Jump to content

Rear end and lockers question


Exile

Recommended Posts

Looking at a truck with some crazy low rear end, something like 4.33 or lower, and it has full lockers. (But price is low enough to put money into it)

if i change the gear ratios, would i end up removing the lockers?  Or is the locking mechanism separate from the gears?

Thank you

98 379 with 12.7 DD

LG Dodge w/5.9 CTD

Chrome habit I’m trying to kick.

Link to comment
Share on other sites

Hi Exile - try a gearing and speed tool that you can discover speeds for a given set of trans and rear axle ratios and tire size. 

Ratio calculator

Some more info about the truck you like, how many miles/yr you drive, where, and how heavy you ever want to be would be handy re giving you ideas around the gearing.

The “interaxle” lock on a tandem locks the front and rear drivelines together through the front drive axle “power divider” which is a differential. 

Axle diff locks lock the wheels together on the same axle. 

Diff lock axles usually have different axle shafts vs open diffs. 

You can do a ratio swap “later” if you can’t live with the specs - but everything else about the truck fills the bill. 

That truck will pull grades and push great big 3 axle trailers backwards up hill around corners really nice.

 

 

"Are we there yet?" asked no motorcycle rider, ever. 

 

Link to comment
Share on other sites

Need to know the final drive of transmission. Some may be 1-1 ratio but others have one or two overdrives. With 4.33 I would want a double over. I have a single over with 3.90 and run 1750 rpm @ 65 mph. I am sure the old cat would like less rpm's but never a problem for close to a million miles. I only drive 60-65 mph. Get the info and do the math for rpm @ mph or do it backwards if tach and speedo are correct. Tire size (diameter) = circumfrence-inches-5280 ft.? mi. etc. also plays a role.

Link to comment
Share on other sites

Yeah, i looked for the ratio, but didn’t find it.

this truck has full differential  lockers -and the interaxle lock, my apologies for not being clear.

driver said it would do 80 at 2100 rpm, so maybe it has an overdrive. Looks like .79 is the ratio for a 15 speed overdrive- which would be a 3.55 rear end with 37” tall tires and 2100 rpm at 82 mph.

xmission is a 15 speed, didn’t see the model number posted anywhere to look it up, or see if it ended with an “o”.

Yeah, with the 15 speed, it will pull anything up a hill. Slowly.  Nice for hitching up.

thank you.

98 379 with 12.7 DD

LG Dodge w/5.9 CTD

Chrome habit I’m trying to kick.

Link to comment
Share on other sites

Our HDT has 2 lockers and it has been great.  We boon dock and have encountered some difficult conditions.  We have been able to pull out of some areas our friends needed 4x4 to move with trailers.  We also have a fair amount of weight on the rear axles.  Turning in difficult conditions when both axles are locked is interesting though.

Randy

2001 Volvo VNL 42 Cummins ISX Autoshift

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...