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How do you replace differential bushings?

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#1
Jake Bailey

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does anybody know how to change/get out the differential bushings? The large differential donuts at the ends of the housings. Thanks -Jake
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#2
Bench Racer

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Jake, if the bushing in a Spec Miata & are not rotten or super soft why are you taking the bushings out?

I have a 1990 & they are the only bushings I didn't change. I also have a back-up rear end completly assembled into the aluminum housing & I didn't change those bushings either. The bushing seem solid & hard, good to go.

Presuming your replacing them & don't mind destroying them (I don't believe they can be taken out without destroying), use a Saber saw being sure you don't cut/mark the aluminum housing. IIRC there is a steel bushing in the center for which you might use a fine toothed blade & use a courser blade for the rubber. Once you've made two seperat cuts about 90 degrees apart through almost to the aluminum housing I would beleive you should be able to use a hammer & chisel to knock the stuff out.
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#3
Panic Motorsports

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Drive them out with an air hammer. 30 seconds each side. Done. The new ones press in on a real press, or rig up a vise as a press. Not hard to press in either way, be sure the "slots" are aligned parallel to the axle shafts.
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#4
Jake Bailey

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Thanks Bench Racer. The reason for replacement is that that the current bushing is partially cut out and can not be used as is. The bad bushing is on a differential that is only on our car for temporary use while our limited slit is being repaired. We tried just hitting it out and that didn't seem to work lol. I really appreciate your advice! :spin: -Jake
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#5
Jake Bailey

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Thanks for the help guys
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#6
Alberto

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Best tool for doing bushings that I've ever used is this one:
http://www.harborfre...ress-33497.html
Makes pressing bushings out/in an easy task - if you know how to use it and how to place sockets and such on the bushing so that you don't damage the part the bushing is pressed into.
Haven't used it on the Miata yet but have on my Rx7.
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#7
wheel

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I've had one of these for about 12 years and it is still working great. With the usual 20% discount coupon, it was only about $89 back then. I use it all the time.

#8
Jim Drago

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Look at the service manual when installing.. It is my belief that manual is correct and every Miata ver built has the bushings in incorrectly..
I would install like the service manual suggests.
Jim

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#9
Glenn

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Look at the service manual when installing.. It is my belief that manual is correct and every Miata ver built has the bushings in incorrectly..
I would install like the service manual suggests.
Jim

WHAT???? Read the instructions,.....we don't need no stinkin instructions...... :whistling:

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#10
Bench Racer

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Look at the service manual when installing.. It is my belief that manual is correct and every Miata ver built has the bushings in incorrectly..
I would install like the service manual suggests.
Jim


Jim, if the reference is to the fore & aft for the voids is there a known reason for there radial location? :noidea:

My spare unit (presume OEM installed) has the voids pass side, drivers side. :scratchchin:
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#11
Jim Drago

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The manual shows the voids front and back, the manual shows the voids left and right. My logic is that the rear is braced by the power plant brace front to back. I would think the manual is correct in that you want the voids front and back, because the brace holds that dimension. I wouldn't think you would want the voids left and right because the rear would shift that way and compress the voids? When we replace, we put in as the manual suggests? Any engineers want to take a crack at it?
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#12
Bench Racer

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The manual shows the voids front and back, the manual shows the voids left and right.



The FSM written words say, "Install the mounting rubber with the voids fore & aft", not the position they seem to come OEM. The FSM drawing picture shows the voids left & right with the words front on the right side & rear on the left side. A little contradiction maybe.

Would be interesting for the FL Auto Tech to view this thread.

I do understand your word description logic.
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#13
Jim Drago

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I do understand your word description logic.


What is your opinion on which way to install?

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#14
Bench Racer

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What is your opinion on which way to install?



I would throw my hat towards left side, right side. Only because the Power Plant Frame holds the diff housing pretty firmly fore/aft.

Maybe the void position plays along with the other dufingy rubber bushings/steel plate that attach to the chassis, maybe it's a cost savings of rubber, comes out of the mold better, ???

The FL Auto Tech's name is Dave Stien, I 'll send a pm for another thought.
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#15
Jake Bailey

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Thanks for all your help. Jim, congrats on the run-offs win.
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#16
Jim Drago

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Thank you

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#17
DES4

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I'd go with the voids being oriented front and rear as the drawing has them labeled, rather than as the drawing seems to illustrate (laterally). Ultimately, pinion/diff housing angle will be set as the PPF locates it, and the voids (if positioned fore and aft) will relieve tension/flex on the diff bushings. Keep in mind the differential tries to rotate under acceleration and braking as well, in spite of the PPF.

... at least that my thoughts on the logic behind it.
Dave Stine


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#18
mrmonk7663

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Bumping very old post to perhaps shed light. This is a RX7 differential housing. This is a set of factory bushings. This is the diff housing that many folks swap to and is a direct fit in the Miata. As you can see the bushings are Fore and Afft from the factory.

Attached Files



#19
Ron Alan

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This is the diff housing that many folks swap to and is a direct fit in the Miata. 

It is a direct fit if you remove the OEM RX7 bushings and replace with the OEM Miata bushings...that simple!


Ron

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#20
RWP80000

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The manual shows the voids front and back, the manual shows the voids left and right. My logic is that the rear is braced by the power plant brace front to back. I would think the manual is correct in that you want the voids front and back, because the brace holds that dimension. I wouldn't think you would want the voids left and right because the rear would shift that way and compress the voids? When we replace, we put in as the manual suggests? Any engineers want to take a crack at it?

I could see the case that the NVH developers may have wanted that for impact harshness as in tar strips and concrete parting lines.  Customer comfort duing daily use having priority over driveline displacement.

Rich Powers






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