[Axl Jack]

Originally Posted by jonzjeepyj

With What Tire ?

205/75R/15's --- 27" tire --- 65Mph --- 4th gear --- 4.11's --- 3325 Rpm's
215/75R/15's --- 29" tire --- 65Mph --- 4th gear --- 4.11's --- 3095 Rpm's

There were 2 stock sizes for Jeep YJ's depending on Model

They are both 27" tires.

235/75/15 would ALMOST be a 29" tire.

[shaggyjim]

One other thing you can do Vodad is to lose weight.... If you have a spare tire on the back you can leave it at home untell you go for a wheeling trip. Dump the back seat aswell and any other weight you can.

[GRN_BEAST95]

im running 33's

[plumber1]

Go w/ the 4:88's that what I did and WHAT a difference. Mine was fine running the 31's went to 33's and it died, anyone who says they can run 33's w/ stock gears is full of BS. Mine sucked on and off road w/ 33's & 4:10's go to the 4:88's and you will love your JY again

[1998zj]

I run 35's with 4.88 gears and it will run down the highway at 80 mph. You can waste money on bolt on parts for the engine, but the biggest bang for the buck is gears. Keep the engine revved up around 3500-4000 rpm and it will have plenty of power. The 2.5 makes as much horsepower as the 4.2.

[jonzjeepyj]

Axl Jack Wrote :

They are both 27" tires.
235/75/15 would ALMOST be a 29" tire.

After doing the math again and checking the charts, I stand corrected.
They are....
205/75R/15's --- 27.10
215/75R/15's --- 27.69
235/75R/15's --- 28.87
245/75R/15's --- 29.46

[jonzjeepyj]

I've saved up and purchased the 4.88's for the Dana 30/35 with install kits. I found a local
fellow Jeeper that bought them for his rig and ended up selling his 2.5L and bought a 4.2L
Jeep, before he installed them. He had them laying around for a few years and just wanted
to unload them.
I ended up
scoring both Yukon 4.88 gear sets and both master install sets for $200.00. I also have a
local fellow Jeeper in my area going to install them, as a favor to members of our local Jeep
club, for $100.00 per axle.

I'm glad to be a part of the Jeep community and feel lucky to have fellow members willing
to help you out!

[GRN_BEAST95]

so with me running 33's and going 65 at just over 3000 rpm in 4th gear it seems that the chart sais i have 4:88 gears. Am i correct?

[vodadub]

Thanks for your answers! Keep em coming.

To me it sounds like the whole differential conversion to the 4.88" ratio IS the best thing to do, but may cost as much as a 4.0L engine! ... which sounds more attractive TO ME.
Recently a friend who had a Cherokee with a 4.0L bought 2 other Cherokees, one goes to his father, other one is for pieces... so I may have an offer on one of those 4.0L's... I'll let u know on that.
But if you've had adverse experiences involving a SWAP may u PLEASE let me know.

Also, installing upgrades to the engine (as the 4.0L throttle, intake, injectors, exhaust...), all seem to score in one thing... MORE FUEL CONSUMPTION... which at the time I think the 2.5L burns a lot already.
I only get around 140 miles A TANK (city/highway combined)!


PS: I think my engine is hurt. Got a groovy noise going on on the rods I think.

[vodadub]

bUmp!
Upp!

[joe's_yj]

im on 36 inch swampers on my DD

[navman]

Originally Posted by vodadub

Also, installing upgrades to the engine (as the 4.0L throttle, intake, injectors, exhaust...), all seem to score in one thing... MORE FUEL CONSUMPTION... which at the time I think the 2.5L burns a lot already.
I only get around 140 miles A TANK (city/highway combined)!


PS: I think my engine is hurt. Got a groovy noise going on on the rods I think.

I had a 4cyl in mine and ran 35's. 5th gear was useless and 4th was only good on downhills. It did have 178,000+ miles and it was very tired. Some guys on here have said that they've had no problem pulling 33's-35's at speed and others have. I think the condition of the motor makes a huge difference. Even with 32's I could barely pull 60mph. You may be burning more fuel cause of the condition of your motor and adding go fast parts may not make any difference. I would do a compression test etc. on that motor to see what you want/need to do next. If you need a new motor or rebuild, you may reconsider what you want to do.

[vodadub]

... ^ that 5.0L idea sounds tasty'

[clemsonfan16]

I ran 33 12.50s on my 4 banger for a good while. I did the electric fan thing and yeah it gives you 4-5 more ponies but not a noticeable amount. Off road- it SUCKS. I wanted to go low....5.13s. But as you read, the dana 30 can only fit 4.88s. So i found a pair of dana 44s from a waggy and got to work. Now im running 5.13s with PLENTY of power. I can run 25mph in 5th gear or 80mph, whatever i choose. Oh and at 80 it doesnt even come close to 3000rpm. with 4.88s you should be fine. And i got my gears for 200 apiece with the install kits and installation was only 100 per axle. look around, you will find a deal. Hope this helps

[justanotherjpr]

Ran 33's on my 89 2.5L YJ. Top speed was 65mph but that was fine with me. Never had a problem with it?

The best mod for more power when you've installed bigger tires is the correct gear ratio for those tires.