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Discussion Starter #1
I have an '87 Sammy with what I THINK is a noisy rear differential (could be transfer case?*), and was told that I could simply remove the entire FRONT differential carrier from the axle and bolt it into the REAR axle, and I would have a low-use "new" one for just the labor of swapping them.

Obviously, the front one gets at most 5% of the use of the rear one given that most Samurai miles have been highway miles w/ the front hubs unlocked.

Is this true, and has anyone actually done it?

Bob
*At first I was told the noise was transmission, but I switched to LO range, and the noise was not present until reaching the road speed of 35mph, where the whine started in HI range, so the noise is ROAD SPEED related, and not engine or transmission output RPM related.
I am losing faith in the "experts" advising me.
 

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Well - I'm not an expert, in fact I don't even have a Sami - but - I have a friend who does, and he says it can be done (he's planning to do it once he puts the engine back in) - I also checked the 86~87 parts manual, it shows only one set of part numbers for the differentials and shows quantity as two, so I'd say it looks like it can be done.

By the way - my math teacher (God rest his soul) used to define expert like this ...

x is an unknown quantity, spurt is a drip under pressure, so an xspurt is an unknown drip, under pressure. ;)
 

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could be the output on the transfer case too. Just a thought.


The differentials are the same 4 roller carrier front and back on the older samurais (your model). Later models had a two roller diff carrier in front instead of the 4 roller. They are still interchangeable but the 2 rollers aren't as strong.
 

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I have an '87 Sammy with what I THINK is a noisy rear differential (could be transfer case?*), and was told that I could simply remove the entire FRONT differential carrier from the axle and bolt it into the REAR axle, and I would have a low-use "new" one for just the labor of swapping them.

Obviously, the front one gets at most 5% of the use of the rear one given that most Samurai miles have been highway miles w/ the front hubs unlocked.

Is this true, and has anyone actually done it?

Bob
*At first I was told the noise was transmission, but I switched to LO range, and the noise was not present until reaching the road speed of 35mph, where the whine started in HI range, so the noise is ROAD SPEED related, and not engine or transmission output RPM related.
I am losing faith in the "experts" advising me.
Ok, I believe I can answer this one.

If you get the older model front diff, with four spider gears/three pins, then you just need to swap the side gears. The front side gears have 21 splines in them, while the rear ones have 26, so to install the rear axles with 26 splines you need to change the side gears. If the side gears in your old diff are ok, you can just remove them and install them in your new front diff. Other than the spline count, they are completely identical.
 

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Damn! You guys beat me to this on :) I was hoping to be the first to answer him.

By the way - my math teacher (God rest his soul) used to define expert like this ...

x is an unknown quantity, spurt is a drip under pressure, so an xspurt is an unknown drip, under pressure. ;)
LOL Nice one ... really nice.
 

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Discussion Starter #7
Ok, I believe I can answer this one.

If you get the older model front diff, with four spider gears/three pins, then you just need to swap the side gears. The front side gears have 21 splines in them, while the rear ones have 26, so to install the rear axles with 26 splines you need to change the side gears. If the side gears in your old diff are ok, you can just remove them and install them in your new front diff. Other than the spline count, they are completely identical.
Hmmm...

My question is whether I can just remove the entire carrier w/ gears from the axle assemblies by unbolting them from the housings and swap them as one assembly.

You are saying I have to disassemble everything because the axle spines are different with 21 in the front and 26 in the rear, then swap the gears before reinstalling the front ring and pinion units in the opposite ends?

If I read this correctly, I would not have to disturb the ring/pinion adjustments?

I was PLANNING to swap the gear-sets in my OWN car front-to-rear, but I may have located a front axle complete, but with bad spindles and hubs (for $100-does this seem reasonable).

That way I wouldn't have to remove and swap so may parts out of my car-just remove the assembly from the salvage unit, and swap the side gears from the rear unit I remove from my Sammy into the donor assembly, then bolt the donor assembly into the rear axle assembly on my car. Is this right?

Thanks-
Bob
 

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Discussion Starter #9
Alternator hit it right on the money!

Here is a quick link to a look at what you are in for (if you have never done it before).
GREAT link.

THANK-YOU!!

My question now boils down to this:

I am a pretty competent mechanic (besides auto experience I am also a licensed aircraft mechanic), but have never set up a rear end with regard to setting the ring-to-pinion relationship, and I understand this is something of an art to end up with a differential that is not noisy. I understand in theory the use of Prussian blue and the gear contact points and all, but I've also heard all sorts of horror stories about having to pull and replace multiple times to get a quiet gearset.

In the case of the Sammy, it appears from the photos that backlash is set by threaded collars, rather than shim packs, and that by marking the thrust side adjustment of the carrier, the only thing one needs to do upon reassembly is to reset the end play with the collar on the non-torque side, so the ring-to-pinion relationship should return to original without hassles (no noise).

Also since they say to retain the original shim with the carrier, the side gears must be well-standardized so that selective shimming is not necessary. I would be using my stock Suzuki side gears (rather than after-market ones), so I would hope standardization would be especially good.

While I may have phrased the above as "statements," I really mean them as questions since I've never done it before, and want to know what I am getting into before I open things up (the photos and text links are priceless), so please feel free to correct any misconceptions I may appear to have.

If I buy the front differential I found on Craigslist to obtain an unworn gearset, I'll have the luxury of disassembling it as a Guinea pig before messing with my own rear differential on my running Sammy, so all I can lose is my $100.

Thanks,
Bob
 

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Yup. Marking and resetting to the marks will get you 99% of the way there. The part that still has to be determined is how much wear the 25+ year old parts have on them. You can make final adjustments to the retaining rings. As you will figure out, the rear diffs will have a bit more slack you have to take up than the fronts (more worn).

Here is a link to a few more of those articles. They may help you as you get deeper in the 'addiction'.
Old Articles

Welcome!
 

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Yup. Marking and resetting to the marks will get you 99% of the way there. The part that still has to be determined is how much wear the 25+ year old parts have on them. You can make final adjustments to the retaining rings. As you will figure out, the rear diffs will have a bit more slack you have to take up than the fronts (more worn).

Here is a link to a few more of those articles. They may help you as you get deeper in the 'addiction'.
Old Articles

Welcome!
LOL

I love the phrase: deeper in the 'addiction'; really does feel like it. The wife is starting to get jealous!

I must say, although I lost quite a lot of money on my project, I did not regret it. Because I learned so much from it and ended up with eye-candy.
 
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