Nb clutch replacement

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Mark2Nb
Hey. They are NOT Training wheels.
Hey.  They are NOT Training wheels.
Posts: 5
Joined: Tue Nov 17, 2020 3:37 pm

Nb clutch replacement

Post by Mark2Nb » Tue Nov 17, 2020 4:18 pm

The clutch thowout bearing seems to have died in our 98 NB. Maybe it had been getting rumbly / squeaky, but I hadn't noticed. It seems to be toast now - died when my wife was pulling in to the carpark at work. Have checked master/slave cylinder, all seem good. Idling out of gear with clutch depressed, sounds a bit like a can full of marbles rolling down a hill and clutch won't disengage. FWIW, car has done about 125,000km, we've had it since about 2007.
A couple of quick questions, should I replace with OEM clutch, or is there a preferred aftermarket option? (This car gets normal road use, 1.8 / 6 speed - no hard thrashing on tracks etc).
Looks like fun (not really) at home DIY, a few bits to come off before removing the gearbox. I've got a shallow pit in the garage, ramps, but probably still a bit awkward.
Are there any "gotchas" - and/or recommended guides on line?
FWIW, Mazda price for kit is $385. 2 week delivery ex Aus.
Edit. Seller on TM has Exedy kits with alignment tool included for $300. I think that'll do the trick.
Looks like my weekend entertainment is sorted.
FWIW, towed the MX5 home (very gently) with my ute using a bridle tied between the "eye teeth" loops. I've read conflicting advice as to whether this is okay or very bad. No problems, kept speed below 30 km/h, very gently idled the ute to take up tension after stopping a few times.

Keith Jones
I count 5-s in my sleep
I count 5-s in my sleep
Posts: 328
Joined: Thu Jul 06, 2006 6:30 pm
Location: Waiuku

Re: Nb clutch replacement

Post by Keith Jones » Wed Nov 18, 2020 1:21 pm

If the car just gets normal road use, a stock OEM clutch is fine. No sense in spending more money on something you don't need.

Replacing the clutch with the engine in the car is a bit of a mission. It's difficult to get at some of the bell housing bolts and they are done up pretty tight (48-65 lb.ft). The PPF (power plant frame) can also be difficult to remove as well, especially at the diff end. The pit will help though.

There are numerous Youtube videos on-line about changing clutches. Most of theses are from He US, so Google "Miata" not MX5.

This link https://www.miata.net/garage/clutch/ gives a good written description.

Good luck.

Mark2Nb
Hey. They are NOT Training wheels.
Hey.  They are NOT Training wheels.
Posts: 5
Joined: Tue Nov 17, 2020 3:37 pm

Re: Nb clutch replacement

Post by Mark2Nb » Wed Nov 18, 2020 4:35 pm

This afternoon I set it up on ramps/stands, nice and safe. Removed the PPF no problems, slung aside and out of the way. I've left the exhaust in place for now - managed to sneak a small impact driver above - with 3/8 adapter, extension and socket, it had enough grunt to get the top bolts out. The lower bell housing bolt holding the exhaust bracket caused me some serious pain, couldn't get my full size rattle gun on it without two extensions, and it wouldn't budge giving it full juice. Finally cracked it with a breaker bar and a length of pipe, long impact socket, extension - nasty.
I've had enough for the day, will get the gearbox out in the morning when I have a helper here, all the bolts (I hope) are either out, except I left a few finger tight that I can get at easily in the morning.
So far so good. I can see it's going to be pretty nasty getting some of the bolts back in, the ones holding brackets for hydraulics etc are really hard to get at. Seems to confirm what I've read - kind of straight-forward, but nasty access issues.
I've found that Supercheap can supply the Exedy clutch kit at about the same price as the Trademe seller. Seems better than waiting 2 weeks for the OEM clutch kit, and the Exedy one is lower cost and comes with alignment tool. I'm going to need new upper and lower shifter boots, gearbox seals and rear main seal.

Keith Jones
I count 5-s in my sleep
I count 5-s in my sleep
Posts: 328
Joined: Thu Jul 06, 2006 6:30 pm
Location: Waiuku

Re: Nb clutch replacement

Post by Keith Jones » Wed Nov 18, 2020 8:23 pm

Sounds like you have a job on your hands if you've got to replace seals as well.
Try Mazda first for these, but they may need to get them in from Japan, particularly the gearbox seals.
If that's the case check with Benny at Garage 5 in ChCh. https://www.garage5.net/ Benny stocks a lot of OEM parts that Mazda don't.

