Thread: Questions about Drivetrain for 4WD Sand Rail Build

Tweet

submit

Hello All! This is my first post on this forum, and I hope I've got the right section!

I am doing a project for school, and I have decided to take it to the extreme and build a sand rail. It will be a 4WD 4 seater made from 1 3/4 mild steel (I'm fabricating the frame myself)l, so it will have a little bit of weight to it. It will also be running a set of 37" mud tires.

My intended use: Summer only, to drive short distances around town, or to the "desert" area where we can do small rock climbs, run through sand, or just have some all around trail cruising fun.

I have been doing a lot of research on what I should put in it mechanically. Here is where I sit right now.

Engine: Mid 70's to Early 80's Chevy 350 Small Block
-After considering a TBI, I would like to stay carbureated
-Engine mods to build it up to 300 bhp


Transmission: 4L80-E
-A lot of people have recommended the Turbo 400 as it is a ridiculously strong transmission. However, I would like to be able to get up to 60-70 MPH and cruise at those speeds occasionally. After further research, I decided that the 4L80-E would be better as it has an overdrive gear. Its ratios are as following: 1st- 2.48 --- 2nd-1.48 --- 3rd-1 --- Overdrive- 0.75

Charting this out on a calculator with my other parts gave me 72 MPH at 2100 RPM, which I think is an acceptable cruising RPM

Axles: Dana 44's
- Since I plan on running 37" mud tires, it was recommended that going with Dana 44's would be a good fit based upon the intended uses (crashing into rocks and trees). Also, if I went with something bigger like Dana 60's I wouldn't break the bank if they need a repair. Dana 44's are much easier to find where I live.
I then picked my ratio that I was looking for based off what I wanted for a cruising speed, which I demonstrated in the last paragraph (72MPH at 2100 RPM). This left me at a gearing ratio of 4.10.
-If I find out that I need more power, I plan to upgrade my engine more to get some more torque from it.

I'm not looking for crazy power. Just something thats unique and fun to take my friends out in that has a little go to it.

My questions are:
1. Does this spec out seem like a logical approach to my intended application?
2. Is the 4L80E overkill for a Dana 44? Should I be looking at a lighter transmission? I figured since the vehicle will be pretty light overall, the weight isn't a big factor to me, and it will be absolutely bullet-proof.
3. What do I do about a transfer case?
4. I am disc brake dumb. Whats the a good disc brake system for what I am doing? Braking is very important to me. I like being able to stop just as much as the next guy.
5. Any comments?


I have access to a shop at my ready (my friend owns a massive shop, and has graciously lent me a bay and welding equipment to build my frame and assemble the parts). I have also sourced our a machine shop for any extensive engine work that might need done (boring and honing) and another shop that can make the driveshafts for me.
Other things like race seats, pedals, power steering, lights, cooling, etc still need to be figured out, but I want to make sure I am solid on my drive train before I start on secondary systems.

Any comments are appreciated! Thanks!!