Freightliner Differentials

[zaheerkarim]

Hi Guys,

I need your assistance and advice once again.

I have a 2001 Freightliner FLD with a Cummins ISX motor, and the issues I am having is with the front differential. It originally has a Rockwell 2.64 ratio Differentials (14/37) and a 10 speed Meritor Gearbox.

A few months ago the crown wheel teeth broke and I discovered that it was caused by a faulty bearing in the diff. I got it repaired and it was running well, but now it seems it has the same problem again. I was advised to replace both 2 differentials with the 3.73 ratio diffs (11/41) as there are common here in Africa. My problem is will it not have any affect on the engine and gearbox? Since it was running on a 2.64 ratio and now it will have a 3.73 ratio.


I will appreciate any advice.

 

[Duck]

Well a 3.73 ratio is a low lower. You'll have more pulling power. What kind of roads are you driving on, what kind of loads are you pulling (how heavy) and are there a lot of hills or is it mostly flat?

Going with the lower axle ratio (3.73) will give you more power but since it'll be a lower overall ratio, you'll burn more fuel. If you typically make long hauls through the middle of nowhere, you'll have to be careful to make sure you can make it there on the amount of fuel you carry. I wouldn't want to hear about you running out of fuel in the middle of the Kalahari & get eaten by a leopard or something.

The effect it will have on your engine & gearbox (transmission) is there will be LESS load on the transmission, however if you drive the same speeds as before, everything will turn faster. If the engine is old & worn out, running it at higher RPMs than it's used to could cause piston rings to break if there are ridges in the cylinder walls at the top of the stroke. Higher RPM forces the rings to top out slightly higher than normal & eventually the rings repeatedly hitting the top of the wear mark will damage them. If the engine has had a recent overhaul I wouldn't worry about it too much.

I assume you're probably not running the kind of speeds we run here in the USA though.

 

[zaheerkarim]

The roads here are mostly flat although we have some hills but not so high. My maximum load capacity is 30 tonnes (30,000kg) which is the maximum permitted here.

I wonder if it will make a very big difference on the fuel. Currently the consumption is about a 6 miles to a gallon (hope my calculation is right, because we use kilometres and litres here).

 

[Les2]

Is that trans a 10 direct or OD? If its a direct the 3.73 will have you at 1800 rpms at 70 mph, not good for fuel mileage.

 

[zaheerkarim]

Les2, what do you mean when you say 10 direct or OD? How do I check? I am not very conversant on that.....

 

[Duck]

The roads here are mostly flat although we have some hills but not so high. My maximum load capacity is 30 tonnes (30,000kg) which is the maximum permitted here.

I wonder if it will make a very big difference on the fuel. Currently the consumption is about a 6 miles to a gallon (hope my calculation is right, because we use kilometres and litres here).

30,000 KG = 66,138 pounds. Here in the USA our legal maximum weight for a 5 axle truck with a 53 foot long (16.15 meter) trailer is 80,000 lbs (36,287 kg).

Is that trans a 10 direct or OD? If its a direct the 3.73 will have you at 1800 rpms at 70 mph, not good for fuel mileage.

I don't know how many places there are in Africa where the roads would be smooth enough to get up to 70 mph. (113 km/h)

 

[zaheerkarim]

Roads are not all that smooth but there are place where we normally go up to 100 km/h. (62 mph)

Can you please explain to me what it means when they say 10 direct or OD. How do I check to find out what transmission I have on the truck?

 

[Duck]

Can you please explain to me what it means when they say 10 direct or OD. How do I check to find out what transmission I have on the truck?

You can probably crawl under the truck & write down any numbers you see on that 10 speed gearbox case and one of these experts on here will probably be able to tell you what it is.

 

[Les2]

I have no clue what Africa roads are like, sorry.

Once you get the number off the trans you can check it on Meritor's site I presume? You can then find out what the final gear ratio is.

 

[zaheerkarim]

Guys, thanks for the advice. Will check the details tomorrow and get back for more info.....

 

[Tim]

I have no clue what Africa roads are like, sorry.

Once you get the number off the trans you can check it on Meritor's site I presume? You can then find out what the final gear ratio is.

Kinda like the In~Ill turnpike and I40 in Arkansas .