Sprinter 4WD Conversion Idea, GMT-800 IFS.

luthj

Engineer In Residence
Indeed, off the shelf parts are the way to go.

Did a bit of mixed driving with the new shaft. Still have some vibration, but its not the shaft. Runs smooth at 20 and 70mph. I do have engine rpm vibration in the 2-3k rang. Its erratic though, seems related to engine torque. So it could be the trans, or could be the mounts. The trans mount is showing about 1/4" or so of forward shift. I probably need to adjust it some, as my hand drilled holes aren't straight enough. If the engine is getting pushed forward, that could cause the issue. It could also be the extra couple degrees of twist on the engine mounts. Thats easy enough to remedy with a couple shims as well.

Anyways the vibration isn't severe, so I know I can drive the van, which is helpful. I need to go to the home store and grab some cement board to make a welding table.

The shaft is very close to the front of the fuel tank. So I need to strap the tank over, as it has a tendency to shift a bit after I relocated it.
 
Indeed, off the shelf parts are the way to go.

Did a bit of mixed driving with the new shaft. Still have some vibration, but its not the shaft. Runs smooth at 20 and 70mph. I do have engine rpm vibration in the 2-3k rang. Its erratic though, seems related to engine torque. So it could be the trans, or could be the mounts. The trans mount is showing about 1/4" or so of forward shift. I probably need to adjust it some, as my hand drilled holes aren't straight enough. If the engine is getting pushed forward, that could cause the issue. It could also be the extra couple degrees of twist on the engine mounts. Thats easy enough to remedy with a couple shims as well.

Anyways the vibration isn't severe, so I know I can drive the van, which is helpful. I need to go to the home store and grab some cement board to make a welding table.

The shaft is very close to the front of the fuel tank. So I need to strap the tank over, as it has a tendency to shift a bit after I relocated it.


I installed the tranny and T-case. By moving the fuel lines out of the way, my cross brace has only 3" drop, and only 2 degrees difference in T-case output axis and pinion. And less twist on the motor mounts I am sure. I think I remember you said 4.5" drop and 4 degrees?

I have not had the chance to run it. it will be a while since I dropped the rear axle today to do the GM swap, which with the coming snow will probably not be done for around 10 days-2 weeks.

I'll be curious to see if I have any comparable vibration
 

luthj

Engineer In Residence
I ended up with 3 degrees difference between the Tcase and axle. I am pretty sure I will be able to eliminate the vibration by tweaking my rear trans mount and engine mounts. Its not bad overall, but I am pretty sensitive to this kinda thing, and I have a lot of miles with our van. I have always had a little bit of resonance/vibration at about 2,800rpm since about 80k miles ago.
 
I ended up with 3 degrees difference between the Tcase and axle. I am pretty sure I will be able to eliminate the vibration by tweaking my rear trans mount and engine mounts. Its not bad overall, but I am pretty sensitive to this kinda thing, and I have a lot of miles with our van. I have always had a little bit of resonance/vibration at about 2,800rpm since about 80k miles ago.

Hmm, one other possibility is there is a different level of vibration due to the new wrangler mount compared to that single point Sprinter mount.
 

luthj

Engineer In Residence
Hmm, one other possibility is there is a different level of vibration due to the new wrangler mount compared to that single point Sprinter mount.

Its possible, but my previous experience with engine swaps has been that rubber isolators/mounts are sensitive to position, once you get outside a certain range, they transmit vibration significantly. I will give it a look this weekend. I am not going to spend to much time on it, as I may need to address this again with the new subframe, as the engine mounts will need adjusted to get the placement perfect.
 

luthj

Engineer In Residence
I ordered this shifter with 48" cable. This unit should fit between the seat and E brake handle, and has enough flex cable to loop around to the Tcase.

SINGLEFLUSH_DIMS_1024x1024.jpg


I also installed a 220V outlet in the garage, so I could test the welder at full power. Much better than a 120V flux core.



The Front pinion yoke is now a 1350. Turns out GM switched the 2500s to a 1350 up front in 2016. The seal and splines are the same, so its a straight bolt-on. AAM 40152063.

 
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luthj

Engineer In Residence
You an me both! 50% more unsprung weight, but the FOX 2.5s are about 99% better than MB OE struts... So applying the transitive properly of suspensions.

(99% / 50%)

Now we apply Identity property via a cool sticker to the rear window. Yields
1570966363806.png

(99% / 50%) x 1000% = 1980% ride improvement.


1570966485873.png
 
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shade

Well-known member
It took me several months before I set aside the time to dump the OE junk on my truck. The improvement was almost as dramatic as the results borne of your calculus.
 

luthj

Engineer In Residence
For the fairly minimal added cost, I don't get why so few OEMs use decent dampers... Even adding fox 2.0s at a 2:1 motion ratio made my factory suspension dramatically better. It was a bit of a kludge, being attached to the sway bars, but it worked. Swapping to Fox 2.0 in the rear was an even bigger difference. The rear currently rides much better than the front, especially on the dirt. Which is unfortunate, cause we don't ride in the back... Hoping to reverse that trend with the new front suspension. ?
 

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