overdrive t-case idea?

gearwhine · Jan 19, 2004

OK, I'm very bored, and keep seeing mog axles for sale. Like a pair for the same price you can buy one rust bucket RC 60 front. so it got me thinking.

The hardest part to overcome I can see is the deep gearing for a steet legal vehicle. This got me thinking, which can be applied to anything with deep gears in the axles, like rockwells, or anything.

How about getting a gear driven case, dana 20 or something, and getting some custom HIGH range gears cut, to make it an overdrive, while still keeping your same low range. something to keep highway RPM's at normal. The gears will probabaly be $$$$, and you'll probabaly have to cut into your case and reweld to make room for them, but to me it sounds feasible and a decent idea. anyone?

:dunno: _nicko_

Gary E · Jan 19, 2004

ah just run 40s then your gearing will be allright.

Gecko · Jan 19, 2004

Ever heard of a gear venders overdrive? That might be a way to overcome it too. Its basically the opposite of a Klune underdrive. Just a sort of .5:1 gear reducer with a toggle, like an overdrive t-case without the 4wd action. My buddy wants a gear vendors for his street/strip car to keep the revs down on the high way. I suppose youd have to put it in between the tranny and t case but it might work well if you kept it engaged all the time. I dunno, but I think youre on to something.

BrettM · Jan 19, 2004

getting gears cut would be WAY expensive, then you would need adapters and such as well. I see a few other, cheaper options:

build your motor for higher RPMs, or swap a motor designed for higher RPMs (rotary!?)

run 40s

Saturn underdrive, I don't know anything about them, but do some web searching

Finally, run a strong, 2:1, gear driven case (np205?) backwards to get .5 overdrive

gearwhine · Jan 19, 2004

Gecko said:
Ever heard of a gear venders overdrive?

yeah, I was just directed to gear vendors by a buddy, but 3000 bucks to get a one foot growth sticking out the back of your t-case is not cool. I'd much rather get custom cut gears, plus 3000 bucks would put the cost of the mogs waaaaay out the window.

ah just run 40s then your gearing will be allright.

Who hasn't thought of that

...well in NJ, the max tire size I can have legally on the road is 34" true size. Bigger depending on gross weight of your vehicle. But going to the trail I can throw bigger tires on, and get out of the state quickly...

Magoo117 gets away with 38.5's. _nicko_

gearwhine · Jan 19, 2004

mad maXJ said:
Finally, run a strong, 2:1, gear driven case (np205?) backwards to get .5 overdrive

I looked into a np205, but what do you mean backwards? swap the gears? Those are the low range gears and probabaly would probabaly not be able to swap.

Gecko · Jan 19, 2004

Yea, i was hoping no one would notice the pricetag on the gear vendors and i would be hailed as a genious. Oh well.

gearwhine · Jan 19, 2004

mad maXJ said:
Saturn underdrive, I don't know anything about them, but do some web searching

Those are only for T18's as far as I know and is a seperate unit(I think after the t-case...sticking inside the case would be the only way I would think about doing this. Or klune type that's sadwiched.

Willis · Jan 19, 2004

I've heard rumors that Atlas is coming out with a 3 speed t-case with overdrive (the 3rd gear). That would be a sweet setup to have 4.3 low, 1:1 and an overdrive. Don't think I haven't thought about portal axles too. Might want to search PBB or google it to see if the rumors are true.

BrettM · Jan 19, 2004

gearwhine said:
I looked into a np205, but what do you mean backwards? swap the gears? Those are the low range gears and probabaly would probabaly not be able to swap.

flip the whole case around, they are 2:1 when run normal, so flip it around and it will be .5:1. Is it the 205 or the 203 that has the seperate rangebox that Chevy guys use for a doubler? you would just need some custom adapters, and there may be a market for them so you could make a bunch.

gearwhine · Jan 20, 2004

mad maXJ said:
flip the whole case around, they are 2:1 when run normal, so flip it around and it will be .5:1. Is it the 205 or the 203 that has the seperate rangebox that Chevy guys use for a doubler? you would just need some custom adapters, and there may be a market for them so you could make a bunch.

If I get what you're saying correctly. You would have a 1:1 high range, and a .5:1 "low" range....where is the low range?

Never heard about seperate range box stuff, I'll look into it sometime.

Atlas is already too expensive for me now, that new one is gonna be even more mucho $$$$.

BrettM · Jan 20, 2004

yeah, you got it, but then run it to your normal t-case. throw the 205 in "low" and the 231 (or other) in hi and cruise the streets, throw the 205 in "hi" (1:1) and the 231 in low for trail. both in "hi" for in between....

gearwhine · Jan 20, 2004

mad maXJ said:
yeah, you got it, but then run it to your normal t-case. throw the 205 in "low" and the 231 (or other) in hi and cruise the streets, throw the 205 in "hi" (1:1) and the 231 in low for trail. both in "hi" for in between....

I can't see mounting a "flipped" t-case easily at all...lots of expensive machine work. And if I put a 205 in, (are there even adapters for a 205 to an ax-15, I didn't see one at AA, I'll check novak), it's getting twin sticked. If that's in front of the 231, can't do it. I would like to have one t-case too..

It's an idea though.

hmm...well since that's a 2:1 low range(1.98 really, close enough), if the shafts are the same....maybe you can just swap the gears on the shafts? that'll give about a .5:1. I am gonna need to find some t-cases to mess around with.

BrettM · Jan 20, 2004

if you somehow manage to flip the shafts, you'll still loose your low range, at this time, you pretty much have to run 2 cases of some sort to have 1:1, a low range, and an overdrive. though I have heard of some 3 speed t-cases in land rovers, or range rovers... something like that...

Ghost · Jan 20, 2004

The 203 is what they mate to the 205. Its the 203 that gets butchered......

gearwhine · Jan 20, 2004

Ghost said:
The 203 is what they mate to the 205. Its the 203 that gets butchered......

yeah, but still, I can't find any adapters for a 203 or a 205 to any XJ trannny. The only thing I can see doing, is getting a d300 and play around with the gears. Then flip it, and mod it up so it still works.

Static-XJ · Jan 20, 2004

Why try to get on OD t-case? Just get a 4:1 set for the t-case, 203 range box, KluneV, etc. then don't go so low in the axles. Same end effect.

andyr354 · Jan 20, 2004

you don't have to butcher the 203 at all. On a 203 the gear ruduction case unbolts right off of it as a separate piece.

BrettM · Jan 20, 2004

Static-XJ said:
Why try to get on OD t-case? Just get a 4:1 set for the t-case, 203 range box, KluneV, etc. then don't go so low in the axles. Same end effect.

because read the first post, he's looking at MOG axles which only come with 7-point-something gears.

basically there is going to be major machining involved any way you look at it, I just think it would be easier/cheaper to get adapters made than getting gears made.

at 70 mph on 34s, you'd be tach'ing 3600rpm. the 4.0 can take that, but it would be pushing it a bit, but it could be built fairly easily to really handle those higher rpms. this would definitely be your easiest/cheapest option if you are already needing an engine rebuild.

Static-XJ · Jan 20, 2004

mad maXJ said:
because read the first post, he's looking at MOG axles which only come with 7-point-something gears.

Oops, missed that part. Didn't know about mog gears anyways...

Mog's will handle that speed fine?

overdrive t-case idea?

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