Sprinter 4WD Conversion Idea, GMT-800 IFS.

[luthj]

Typical chaos.




Mostly finished. I still need to install the locker control solenoid. Just got some more fittings today, so that will go in tomorrow.



I was looking through my axle options. It looks like all 06 and down 2500s got an ABS sensor on the Tcase, so 3 channel ABS. 2007+ have 4 channel abs, But 9.5s were dropped for the 10.5 FF. I think in 2011 they also changed the gear ratios, and 3.73 was not an option. The express 9.5" I found has 55 count rings, but 3.42 gears. It's in good shape, and I could probably drop it in 20 minutes. There are several other GM 9.5 14 bolts, so I could probably find a 3.73? Otherwise new gears are ~300$.

Otherwise it looks like an axle from a full service yard is about 1,000$. I don't know if I want all the extra unsprung weight of a 10.5 FF, especially with 30" tires.

 

[shade]

The console looks sharp and easy to interpret. What's the gray cover to the right of your 4WD panel for?

On weight, will the end result of this project put you close to any restrictions you've seen in your travels?

 

[luthj]

The console looks sharp and easy to interpret. What's the gray cover to the right of your 4WD panel for?

On weight, will the end result of this project put you close to any restrictions you've seen in your travels?

The little gray thingy is a paper clip/holder. I have used it maybe 4 times. Removing it would leave an ugly hole. Somewhere in AZ it split down the middle, hence the glue line.

As far as weight goes, a good part of the world draws the line at 3,500kg (7,700lb). The van is well over that loaded. I have occasionally seen wonky bridge weight limits, but those are pretty random, and typically ignored by the locals.

North America is strange in some ways. We let folks with no commerical training drive 40klb Class A RVs, or two 15klb trailers. As long as its for personal use.

 

[shade]

Quote of the Day: "North America is strange in some ways."

Hmmm ... some kind of pivoting beverage or camera holder might make a good replacement for the bribe clip.

On the rear axle, will there be much of a difference in parts availability between your options?
What are the actual weight differences?
Will changing the axle require spending more on new suspension parts or other things?

If it were me, and all those factors are basically a wash, I'd spend $700 to put a heavier axle under my house.

 

[luthj]

That plastic panel is not very strong, otherwise there would be a phone swivel mount there.

The 10.5 FF weighs a good 70lbs more than the 9.5 semi float. The gross weight isn't as much of a concern, its the unsprung weight. Its going to really impact the ride I think.

As far as axle swap costs, I need to modify the Ebrake cables to fit (should be pretty easily I think). I need to modify the spring perches to fit. Either narrow them a bit, or modify the vans spring towers to accommodate the GM springs. I would also need to weld on shock and sway bar brackets. I would just copy the sprinter ones.

As far as parts availability, the 9.5 14 bolt is really common. 1500s had it many years, and the 2500s optioned it up through 2007. The van axle is slightly wider, so axle shafts won't be as common. The odds of me breaking one is pretty low though.

 

[luthj]

Getting down to business.







Managed to wrestle that thing myself. Was doing pretty good, only smushed the little finger on one hand.

The U bolt plate isn't welded to the axle, only the upper perch is. With only 2 small welds, It will be easy to relocated to fit the sprinters frame width. The leaf springs are a nicer multi leaf pack with overload, I am hoping they have a good rate. I believe with some light grinder word, they will fit on the sprinters spring attachments. That just leaves the parking brake cables to adapt, shock/sway plates, and possibly shortening the driveshaft an inch.

Well, and I need to swap gears. There is several 14 bolt 9.5s in the yard right now. I am sure at least one is 3.73. I figure I will grab the whole carrier assembly. Getting the pinion nut off may be a challenge though.

 

[shade]

Nice of them to let you do your own wrestling. That ended long ago in my area.

 

[Herbie]

Wait, your self-pick yard has PAVEMENT? WTFITS? All my pull-a-parts are nothing but dusty, oily, uneven packed earth.

 

[shade]

When I saw the first shot, I thought his driveway was getting a little dirty.

 

[luthj]

Wait, your self-pick yard has PAVEMENT? WTFITS? All my pull-a-parts are nothing but dusty, oily, uneven packed earth.

When I saw the first shot, I thought his driveway was getting a little dirty.

Back in Oklahoma, they are all just gravel lots, very light on the gravel. After the winter rains they can be mud pits. I saw one of their big fork trucks stuck once.

About 3/4 of this yard is paved. It was a big truck staging yard for a shipping hub a while back. Unfortunately it doesn't drain the best, so there is plenty of dirt, though at least the mud isn't too deep? It rains enough here that the ground would turn into a swamp, the clay just doesn't drain at all. Of course the price of crappy pavement is 20% higher prices, but few pick-n-pulls around here stock the trucks.

 

[shade]

Back in Oklahoma, they are all just gravel lots, very light on the gravel. After the winter rains they can be mud pits. I saw one of their big fork trucks stuck once.

About 3/4 of this yard is paved. It was a big truck staging yard for a shipping hub a while back. Unfortunately it doesn't drain the best, so there is plenty of dirt, though at least the mud isn't too deep? It rains enough here that the ground would turn into a swamp, the clay just doesn't drain at all. Of course the price of crappy pavement is 20% higher prices, but few pick-n-pulls around here stock the trucks.

Cardboard must be popular there.

Being able to do the selection and removal yourself is worth a premium. I saved a lot of money getting some older vehicles back in order by spending a few afternoons crawling over wrecks and harvesting everything that looked useful. I would've missed out on many little parts by trying to do the same through a web interface, or by talking with the counter guy.

 

[luthj]

Being able to do the selection and removal yourself is worth a premium.

It is nice to be able to choose your own parts. The full service yards can often leave out important bits. Of course the self serve yards will nickle and dime you. They wanted to charge me separate for the E brake cables, which I had to cut to drop the axle. Ridiculous.

Making some progress.



Confirmed 3.42 ratio. Looks pretty good, typical small debris. Oil was in good shape. I have not decided what locker/diff, if any, I want. I identified a couple donors in the yard with 3.73, and I may pull one. There are a few options on ebay as well, and the prices don't seem bad for used.



Here is the shock and swaybar bracket I need to replicate. Its all coplanar, so a single lase profile should do the trick. I can then reuse the sway bar and attach brackets.



The express/savanna springs are within an 1" of the sprinters springs in length. They are 1/4" narrower. The shackle is a bit too tall for the rear perch, so I will just use the sprinters with 1/8" spacers. The locating pin appears to be 1/2-3/4" farther aft? That should be okay with the wheel well clearance I have.



The donor axle is at least 1.75" taller in the main casting, and the axle tubes are 35% larger. Brakes are vented (instead of solid) and ~1" larger.

 

[Pinnacle Campers]

How about track width with same wheels as the front?

 

[luthj]

How about track width with same wheels as the front?

67"? I need to get a proper measurement.

 

[luthj]

Working through my code for the canbridge. I currently have it setup to lock out 1st gear in low range (its crazy low for anything but crawling). I have 1 spare wire in my Ethernet cable, but I want to wire two switches. Since I have 3.3V at the panel, I am going to use a couple resistors and 2 switches through an analog input. With a voltage divider, the analog input will see different voltages for SW1, SW2, and SW1+SW2. That will let me toggle their variables in the code. One switch will control 1st gear lockout, so if I really need 1st gear, I can enable it. The second will control winter mode, not 100% sure what all that does, but it seems possible to toggle it via canbus. Hopefully I can turn it off.