? on axles

[mtngrizz]

I ve read that 4.10s with a 4.0, 5 speed and 33" tires are a good match. My ? is:

Most all 4 cyl tj,wrangler and cherokees come stock with 4.10s or 4.11s with a 5 speed.

would a stock 4 cyl tj front axle and stock wrangler or cherokee rear axle work on my 88

eliminator 2wd to 4wd conversion? Thanks

[mnkyboy]

A TJ axle would work but its low pinion,a YJ rear would work but the perches would probably need moved and they are c clip axles.

 

I would get front and rear axles from a 4cyl 5spd MJ/XJ,also if you get lucky the AMC 20 from an Mj came with 4.10s and bolts in.

[mvusse]

I ve read that 4.10s with a 4.0, 5 speed and 33" tires are a good match. My ? is:

Most all 4 cyl tj,wrangler and cherokees come stock with 4.10s or 4.11s with a 5 speed.

would a stock 4 cyl tj front axle and stock wrangler or cherokee rear axle work on my 88

eliminator 2wd to 4wd conversion? Thanks

 

Be aware that changing from 3.07 to 4.10 will overshoot big time with 33" tires. 36" would be closer.

 

Speedo will be off, 1st gear will be very short and cruising rpm doing 70 on the highway will be higher (but not unacceptably so).

 

3.73 may be a better fit, although possibly more difficult to find.

[Garvin]

For comparison, I was running 36x13.5R15 Super Swamper IROK's and the 4.56's set the speedometer correct (had 3.55's from the factory). mvusse is correct that 4.11's would make the speedo correct for 36's. What you can do is get the speedometer gear out of a Cherokee with the AW4 with 3.55's and 4.11's should correct the speedo (or make it really close atleast).

[btm24]

I ve read that 4.10s with a 4.0, 5 speed and 33" tires are a good match. My ? is:

Most all 4 cyl tj,wrangler and cherokees come stock with 4.10s or 4.11s with a 5 speed.

would a stock 4 cyl tj front axle and stock wrangler or cherokee rear axle work on my 88

eliminator 2wd to 4wd conversion? Thanks

 

This may help you with the 4:10 on 33's ? http://www.comancheclub.com/forums/viewtopic.php?f=9&t=28875

Also go with a XJ or MJ axle you will be much happier.

 

Brandon

[mvusse]

One thing to note on the spreadsheet in the above mentioned thread is that it's set up for a 0.75 overdrive ratio. The OP has either a BA/10-5 or an AX15, both of which have a 0.79 overdrive. That will affect the rpm calculations somewhat.

[Pete M]

I've put thousands of miles on my 4.0/stick/33s/4.10s and if anything I'd want 4.56 gears. you couldn't pay me to only go as far as 3.73s.

 

4.10s is a good compromise. :thumbsup:

[mtngrizz]

Thanks for the quick replies. Seems like my best bet would be to just get hp 30 out of a 97+ cherokee with the bigger u-joints and a 8.25 and have 4.10s or 4.56s put in them.

[Eagle]

I ve read that 4.10s with a 4.0, 5 speed and 33" tires are a good match. My ? is:

Most all 4 cyl tj,wrangler and cherokees come stock with 4.10s or 4.11s with a 5 speed.

would a stock 4 cyl tj front axle and stock wrangler or cherokee rear axle work on my 88

eliminator 2wd to 4wd conversion? Thanks

 

Be aware that changing from 3.07 to 4.10 will overshoot big time with 33" tires. 36" would be closer.

 

Speedo will be off, 1st gear will be very short and cruising rpm doing 70 on the highway will be higher (but not unacceptably so).

 

3.73 may be a better fit, although possibly more difficult to find.

Gotta disagree.

 

My '88 MJ had 31" tires and 3.73 gears. The overall final drive ratio (speed vs. RPM) was exactly the same as my wife's stock 2000 XJ with automatic and stock tires. The 3.73 gears were originally purchased to go with 30" tires in the '88 XJ, but the MJ came along before the gears got installed, so they went into the MJ 'cause I had 'em.

 

4.10s are actually an ideal ratio with 31" tires, and okay for 33" tires.

 

70 MPH with stock tires and 3.07 gears is 1961 RPM in 5th gear.

 

70 MPH with stock tires and 3.54 gears is 2261 RPM in overdrive.

 

70 MPH with 31" tires and 4.10 gears is 2440 RPM in 5th gear.

 

70 MPH with 33" tires and 4.10 gears is 2292 RPM in 5th gear -- that's so close to a stock vehicle with automatic that you'd never see or feel the difference when driving.

