Full-Circle Flattie

I originally built my flattie with a Spicer 18 I assembled using a Dana 20 case and a gennie Warn Overdrive. I hooked it to my SM420 with a Novak adapter.




All my buddies at the time were into crazy-gonzo wheeling (Johnson Valley, Upper Helldorado, etc) and we were hitting the trails just about every weekend, so I really abused the Spicer 18. I rebuilt it twice over 4 or 5 years, then when it started jumping out of gear in Glamis I decided rather than rebuild it a third time I'd install a Dana 300. I sold off my Warn overdrive, adapter, and T-case separately so I could afford to call up JB Conversions.




In went a 2.61:1 Dana 300 with 32-spline output shafts and a 1350 driveshaft in the back. I used another Novak adapter to mate the Dana 300 to the SM420. Goodbye freeway rpms and pretty much any street driving 'cause my rear driveshaft buzzed too bad, but I never worried about busting anything on the trail.

Fast-forward to now and I'm looking at putting together another Dana 20-case with Spicer 18 guts and an Overdrive hooked to my SM420 with a Novak adapter. I miss being able to cruise in my flattie. This time I may do the 3.15 gears 'cause I dropped my axle gearing from 5.83 to 5.38 when I did the Dana 300. I don't think a 93:1 crawl ratio will make me too happy on the hardcore trails and regearing the axles isn't an option now that I'm running the True Hi9 rear centersection (5.38 is as deep as they go).

Guess the moral of the story is - never throw anything away!

 

Thanks Christian-maybe the wife will collect even more stuff-FAT CHANCE

 

wow you got that tranny pushed way up there , Hope you don't run in to shifter problems , I pulled my trans back about another 8 inches from were yours is at and still had to modify the shift stick

 

So your saying you want to but that trasfercase back?
I'll trade you for the 300

 

It buzzed because of the short length or because of the low gearing of the tranny and axles?

 

Just the angle. I have the V-6 moved pretty far forward. For a flattie the rear shaft is actually pretty long.

You can kinda tell from the photos how high up I have my drivetrain mounted. The outputs of the Spicer 18 were just about flush with the bottom of the framerails. The rear output on the Dana 300 is much higher. Couple that with the big 'ol 1350 U-joints with offset trunions (Tom Wood's) so I didn't have to grind the yokes for full-drop out and you can see why it buzzes so badly. At the time I was more into brute strength than drivability.

 

Ahh, yeah now I see how high the Dana 300 sits. I take it swapping to a cv joint in the drive shaft wouldn't do enough to fix it?

 

Can't. I have a True Hi-9 and the rear is already angled up to the maximum allowable 15 degrees.

 

Sounds good Christian. That is exactly what I was thinking of doing. I have a older 1 1/8" shaft small hole Dana 18 that I was thinking of building up into a Dana 20 case that a friend of mine will give me. I may also go with the tera low 3.15 gears at the same time. I am thinking along the same lines as you so I can use a overdrive as well. How about doing a buildup for us and doing an article in JP. I am a subscriber and would look forward to that. Do you still have an offset rear axle even though you had the 300 t/case in there? I remember seeing the pictures of your Jeep having the offset rear end and centered t/case but not sure if you still have the same rear end. Anyway, please do it, and show us how.
Greg

 

x2:drool:

 

It'll happen in Jp.

Rear axle was offset, now it's centered. However, I'm thinking I may be able to make the weird offset angle work with that dual double-cardan driveshaft I have. It was smooth as glass the last time I ran it and even then it had a bit of a compound angle. I'll see. Nothing ventured, nothing gained.