Is it ok to tow in "2" for long periods of time?

[vandelay industries]

Trans is TH-350.


Is it ok or harmful to the transmission to drive/tow in "2" for long periods of time?


i'll get into why, if we make it that far.........although you can probably figure out why based on the title and the fact that i'm posting in the towing section.....

 

[imiceman44]

Trans is TH-350.


Is it ok or harmful to the transmission to drive/tow in "2" for long periods of time?


i'll get into why, if we make it that far.........although you can probably figure out why based on the title and the fact that i'm posting in the towing section.....

Well any gear is ok as long as the engine is not screaming.
The th350 has no lock up so it doesn't make a difference which gear it's in .
Now why you ask?

 

[tRustyK5]

Agreed. I'd be more worried about engine speed if the R's are fairly high.

 

[vandelay industries]

First, i want to say that i want to, and believe in, doing things the right way and not 1/2 assing things.

1) Background info:

a) Truck is: 1/2 ton 2wd, 4.3 v-6, TH-350, 2.56 rear diff (i know, TOTALLY wrong for towing and we'll get into that)

b) i want to tow no more than 5300 lbs. (open 14' trailer, "small" G-body/monte carlo etc.), but usually 3900lbs. (open 14' tandem trailer w/ chevette with small block with iron heads)

c) i DO NOT, at this time, want to buy another tow vehicle because of space---already have too many cars, and i want to curtail spending. Although i have not ruled this avenue out 100%, if it's the best way and i certainly can do it budget-wise, although i really don't want to.

d) The 4.3 v-6 has a very similar, if not identical, torque and hp curve as the LG3 305 that was in the truck previously. The 305 combo did not do too well towing even the chevette, hence my asking the question in the first place. The crate 350 that was in the truck before the 305, i feel, could do the towing job pretty good(even though i never towed with it) and we'll get to that in a sec.....

e) i do not plan to tow long distances. Only to local tracks. So, maybe 1-2 hrs away max.

Logic/illogic:

a) As i stated above, the 305 did not do too well towing even the chevette. The truck handled the trailer pretty good and the 305 did ok on flat ground, but even the slightest incline made it slow down. i noticed that one of your avatars is of a tractor-trailer; If you are a trucker, then i noticed real quick how much you guys are in a hurry on the interstates----because you guys were on my ASS. This was very mentally uncomfortable for me and my main reason for starting this topic----i want to reasonably be able to keep up with traffic.

b) i like the 4.3 and want to keep it, although getting a crate or vortec L31 350 is probably the simplest, cheapest, most intelligent way, in my situation, to solve the problem. And is certainly do-able budget wise. i'm pretty sure either 350 will have no problems towing 5300 lbs. all day. The truck has had 3 previous v-8s, so i have all the mounts, exhaust, odds and ends etc.

c) i have never done a differential gear change and am not opposed to doing one. This may be cheaper than b), but not necessarily the most time-efficient----the truck may be down for a long time, because i WILL get stuck and will have to ask for help here and on many other sites. i would want to go to 3.42 and not any lower.

So, i'm thinking if i left the trans in second; 1.52 x 2.56 = 3.89 final drive AND 32 inch tires would be 2600 rpm at 65mph, which i think is ok.
i guess the bottom line is :This strategy may be kinky, but is it feasible?
When i'm not towing, i would just switch back to the 29 inch tires and drive in "D" like normal.

The other approach would be to tow just as is. Maybe try to tow later at night when there is not much traffic.

 

[imiceman44]

First, i want to say that i want to, and believe in, doing things the right way and not 1/2 assing things.

1) Background info:

a) Truck is: 1/2 ton 2wd, 4.3 v-6, TH-350, 2.56 rear diff (i know, TOTALLY wrong for towing and we'll get into that)

b) i want to tow no more than 5300 lbs. (open 14' trailer, "small" G-body/monte carlo etc.), but usually 3900lbs. (open 14' tandem trailer w/ chevette with small block with iron heads)

c) i DO NOT, at this time, want to buy another tow vehicle because of space---already have too many cars, and i want to curtail spending. Although i have not ruled this avenue out 100%, if it's the best way and i certainly can do it budget-wise, although i really don't want to.

d) The 4.3 v-6 has a very similar, if not identical, torque and hp curve as the LG3 305 that was in the truck previously. The 305 combo did not do too well towing even the chevette, hence my asking the question in the first place. The crate 350 that was in the truck before the 305, i feel, could do the towing job pretty good(even though i never towed with it) and we'll get to that in a sec.....

e) i do not plan to tow long distances. Only to local tracks. So, maybe 1-2 hrs away max.

