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Time to transition to lockable, single front diff?

Front diff showing 2757 ppm iron and 15 ppm chromium in January. Changed gearbox oils (Spirax-S) and resampled after 29,600 miles. Now has 1021 ppm iron and 5 ppm chromium.

Always had a mystery vibration in rear but never could get it out of this all Meritor driveline. Guessing I've got a worn gear since there were no obvious metal shavings, or pieces when I changed oil.

Heres my plan and looking for any helpful input:

1. Obtain front locking diff and send to MicroBlue for treatment. Haven't shopped yet but I'm first going to Jasper Engines to see what they have to offer. (Main office and plant is 8 miles away)

2. Gut rear axle, metal shop to fab plate with hub oil cap so I can do visual check of oil level. (I do not care for freeze plug idea because ability to monitor oil level is tough and if plug fails bearing failure will follow. I now this requires more syn oil but that is ok)

3. Plate rear of front axle housing with a fab plate to seal.

4. Volvo's seem to have a problem with rear driveshaft failures so by doing this I will also save on replacing this. (Betting it's expensive)

5.Extend front driveshaft and relocate carrier bearing if necessary.

6.Install a shutoff valve to isolate rear airbags in case of difficulties with terrain.

7.Dump valve for rear air bags.

8.Install MicroBlue drive bearings that I already have.

9.Save all old parts to easily convert back to 6x4 if this helps my trucks value later on. 675,000 miles now and plan to keep for 2 more years and maybe more.

I'm no mechanic but this is my plan. Welcome any helpful input.

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Where are all my axle and differential guys with some comments?

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My input for 6 and 7: when you dump the rear bags the trailer/load weight might cause your steer axle to lift off the ground...unless your 5th wheel is right above or in front of the 1st drive axle.

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Thanks but that is only for when I am in a bad spot. I do lots of stops every week and some of the parking lots are full of potholes. It would be pressurized 99.9% of the time.

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I like your plan, even if your current gears weren't worn. Not really sure if you NEED a locker, I think the combo of a regular single axle diff. and a dump valve would get you where you need to go.

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I do 15-20 furniture stops a week in FL driving on dirt, pavement, sand, potholes, curbs and sometimes a yard or two! One place I go to regularly the left drives and the right trailer tires are up on curbs at the same time.

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Don't know what it's called, but when I had Rowe axle (otterbein, in) install lift axle, they added a adjustable airbag pressure regulator. I have it set even between drives when both down, but with a few turns of a half inch wrench I can increase or decrease pressure. I haven't had to mess with it, but this might be more useful than strictly an airbag dump.

Why? If you have a heavy load, it can lift front str axle depending on fifth wheel placement as someone mentioned. Also, if you are loaded fairly heavy and dump axle, the other axle's airbags will not lift that much weight and both axles will sink to the stops on my truck at 43k. Not good for airbags or bearings. If you are in inclement weather where traction is an issue, you can put more weight on th drive to improve traction. Just be carful of weight stations that split duals.

My cost for new drivshaft sections, carriers, u joints, new airbag plumbing and axle install was approx $6400

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Where in the US can I talk to a place that will do this to my 1996 fld 120. I am Ole Truck on My Gauges.

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Depending on your housing not all are interchangable, that is what I ran into with ds404 so just guttedfront housing, and made longer driveshaft and carrier bearing and run thu the middle of front housing to rear housing.

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I wouldn't do it. I did this same thing a little over 2 1/2 years ago made my truck a single drive with a tag and regretted it I was lucky I kept all my parts and put it back to tandem drive. First of all if you run up to gross weight and pull a lot of hills your going to eat drive tires up. I was going through a set of XOne XDA Engery every 50,000 miles or less. Your traction will suffer in the winter and summer I went to pull out of a Blue Beacon truck wash in Oak Grove MO and broke traction trying to get out of their driveway and that was in July you will increase mpg by about 2% I will say if your running around with lite loads all the time this would be great setup. I still have my 23,000 locker single drive that I took back out of my truck.

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This question is to you mel, do you want to sell that locker? If so what is the ratio

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I do and it is a Meritor 23,000lb Locker with 3.58 gears it is reman diff it has 175,000 miles on it. Housing has been powder coated black and has Mirco Blue wheel bearings.

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David White will be eternally grateful.
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