How to remove and replace differential bushings
 

Just did this now and it works great. You need a jaw puller (I used a 4" 3-jaw puller from Advance Auto) and harbor freight ball joint press (you need this for suspension bushings anyways).

Anyways, pictures of how it all works.

You take the puller. Put a 1/2 to 3/4 adapter on it. From the ball joint tool, use the disk and 2.5" OD receiver tube.
https://www.miataturbo.net/attachmen...ine=1329193617

Heat up the area with a torch for best effect. Go slowly. Check to make sure your puller doesn't come off.
https://www.miataturbo.net/attachmen...ine=1329193617

Bushing comes out fairly easy and without any mess.
https://www.miataturbo.net/attachmen...ine=1329193617

Use a 2.5" wire brush attachment to quickly clean up the bushing bores.
https://www.miataturbo.net/attachmen...ine=1329193617
https://www.miataturbo.net/attachmen...ine=1329193617

You can press the new bushings in by hand or just use the tool. easy.
https://www.miataturbo.net/attachmen...ine=1329193617

I loaned out my HF tool and never got it back. I wish I had it when I did this last month, it looks like it went a lot smoother for you.

That's a good way to crack the diff. There is someone on here who did that and it cracked. Just sayin.

All I used was a chisel and hammer and mine out in 5min.

The key was breaking the metal ring around the bushing, you hit it right at the seem and pry it inward. That relieves all the pressure and it slides out with a few hammer taps. Drilled a few holes in the bushing too, but I found the metal ring was the key.

https://www.miataturbo.net/attachmen...ine=1329226612


see the one on the ground? notice how the edge is bent in? that's all there is to it.

But I dont reccommend those solid mounts...at least not with a cltuch LSD.

Hmm, good to know.
The worst case I could see happening is breaking a piece of the "lip" off, where the puller holds.

I'm just frustrated with the :jerkit: :jerkit: :jerkit: shops.

I used an air hammer, with a decent compressor it only takes a few minutes per bushing. No need to remove the diff from the car.

I like to use a torch/chisel on mine.

torch is silly and unnecessary.

Massive pry bar and hammer + drilling holes.

Yea that is what happened. The lip cracked. Think the guy welded it back on or something lol.

When using the torch, is there not a risk of adversely affecting the heat treatment of the alloy of the diff?

That's not what I'd be worried about. I just think the idea of a torch is silly. You can drill on the center section of the bushing easy...and a lot faster than waiting for the rubber to burn off.

Take a chisel, hit it in the sweet spot to remove the pressure, and it will hammer right out.

Yeah, I think lip cracking wouldn't render the diff unusable. But that's why you gotta slow. The bushing slides out slowly under pressure, not right away.

The torch is not to "burn the rubber" - it's to make the rubber softer so it slides out easier.

There's still the metal ring around the edge...that's what hold the bushings in so hard...it's compressed in, decompress it by forcing the metal edges away from each other, inteasd of butt-edged tightly and you're in business.

I don't burn the bushing out. I just make it more pliable, so it wants to come out easier. The whole process is about 3 minutes start to finish per side.

So you're not one of the folk here that's posted pictures of theirs sitting there blazing on fire?

LOL no. I don't understand that either. It's like my redneck neighbor who uses gas on ant hills. He thinks the gas is used so you can light the hill on fire, thus killing the ants.

I used the 3 jaw puller method on mine today. I can't imagine there being an easier way to do this job.

I honestly think I sprayed mine with PB Blaster and then hammered them out with a chunk of 2x4 and a framing hammer. In the great British tradition, reinstallation was reverse of removal.

Is this a corrosion thing for you guys?

I'm gonna try this whenever my bushings come in. I'm actually going to try it without taking the whole diff out...we'll see how goes. Thanks for the writeup, doesn't look too bad long as i have my 1,000 ft/lb impact wrench.

Nice writeup.

I supported the diff on the edge of a wood pallet. The bushing was hanging off the edge. I used a couple pieces of wood to support the diff level.

