Thread: Rear end question

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I know that changing the ring and pinion in a rearend requires a certain level of expertise to get it right. I was wondering if you were to change from an open diff. to a posi unit, would you have to readjust the ring and pinion if you kept the existing one?

Andy, yes, the "posi" unit replaces the carrier in the center of the ring gear, so it's essentially the same procedure as changing the gears. While it's apart, you may want to do the bearings too.

I have done a couple of rear ends...it ain't that tough!
Biggest need is tools, followed by the chart for the shims, and of course, shims. You gotta love the smell of 90wt too!

Chris. Just the other day you couldn't make up your mind between motor oil and ATF, now 90wt? Man you're fickle!

I 'participate' in GMC and MCI bus groups. I plan on getting a 40' bus and making a motorcoach. So i need to learn all about that that end of the world - and boy is it different! Diff volts, lots of air controlled things(like belt tension!), no sparkplugs, $3500 clutches, $2000 oil cooled alternators, etc

I have a lot of background in motorcycles, and the additive package and base oil (or synth) is a major issue over there...you CAN run Pennzoil et al in your jap bike, BUT motorcycle specific oil is sooooo much better (due to additive package) that you'd be a fool to run car oil. Remember, a bike oil resevoir feeds teh engine, the trans (stick shift gears type) and the clutch (wet multiplate like in a car automatic). And add in that it has to take air cooled temps....the proper fluid is CRITICAL (ask a GOldwing owner that has run non-Honda Antifreeze...the 'sand' in regular antifreeze will chew up his water pump seal...ahh, details!) Different brakds run different incompatible fluids too - japs use DOT4 and Harley uses silicone brake fluid...and the list goes on and on!

SOO, when these bus wahoos ask stupid questions (what is a 3 point turn, how do you drill out a rivet, etc) and then they put 10w40 in the trannie and claim it runs BETTER, i need to ask a group that has a clue about such things...this group!

BTW, i dislike the smell of 90 wt. I have, umm, bathed in ATF (who hasn't) and it ain't too bad, or at least better than 10w40!

It's just that I have an opportunity to buy a complete rear with the gear I want (3.50), but it is open. I want a traction lock unit, and I'm trying to decide if it is worth the extra money to buy one that already has one installed.

The way I see it, I will eventually have to learn how to do it when I have to rebuild the trac. lok unit down the road, so I might as well learn now and save money.

What is your time worth? it will be quicker to buy one all set up and ready to go.
What is the experience/education worth to you?
the actual time to change ring and pinion is 4 to 6 hours, all set up and ready to go. maybe less on certain rears, but i have only played with those that are in the car, as opposed to the removeable R&P units (which should be easier to set up)

What have you now? From what i can gather, you need 3.50 gears AND a limited slip diff (LSD) rear too? So you can get teh 3.50 NOW and later get the LSD later? Why not go look for a used 3.50 LSD now? Or a good LSD and get the 3.50 gears later (gears i believe are cheaper than the LSD part). Just thinkin outloud...have to do this on teh camaro at some point and my Linc needs better gears than 2.24...

Have not looked at rear..assumed it is a standard ford 9".... have window sticker laying about somewhere, so i may off a point or two on teh gearing (2.28?) but either way it, umm, sucks. Posi would be cool too, but as i no longer drive this in the snow it prolly don't matter. If i upgrade the motor to the point i need a posi, i'll go there.

Didn't know ford made anything 'bigger' than a 9" (unless it was for dem BIG trux)

any notes on telling the diff? i have the car up in the air for wheel well repairs...easy enough to look at this point!

Hey, there is nothing wrong with the occasional bath in various oils/fluids. Keeps the hair shiny! Anyway, if you want to swap a posi unit in a open diff, why not locate a HEALTHY posi setup in a scrapyard and swap it in? Many people would argue against used rear ends, but it has saved me two AMC's and a Crown Vic. Not exactly high performance, but they were good to 200K miles. Word to the wise, avoid salt covered rear ends, high miles and Excessive rust. If these all apply, and it isnt leaking, it should last a while. Or, maybe I'm just lucky?