Hey Thanks guys, so I crawled under there and the tag does confirm that its a D35 with 3.55's, so next thing will be a fluid change and new gasket for the diff. What gear lube are you guys running? Again Thanks!!

 

I'm running Royal Purple 75w140 gear oil. It's pricey, but worth it. My Xj shifted A LOT smoother after running the royal purple gear oil. I don't know about the D35, but my 8.25 takes two quarts of Royal Purple gear oil. I would assume your D35 would take the same, or very close to the same amount of gear oil. A D30 axle only takes about 1 quart of gear oil because, unlike the D35 or 8.25, the gear oil does not go into the axle tube, only the differential.

Running any name brand gear oil should suffice for your rig, but Royal Purple would definitely be an upgraded option. You can get a basic name brand gear oil for your Xj for around $4-$10 a quart, versus $18-$20 for a quart of Royal Purple.

 

I've been at this for over 35 years. I know what happens when you put taller tires on any vehicle.
Basically you are wrong. If you run taller tires on anything without changing the R&P you will be turning less RPMs,
Two examples a 33 inch tire and a 30 inch tires. With the larger tire the engine is turning 189 rpms less than the smaller tire.
70 mph x 3.55 x 336 / 33 x .75 = 1898 rpms
70 mph x 3.55 x 336 / 30 x .75 = 2087 rpms

 

So that's why every truck i've been in with larger than stock tires and stock gears runs at high rpms on the highway? It's common sense... A small gear takes more rotations to turn a larger gear.

 

I have no idea what you are talking about. If you go to larger tires you will need to go to a numerically higher ( lower gear ) gears to turn the same rpms as you were with stock gears. I showed you an example, what is it you don't understand?

 

I was not arguing the fact that you need to change the gear ratio to maintain the same rpm range while driving. Infact, I already stated what you just have in your last post. What I was arguing is that fact that a vehicle with larger tires will in fact run a higher rpm range when driving versus a vehicle with stock tires. It's a fact that's proven every day.

 

You didn't state anything about changing gear ratios! You stated that your Cherokee turned higher rpms with the 33s than with the stock tires. It isn't the tires that cause your Cherokee to turn higher rpms it is the ring and pinion ratios, You also state that every vehicle with larger tires will in fact run in a higher rpm range when driving verwus a vehicle with stock tires.
Bull! I know of 20 or more guys running larger tires that do not turn higher rpms than they did with stock tires.
You need to do some research about 4x4s so you will know what your talking about.

 

In physics terms, a tire would be considered a gear. The tire would be the the large gear, while the axle shaft would be the small gear. The axle shaft has to spin multiple times to fully rotate the tire. The axle shaft is supplied power by the differential gears, which are supplied by the driveshaft, which is supplied by the transfer case, which is supplied by the transmission, which is supplied by the engine. As the size of the large gear is increased (The tire), it takes more rotations of the small gear (The driveline... all the way from the axle shaft to the engine) to rotate the large gear one full turn. If you increase the size of the small gear (Which would be a numerically higher gear ratio) it will take less rotations of the small gear to fully rotate the large one.


The bottom line is that a vehicle with larger tires on stock gears will run at higher rpms on the highway than a vehicle with stock tires and stock gears. Period... End of story. It's a fact that is proven every day on the street by every vehicle running larger than stock tires on stock gears (Including myself).

 

If you re-gear your vehicle, you can obtain the same rpm range as you had with stock tires on the street. With stock gears and larger tires you will run higher rpms. How many times does this need to be stated?

 

You are right everyone is just wasting their money gearing down to run larger tires.

 

When did I ever say regearing your truck for larger tires was a waste of money? It's money well spent; it will restore the wheel to ground torque that is lost when running larger tires and will improve rpm ranges when driving.

Are you honestly not understanding or are you just arguing for the hell of it?

Stock tires + stock gears = optimal rpm ranges on the road
Large tires + stock gears = Higher rpm ranges on the road
Large tires + large gears = optinal rpm ranges on the road restored.

 

I have gave you examples of what engine rpms will be with two different size tires, if you don't understand that you are not correct you are just screwing with me. LOL Or you are to stupid to exist.
PS you don't have a dana 35 axle in the front.
I'm done with this, can't believe anyone is this stupid.

 

I never once said I had a D35 ANYWHERE on my Jeep.

For some reason I am not surprised that you have reverted to insults. You don't exactly seem like the most mature person I've met on this forum. Goodbye. You have wasted more than enough of my time.

We are well off topic, so as for my part I am finished. Good luck with the rear, 90XJNSD.

 

Sorry to say you are ABSOLUTELY WRONG. Couldn't be more wrong. Taller tires will produce lower RPM than a smaller tire if you are using the same gear ratio.