I took the 2.5 OD collar and disk in your picture, placed it over the bushing. Imagine it like you have it in the picture without the puller.

I took another scrap piece of wood to protect the wing of the 3rd member from the next step, in case I missed.

I took a 3-4# sledge and hit the top of the disk. 2-3 real solid swings on each bushing popped it out. Less than 10 minutes total for the entire job.

My puller didn't work out so well, so I just pushed the center out, then sawzall'd the outter race, then tapped it out with a screwdriver and hammer.

I tried this yesterday, after reading about it in another post... the fellow used an air hammer to push them out. Man, what a pain!

I first lowered the diff which did allow adequate clearance for the bushing to be pushed out, but there was not adequate access to the bushing for when things went wrong. What could go wrong, right? One popped out easily, the other one was way harder. It took 45 mins of air chiseling while lying on my back to get it to budge. My aching shoulder!

If you do use the air hammer method, a helpful hint that I discovered is that the OEM bushing casing is actually in 2 pieces. If you knock out the center rubber, you can more easily divide the casing at it's parting line.

I think that the 3-arm press method might work more easily, even with the diffi in the car. The clamp can't be positioned at the top due to the shape of the bushing casing; and I would be worried that it might slip off the lower flange as it is a bit irregular. I only had a 2-arm press and it kept slipping off.

My arm is really sore!https://www.miataturbo.net/attachmen...ine=1344901978

+1 on using the pulller. I used a ratchet strap wrapped around the three fingers to keep them from falling off. Worked great. Soaking the bushings in liquid wrench or even WD-40 will help push them out too.

I did mine using this method last year. Did it with the diff hanging down underneath the car. I should note that I have ears of experience using different types of pullers to remove bearings etc on ship. When I posted elsewhere about this being an easy way, I got talked down about how no one would buy a ball joint kit to get the pieces needed.

Edit: turns out it was this very forum.

Necro-thread bump...

For any of you that got yours out in one piece, do you still have them. I need a pair of stock ones.

pretty sure you're easier off finding a whole diff housing
on a side note, the ball joint tool has now been used for bushings on 4 different cars, for extended wheel studs, and a ton of other things that i forget.

still going strong.

Well, damn. I didn't want to buy that HF tool, but I guess I'm gonna have to now. I need to pull my polys back out to switch diffs. If I manage to not mangle the stockers I'll send you a PM rlogan. I doubt it, though. You're better off getting some ES Poly bushings.

When I did mine I burned through the first bushing only to fight the metal ring with a sledge and punch for a half hour or so because everyone at m.net :greddy: screamed about how you should absolutely not use an impact hammer, you will crack the housing, yadda yadda.

Used an impact hammer on the second bushing, no burning. Took about thirty seconds. Didn't crack the housing. :fael:

Torch is silly and unnecessary. Impact hammer is silly and unnecessary. Removing diff is silly and unnecessary. This takes about 5 minutes; the longest part of which is getting the 3-jaw puller attached and stable.

Inserting new rubber diff bushings, either stock or Mazdacomp, may require significant force and the use of the Harbor Freight ball joint press kit c-clamp tool. My homemade easy-access diff bushing installer, which was a big long bolt with washers on either end and a nut, proved insufficient to the task. Once the rubber bushing starts to tilt sideways, and it will, you don't have enough oomph to get the bushing in. The HF tool is the way.

Always lube the threads on all of these tools.

With my transmission, PPF, and driveshaft on the ground it was much easier to pull the diff and stub shafts than wheels, brakes, uprights and control arms. The hardest part was the stubs until I hit the prybar with a hammer and *pop*.

Will probably use your method if I ever help anyone, though. Didn't think about doing it on-car.

Here is the hammer method

Thread revival/necrobump.

I did Mazdacomp differential bushings and I've got a small gap to the bottom bracket. Is this a problem? I'm chasing a small clunk under heavy braking that I can't find, and just trying to figure out if this might be it?

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