Ford rear end

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  #1  
Old 08-08-03, 04:17 PM
crosswind
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Ford rear end

1993 Ford F-150, 4WD, 5.0ltr, 190,000 miles. Since this is not my primary vehicle, and to sell it would mean to give it away, I have decided to make it a project. First item of restoration is replacing the rear end. I found one that fits my truck, Ford 3.55, 8.8". Any tricks or things that I should look out for when replacing this unit. Also, I would like to add a 3" lift, but don't know where to start, but since the rear end has to come off, now seams like a good time. Any suggestions?
 
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  #2  
Old 08-08-03, 04:53 PM
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Crosswind..... Hey neighbor, I have just one suggestion.... HAVE SOME HELP HANDY!!! That bad boy is gonna be heavy.LOL. There are 2 ways to do it really. You can heave the new unit over the springs (it does have leaf springs right? Not sure here) or drop the springs from the frame at the back and roll it in that way with the wheels attached. This is probably the easiest way. Just have the truck up high enough with some tall jackstands under the frame in front of the leafs. The lift kits should come with instructions as there are several ways to install a lift. Depends on the type you purchase.

P.S. If the rear end installs under the leaf springs scratch the above...... Use a ratchet strap to pull it up to the leafs or you could try balancing it on a jack, but thats not too bad either once you get it up against the leafs. Just dont jack it up too high, dont want to push it off the stands.
Good Luck,
hope this helps ya,
Billy
 
  #3  
Old 08-08-03, 05:11 PM
Joe_F
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Personal belief: Lift kits create more problems than they are worth.

Is the rear end rebuilt or used? Used rear ends are a gamble. It takes good skill to rebuild a rear end, so choose a competent shop if you go this route.
 
  #4  
Old 08-08-03, 05:47 PM
crosswind
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yes I know this is a gamble, the rear end is used, but the price was good, (that should tell me something, but it's a gamble that could be worth it) any rear end would be better than the one Ive got, and if I lose the bet, I'm only out $150 plus my time. Anyway......... I'm sure the axles are below the leaf springs. I am assuming that since I will have to disconnect the brake lines that I will have to refill and bleed the system, yes? P.S. if I do fail, I have found a shop that does rebuilds for race cars and drag cars that race the local tracks. He will rebuild my old one for about $600 including all parts and labor. The lift kit is purely vain.
 
  #5  
Old 08-08-03, 05:54 PM
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Crosswind.... Sorry, yes you have to disconnect the brake lines, as well as the emergency brake cable. If you can find a couple pair of pinch off pliers then you will save yourself some time by pinching the rubber brake lines before you disconnect them, otherwise you will be bleeding them for awhile.
Hope this helps ya,
Billy
 
  #6  
Old 08-08-03, 06:01 PM
crosswind
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I know that everywhere I inquired about a replacement rear end they asked for the ratio and size of the existing one so they would match. I don't understand why a replacement would have to match if it replaces the old one completely. for instance, my old rear is a 3.55, 8.8". Why can't I put in a 4.10 (?) by 9.75" or anything else. can you explain that to me.........
 
  #7  
Old 08-08-03, 06:16 PM
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Well its a 4X4... so why would you want to go with a lower gear? Not trying to be smart, just asking. As long as the rear fits between the leafs it really dont matter. Although, again it is a 4X4 so that may be why. I am not well versed in the dynamics of 4X4's and how they must match. Someone told me once that the front and rear gears had to match so on that note, a different diameter ring gear would change something I believe. But like I said I am not the one to ask this... LOL I do know a guy I once knew had different gears in the front and rear of his Chevy truck so........
Billy
 
  #8  
Old 08-08-03, 06:34 PM
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If the axle ratios don't match one axle will be trying to go faster or slower than the other one. Think about how fast a car/truck accelerates with a 4.11 rear verses a car/truck with a 2.56 rear.
This also applies to tire diameter also,front to rear on a 4x4

Bottom line front and rear axle ratios must match.
 
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Old 08-08-03, 06:43 PM
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Thumbs up

I have to say that makes sense. But then again I dont know much about 4X4's. Thats kinda funny considering I am a southerner.. LOL.

