A buddy wants to run 35s on his 4.0L, auto tranny equiped TJ. What kind of rpms will 4.10s or 3.73s yield?

(P.S. I did a search) :flipoff2:

I believe 4.10's will be just about perfect for that setup. I am running 4.56's with a factory TF999 auto, and 35's, and the highway RPMS are a bit much. Im running about 67 mph at 3,000 RPM. Not good on the old 258... guess its time to step up to 37's. :)
Scott :grinpimip:<><

4.10's perfect...far from it.

3.73's were included in the 2.5l engine with auto.
Highway rpms at 60mph with 3.73's would be approximately 2300 in 3rd gear. But that's not enough to keep it in 3rd gear, it will auto downshift into 2nd when there's not enough power in 3rd at 2300 rpm.

For more info look at

4Lo.com's gear table (http://www.4lo.com/calc/geartable.htm)

Try the search next time...Newbie. ;)

depends on the motor

a 4.0L would be 3000rmp @ 70mph

i turn 3000 rpm @ 75mph (4.0, TF-999, 4.10's, 36" TSL's)

the 4cyl would need 5.13's

do the math..

28" - 35" =125%

3.07 gears (6cyl-auto) *1.25 = 3.83 add in additional drag and always round up to the next lowset gear and you get 4.10

4.10 gears (4cyl-auto) *1.25 = 5.12 add in additional drag and always round up to the next lowset gear and you get 5.13's

Originally posted by redruM
4.10 gears (4cyl-auto) *1.25 = 5.12 add in additional drag and always round up to the next lowset gear and you get 5.13's

You mean 3.73 gears *1.25 = 4.66, that would put you at 4.88:1s

i thought that the 4cyl-auto had 4.10's

either way what ever your stock gear ratio and stock tire size were from the factory

2.5L auto has 3.73
2.5L manual has 4.11

4.0L auto has ?? 3.73 ?? not sure about this one
4.0L manual has 4.11

Now there are some TJ's with different ratios with D44's & other options, but the above are the most common.

Also, I'd recommend the 488's for 35" tires. Yes highway RPM's exceed 3000, but it sure does burn fuel better than 2300 rpm.

my 98 TJ 4.0L Auto had 3.07's

4.0 never came with 4.10. the manuals in 97 and 98 mostly came with 3.07 and 3.55 after 98 but it varies, lowest yah can get in a 4.0 equiped jeep is 3.73 from the factory. the auto 4.0 came with 3.55 mostly and and 3.73 as an option and all the d44 equiped jeeps have the 3.73s. the 4 cylinder manuals all came with 4.10s and most of the auto 4 bangers did also though some may have 3.73. remember were talking about jeep, things arent always what they are sopposed to be

Id go 4.56's you dont need to be bombin along with 35's anyways. I have 5.13's and 38.5's with a TF-999 and it tops out at about 55mph on the freeway (well atleast the one time its been on the freeway :D).

Im with rockbuggy on this one.... no need to be speeding heavily on 35's...
and my 4.56's work well.
Scott

I've been running for years with 33's and 4.10 gears. Now I've got 35's and I'm putting in 4.56 gears. 4.10's are kinda nice on the freeway but too high for crawling. Or go for a 4:1 kit and have the best of both worlds.

I have 97 XJ 4.0 and auto. I run 35s with 4.56s and this brings me just about to stock gearing (235s and 3.55s) I really find my self wanting 4.88s but I just couldn't do that in the front 30.

IMHO, running anything longer than 4.56s is a mistake. You will lug the engine excessively.

SeanP

SeanP

you have a 4spd auto with .75-1 4th gear (overdrive)

the TJ,YJ has a 3spd auto with 1-1 final drive

good point on the 3sp vs 4sp.

Yes but the newer 999 trannies have a lock up converter that drops the RPM by about 250. I have 4:56's with 38.5's witha 999 in my 94 YJ. I am going to 4:88's or 5.13's. I say 4.56's would be the best because you know that the 35's wont last. Soon it will be on to bigger tires. Its only a matter of time.


Originally posted by redruM
SeanP

you have a 4spd auto with .75-1 4th gear (overdrive)

the TJ,YJ has a 3spd auto with 1-1 final drive

If there is a remote possibilitie that u'll ever be pulling a jeep trailer or something then go to 456...

I did... Im happy.... I just drove all the way across the country. Literally... No prob.

I pulled a jeep trailer. Both jeep and trailer were wayyyyyyy overloaded... Jeep just chugged right along like the trailer was not there. I looked like the beverly hillbillies I was so packed.

97TJ.... 4.0... auto tranny... 4:1, 456 gears. 35" MTR's