Building a Tandem Axle Farm Truck?

skegpro

Active VIP Member
Joined
May 11, 2009
Messages
9,930
Reaction score
21,329
Location
In them hills.
What will a guy notice steering wise from tandem to tridem in same wheelbase trucks?
 

Stompin Tom

Active VIP Member
Joined
Jun 7, 2009
Messages
3,787
Reaction score
8,136
Location
BC
What will a guy notice steering wise from tandem to tridem in same wheelbase trucks?

Well, first your wont have the same wheelbase, the tridem will and has to be longer, there are minimum wheelbase specs for a tridrive.

A tridrive will always give you more push with steering, you really wont notice it on dry pavement, you will notice a bit on gravel especially if your turning sharp with any kind of speed, but where you really notice it is in winter with slippery conditions. Its more something you have to be aware of, dont approach sharp turns or approaches with a full head of steam, back off a bit before sharp corners, give your self a bit of room for error.
 

skegpro

Active VIP Member
Joined
May 11, 2009
Messages
9,930
Reaction score
21,329
Location
In them hills.
Well, first your wont have the same wheelbase, the tridem will and has to be longer, there are minimum wheelbase specs for a tridrive.

A tridrive will always give you more push with steering, you really wont notice it on dry pavement, you will notice a bit on gravel especially if your turning sharp with any kind of speed, but where you really notice it is in winter with slippery conditions. Its more something you have to be aware of, dont approach sharp turns or approaches with a full head of steam, back off a bit before sharp corners, give your self a bit of room for error.
I think in Alberta 260" is the shortest tridem body job you can register.

I have a tandem that is a 268"........

Just wondering if a 260" tridem would have the same turning radius as a 260" tandem
 

sirkdev

Active VIP Member
Joined
Nov 2, 2008
Messages
3,127
Reaction score
4,966
Location
Stony Plain
It will be close for sure more drag and forward push with the tri, think of pulling a tridem trailer vs tandem just not as nimble.
 

Stompin Tom

Active VIP Member
Joined
Jun 7, 2009
Messages
3,787
Reaction score
8,136
Location
BC
I think in Alberta 260" is the shortest tridem body job you can register.

I have a tandem that is a 268"........

Just wondering if a 260" tridem would have the same turning radius as a 260" tandem

wheel base is a bit tricky, its apples and oranges with tandems and tridrives. When you measure a tandem its from the center of the steering axle to the center point between the two drive axles, or the rotation point. With a tridrive you measure from the center of the steering axle to the center of the middle axle.

So in reality the turning radius for a 268 tandem should be slightly larger than that of a 260 tridrive, but it also depends on brand of truck and how much wheel turn they have.
 

skegpro

Active VIP Member
Joined
May 11, 2009
Messages
9,930
Reaction score
21,329
Location
In them hills.
wheel base is a bit tricky, its apples and oranges with tandems and tridrives. When you measure a tandem its from the center of the steering axle to the center point between the two drive axles, or the rotation point. With a tridrive you measure from the center of the steering axle to the center of the middle axle.

So in reality the turning radius for a 268 tandem should be slightly larger than that of a 260 tridrive, but it also depends on brand of truck and how much wheel turn they have.
Lol
 

Cdnfireman

Active VIP Member
Joined
Sep 11, 2012
Messages
2,726
Reaction score
9,527
Location
Alberta
What is everyone running for transmissions?

Are these Eaton ultra shifts any good?

Allison automatic?

13 or 18 speed eaton?

https://youtu.be/bJ1i5Bvujbg

FWIW, all our fire apparatus use the Allison automatics. The ladder trucks all weigh in at over 70k and rarely are there any transmission problems. And the trucks are not driven nicely at all. Full throttle starts, hard brake applications then hard on the throttle again. I’m amazed the transmissions stand up as well as they do.
 

skegpro

Active VIP Member
Joined
May 11, 2009
Messages
9,930
Reaction score
21,329
Location
In them hills.
FWIW, all our fire apparatus use the Allison automatics. The ladder trucks all weigh in at over 70k and rarely are there any transmission problems. And the trucks are not driven nicely at all. Full throttle starts, hard brake applications then hard on the throttle again. I’m amazed the transmissions stand up as well as they do.
This is good info.