Logic/illogic:

a) As i stated above, the 305 did not do too well towing even the chevette. The truck handled the trailer pretty good and the 305 did ok on flat ground, but even the slightest incline made it slow down. i noticed that one of your avatars is of a tractor-trailer; If you are a trucker, then i noticed real quick how much you guys are in a hurry on the interstates----because you guys were on my ASS. This was very mentally uncomfortable for me and my main reason for starting this topic----i want to reasonably be able to keep up with traffic.

b) i like the 4.3 and want to keep it, although getting a crate or vortec L31 350 is probably the simplest, cheapest, most intelligent way, in my situation, to solve the problem. And is certainly do-able budget wise. i'm pretty sure either 350 will have no problems towing 5300 lbs. all day. The truck has had 3 previous v-8s, so i have all the mounts, exhaust, odds and ends etc.

c) i have never done a differential gear change and am not opposed to doing one. This may be cheaper than b), but not necessarily the most time-efficient----the truck may be down for a long time, because i WILL get stuck and will have to ask for help here and on many other sites. i would want to go to 3.42 and not any lower.

So, i'm thinking if i left the trans in second; 1.52 x 2.56 = 3.89 final drive AND 32 inch tires would be 2600 rpm at 65mph, which i think is ok.
i guess the bottom line is :This strategy may be kinky, but is it feasible?
When i'm not towing, i would just switch back to the 29 inch tires and drive in "D" like normal.

The other approach would be to tow just as is. Maybe try to tow later at night when there is not much traffic.

Well let's start.
Can't you tow with the medium duty ?
Second if you are going to drive with 29" tires why would you tow with 32" tires?
I towed a built k5(roughly 8k lbs) with my 97 Jimmy s15 with 4.3 150 miles, not sure what ratio I had in the axles but it has a 700r4 and 4x4 so on steep hills I had it in low and on flat it is fine in hi range.
If you want to keep the axle, use smaller tires when you tow. Not bigger .

 

[vandelay industries]

Well let's start.
Can't you tow with the medium duty ?
Second if you are going to drive with 29" tires why would you tow with 32" tires?
I towed a built k5(roughly 8k lbs) with my 97 Jimmy s15 with 4.3 150 miles, not sure what ratio I had in the axles but it has a 700r4 and 4x4 so on steep hills I had it in low and on flat it is fine in hi range.
If you want to keep the axle, use smaller tires when you tow. Not bigger .

1) What medium duty?

2) The reason why i'm proposing 32" tires is because i'm proposing towing in "2": 1.52 x 2.56 = 3.89 gear ratio. With 32" tires rpm at 65mph, which i think is a reasonable, realistic speed will be 2900, which is actually still a little too high, so i'd like to propose 35" which would then be 2600 rpms at 65---more reasonable.

Second gear in a TH-350 is 1.52. My rear axle is 2.56. 1.52 X 2.56 = 3.89
My current setup if towing in 3rd gear: 2100rpm with 29 inch tire (235/75 15)

32" tire = 2900 rpm at 65 mph towing in 2nd. Lil' too high, but not crazy high or out of the question.

35" tire = 2600 rpm at 65 towing in 2nd More like it.

Anyways, the point is i'm proposing towing in "2," and the larger tire diameter brings the rpms down to a more reasonable level.

3) My current setup will do "ok" on totally flat land. But even the slightest incline slows me down. When you truckers get on my ass, you know you've got a power/gearing problem................

The torque peak for the LB 4 4.3 is 240ish lbs around 2400 rpm.

 

[vandelay industries]

David Freiburger actually goes into detail for once:

 

[imiceman44]

1) What medium duty?

