded to him that it was running pretty hard at @ 60mph. He believes that it has some very low gears, but has no idea what they may be.
My grandfather bought it used with low miles for his farm.
Anyone have some idea's on the gearing?

[avgjoeracing]

Does it have the tag on the glove box door? The SPID I think it's called? That might give you a clue but if it's ever been out of the family's hand someone may have done a rear end change. The best way to get a ball park ratio is to get the rear in the air, put in nuetral and mark a spot on the tire and the driveshaft. Then spin the wheel one revolution and count how many times the drive shaft goes around. Typically farmers bought a cheaper truck and put an optional gear in the rear end to increase towing capacity.

[PanelDeland]

If it is stock without an optional rear gear,it will have 3.08 .The other options are a 3.73 or 4.11.
The sound may be from the fact that most people are used to the overdrive trannys in the newer vehicles.also a 68 may have the powerglide which is a two speed auto and IIRC has about a .95 to 1 high gear.

[Longhorn Man]

Welcome to the board TCASON.
Acording to the ealers books, in 68, a 307 with a TH350/Th400, would get the 3.73 rear unless otherwise optioned. With normal sized tires, that should put the RPMs at about 3000 or so rollin at 60 MPH.
That's not enough to hurt a healthy engine, even at long distance driving, but, if the engine is getting tired and worn, it can make it's mark on the engine.

[TCASON]

Originally Posted by avgjoeracing

Does it have the tag on the glove box door? The SPID I think it's called? That might give you a clue but if it's ever been out of the family's hand someone may have done a rear end change. The best way to get a ball park ratio is to get the rear in the air, put in nuetral and mark a spot on the tire and the driveshaft. Then spin the wheel one revolution and count how many times the drive shaft goes around. Typically farmers bought a cheaper truck and put an optional gear in the rear end to increase towing capacity.

I haven't seen the truck for about 20 yrs.
The truck is not in my hometown at the moment, it's on the other side of the mountains ( Wa, state at least a 2 hr drive from me )
When I can get over to my side of the mountains I'll do that test for sure.
Thanks for the info
I'll also get my brother to check out the glove box, as my grandfather had kept it the way he had bought it waaaay back then.

[mvfd70]

Originally Posted by avgjoeracing

The best way to get a ball park ratio is to get the rear in the air, put in nuetral and mark a spot on the tire and the driveshaft. Then spin the wheel one revolution and count how many times the drive shaft goes around.

If you spin one wheel with the rear end jacked up then the other wheel will just spin the opposite direction. Best way to do this (IMO) is to spin the drive shaft slowly and count how many spins to make the wheels go around once. I would say that you probably have 3.73 gears unless otherwise optioned out. A for sure way to tell is to pull the cover off the differential (the gear oil needs changed anyway, right) and look for the numbers stamped on the ring gear. The smaller number is the number of teeth on the pinion gear and the larger number is the number of teeth on the ring gear. Mine has the numbers 11-41. Divde 41 by 11 and you get 3.727272727, or 3.73

[TCASON]

Originally Posted by PanelDeland

If it is stock without an optional rear gear,it will have 3.08 .The other options are a 3.73 or 4.11.
The sound may be from the fact that most people are used to the overdrive trannys in the newer vehicles.also a 68 may have the powerglide which is a two speed auto and IIRC has about a .95 to 1 high gear.

Originally Posted by Longhorn Man

Welcome to the board TCASON.
Acording to the ealers books, in 68, a 307 with a TH350/Th400, would get the 3.73 rear unless otherwise optioned. With normal sized tires, that should put the RPMs at about 3000 or so rollin at 60 MPH.
That's not enough to hurt a healthy engine, even at long distance driving, but, if the engine is getting tired and worn, it can make it's mark on the engine.

Thanks for the welcome, and the info guy's!
This will be a fun project if I can get it over to my area.
The motor had a rebuild done yrs ago and only has about 15-20,000 miles on it, but isn't running right now, probably carb problems. at the time of the rebuild, grandpa was not really using it much any more at the time, he just got too old to drive. ( he has since passed away 6yrs ago, he made to 93! )
I'm guessing this is what my brother is hearing, he's use to driving semi's all day for work. So 3000 rpms is way too high for his ears@ 60mph!

[TCASON]

Originally Posted by mvfd70

If you spin one wheel with the rear end jacked up then the other wheel will just spin the opposite direction. Best way to do this (IMO) is to spin the drive shaft slowly and count how many spins to make the wheels go around once. I would say that you probably have 3.73 gears unless otherwise optioned out. A for sure way to tell is to pull the cover off the differential (the gear oil needs changed anyway, right) and look for the numbers stamped on the ring gear. The smaller number is the number of teeth on the pinion gear and the larger number is the number of teeth on the ring gear. Mine has the numbers 11-41. Divde 41 by 11 and you get 3.727272727, or 3.73

Thank you for the info.
Once I can get the truck over to my area, I will be going through everything! I need this to be a functional work truck when done for minor hauling of my product. My goals are to have a restored, but not totally stock truck. Maybe a little restomod, nothing too crazy.

[smoked68]

My dad bought my truck new in 68. I looked years ago and remember it was a 4:11. Also @60 mph I'm turning 3400 rpm's and we are running 20"s.

[TCASON]

Thanks again for all the input!
The truck is heading my way!
I have come to an agreement with the original brother ( I have 3 older ones ) that first had it from my grandfather, he wants to share the truck, as long as it stays in the family. That was my whole intent from the start. So in the next couple of weeks I'll have it back hear and my brother and I will start on getting it roadworthy again and start the resto-mod project!.
I'll definitely be hitting you guy's up for future info soon, thanks again and looking forward to sharing yet another restoration project!