Towing With Big Tires (Split from "BDS 9500" thread)

[Trail X]

(LINK TO FORMER THREAD)

Wait a tic... towing and 33" tires don't really mix well, do they? Are you upgrading to 4.10 gears too? I just want to make sure you've thoroughly thought this through.

[irishboy02]

Wait a tic... towing and 33" tires don't really mix well, do they? Are you upgrading to 4.10 gears too? I just want to make sure you've thoroughly thought this through.

3.42s and no issues to date with towing. Well see the difference once i add the tires. Gearing will probably be down the line.

[Zero]

all i have to say is if you had an EXT with the 6cyl, I would def....def....def tell you to change your gears. There is a huge power loss even with my tune once I got the big ol mud tires on there, so towing will be a pain.

right now I am looking into a 3.73 swap, or a 3.90....I dont have a need to go 4.10, plus that will destroy my highway millage.

[foosh]

It should be more about the driver than the gears... I don't tow far, but i tow alot more weight then he does and have been fine. The gears affect the acceleration and the 33's affect the breaking, so as long as your careful and pay attention there shouldn't be much of an issue.

[Trail X]

Oh, agreed, for periodic or short tows it's fine. I have 32" with 3.42 gears and it works ok.

But if he really does tow heavy loads often and for long distances... he needs to consider the sluggishness of the vehicle. Towing a big trailer into the wind at about 60mpg I was having to keep it in 3rd gear to keep up with traffic. If I did that often or for long distances, I'd certainly be planning a gear upgrade... it was miserable. Plus the transmission was getting up to about 235F. Yikes!

[rgraboske]

all i have to say is if you had an EXT with the 6cyl, I would def....def....def tell you to change your gears. There is a huge power loss even with my tune once I got the big ol mud tires on there, so towing will be a pain.

right now I am looking into a 3.73 swap, or a 3.90....I dont have a need to go 4.10, plus that will destroy my highway millage.

I ordered mine with 4.10s, and I was a little concerned about hoighway fuel economy. I check every tank with both DIC and occassionally putting pen to paper, and I consistently get 22 on the highway with the whole family at 75 mph. When all I do is city driving, it goeas into the 14 mpg range. The lowest I've ever gotten was 12.5 with my GTO on the trailer. Since the GTO gets 11, it was an improvement.

I know in the past that bigger gears meant worse mileage. With overdrive and the various computer controls, that's not necessarily the case anymore.

[bartonmd]

FWIW, 3.42 with 33" tires is effectively a ~3.22... Lots of people tow with 3.08 1/2 tons...

Keep an eye on trans temps, and "it be aight"...

Mike

[irishboy02]

Mods? Possibility of a new towing thread?

James, PLEASE dont tell me that youv towed in D. Thats very bad. Whenver you tow, you should always be in 3, not D. Even says so in our manual. By Being in 3, it eliminates our overdrive, which will grenade while trying to engauge/disengauge under tow loads (not immediately but it will break it down)

3 gives you more power, and eliminates switching gears too much, which actually gives better gas mileage with a tow as well

Anywhoo...just got a call from the shop, the order has gone out for my 9500s Harringtons Speed Shop, on rt23 in butler, nj ( found them through the bds-suspension.com distributor locator)

[Trail X]

But by eliminating overdrive you're adding much more heat to the transmission because you're using the TC 100% of the time, right? I guess I figured the heat was worse than changing gears a few times. I like when the engine's sitting at about 1800 revs pulling steady at 65mph. Going with the wind I got like 17 mpg towing the trailer in D. Of course, against the wind in 3 I got like 12 ... the transmission heated up to about 235... plus my revs were more like 2800.

[bartonmd]

But by eliminating overdrive you're adding much more heat to the transmission because you're using the TC 100% of the time, right? I guess I figured the heat was worse than changing gears a few times. I like when the engine's sitting at about 1800 revs pulling steady at 65mph. Going with the wind I got like 17 mpg towing the trailer in D. Of course, against the wind in 3 I got like 12.

Nope... Staying in OD, you're going in and out of TC lockup, as well as between 3 and 4, all the time... Not only that, but the input sprag (think one-way free-wheel clutch on your bicycle) is still allowing you to coast in all gears. And remember, the input sprag is the weak link of any transmission that has one...

When you're towing in 3rd, it almost never drops lockup, almost never down (or up) shifts, and the sprag clutch is engaged in all gears, which takes the load off the (weak) input sprag...

The engine doesn't care about the higher RPM, but it does like not being lugged, and it does like the lower cylinder and rod/crank pressures, as well as the added oil pressure... The transmission likes the higher RPM (more fluid flow = more cooling) and the smoother power delivery associated with it (more "smooth" load than shock load of each cylinder firing), and the shafts, gears, and TC like the high speed/low load vs. the low speed/high load...

ETA: Also, the OD (4th) gear on this transmission (as well as 2nd) is a band, and 1 and 3rd are clutches, which are much more durable

Mike

[irishboy02]

Higher rpms = more power,this is expected and needed when towing, thats the whole idea to have power to move-as long as your not at 6k for 3min on a hill climb your good. Iv towed 8-9k and passing people doin 60 going up hill with no problems with water temp or trans temp. Just dont drive like a dbag and know your vehicle and youl have no problems. Gearing is no requirement, id prefer to stay as low as possible, i dont want to be cruisn at 60mph with my gearing putting me at 4k rpm, thats when youl really be seeing temp issues. We have cooling systems to deal with the rest.