2) The reason why i'm proposing 32" tires is because i'm proposing towing in "2": 1.52 x 2.56 = 3.89 gear ratio. With 32" tires rpm at 65mph, which i think is a reasonable, realistic speed will be 2900, which is actually still a little too high, so i'd like to propose 35" which would then be 2600 rpms at 65---more reasonable.

Second gear in a TH-350 is 1.52. My rear axle is 2.56. 1.52 X 2.56 = 3.89
My current setup if towing in 3rd gear: 2100rpm with 29 inch tire (235/75 15)

32" tire = 2900 rpm at 65 mph towing in 2nd. Lil' too high, but not crazy high or out of the question.

35" tire = 2600 rpm at 65 towing in 2nd More like it.

Anyways, the point is i'm proposing towing in "2," and the larger tire diameter brings the rpms down to a more reasonable level.

3) My current setup will do "ok" on totally flat land. But even the slightest incline slows me down. When you truckers get on my ass, you know you've got a power/gearing problem................

The torque peak for the LB 4 4.3 is 240ish lbs around 2400 rpm.

The medium duty you picked up the tires with .
I am guessing that is a company truck .
As for rpms, you insist on driving in 2nd to get more power then you want to get a bigger tire to lower your rpms.
I towed with my 4.3 and I was going up the hills a little slow but I still was going fine on flat when I got to the top gear.
You still don't see how you're contradicting yourself?

 

[86454K30]

IMO if you were going across town I don't think you'd have a problem but, running 1-2 hours away I'd think you are going to have transmission issues. Though your final ratio is would be close I would think the transmission is going to build heat which is going to kill it.

 

[red EOD]

Other issue being overlooked is just getting going/lower speed driving. Your idea eliminates the gearing advantage that is needed at those lower speeds.

 

[imiceman44]

Other issue being overlooked is just getting going/lower speed driving. Your idea eliminates the gearing advantage that is needed at those lower speeds.

That's exactly what I was saying, not sure if I was clear.

 

[sweetk30]

this whole plan is super scetchy and sounds like a death wish .

just pay a roll back tow truck or other to move it for you and be safe for your self and others around you .

 

[longbedder]

So, i'm thinking if i left the trans in second; 1.52 x 2.56 = 3.89 final drive AND 32 inch tires would be 2600 rpm at 65mph, which i think is ok.
i guess the bottom line is :This strategy may be kinky, but is it feasible?
When i'm not towing, i would just switch back to the 29 inch tires and drive in "D" like normal.

Leave the 29" tires on all the time, tow in the gear where you don't have the engine wrung out, shift on hills, and live with the limitation of the power your engine can make. Also, get a transmission temperature gauge, install it, and use it.

Mechanical advantage is mechanical advantage - doesn't matter where it's coming from (trans, tires, or diff). Swapping hard parts to chase 300RPM is splitting hairs.

 

[vandelay industries]

i think the easiest, cheapest, most-intelligentest way is to go to the salvage yard and get a complete drum-to-drum rear with 3.42 already installed and bolt it in.

Looks like you can find them for under $200 complete. This is an 8.5" 10-bolt.

With 3.42, i'll tach at 2500rpm at 65 mph vs. 2100rpm with the 2.56 i have now. The 400 extra rpm is not a big deal, and gas mileage may not suffer that much, if at all.

Moving from 2.56 to 3.42 gears is , i think a 34% increase in torque which should be good enough for what i want to tow.

 

[imiceman44]

i think the easiest, cheapest, most-intelligentest way is to go to the salvage yard and get a complete drum-to-drum rear with 3.42 already installed and bolt it in.

Looks like you can find them for under $200 complete. This is an 8.5" 10-bolt.

With 3.42, i'll tach at 2500rpm at 65 mph vs. 2100rpm with the 2.56 i have now. The 400 extra rpm is not a big deal, and gas mileage may not suffer that much, if at all.

Moving from 2.56 to 3.42 gears is , i think a 34% increase in torque which should be good enough for what i want to tow.

That would be the smartest and cheapest way to get what you need now.
And sorry for the confusion, I mistook you for someone who has a very similar avatar and has a medium duty truck.