max stock dana 20 transfer case can take on the wet pavement

[yakelys69]

what's the max range of torque/hp a dana transfer case can take on the wet pavement / dry pavement with 35's and decent gearing? ignoring other components.

 

[Broncobowsher]

Really anything applies. People have broken them with a stock V8. They have survived 800 HP. You will not find a number.

That wet pavement/ dry pavement line can be a problem. As you transition from wet to dry, the sudden grip can cause a nasty shock load. Shock loads break parts more than power does.

 

[Rustytruck]

The weak point in the Dana 20 is the output shafts the 50 year old shafts with stock 300 Ft pounds of torque and large tires and lockers can break them giving the right circumstances. Up grading to 300 m shafts moves the breaking point elsewhere. a careful driver can make most anything last forever or just staying out of harms way.. there are more people here who have broken the Dana 20 so lets see where the problem ends up. I am guessing this will end up at with a motor around 350 HP 400 Ft pounds of torque and tires bigger that 33" and you will move on to an Atlas after breaking your 2nd Dana 20. Just depends on how hard you play and the lift and tires will take you through and how often you do it. Ford abandoned the Dana 20 to the NP205 when the Bronco got bigger for Good reason.

 

[brewchief]

I don't know why it would be locked in 4wd on pavement, without a center diff it's going to bind on every slight corner. If using 4wd to launch stoplight to stoplight don't expect it to live a long life.

Sent from my SM-T510 using Tapatalk

 

[rjrobin2002]

I use to drive mine with a 5 spd and 350hp 347 stroker like I stole it on pavement, drag raced it, power shifted, and rock climbed with 35's and never broke it.

I raced it with 3.55 and 4.56 gears with 35's with no problems.

 

[bax]

Broken several. All of them rear output shafts. But they are tuff little suckers

 

[nvrstuk]

The little D20 does pretty well. It was designed for use on Broncos & light trucks with max 28" tall tires with clutch type rear ends at best.

Torque kills gear boxes.

I twisted axle shafts at times it seemed like random and never hurt a D20 with tires under 35" and with toploader 4 spds, 3 spds and C4's in sand, snow and trails. Then came rocks and gear doublers and ZF's and holy cow... D20's (and other parts) exploded like popcorn in a hot skillet! I am not exaggerating

First real rock wheeling in Moab with my ZF and 203/D20 combo with ARB"s frt and rear around '00 and on the first waterfall on Poison Spider I was walking up in low, low and locked frt and rear at about 1mph and ka-BANG! I had twisted the tiny teeth off the idler. We had a spare D20 with us and I was wheeling again.

I put together the 300M output shaft mass buy from Chuck about 20 yrs ago. We carried spares everywhere before then. Gary Y came up with his way cool 31 spline and slightly longer output shaft that WH has carried all these years. I couldn't run Gary's because of the extra 1 1/2" long output shaft but it is a D20 saver.

I cracked 4 D20 cases as they couldn't handle the torque. I ate 1 output shaft before the 300M mass buy. I ate one idler gear. THAT is a LOT of wasted vacations, time and money. I was hard headed I guess. I can say this, not one of the D20 failures was caused by the skinny pedal, by bouncing the Bronco by trying to get over a rock obstacle, by hammering a shift on pavement. They all grenaded with normal use but extremely high torque miltiplication applied through the box.

I'll post up a pic (D20 gear on the left) showing why the D20 can't begin to hold up to what a 205 can. The little straight cut D20 teeth are less than half the width of a 205 tooth, has much less contact area due to helical cut instead of straight cut (similar but different than a 9" hypoid gear contact).

Anyway, expect it to fail if you rock crawl with extemely low gear ratios where ALL 4 tires are on rock, won't slip until tires slip or gears slip.

Wet pavement? There's very little resistance. Dry pavement? Shock load will get it- there is no magic number..

 

[76Broncofromhell]

what's the max range of torque/hp a dana transfer case can take on the wet pavement / dry pavement with 35's and decent gearing? ignoring other components.

Odd question. In 2WD the rear output shaft is the weak link. In 4wd it's a toss up of case strength vs output shafts. 4WD on pavement is stupid. Don't do it.

 

[Rustytruck]

We use to tow Rose Parade floats on dry Pavement in 4wd low range with the front hubs unlocked. we were just a little tug back then. the big 4 wheelers Kept getting smaller and the floats kept getting bigger until we gave up. Then they got sponsored by the Auto Club and we retired.

 

[sanndmann3]

Dana 20s also do not like high revs when in low range... the idler gear is thrust aft and grinds the copper bushing/washer until its gone then grinds on the case... 2 or 3 cases later, went 205 and it has been rock solid. no regrets other than less low range.

 

[nvrstuk]

Yeah it's just hard to beat that 205. That and the fact that it's $2000 less than that shiny little Atlas!!