[foosh]

Well i've towed this through local cities, up bridges, at 65, though tight turns and things that most 1/2 tons couldn't cause they're too big.

Roughly 7k lbs

[Trail X]

Nope... Staying in OD, you're going in and out of TC lockup, as well as between 3 and 4, all the time... Not only that, but the input sprag (think one-way free-wheel clutch on your bicycle) is still allowing you to coast in all gears. And remember, the input sprag is the weak link of any transmission that has one...

When you're towing in 3rd, it almost never drops lockup, almost never down (or up) shifts, and the sprag clutch is engaged in all gears, which takes the load off the (weak) input sprag...

The engine doesn't care about the higher RPM, but it does like not being lugged, and it does like the lower cylinder and rod/crank pressures, as well as the added oil pressure... The transmission likes the higher RPM (more fluid flow = more cooling) and the smoother power delivery associated with it (more "smooth" load than shock load of each cylinder firing), and the shafts, gears, and TC like the high speed/low load vs. the low speed/high load...

ETA: Also, the OD (4th) gear on this transmission (as well as 2nd) is a band, and 1 and 3rd are clutches, which are much more durable

Mike

Good to know Mike. Thanks for the input. I'll be honest, transmissions are one of my weak-points knowledge wise. I didn't consider the higher fluid flow when considering heat dissipation/creation. So if in D3, the TC still locks up? For some reason I figured it commanded the lockup off.

Thanks for the input guys.

[bartonmd]

Nope... Staying in OD, you're going in and out of TC lockup, as well as between 3 and 4, all the time... Not only that, but the input sprag (think one-way free-wheel clutch on your bicycle) is still allowing you to coast in all gears. And remember, the input sprag is the weak link of any transmission that has one...

When you're towing in 3rd, it almost never drops lockup, almost never down (or up) shifts, and the sprag clutch is engaged in all gears, which takes the load off the (weak) input sprag...

The engine doesn't care about the higher RPM, but it does like not being lugged, and it does like the lower cylinder and rod/crank pressures, as well as the added oil pressure... The transmission likes the higher RPM (more fluid flow = more cooling) and the smoother power delivery associated with it (more "smooth" load than shock load of each cylinder firing), and the shafts, gears, and TC like the high speed/low load vs. the low speed/high load...

ETA: Also, the OD (4th) gear on this transmission (as well as 2nd) is a band, and 1 and 3rd are clutches, which are much more durable

Mike

Good to know Mike. Thanks for the input. I'll be honest, transmissions are one of my weak-points knowledge wise. I didn't consider the higher fluid flow when considering heat dissipation/creation. So if in D3, the TC still locks up? For some reason I figured it commanded the lockup off.

Thanks for the input guys.

Yes, in D3, the TC stays locked up really well, actually... My 5.3L, towing a car trailer (6500#) at 60mph up some pretty good hills, will very rarely drop lockup at all in D3... If you've got the selector in D4 going up a hill, it drops lockup, then goes down to 3 still unlocked, for the power cycle, then usually locks up, then goes back to D4... If I'm towing something not really heavy, I will typically tow in 4th on the flats, then select 3rd, as I start up the hill... This way the TC stays locked, and the sprag is locked up for the high load times...

About the heat, though, the trans actually makes less heat in 3rd, as well... Less clutch slippage because of a better mechanical advantage from the lower gear (and because 3rd uses clutches, instead of the band that 4th uses)...

I really can't say it enough, though... The DOHC I6 LOVES to spin (as does the 5.3)... Towing in 3rd is REALLY not hurting it... At all...

Mike

[rgraboske]

The DOHC I6 LOVES to spin (as does the 5.3)... Towing in 3rd is REALLY not hurting it... At all...

Mike

As I recall, at 70 mph on flat terrain, mines only turning about 3,200 RPM, so it's not really revving that high. This is with a 3,600 lb car on an 1,800 lb trailer, plus the family and assorted luggage, tools and spares.

[bartonmd]

The DOHC I6 LOVES to spin (as does the 5.3)... Towing in 3rd is REALLY not hurting it... At all...

Mike

As I recall, at 70 mph on flat terrain, mines only turning about 3,200 RPM, so it's not really revving that high. This is with a 3,600 lb car on an 1,800 lb trailer, plus the family and assorted luggage, tools and spares.

Exactly... They'll spin <4000rpm all day long, no sweat...

Mike

[HARDTRAILZ]

The DOHC I6 LOVES to spin (as does the 5.3)... Towing in 3rd is REALLY not hurting it... At all...

Mike

As I recall, at 70 mph on flat terrain, mines only turning about 3,200 RPM, so it's not really revving that high. This is with a 3,600 lb car on an 1,800 lb trailer, plus the family and assorted luggage, tools and spares.

At 70 Mine is like 2200 rpms

[bartonmd]

As I recall, at 70 mph on flat terrain, mines only turning about 3,200 RPM, so it's not really revving that high. This is with a 3,600 lb car on an 1,800 lb trailer, plus the family and assorted luggage, tools and spares.

At 70 Mine is like 2200 rpms

We're talking about in D3, not in D4...

Mike

[rgraboske]

Like Mike says, I'm talking D3. I also have gears that are a little steeper than yours and tires that are a lot shorter. In 4th at 70 I'm right about 2,400.

[fishsticks]

I really miss the pull I had with 4.10s and stock tire size. I don't know how you guys with 3.42's and tires do it.