91 Rear end swap, do i have right one?

[91notdone]

I just replaced the original (i think) rear end w/ 1 from junkyard. Now truck is a dog at hwy speeds (once it gets up to hwy speed) Runs fine in town but after about 45mph it has trouble shifting and wont get over 65 mph. Is this a possible wrong repl RE? Or am I now having auto trans problem?

Orig RE had tag that indicated 3 45 75. this corresponded to 84 on door tag for axle. Orig had 10" drums/hubs.

Junkyard RE looked identical but had no tag. The axle was not attached to any vehicle. The guy looked at my orig tag and said it would work. Later, when swapping noticed the junkyard RE had 9" drums/hubs. Swapped anyway.

truck is 91 ranger xlt 3.0L. Please Help

 

[Sasquatch_Ryda]

It could have a higher gear ratio. Was there a tag on the diff cover of the new axle?

 

[91notdone]

no tag on the new one. they looked identical laying next to each other except for hubs.

 

[Earl43P]

Jack up and support the vehicle so that both drive wheels are off the ground. Make a chalk mark on the drive wheel and the driveshaft. Put the transmission in neutral. Turn the wheel one complete turn and count the number of turns that the driveshaft/halfshaft makes. The number of turns that the driveshaft makes in one complete revolution of the drive wheel approximates the axle ratio.

From: http://www.procarcare.com/icarumba/...r_resourcecenter_encyclopedia_driveshaft2.asp

 

[dirttrackracer]

mine is a dog and it is all stock, nothing wrong with it just that it is geared higher.

 

[Hahnsb2]

no tag on the new one. they looked identical laying next to each other except for hubs.

It's the gears inside that make the difference.. Either pop the cover and divide the ring gear teeth by the pinion teeth or do the counting method described above except do it with one wheel on the ground and turn the wheel in the air 2 times, this is more accurate when dealing with an open rear end.

 

[91notdone]

I tried count test by Earl43P. The opposite wheel spun in reverse direction so I know it an open RE. However, when spinning wheel 1 turn, the drive shaft rotated 1.75 times with both wheels in the air. I did not see Hahnsb2 post at time.

So is it number of driveshaft turns per 2 wheel turns (with other wheel on ground), to get an approximation of the correct ratio? 2 turns with wheels off ground would have been 3.5 shaft turns. My original was 3.45ratio.

Also, new RE had E77W-AA on front passenger side of diff housing. I understand that E77W means 87 Ranger/BroncoII Trans & Axle Engineering. No clue what AA means. On the front driver side of housing "1295" is stamped.

???????

 

[ecablarn]

I would say try it again as hahnsb2 stated rotating driveshaft, counting wheel rotations and driveshaft rotations. Total driveshaft rotations divided by wheel rotations should be the rear end ratio. Otherwise pull the cover and count the teeth, you'll want to change the fluid in there anyway before you bolt it up.

 

[91notdone]

I tried the test as stated by Hahnsb2, spun one wheel 2 times (with other on ground) the drive shaft spun just a hair under 3.5 times. That would be 3.45 (what I wanted) if I'm interpretting hansb2 correctly. However, by ecablarn's explanation the ratio would be just under 1.75. Doesn't make sense because 7.5 RE came in 3.08, 3.45, 3.73 & 4.10 ratio for 83 + Rangers & BRII

I have a 2WD Ranger (91 3.0L Ext Cab, Auto Tran A4LD) Trying to replace Axle Type Code 84

 

[ecablarn]

Read thru the link Earl43P noted for more details. Gear ratio is at the bottom of the page.