Which clutch for an NB8B?

ducktape69 · Postby **ducktape69** » Wed Nov 24, 2010 4:33 pm

Hi guys,

time to replace the clutch on my nb8b.
I definately want a heavier duty clutch than OEM as the stock clutch has always been very 'soft'. I will also ve getting the flywheel shaved while im at it.

So here'es my questions:
1)So which clutch to get that will also remove the damned clutch shudder?

2)Which geartbox oil does everone recommend for the 6spd? Im currently using the shockproof stuff and its OK but still notchy shifts. Should i try Redline MT 90

3) Which diff oil? Ive heard good things about Redline 75W90 gear oil.

Cheers,
Sam

rascal · Postby **rascal** » Thu Nov 25, 2010 9:32 am

1) any new clutch you get should not have any shudder... (chatter from twin plates excepted) Shudder from a new clutch usually means it hasnt been aligned properly.

2) I use MT90 in my tracked 5 sp but not sure if relevant for the 6 speed...

3) do you have a LSD or just an open diff.. If open then 75W90 is good, though if LSD I'd recommend a 80W140 oil.. I use Penrite Sin80 (80w140) in my lsd, and find it excellent, and it also comes in a 75w90 (Sin75)

My 2c

Charlie Brown · Postby **Charlie Brown** » Thu Nov 25, 2010 10:24 am

rascal wrote:1) any new clutch you get should not have any shudder... (chatter from twin plates excepted) Shudder from a new clutch usually means it hasnt been aligned properly.

My 2c

Clutch shudder in the NB8B & C was a know problem. I had Mazda replace mine twice under warranty. It was generally thought that the problem arose because the manufacturers were moving away from using asbestos in their linings.

Ducktape69, a new clutch plate won’t make the clutch heavier, an up rated pressure plate will. I believe that the SE clutch plate solved the shudder problem if you want to go OEM, otherwise do a search on the US & UK sites to pick what you need. MX5 Parts have some good deals going at the moment.

manga_blue · Postby **manga_blue** » Thu Nov 25, 2010 12:10 pm

Does Mania supply an Exedy Sports Tuff clutch for the NB8B? Same pedal pressure but much better bite and feel than the OEM.
http://www.mx5mania.com.au/product983.htm

Mr Morlock · Postby **Mr Morlock** » Thu Nov 25, 2010 5:43 pm

A provider told me that the clutch effort goes up with the sports clutch and you would expect this with heavier spring force in the pressure plate- recommendation was stay with the standard clutch for normal driving duties. The advice I got might be different for someone else. Many drivers of sports cars or for that matter any manuals love a clutch action that is light since after a bout of city traffic it all becomes so tiresome.

Logic would tell me that the OEM clutch maker is likely to have the best clutch system for a standard MX5 as any other maker is far more likely to merely copy a design and spec rather than doing any long term testing. As CB said the 2001 did have a problem with shudder and a fix was implemented and hopefully it was effective.

Insofar as gearchange is concerned the big problem for many is the belief that all changes in all gears should be perfect and that technique is not a factor. Many run standard oil without complaint. If a car has been abused and synchros are worn perhaps different oil and not rushing changes may assist.

ducktape69 · Postby **ducktape69** » Thu Nov 25, 2010 5:45 pm

manga_blue wrote:Does Mania supply an Exedy Sports Tuff clutch for the NB8B? Same pedal pressure but much better bite and feel than the OEM.
http://www.mx5mania.com.au/product983.htm

that's what I'm also wondering! Has anyone got an exedy sports tuff clutch in their nb8b's??
I want a clutch which will give a lot more bite than the OEM clutch.

What's everyone else using for their diff oil?

Mr Morlock · Postby **Mr Morlock** » Thu Nov 25, 2010 6:52 pm

How do you get equal effort for operation and yet greater clamp loads? Are we saying that the hydraulic mechanism and design negates the increased clamp force? What does the term extra bite mean in this context- greater clamp load or harsher take up? On old motorbikes you could adjust springs for greater load but you would immediately be rewarded by heavier operation and a sore arm- no hydraulics of course.

NMX516 · Postby **NMX516** » Thu Nov 25, 2010 9:08 pm

ducktape69 wrote:Has anyone got an exedy sports tuff clutch in their nb8b's??
I want a clutch which will give a lot more bite than the OEM clutch.

I have one in my SP. MUCH better than the stock SP clutch, and no problems with 142kw at the wheels. The operation of the clutch might be heavier, but not so as you would notice - it's certainly no more difficult to drive than a standard clutch.

People who want to sprout that that can't possibly be so, have obviously never used one. Just because a clutch has better "grip" on the flywheel, doesn't mean it has to be heavier to operate. Friction materials for example can easily effect clutch performance...

ducktape69 · Postby **ducktape69** » Fri Nov 26, 2010 1:06 pm

Perfect! Thanks for all the advice so far. One thing left... Which diff oil does everyone prefer for the nb8b?

manga_blue · Postby **manga_blue** » Fri Nov 26, 2010 1:18 pm

I found the Exedy clutch in my NA8 was actually a bit lighter on the foot than the OEM was. That came as a bit of a surprise. I assume the friction material is better. In any case I'm pleased that it's done 50,000km and about 30 track days so far and it's still good as gold.

Mazda's spec for NB8B diff oil is 1 litre of API service GL-5 SAE90. Diff oil is not that critical - any good quality brand will do it, just so long as you also do the regular replacements.

wun911 · Postby **wun911** » Fri Nov 26, 2010 5:35 pm

I have an exceedy HD, its pretty good easy to push down, prob a bit lighter than oem...
might want to do a flyhweel while you are there..

Mr Morlock · Postby **Mr Morlock** » Fri Nov 26, 2010 7:45 pm

reiterating..... the NBP2 OEM clutch is Exedy. The standard clutch you buy with Exedy branding is the same as the one sold by Mazda. Exedy make a sports tuff clutch which for sure has higher clamp force. Exedy was Daikin and rebranded for reasons I am not aware of. Oils in diffs as Manga pointed out is no big deal- follow the spec and use a known brand and change in line with recommendation. Ultimately if one want a sports tuff clutch or anything else go for it - it will be a good product. When I was a young bloke I had a Runbaken oil coil on my car because I liked the look of it!

ducktape69 · Postby **ducktape69** » Fri Jan 28, 2011 8:48 am

Finally got the exedy tuff clutch put in last week with machined flywheel and redline MT-90 oil. First impressions are:
Softer clutch engagement. Yes! Softer!
HUGE improvement on the 'grab' from the clutch...feels like some power has been restored to the wheels.
MT-90 is not as good as the redline lightweight shockproof I had in their before.

Mr Morlock · Postby **Mr Morlock** » Fri Jan 28, 2011 8:34 pm

so a new clutch is better than a stuffed one- I found the same thing . The only way you can test anything is back to back ie standard new versus tuff new. If it suits fine but for normal driving I would stay with the standard set up.