1 ton leaf springs

[Submariner]

What can you tell me about a 1-ton leaf spring for a mj?  the good the bad and the ugly

 

I got a lead on a pair for $200 on craigslist.  

[Jeep Driver]

Buy new, not used. 

[Eagle]

21 minutes ago, Submariner said:

What can you tell me about a 1-ton leaf spring for a mj?  the good the bad and the ugly

 

I got a lead on a pair for $200 on craigslist.  

 

Are you talking about Jeep Metric Ton springs, or springs from a Ford or Chevy 1-ton that you want to adapt into an MJ?

[Submariner]

metric ton jeep

[Pete M]

they are part of what gives an MJ a 2k load rating.  from the factory the truck would also have had tougher shocks, front springs, wheels and rear axle.  In theory it'll ride a bit stiffer than a regular MJ, but it's not all that bad.   oh, and the leaf packs came in 2 varieties over the years, 4+1 and 3+2. 

 

be cautious.  time/abuse can be a killer to springs.  just because they were rated for 2k 30 years ago doesn't necessarily mean they are capable today. 

[gogmorgo]

The Metric Tonne (sometimes called Big Ton) package was the heavy payload package. It increased payload capacity from ~1400 lbs to ~2200 lbs (1000kg, or one metric tonne). In addition to heavier leaf spring packs, It also came with a heavier duty rear axle, either the AMC 20 or Dana 44 depending on year. With that, the tow package (frame mounted hitch and heavy duty cooling package) and the automatic, it increased tow capacity to 5000lbs as well. 

Ditto on you probably not wanting original used springs. That's only about 50% off what new aftermarket spring packs cost. If your original standard load springs are sagged, it might be a bit of a bump up if the metric tonne springs are still in good shape, but they're probably not good for 2200lbs any more. The other things to take into consideration about used leaf springs is that they almost always seem to wear unevenly on each side; and they're also what hold your rear axle in place, so if a worn out main leaf breaks, it's not going to be good.

But that said, your current springs are also used springs. Just don't reuse axle u-bolts when removing and replacing them, if you think those springs are in good enough condition to run. 

[Submariner]

20 hours ago, gogmorgo said:

The Metric Tonne (sometimes called Big Ton) package was the heavy payload package. It increased payload capacity from ~1400 lbs to ~2200 lbs (1000kg, or one metric tonne). In addition to heavier leaf spring packs, It also came with a heavier duty rear axle, either the AMC 20 or Dana 44 depending on year. With that, the tow package (frame mounted hitch and heavy duty cooling package) and the automatic, it increased tow capacity to 5000lbs as well. 

Ditto on you probably not wanting original used springs. That's only about 50% off what new aftermarket spring packs cost. If your original standard load springs are sagged, it might be a bit of a bump up if the metric tonne springs are still in good shape, but they're probably not good for 2200lbs any more. The other things to take into consideration about used leaf springs is that they almost always seem to wear unevenly on each side; and they're also what hold your rear axle in place, so if a worn out main leaf breaks, it's not going to be good.

But that said, your current springs are also used springs. Just don't reuse axle u-bolts when removing and replacing them, if you think those springs are in good enough condition to run. 

I see.  My springs don't look like they are sagging. Was thinking that if I went to the 1 ton springs that would give me a 3" lift.

I am looking for another rear end with a different gear ratio.  I have 3.07 gears.   thinking of changing to 3.53 when converting it to a 4wd.  The hole plan is to do a 3" lift, convert to 4wd, change gear ratio's, stiffen up area around steering box and upgrade the steering system.   Not to much to ask is it?   While I am at it freshen up  the engine and put in a new clutch and pressure plate.   I could have said rebuild the running gear I guess.

[HOrnbrod]

For me the MT (Metric Ton, not 1 ton) rear springs initially provided close to 3" of lift from what I was originally, but over about a years' time they sagged down an inch, as leaf springs normally do. To get the rear end back up to match the front I used some lift shackles. Most leaf springs don't look sagged, but load the bed up and you will soon be able to see if they are shot or not. If your springs are still the originals, most likely they should be replaced.

