T90C, D18 and 33's on a L-head

Anyone with a stock L-head and 33's have a problem with offroad gearing? I am concerned I may be a tad high geared compared to what I am used to. I am doing a t90c swap for the lower first and second.

I am used to a 4.0 HO, ax15 and a np231 with 4.88's and 38 inch tires for comparison. It was in a 98 wrangler. It went good, but just wasn't a flattie.

Nothing really hardcore, but on the hardcore side of moderate.... I am just hoping it will be geared low enough to keep the L-head. I just like them and it'd be a shame to have to swap it out.

Thanks guys

P.s. I have swapped out the axles for more stout units with front discs etc. EDIT: still has 5.38 gears, after the swap.

 

Whats your axle ratio? Still 5.38 or something different?

 

yeah its still 5.38. Sorry I forgot to list that. My brain works faster than I can type.......

 

Not a problem. I figured someone would ask. I have driven a few F-heads with 5.38s and 33in tires. They seemed fined to me. But they are not the same motor so I can't compare.

 

Not worried about on road too much. I can live with 45-50 max speed (or slightly less if need be) I am more worried about crawl ratio. Anyone know of a good crawl ratio calculator that accounts for tire size? I would like to compare it to my old wrangler.

 

See Willys Utility Vehicle Speed Calculator :

http://www.public.asu.edu/~grover/willys/speed.html

Driven offroad theres hardly a noticable difference between L and F-134 engines.
The F-134's 12 to 15 more HP for the road is the only notable difference between those 2 engines.

 

I ran 33"x12.50"x15" with the stock F-head and had no problem off road. A bit underpowered on road but not bad. The issue was stopping with the stock brakes. If you have the stock 9" brakes I'd highly recommend upgrading to 11" or discs.

 

Here's my favorite gearing calculator-it allows you to compare two scenarios side by side:

http://www.grimmjeeper.com/gears.html

 

I run an F-head, t 90A1, 5.38 gears, off road it does fine until I get into deep mud. But my motor is tired. On the road I can run 45+ all day but where I drive it is pretty flat. I would LOVE to have a t 98 for it though!

 

iv got my 2a all stock with 35s and its fine imo. The brakes were not great offroad down steep grades especialy with a trailer on back so i put 11" drums on it . The crawl gear is good. it could be slower but 33s should take care of that. on road its fine i never have any trouble keeping up with traffic at 50-55. never did take it on the highway though

 

How noticable is the difference between a t90a and a t90c? I have all the parts to build a "c" but how much difference will it make?

 

The numbers indicate a 19% lower first gear.
The typical first gear to final drive reduction ratio for a Willys is a 15 to 1 ratio.
If you replace the T90A with a T90C first gear becomes an 18 to 1 ratio.
Multiple those numbers by 2.43 or 2.46 (transfer case reduction) to get the crawl ratio.
Enough lower to notice the difference but certainly not for hard core extreme incline or rock crawling.

 

IMHO, instead of reworking the T90 I'd be looking for a T98.

 

I am looking for t98, but in the mean time, it needs something for a trans....

 

I run an L head and t90C gears in my 3A. I currently am running 32 x 11.50 swampers. I think it's great on the trails. If sticking with the T90, then the T90C gears are worth the effort. I swapped mine and am happy I did. The little L head has enough torque to idle right down on the trail, so as long as you know your engine and how low you can get the rpms, it does great.

On the road don't expect to maintain much of a top speed. Where I live there are hills everywhere, which require 2nd gear. I do wish I had an overdrive to essentially have a 2 1/2 gear because 2nd winds out kind of quick, but 3rd won't pull the hills. My motor is pretty healthy too...rebuilt a couple years ago.

Long story short, I think you'll be fine...and just keep an eye out for a 4spd if you want lower gearing.

 

I already have a t90c, so its a no brainer there. I have a dana 20/ dana 18 hybrid case (lower d18 gears in a centered output configuration) and 5.38's in the axles. I am thinking its gonna be ok, but am looking for a 4 speed too. It currently has 33x12.50's on it, but I may swap it back to a 32x9.50 or if I can find a t-98, I may change to 34x10.50's

Basically the issue is that I used to have the biggest baddest jeep in our club. It was a 98 wrangler 4.0, long arm 4 link. Lockers in both ends, chromo shafts and 38 inch TSL's. Everyone now is kind of eyeing me up, or thinks I am crazy for wanting to run an L-head. I can still drive better than 90 % of the guys I go with, and have been doing it alot longer than almost all of them. I just want to make sure I am not gonna get skunked in the woods..... I learned how to wheel in my 47 about 15 years ago, I am always amazed at where the "little guys" will go!

Thanks for the advice everyone. I will be keeping my eye out for the elusive t-98

 

In case you have not seen, here's some good information on the Borg Warner T98:
http://www.film.queensu.ca/cj3b/Tech/T98A.html

 

Sorry to be blunt but if you are building this solely "to not get skunked" you are building it for the wrong reasons and probably won't be happy with the outcome. Sounds like your old vehicle was well built and was more appropriate for what you want. These old Jeeps are surprisingly capable in stock form and with a few modifications are even more so. Just realize the basic design is 70 years old and will never perform the same as a more modern vehicle with very large tires.
My suggestion is to build it for YOU to enjoy and forget about the other folks in your club or find a more appropriate vehicle to build to show up your buddy's

 

I am not building it To beat anyone else. With lockers in both ends, different axles and some steering / brake uprades with 33's it should go just fine. I just needed someone else to say it (or type it...)

We don't do anything extreme, some stuff on the moderate side. Most of the guys are running 33's or 35's on open/open or open/locked TJ's or xj's

 

slow moving thread lately huh?

Ordered a carrier for my centered, flanged D44.