Advice needed please

[77orange]

I have enjoyed this forum for quite awhile and have appreciated the great insight. My Jeep performed great last summer not failing me at any point. I use it to haul an 18' camper up into the mountains here in Montana and I also hunt with it in the fall. My issue with it is the speed that I can attain (60mph) on a flat highway with the trailer and the ability it has to haul the trailer up hill on the highway (down 25mph or less). I become limitted were I can go because of its ability to haul the trailer. Is there any upgrade to the tranny or the gears, whatever to get it to pull better. I have upgraded the engine with comps cam 260, TFI, MSD 6A ignition box, Performer intake, Edelbrock 600 carb. Any help would be appreciated. Thanks

[addicted]

Your best bet is going to be to change the gears out for something deeper around 3.73 or 3.55 depending on what you currently have stock anything deeper will make it pull better but limit your top speed and decrease your already low FSJ mileage.

[710 Burner]

Plus in your signature it says you have a 4" lift. I am assuming you have probably something in the neighborhood of 31" tires, so a lower gear ratio will definetly be in order, but you can expect higher RPMS and lower mileage. (not that you are getting much pulling an 18' box with a 5000 lb box)
edit: one question (i think I know the answer) Have you considered a tow vehicle?

[77orange]

I do have 31" tires. There are times I swear this thing has a governor on it. I have enjoyed and it is still a lot of fun but I need to get to more places and quicker. How do I determine what gears I presently have?

[Dirtball]

There should be a tag on your rear axle... it will have two numbers on it if it's there... divide the smaller number into the larger one to get your ratio. If you don't have it then jack up the rearend. Turn one of your tires one revolution and count the number of times the driveshaft turns (tranny in neutral, of course... chock your front tires well). Your ratio is the number of times the driveshaft turns...

Hope this helps...

[78J10honcho]

being a 77, it probably has 3.54 gears, which means you will want to look at 3.73s or maybe even 4.10s, which as stated before will limit your upper speed range but will definitely help with the pull, my thought is that you are pulling an 18' camper with a lifted 2-door suv, how fast do you really want to go??

[FSJ Guy]

Cat plugged?

That will cause the engine to bog down @ highway speeds.

[Jeepstress]

being a 77, it probably has 3.54 gears.....

Not necessarily. Both of my 77 wags have 3:07s.

[joe]

The 77 model 16 and 18 360 Cheros (2 and 4 door narrow tracks) came w/ 3.07 gears which are not tow gears by any stretch. The Wide Track 17's came with 3.54's though which are doable in a pinch for occasional towing.
If you're going to regear for towing go with 4.10's. 3.73's are a good compromise for tow/hwy/street use but not a big bang for the buck moving from 3.54's.

[Kali]

I bet you have 3.07s. Regearing to 3.73s would be decent for 31" tires, but you will see an RPM increase for sure. 31s and 4.10s put you at 3000 rpms at 65... I dont consider that a good cruising RPM.

[addicted]

My 80' J10 with stock 360/NP219/727, 32x11.50 15's and 4.09 gears would turn roughly 3500 rpm at 70 mph. Would out run a co-workers 98' GMC Sierra until about 65 and then it would start running out of steam. The mileage was horrible at an avg. of 8 mpg but it was consistant no matter how hard or easy I ran it, 8 mpg.

[78J10honcho]

Not necessarily. Both of my 77 wags have 3:07s.
thank you my queen, i had forgotten about the 3.07s

[The PIG Smith]

Goodness!
3:07 gears would make just about any truck seem gutless!

It has already been mentioned, lower gears is really the way to go!
IMHO, lower gears will relieve your engine from lugging all the time.
Consist lugging is not a good thing.

[HOOT]

I run 3:73 with 33" tires on my J20 and hauling a car trailer loaded with another FSJ is no problem. I run about 70 MPH. even on the hills it does better than what you describe.

My engine is rebuilt with a 4V 4350 carb/Offenhauser Dual Plane and MSD6a/TFI,.

I'd definitely would check your cat if you still have it.

[fulsizjeep]

I towed a 6x12 Uhaul from Sarasota to Cortez, CO with my 187k mile 360, 2.72 gears and 32s. THAT is gutless. :banghead: Going to 3.73s made a big difference all the way around. We have plans to take the trail Waggy of Krista's and throw a set of 3.54s under it. The 3.07 gears and 31s are awesome for the highway trips, even with a couple hundred lbs of junk on top. That is how we can get 14.5 mpg with a 401 on 1300 mile trip through AZ. :cool:

[Jeepstress]

Goodness!
3:07 gears would make just about any truck seem gutless!


tsk tsk tsk. Bryan, you have never driven MY jeeps. They are road screamers. Even hauling my horse trailer they git up and go. :D

I would like lower gears for off roading - I spend a little too much time on the brakes in steep decents, even with engine braking.

[77orange]

Once again great advice. Thanks. I sure do enjoy my Jeep and my family has had a lot of fun in it over the past few years. Sounds like 3.73 gears are the way to go. Now the question is where to buy them and is it possible for a hack like myself to install.

[RAMBLINFSJ]

BJ's did me good so I recommend BJ's Offroad.