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Hello,

I'm after some feed back from anyone that has a PAR gearset in there Mx5...preferably for the 6 Speed NB box.

I'am looking at upgrading my gearbox to the syncromesh gearset from PAR, rather than the DOG engagement..

I have been doing a lot of researching, but little comes up in regards to the PAR stuff...and the reason why I'am upgrading is stock 6 speeds wont handle the power.

Seems the quaife close ratio set is still break able but only made for 5 speed mx5 box.

The other alternative is a RB25 conversion with cut and shut bellhousings and the rest of the conversion requirements with the PPF.
If anyone has any leads on a RB25 conversion specialist please let me know as that is another avenue I might go down.

I know nothing of the RB box swap other than I have heard of it being done.

However, I know that Wazman on the forum has put a Silvia 6 speed into his turbocharged NB.
If the Silvia box is strong enough for your needs it may be a thought.



What part of the box are you breaking? stripping teeth or cracking housings?

You could also look at having the existing gearset nitride treated, a guy I used to know had it done to his box. It worked, the gears stayed fine...... but the side of the gearbox exploded (I think where previously the gears stripped before the housing cracked, with the strogner gears the next weak link in the chain was the housing)

The 200sx s15 is the same internally as nb 6spd mx5 box made by aisin model az6.

Waz is tight and just changed to the 200sx s15 box because he can buy them for less than $600 compared to any mx5 wrecker chargers $1000+ for them as s15 guys pull them out because they can't handle the power once they make more power/torque and either go back to s14 5 speeds or adapt the rb25/vg30 box to an sr20 which is a fairly straight forward job as they have adapters off the shelf these days and is well documented.

I like to do things once and do it right.. I have better things to than work on cars!

I heard that the PPG gearsets are very delayed. I'd give them a call to ask abput availability.
The PPG dogbox set would be awesome for a high powered MX5. Better than putting a different box in I think. There is a very long thread on MT.net on various gearbox options.

There was a thread on modifications to an fc rx7 gear box to fit in a 5... somewhere on the Internet. Might be another option

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I thought the weakness in MX5 gearboxes was in the strength of the casing. It wouldn't matter how strong a gear set you put in if the casing itself was buckling enough to let the gears inside separate. That's the fundamental benefit of going RB25: to get a strong case as a base for a good gear set.

manga_blue wrote:I thought the weakness in MX5 gearboxes was in the strength of the casing. It wouldn't matter how strong a gear set you put in if the casing itself was buckling enough to let the gears inside separate. That's the fundamental benefit of going RB25: to get a strong case as a base for a good gear set.

yeah it's a theory. The big horsepower guys are breaking the Quaife gearsets... But no-one is sure if it due to the gearset (how much stronger is the quaife set over stock) or the casing flexing, maybe both. I haven't seen anyone running the PPG gearset so who really knows?

Also is PAR still around? Their website is done.

There was a discussion here on or MT about welding reinforcing ribs onto the standard MX5 casing to get a better result with a standard gearset than you could get with aftermarket. It was years ago but I think Nitrodann might have been in on that.

This is only $12.5k
https://shop.quaife.co.uk/mazda-mx-5-na-nb-60g-6-speed-sequential-gearbox-1742

damn, wish I could win lotto!

manga_blue wrote:There was a discussion here on or MT about welding reinforcing ribs onto the standard MX5 casing to get a better result with a standard gearset than you could get with aftermarket. It was years ago but I think Nitrodann might have been in on that.

yeah... I've read that ages ago but I don't think anyone actually did it and tested it. There are also threads on fitting the S15 gearbox as the MX5 belltower would fit on and you can get cheaper gearsets like a NISMO upgrade and cehaper dog sets. Once again I don't think it was every fitted.

If your going to the trouble of a non-factory dog box then you may as well drop the dollars on a sequential. I doubt there would be much cost difference once it's all said and done.

That's interesting about a nismo upgrade for the s15 6 speed... a little bit more research (if you owned a s13/14/15) that HPI make a 6 speed cross mission complete unit unsure if based on the Aisin gearbox though? But-Just Jap price $6200... So even if I could get it a little cheaper direct from japan or second hand that an RB25 conversion is still winning on the price front... Just not straight forward bolt in

That's the beauty of trying to keep everything in the original casing. everything just bolts up and no headaches.

if only we call all win tattslotto... wouldn't be asking questions on gearsets... straight to the top with a quaife sequential!

rjr666 wrote:if only we call all win tattslotto... wouldn't be asking questions on gearsets... straight to the top with a quaife sequential!

rjr666 wrote:I need a sponsor

Not contributing to the conversation, but I lol'd.

manga_blue wrote:I think Nitrodann might have been in on that.

he is in on most chats

jeo- yes that's been my signature for about 6years lol. You first need to get results before you get sponsorship!

Pretty sure I'm leaning towards the RB25 gearbox swap even though it's more work involved with PPF and cut and shut the bellhousing, still most likely work out cheaper than a PAR gear set at around $4500-5000! I PM Neil D a few days back but no response yet...

For $900-$1000 sell my Current working nb 6speed before I subject it to my new long motor I've just spent close to $10,000 on. buy RB 25 box anywhere from 900-1200 going rate.
Find a blown 5speed mx5 gearbox for cheap. Use that for front of the bell housing cut and shut.
Order new clutch discs from OS giken to suit Rb25 spline.
Pay someone to do the cut and shut
Workout the gearbox crossmember (prob do something same as Wazmans conversion from each side of the tunnel and then try integrate the PPF back on the rb25 gearbox maybe some cable ties or something... .....

Can someone please point me in the right direction with the rb25 conversions please who do I need to ring/see/email.

How well does the RB25 gearbox match the gear ratios on the mazda 6-speed? I really like the current ratios and I think it would be fairly pointless doing all that effort to move to a worse gear set. There is also the 6-speed Z33 box. I suppose putting out enough power to break a 6-speed means you don't really care about gearing that much.

You could look into putting in something with more gear choices like a tremec. If you're having to customise the bell housing, custom flywheel and manufacture supports anyway you may as well go for a box with more options.

Still, I recon the PAR gearset (if they are still around) would be pretty much ideal. Sure it's pricy and you'd be limited to an extra 100 HP over what a stock 6-speed can take but it saves all the problems of fitment and plus you get a dog set.

How much power are you planning on putting through the box?

edit:grammar