3.73 rear gear opinion

lefty · Post by **lefty** » Wed Jan 30, 2008 11:52 pm

is anyone running a 3.73 rear gear with a c4 / c5 auto trans ?
I picked up an 8.8 rear from an explorer for FREE 3L73 gear could use your opinions and suggestions. I'am currently running a 7.5 with an 3L45 gear with no problems so far, before I make the swap I would like to find out what RPM changes would be at cruise speeds . I know the lower end performance will be improved from what I come up with is about a 400 RPM difference at about 70 MPH . I would like to get some feedback on this matter . cruising RPM now is around 2700 @ 70 mph Thanks in advance also truck used as a weekend street toy

blk94xlt · Post by **blk94xlt** » Thu Jan 31, 2008 12:58 am

I don't think it is gonna work. I defintely think you should get rid of the explorer rear and give it to me. I'll give you DOUBLE what you paid for it.

My truck came with a 3.08 open diff. The last time I was at the junkyard I asked if they had any 4.10 limited slips from a ranger and they wanted $450 PLUS an exchange. Gotta love southern california. I don't know why the junkyard wants an exchange other than to turn around and sell it. You sure scored with that rear for free.

cgrey8 · Post by **cgrey8** » Thu Jan 31, 2008 9:31 am

I ran your numbers through a speed calculator I have and guessed at some of the input. I'm figuring it'll only make a difference of 250RPMs at 70. So instead of 2700, you'll be in the neighborhood of 2950RPMs, maybe just a little shy of that.

What size tires are you runnig? To get the ratio right in the calculator I assumed 255/70R16s which gave a diameter of 30".

Dave · Post by **Dave** » Thu Jan 31, 2008 10:10 am

It's just a simple math equation. 3.73 divided by 3.45 times your current RPM. Difference in ratios is about 8% so if you went to a 8% taller tire, your RPM's would stay the same.
Dave

lefty · Post by **lefty** » Thu Jan 31, 2008 7:30 pm

your offer of DOUBLE the price is rather nice but I think I will hold onto it . thanks for the input guys that is what I kind of thought but it never hurt to get some others input . so I 'm gonna go through the hole thing brgs, brakes , brake lines befor it goes in the truck.
also is this a direct bolt in for the 84 ranger or will I have to relocate the perches?

cgrey8 · Post by **cgrey8** » Thu Jan 31, 2008 7:43 pm

If it was a Ranger rear, it would be a nice bolt-in. But it's an Explorer rear. Have fun relocating perches and shock mounts. You can cut them off your old rear to weld them to the new.

Dave · Post by **Dave** » Thu Jan 31, 2008 9:13 pm

Malcolm had a good write up on what all it took to put it in his truck on his home site. Move/flip perches, shock brackets and deal with the emergency brake cable and some have changed the master cylinder because of the disc brakes. Not just a bolt in. Have to change the pinoin yoke to match.
Dave

v8ranger · Post by **v8ranger** » Mon Feb 04, 2008 7:34 am

I am runnig the stock rear end in my Ranger 7.5 with 373 and posi but I am also running a T-5 and at 65mph it runs around 2000 2100 with 235/60/14 tire.

lefty · Post by **lefty** » Tue Feb 26, 2008 8:58 pm

another great day at the local u pull yard ! got a complete 8.8 out of a ranger and it was SALE WEEKEND so the complete rear with drums cost me $65.00 . so using the carrier and gears from the explorer rear and in the ranger ready housing not a bad deal so far

cgrey8 · Post by **cgrey8** » Tue Feb 26, 2008 9:09 pm

What year 8.8" rear? You'll need to know that when doing a brake job. I found that the brakes did change. A hardware pack made for my 97 Ranger's 10" drums didn't work on my 93 Ranger-rearend's 10" drums.

When you pull the axles, make sure they are the same length before you pull the rearend carriers. If they are different lengths, then the drums won't line up with the brake shoes. And thus you'll either need to stay with the Ranger axles OR have the Explorer axles cut down and resplined.

Did you get the brake cables and bracketry to go with them?

Did the rear come with an anti-sway bar?

lefty · Post by **lefty** » Tue Feb 26, 2008 9:54 pm

it out out of a 94 stx I have already made a note of that for the brake info . because you know how fun it is to go into the local parts house and get the right stuff. I did not need the ebrake cable nor the sway bar. I will be keeping the ranger axles for now ( will have to change out the side gears with 28 spline) but in all when I am done should have about $100.00 in it

jbaer619 · Post by **jbaer619** » Wed Feb 27, 2008 1:59 am

hey blk94xlt, where in so. cal do you live? cause i rolled my f-150 a little while ago with an 8.8 rear end and 4.10 gears (supposivly posi im not sure though). and its sittin up in descanso right now i probably wont have any need for it, so **** id give you the whole rear end even the disks for $100, if you just come pick it up

spoolinranger · Post by **spoolinranger** » Tue Mar 04, 2008 6:29 pm

hey i have 373 with c4 and 26'' tall tires 60mph is 3000 rpm, but it is tolerable i've drove it on interstate over 2 hours before,