[Pete M]

If I was to ever pay for gear install, I'd go 4.56 minimum.

 

car-part.com may help with the search for an axle. :thumbsup:

 

also, I'd be hard pressed to pass on a 4.10 TJ front axle if the price was low enough. yes it's low pinion, but it has 4.10 gears and the bigger U-joints.

 

gear installations are very expensive.

[Eagle]

One thing to note on the spreadsheet in the above mentioned thread is that it's set up for a 0.75 overdrive ratio. The OP has either a BA/10-5 or an AX15, both of which have a 0.79 overdrive. That will affect the rpm calculations somewhat.

5th gear ratio for the BA 10/5 is actually 0.72:1. In the original version of the spreadsheet I can enter the correct overdrive ratio. For the version I posted, I used 0.75:1 because that's what the AW4 uses and what most owners seem to have. The difference is very minor.

[mvusse]

One thing to note on the spreadsheet in the above mentioned thread is that it's set up for a 0.75 overdrive ratio. The OP has either a BA/10-5 or an AX15, both of which have a 0.79 overdrive. That will affect the rpm calculations somewhat.

5th gear ratio for the BA 10/5 is actually 0.72:1. In the original version of the spreadsheet I can enter the correct overdrive ratio. For the version I posted, I used 0.75:1 because that's what the AW4 uses and what most owners seem to have. The difference is very minor.

 

I thought the 90 and older (21 spline)AW4s used a 0.70 OD. Or do I have them reversed again?

 

Going by that spreadsheet, a stock size tire (assuming P225/75R15 is stock, because I have two MJs and an XJ and all three list a different size stock tire on the door jamb) does 730 revolutions per mile. Divide that by 4.10 (new gear ratio), multiply by 3.07 (old gear ratio) and the result is a tire that does 547 revolutions per mile for the speedo to be correct, OIW for the same final drive ratio. Again, according to that spread sheet even a 35" tires (largest in there) does 599.

[mvusse]

Every bit of information I can find on the BA 10/5 is 0.79 OD in Jeeps, 0.82 OD in Peugeot gasoline cars and 0.84 OD for Peugeot diesel cars.

 

33" tire, 70mph 4.10 gears (fromt the spreadhseet) is 2285 rpm. Divide by 0.75, multiply by 0.79 gives you 2407 rpm. IMO, that's way above ideal for a Renix engine.

[Eagle]

Every bit of information I can find on the BA 10/5 is 0.79 OD in Jeeps, 0.82 OD in Peugeot gasoline cars and 0.84 OD for Peugeot diesel cars.

 

33" tire, 70mph 4.10 gears (fromt the spreadhseet) is 2285 rpm. Divide by 0.75, multiply by 0.79 gives you 2407 rpm. IMO, that's way above ideal for a Renix engine.

I took the 0.72:1 directly from the AMC/Jeep BA 10/5 FSM that I bought when I bought my '88 XJ.

 

The spreadsheet is based on tire manufacturers' actual revolutions-per-mile specs for tire sizes, not on theoretical calculations that don't account for sidewall "squat."

 

And 2400 RPM at 70 MPH is not at all "way above" ideal for the 4.0L engine. In fact, it is about as close to ideal as you can get. It's just barely above the torque peak. The engine as originally designed by AMC in the 1960s (in its 199, 232 and later 258 c.i.d. forms) was typically geared to run 24 MPH per 1000 RPM. That resulted in cruising RPMs of 2500 RPM at 60 MPH and 3000 RPM to run 72 MPH. My brother's 1970 Gremlin X went over 300,000 miles with that setup.

 

However, if you insist on correcting for the actual OD ratio (not a bad idea), you take the 2292 RPM, divide by .75 and multiply by .72. That gives you 2200 RPM -- almost dead nuts on the torque peak.

 

The 3.07 gearing Jeep used with the 5-speed XJs and MJs was a horrible choice that kept the engine running far below the torque peak (which is the most efficient range in which to operate). My '88 XJ gets equal or better gas mileage in 4th gear as in 5th gear up to about 65 MPH, which is proof that 5th gear is too high and not helping anything.

[HOrnbrod]

I thought the 90 and older (21 spline)AW4s used a 0.70 OD. Or do I have them reversed again?

 

You are correct. :cheers:

[alleydog]

Although my 4.0 is worn out, I am just slightly under powered with 4.10 gears, 33 inch tires and Ba10-5