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Rockwell 5 ton input torque rating... What breaks first. Bearing caps? Shafts? Ring gear? Pinion?

Superthermal

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Hello all! I haven't been able to locate any info on the specification for the Rockwell 5 ton input torque rating. Looking at engine torque to transmission gearing to transfer case gearing and the end torque that could be placed onto one axle input. Anyone know this? I know they are incredibly tough but I would like to see some numbers. Thanks in advance.
Would adding stud girdles to these 5 ton Rockwells be good insurance for the top loader? Is this the weak link of the axle? I am guessing the front axle weak link in the U-joint.
 

simp5782

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Hello all! I haven't been able to locate any info on the specification for the Rockwell 5 ton input torque rating. Looking at engine torque to transmission gearing to transfer case gearing and the end torque that could be placed onto one axle input. Anyone know this? I know they are incredibly tough but I would like to see some numbers. Thanks in advance.
Would adding stud girdles to these 5 ton Rockwells be good insurance for the top loader? Is this the weak link of the axle? I am guessing the front axle weak link in the U-joint.
Weak link is the Input bearing. But it takes severe torque. This was big cam with 1500ft lbs thru a CAT 7155 with a 2.66 low range transfer case. It used to eat 1710 u joints in low range. But I wore an input bearing out a few times.

Without being a heavy modified 5 ton it'll hold up for awhile
 

Superthermal

Well-known member
268
769
93
Location
Utah, Murray, United States
Weak link is the Input bearing. But it takes severe torque. This was big cam with 1500ft lbs thru a CAT 7155 with a 2.66 low range transfer case. It used to eat 1710 u joints in low range. But I wore an input bearing out a few times.

Without being a heavy modified 5 ton it'll hold up for awhile
SIMP Thanks again on the reply. Looking for info on failure mode on the "eating" parts. Was this in low range out in the mud or pulling your heavy loads in high T-case range but lower gears on your 7155? Was this on the intermediate shaft between the Trans to T-case or the T-case to the rear axle or to the front axle etc...
I do expect to drop in the Big Cam as you have and the 50000 HEMTT case, the only difference is I do think I am going to use a manual transmission with a manual shifter maybe an RTO-16908LL or something like it. I know you would cringe at me saying this having much more driving experience with big rigs than I will ever will have but this seems more my style. I am also not going to be driving this regularly. An Eaton fuller 10 or 15 speed looks nice to me and I think I can figure out the shifting. Your 7155 looked very compact (short) for what it is (CAT being 36" long in comparison to the RTO at 33") not knowing bell housing variances and exact shaft selections It is a close toss up and would use similar shafts...?
Added question. Which gears are you finding you like to start driving in when pulling off from a stop when you are unloaded. Start in 7th is what I thought I heard in your video. What is the transmission ratio for your "sweet start gear".
 

simp5782

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SIMP Thanks again on the reply. Looking for info on failure mode on the "eating" parts. Was this in low range out in the mud or pulling your heavy loads in high T-case range but lower gears on your 7155? Was this on the intermediate shaft between the Trans to T-case or the T-case to the rear axle or to the front axle etc...
I do expect to drop in the Big Cam as you have and the 50000 HEMTT case, the only difference is I do think I am going to use a manual transmission with a manual shifter maybe an RTO-16908LL or something like it. I know you would cringe at me saying this having much more driving experience with big rigs than I will ever will have but this seems more my style. I am also not going to be driving this regularly. An Eaton fuller 10 or 15 speed looks nice to me and I think I can figure out the shifting. Your 7155 looked very compact (short) for what it is (CAT being 36" long in comparison to the RTO at 33") not knowing bell housing variances and exact shaft selections It is a close toss up and would use similar shafts...?
Added question. Which gears are you finding you like to start driving in when pulling off from a stop when you are unloaded. Start in 7th is what I thought I heard in your video. What is the transmission ratio for your "sweet start gear".
On a 9 10 or 13 you are going to have to start off in 2nd or 3rd anyway. Otherwise you will be grinding without enough speed up. The CAT I could start off as high as 8th. But the cat is a whole different beast

Most 9, 10s 13s can swap on an SAE 2 housing to match the small cam or 6cTa bellhousing The CAT is only available in SAE 1.

The cat is near double the weight or a 9 10 13 spd and much bigger.

I ran the transfer case in high and low and still had issues.

Most of the 9,10,13s are going to be 1710 outputs available. You would have to remove the T1138 Input yoke in place for a companion yoke used on the other outputs. And use a companion flange to attach to the 1710 shaft. This is the same thing used on the 938 T1138 to front tandem axle.
 

Attachments

Superthermal

Well-known member
268
769
93
Location
Utah, Murray, United States
One reason I like the 8LL is the three revers gear ratio choices (six in all) to be able to rock the rig back and forth as needed. Again I haven't used one of these transmissions and don't know the "feel" of a 21,000 lb rig and what power/ratio makes the ideal scenario for throwing mud off your tires (if that is even possible with 16.00s) or the ideal low speed try not to break traction gear when loaming in deep snow. Which makes me ask an additional question, what do you feel the red line is on the Big Cam 400? 2150ish? Cruising Freeway RPM for reasonable gas mileage.. 1750 (60mph)?
1638823388410.png
 

simp5782

Feo, Fuerte y Formal
Supporting Vendor
12,095
9,260
113
Location
Mason, TN
One reason I like the 8LL is the three revers gear ratio choices (six in all) to be able to rock the rig back and forth as needed. Again I haven't used one of these transmissions and don't know the "feel" of a 21,000 lb rig and what power/ratio makes the ideal scenario for throwing mud off your tires (if that is even possible with 16.00s) or the ideal low speed try not to break traction gear when loaming in deep snow. Which makes me ask an additional question, what do you feel the red line is on the Big Cam 400? 2150ish? Cruising Freeway RPM for reasonable gas mileage.. 1750 (60mph)?
View attachment 852549
You can run a big cam up to 2700rpms before it puts a valve in a piston. Max hp is 2100 2150rpms. I run mine up to 2300 or 2400 on a heavy load shift to get me out of the hole around 1700 on a wide gapped transmission. This is especially something to do on an Allison 4000 series in a 915/916 as the 3 and 4 shift points are so wide it bogs the motor.

Nothing below 1700 is safe with a load . It's bogging it too much.
 
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