Dont they all own big 4X4 trucks???? ROFL

Billy
 
  #10  
Old 08-08-03, 08:33 PM
crosswind
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well now that you mention it, I forgot that it was a 4x4. Sure, the front and rear should match. I was not suggesting that I go with a different ratio, just wondered why it had to match, but now I see, it is important to match the front. I guess in a 4 x 2, that wouldn't matter. One other question though, what would be the result if you went with a larger ring gear, or smaller one, how does it effect the performance. I can think of it in terms of a motorcycle rear sprocket, but is the relationship the same?
 
  #11  
Old 08-08-03, 08:42 PM
Joe_F
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Original poster:

What are trying to accomplish? That would guide your decision of what to do.

If you're just trying to fix a wiped rear end, go the junkyard route. Make sure to pull the cover off the unit in the yard and have a look inside. You buy it you own it in many cases.

Me? My time is too valuable to waste on stuff like that. Just my .02....junkyard parts have their purposes reasons, but powertrain stuff isn't one of 'em for me.

You can probably call up Auburn or Dana or one of the gear companies and inquire about beefed up gearing.

Remember that your truck is geared the way it is based on options, emissions, payload and fuel economy.

I can tell you that the GM 10 bolt I have in my ' 79 Trans Am lets the RPM's get up there in 4th gear (those cars really need a 5 speed), and 3.23/3.42 is about as high as it gets with having A/C on a car like that. I have seen 3.73's in my era car, but those folks are sweating, I'm comfy. LOL.

My vote: Have a shop beef up your existing rear end with HD parts and know that everything's new back there with no problems.

Drive it another 200k .
 
  #12  
Old 08-08-03, 09:03 PM
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not only do front and rear axle ratios have to match, the tire sizes have to match, the tire 'wear' has to match too. put two new tires on the rear or front of a grand cherokee and leave the old worn out ones on the other axle and you will have a nuclear meltdown inside the transfer case. i've seen it!

i think you'd be suprised how easy it is to rebuild that 8.8 rear without any special tools other than a shop press and a strong impact gun, i've changed many a mustang rear gears that way. (update for joe---it's still together behind my brother's turbo 5.0L mustang)
 
  #13  
Old 08-09-03, 03:15 AM
crosswind
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I was only trying to learn a little bit more about the drive train. I figured since I was diving in, it would be good to know a little bit more than which direction the gears turns (I don't know that either by the way), And then there's a "Posi" unit. Now how do they work. I know what they do, but how do they work?
 
  #14  
Old 08-09-03, 12:59 PM
Joe_F
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Most rear ends require special tools to set up properly (backlash, gaps, etc).

I'd suggest you pick up a Ford service manual if you're going to dive in, so you have all the correct and accurate information and measurements for the job. Money well spent.
 
  #15  
Old 08-10-03, 06:41 PM
crosswind
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just to be clear, I have no interest in diving in to the rebuild. I respect the advice that that job requires special tools and training.
 
  #16  
Old 08-12-03, 04:45 PM
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I have dealt a lot with the ford 8.8 rears.

WHile not a 9", they are absolutely wonderful rear ends. They are VERY strong, and many people are running them for years in 10/11 second mustangs--while that is extreme, and they WILL break with that kind of abuse, I would be VERY surprised if you came across a ford 8.8 in the junkyard that was bad.

A good tip on those rears though is to replace the rear wheel bearings, as they seem to go out after about 200k from my experience.

They made rear ends from anything from mustangs to tbirds to trucks. the 87/88 thunderbird turbocoupes had the 8.8 with 3.73 gears stock (auto) and 3.55 gears from the stickshift models, also, the stangs(86 and up v8-only models) and the tbird turbo coupe rears come with traction lock, not sure if the trucks do or not. While the axle housings are going to be different between the car and truck rears, you can likely keep the center section and swap on the axle housings, etc.

The rebuild on these rears tends to be very complicated, as there are many shims and precise measurments to be done, and if you are a little off, you will have BIG problems.

Good luck!!
 
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