Do you find they spend a reasonable amount of time in the intermediate gears?

I have an older Allison 6 speed.

They seem to want to get to 6th gear real fast.
 

the_real_wild1

Active VIP Member
Joined
Oct 13, 2010
Messages
6,966
Reaction score
7,389
Location
cardiff
What is everyone running for transmissions?

Are these Eaton ultra shifts any good?

Allison automatic?

13 or 18 speed eaton?

https://youtu.be/bJ1i5Bvujbg

Most reliable is 18 speed eaton if you know how to drive and not rip out clutch brakes. I don’t like the Allison unless it is in my pickup. Usually reliable but if something goes wrong you can’t just get it fixed anywhere like the eaton 18 spd. Ultra shifts are “ok” but the electronics can be a real pita to deal with when something fails. The lower is just a standard trans with the add kms for the clutch. 18 spd is preferred over 13 speed.
 

skegpro

Active VIP Member
Joined
May 11, 2009
Messages
9,930
Reaction score
21,329
Location
In them hills.
Most reliable is 18 speed eaton if you know how to drive and not rip out clutch brakes. I don’t like the Allison unless it is in my pickup. Usually reliable but if something goes wrong you can’t just get it fixed anywhere like the eaton 18 spd. Ultra shifts are “ok” but the electronics can be a real pita to deal with when something fails. The lower is just a standard trans with the add kms for the clutch. 18 spd is preferred over 13 speed.
So what would be the main benefit of having an 18 vs 13?

Other than being able to split the lower gears?
 
Last edited:

the_real_wild1

Active VIP Member
Joined
Oct 13, 2010
Messages
6,966
Reaction score
7,389
Location
cardiff
So what would be the main benefit of having an 18 vs 14?

Other than being able to split the lower gears?

Parts availability and just that, Being able split when needed. Everything with a 13 spd always seems to feel underpowered. Same with that Alison trans. Mack and Volvo have the nicest auto trans in the business IMO but if you get one of those make sure you get every bit of extended warranty you can. Newer Mack’s are nice to drive now. Not like the older trucks.
 

skegpro

Active VIP Member
Joined
May 11, 2009
Messages
9,930
Reaction score
21,329
Location
In them hills.
What rear end ratios are guys running?

Got quoted a 4.11 and a 4.56.......

475 HP 1750 ft-lb at 1100 RPM

From what I gather reading inline I want to be able to cruise at 120km/hr at 1100-1200 rpm in 18th.......

My other concern is that I drive a metric **** tone of gravel rodes at 80 km/hr Soni also wanna be able to cruise that speed at the proper rpm.

I am thinking some of my concerns would be addressed with an 18 speed?
 
Last edited:

the_real_wild1

Active VIP Member
Joined
Oct 13, 2010
Messages
6,966
Reaction score
7,389
Location
cardiff
I have to add the disclaimer that I work on the stuff and have my class 1 but don’t drive professionally.
 

skegpro

Active VIP Member
Joined
May 11, 2009
Messages
9,930
Reaction score
21,329
Location
In them hills.
Parts availability and just that, Being able split when needed. Everything with a 13 spd always seems to feel underpowered. Same with that Alison trans. Mack and Volvo have the nicest auto trans in the business IMO but if you get one of those make sure you get every bit of extended warranty you can. Newer Mack’s are nice to drive now. Not like the older trucks.
Good to know, I was king of wavering between the 13 and 18 speed.

Most of my trucks have a 9 speed Eaton in them.

And if I understand correctly I can drive an 18 speed exactly the same or split the shifts if I need the extra?

Sorry, not a pro.
Specing a truck is a daunting task.
 

the_real_wild1

Active VIP Member
Joined
Oct 13, 2010
Messages
6,966
Reaction score
7,389
Location
cardiff
More or less. Unless it is a heavy load the low range I don’t split. But they are there if you need.
 
Top Bottom