Mark2Nb
Hey. They are NOT Training wheels.
Hey.  They are NOT Training wheels.
Posts: 5
Joined: Tue Nov 17, 2020 3:37 pm

Re: Nb clutch replacement

Post by Mark2Nb » Thu Nov 19, 2020 2:51 pm

OK - I should have removed the exhaust, it wouldn't have been in the way of getting to the bolts on the bellhousing, but the bracket would stop the bellhousing from going back. Unfortunately the flange on the Jap import 1.8 with 4:2:1 headers has three studs on the flange. The only way to get to the middle one is through the wheel arch. Would be much easier with the LH front wheel off, I only just managed to get it to budge using a 6 point socket with a bar, then a ratchet spanner. There's no room to get the head of either my 1/2" or 3/8" rachet in to the spot, use a 12 point spanner to get it free and there's a high chance of rounding the head off, then you'll be in deep trouble - manifold off. I'll definitely be replacing stud and nut with new.
So the good news is I got all the bolts out ready to go, exhaust off rocked and pried the bellhousing back clear of the locating pins, levered it back maybe 20mm so I can see the flywheel - and that's it. It's defied efforts since - I've wasted hours.
I'll try putting bolts in from the engine side, blocking the holes on the bellhousing by covering with some steel, then pushing the bellhousing off evenly by screwing in the bolts. If that fails, then engine out. I'm getting the feeling that engine out for a clutch job may be a better bet. Pretty sure it would have been in this case anyway.
Thanks for suggestion about Garage 5. I might contact them.

Mark2Nb
Hey. They are NOT Training wheels.
Hey.  They are NOT Training wheels.
Posts: 5
Joined: Tue Nov 17, 2020 3:37 pm

Re: Nb clutch replacement

Post by Mark2Nb » Mon Nov 23, 2020 3:13 pm

So, I finally got the gearbox out. I levered the gearbox off evenly once I got enough gap to get a 10mm flange nut in, tightened the bolts from the bellhousing side with flat steel plates to block the threaded holes in the block. This was a slow and a very nasty job. I lost a bit of skin and blood. The pilot bearing had seized, what remained of it collapsed with a frightening bang, shell came out of the flywheel and ball bearings rained on my head. Gearbox is now on the ground - nothing broke that didn't need to. I think maybe dropping the gearbox to do a clutch job is something lucky people could try. I'd have been better to pull engine and box together.

I thought the release bearing was shot - but nope, it seems ok.

Mark2Nb
Hey. They are NOT Training wheels.
Hey.  They are NOT Training wheels.
Posts: 5
Joined: Tue Nov 17, 2020 3:37 pm

Re: Nb clutch replacement

Post by Mark2Nb » Tue Dec 01, 2020 3:00 pm

Had to leave it for a week - busy with other things. All back together now. That was a mission - probably not an easy job at the best of times due to how tight it is working around the bellhousing, but the problems splitting the box from the engine due to the seized pilot bearing really did my head in - and wasted a lot of time.
Tips for next time (hopefully not):
Have plenty of extensions and universals, 1/4, 3/8 and 1/2. The PPF bolts and a few of the bellhousing bolts are a mission to undo, rattle-gun essential IMO. (I think my 18v one has >1200 foot pound unfastening, and it only just did the trick).
Remove the exhaust entirely from the flange to the headers and last flange before the muffler. If you leave the back piece in place, it gets in the way refitting the drive shaft - maybe you can work around it, but it's really annoying. I replaced the 3 studs and bolts on the front flange with new ones - ouch they were expensive (>$30 for 3 studs and bolts), but on the JDM flange they're such nearly impossible things to get at as you've got to get a socket extension and universal around the 2:1 section, if the bolt heads are knurled or threads a bit dicky, then you've got yourself a real nightmare. Getting the two bolts holding the exhaust bracket to the bellhousing back in the holes is also extremely tricky - I did it by myself, but an extra pair of hands to twist the exhaust to align things while you get the bolts in would be good.
A tip I read somewhere was to get two bolts the same or a bit longer than the bellhousing bolts, cut the heads off, round the end and cut a screwdriver slot in them. Bung them in the lower threads in the engine (sump). Then when you push the gearbox into place, they'll guide and support the front of the box, move to the back of the box while holding the box and stopping it from going backward and wiggle the box in - a helper looking from the top can tell you when you're there and then hopefully also get one of the top bolts in for you. Remove the studs with a screwdriver and replace with the bellhousing bolts. Getting the starter motor bolted back in was also a mission. I think I made a mistake by letting the PPF drop and hang free, that twisted the loom so that the two brackets on the loom that have to be secured to the top two starter bolts wouldn't line up, there's no room to get your hands in to twist the brackets back into alignment while inserting the bolts. That was probably at least an hour wasted this morning - so tie the PPF up and out of the way immediately as you unbolt it - don't let it hang on the loom.
I made the mistake of refitting the exhaust before filling the gearbox - and the exhaust is really in the way, had to hunt around for a short 23mm (?) socket to get the top filler bolt out, then at least with the 6 speed I could fill the box from the turret. Replaced the oil with 75/90 GL5. The old oil was very clean, no bits of metal on the magnet on the drain bung. Maybe it shifts more smoothly, maybe I'm dreaming.
I replaced upper and lower shifter boots, and made a black lambskin leather top cover to replace the vinyl one which was looking shabby.
Anyway, job done. I'd had some doubts about the clutch for a while, sometimes it seemed a bit shuddery/uneven but never bad enough to cause me concern and didn't seem noisy. But I'm guessing that the pilot bearing had been stuffed for a long time before it seized, now with clutch action as smooth as silk I realise how bad it was. If I'd fixed it before the bearing completely seized I'd have save myself a lot of grief.

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