Sprinter 4WD Conversion Idea, GMT-800 IFS.

luthj

Engineer In Residence
This is my first exposure to brake calculations, but I think you forgot to square the value in the 'Pressure Ratio' column, which I'm interpreting as the force ratio between force applied at the MC to force at the caliper piston which is proportion to the piston areas.

P = F1/A1 = F2/A2
F1/F1 = A1/A2 = Pi D1^2 / ( Pi D2^2)

So consider the first case
A1 (@ caliper piston ) = 2* (2.24)^2 * Pi (multiple by 2 for (2) piston caliber)
A2 ( @ MC) = (1.46)^2 * Pi
A1/A2 = 4.7
Your right, it should be converted to area.
 

jhl99

New member
I'm also wrong in my formula, area of circle = Pi * D^2 / 4 Forgot to divide by 4, but since the end result is a ratio of areas, Pi/4 drops out of numerator and denominator.
 

luthj

Engineer In Residence
Looking at the shift linkage, There is only about 9" between the selector shaft and the location I would want to mount it on the floor. This is also about where the trans/Tcase flange is located. I am not sure there is enough room for the 180 degree bend a cable shifter would need. I think the GM style straight rod shifter may work. Or possibly one of these trans mounted units. I am not a big fan of the trans mounted approach though, as all the NVH gets transmitted up the shifter. My current thoughts are to use a narrow nob, and put the shifer between the parking brake and the seat pedestal. Its going to be a bit tight, but it won't pose a trip hazard there.

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shade

Well-known member
Considering how often you'll use it, and that it won't be something you'll be doing quickly, I'd favor trip hazard mitigation over easy access.
 

luthj

Engineer In Residence
Pinion is 3 degrees down from Tcase. I will have to play with it, I am thinking I will wait till I have the new shaft installed. 3 degrees may be fine, though my previous experience says 1-2 degrees down is likely what is best.



Here is the space I am working with. You can see the parking brake cable in the center right where is passed through the floor. The handle is about an inch or two past the floor support. Looks like the fuel lines will need moved over a bit.
 
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luthj

Engineer In Residence
Did a bit of measuring for the shifter. Looks like If I mount a bit farther forward I can avoid cutting the floor support.

Looking at this shifter, I believe I can clearances the seat side, and it will fit between the parking brake and the seat. Mounted with the cable exiting forward, the shifter will be all the way back in 2H. Which gives enough room to grab the brake handle without hitting knuckles.

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I think a 48" cable should work. The bend radius isn't ideal, something around 5", but it should work. I will contact the seller and see what the Tcase side mounting bracket looks like.

 
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luthj

Engineer In Residence
I also finished up painting the suspension bits. I preemptively painted all the new parts to (calipers, CV axles, etc). A little extra protection now will make big difference down the road.



The last of the front end parts are on their way. It turns out the GM OE style tie rod ends are pretty crappy design. Thankfully Moog has some good stuff with larger bearing surfaces.
 
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Len.Barron

Observer
Th It turns out the GM OE style tie rod ends are pretty crappy design. Thankfully Moog has some good stuff with larger bearing surfaces.
It's not just the ends that are crappy, they have very small diameter adjuster sleeves as well, there are a bunch of companies that make good replacements, something like this is worth the money: https://www.dieselpowerproducts.com/p-9457-fleece-performance-tie-rod-sleeves-99-10-gm-2500-3500.aspx?gclid=EAIaIQobChMI4tCZg4-K5QIVDb7ACh2fJwpLEAQYASABEgItcPD_BwE
 

luthj

Engineer In Residence
It's not just the ends that are crappy, they have very small diameter adjuster sleeves as well, there are a bunch of companies that make good replacements, something like this is worth the money: https://www.dieselpowerproducts.com/p-9457-fleece-performance-tie-rod-sleeves-99-10-gm-2500-3500.aspx?gclid=EAIaIQobChMI4tCZg4-K5QIVDb7ACh2fJwpLEAQYASABEgItcPD_BwE
I am not terribly worried about bending the tie rods with 31" tires. Since I am using 2" extenders on the sprinters rack, I would prefer the tie rod to bend, rather than possibly damaging the rack. The Moog units use a stronger steel according to the literature, and the tie rod body itself is a bit longer, so the shaft bit is shorter, reducing the buckling risk.
 
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luthj

Engineer In Residence
I took some advice and added an unobtrusive mark of my trade. I originally though something engineering related would be make sense. But really engineering is my day job. My passion is more closely related to wandering. So I drew up a quick compass face. Its also suitably vague. I get a bit of twisted enjoyment from the idea that some poor guy is going to buy an ancient Mercedes van 18 years from now (with like 500k miles) with a 4x4 conversion. They will desperately search for the conversion company with no clues but a rusty compass mark on a subframe. MUAHAHAHAHAHAAH!

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shade

Well-known member
I took some advice and added an unobtrusive mark of my trade. I originally though something engineering related would be make sense. But really engineering is my day job. My profession is more closely related to wandering. So I drew up a quick compass face. Its also suitably vague. I get a bit of twisted enjoyment from the idea that some poor guy is going to buy an ancient Mercedes van 18 years from now (with like 500k miles) with a 4x4 conversion. They will desperately search for the conversion company with no clues but a rusty compass mark on a subframe. MUAHAHAHAHAHAAH!

View attachment 543480
Perfect. :)
 

b dkw1

Observer
Tie rods were one of the first things to get swapped out on the chase trucks we used. Big tires and any off road would pop them apart. Fortunately, there are several aftermarket solutions.
 
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