 

No 3.53 ratio axles, closest is 3.55. Those are fairly common. Personally I went from a 3.55 to 4.10 by swapping in a stronger D44 axle. I'm assuming you have a D35 axle now? If you're going to replace it and go 4WD, might as well replace it with a stronger axle, like a Dana 44, Chrysler 8.25, Ford 8.8, AMC-20, etc.

[Pete M]

from the factory the metric ton MJs were not any taller than regular 4x4 MJs.  Aftermarket metric ton packs might give you a lift.  or not.  they aren't really designed for lift. 

[Strokermjcomanche]

I have new 3/2 my springs on my SWB 88 MJ . I seen a 3 inch lift as well , mine are relatively new and haven't sagged yet . I will say they ride stiffer ( for the better ) and will definitely handle the heavier loads better , just today I hauled a four wheeler and several rims/ tires and the truck barely    dropped at all . 

[HOrnbrod]

22 minutes ago, Pete M said:

from the factory the metric ton MJs were not any taller than regular 4x4 MJs.  Aftermarket metric ton packs might give you a lift.  or not.  they aren't really designed for lift. 

 

This is true, the free arch of an unloaded MT spring and stock spring is the same. However the load rating on a new MT spring is ~1" per 1700 lbs. including the body and payload. A stock sagged out rear leaf spring's load rating is probably less than 10% of that. So even the body weight knocks the spring down a couple of inches or more down. Thus when new MT springs are installed, aftermarket or stock, you get an instant 2"-3" lift.

[79AMX401]

On 11/4/2018 at 8:54 PM, HOrnbrod said:

For me the MT (Metric Ton, not 1 ton) rear springs initially provided close to 3" of lift from what I was originally, but over about a years' time they sagged down an inch, as leaf springs normally do. To get the rear end back up to match the front I used some lift shackles. Most leaf springs don't look sagged, but load the bed up and you will soon be able to see if they are shot or not. If your springs are still the originals, most likely they should be replaced.

 

No 3.53 ratio axles, closest is 3.55. Those are fairly common. Personally I went from a 3.55 to 4.10 by swapping in a stronger D44 axle. I'm assuming you have a D35 axle now? If you're going to replace it and go 4WD, might as well replace it with a stronger axle, like a Dana 44, Chrysler 8.25, Ford 8.8, AMC-20, etc.

 

On 11/4/2018 at 8:54 PM, HOrnbrod said:

For me the MT (Metric Ton, not 1 ton) rear springs initially provided close to 3" of lift from what I was originally, but over about a years' time they sagged down an inch, as leaf springs normally do. To get the rear end back up to match the front I used some lift shackles. Most leaf springs don't look sagged, but load the bed up and you will soon be able to see if they are shot or not. If your springs are still the originals, most likely they should be replaced.

 

No 3.53 ratio axles, closest is 3.55. Those are fairly common. Personally I went from a 3.55 to 4.10 by swapping in a stronger D44 axle. I'm assuming you have a D35 axle now? If you're going to replace it and go 4WD, might as well replace it with a stronger axle, like a Dana 44, Chrysler 8.25, Ford 8.8, AMC-20, etc.

I hate to be that guy and I know this is an old post… But actually AMC‘s were 354‘s not 355’s

[Pete M]

1 minute ago, 79AMX401 said:

 

I hate to be that guy and I know this is an old post… But actually AMC‘s were 354‘s not 355’s

 

 

[gogmorgo]

On 7/27/2022 at 7:46 PM, 79AMX401 said:

 

I hate to be that guy and I know this is an old post… But actually AMC‘s were 354‘s not 355’s

Rounding. 39/11=3.5454 repeating. Some will correctly round up to 3.55, others have convinced themselves that because there’s a 4 following the 5, it should be rounded down to 3.54. 
Yes it’s true that some gear sets are 46/13 = 3.5384 which will always round up to 3.54.

However the difference is negligible. It’s common for a vehicle to have a 3.55 gear set in one axle and a 3.54 in the other, differences in tire wear, pressure, loading, etc., will account for bigger differences in wheel speed. 

If youre going to be pedantic about it, at least be correct. The decimal point is critical and necessary. 3.55:1 is a very different ratio from 355:1. 355:1 is so low as to be useless in a Jeep axle. The gear teeth would have to be so small to fit them all on there within the confines of a passenger vehicle axle housing that there wouldn’t be much strength at all.