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I see this is a common problem and as the gearbox and it's 6 gears is the heart of the car, I find it very important that this be "right"
I have just bought a 2002 NB Series 3 with 80,000km. Everything else seems perfect (I did the "hood latch not locking" fix from here) I get a bit of crunch going into second when cold - seems common - but even though it's better when warm, The GB changes are still a bit baulky and hard to judge perfectly. Clutch has been removed during last owner and flywheel machined as he reported jerky startoffs. clutch operation itself seems fine.
What order is good for diagnosing and fixing the gear change towards smoothness?
Because the clutch was removed less than a year ago I did not change the GB fluid , but did with coolant, brake fluid,diff and engine.
Change GB oil? Adjust clutch rod length?.....a suggested check list would be helpful, thanks .

hey mate wat u report nearly all mx5 owners know about.

you can try a 75-90 gear oil to help the cold shift but as far as i know there is no way to entirely fix the problem unless you rebuild i guess......

good luck

try nulon gb additive

Useless thread is useless.

Dann

Sorry to provoke your response Dann.
I'm honestly seeking advice here.

Yeah I know you were. I apologise for my forward response.

You havent been here long enough to understand my tact, or lack thereof.

Basically what I meant was:
This topic has been covered probably 1000 times across the forums of the interwebs. No exaggeration at all.

There is no solution.
Some people say they used redline MT90 and it was a miracle. Others say no improvement, some people use the GL90 or whatever it is nulon additive, most report a slight improvement (probably placebo). No one has found anything at all that actually works and works for everyone. The fact that only few people say MT90 redline works should tell us all that it doesnt really and they are just believing hype. Didnt do anything in my box.
I use a synthetic castrol product, it work just as good as redline, and yes its clunky like a race box. Thats just how they are. Its the same box as a 6 speed S15, they have the same issues, and no one has found a single thing that actually makes a tangible improvement.

Dann

Silvia wrote:What order is good for diagnosing and fixing the gear change towards smoothness?
Because the clutch was removed less than a year ago I did not change the GB fluid, but did with coolant, brake fluid, diff and engine.
Change GB oil? Adjust clutch rod length?.....a suggested check list would be helpful, thanks.

The optimal order for attempting to diagnose & hopefully fix issues is generally to check/ test &/ or replace the least time consuming &/ or the least expensive things first.

It also helps if you know the common issues, especially if there is a quick check &/ or cheap fix for them.

If you're saying you're assuming the GB oil was changed because the clutch was removed less than a year ago, then I wouldn't make that assumption. Also wouldn't assume, if that's what you're doing, that the clutch fluid was changed.

As many have said, the 6 speed is not as widely a well regarded a GB as the 5 speed, so to some extent you simply need to adjust to that. In terms of the 1st to 2nd change bauking when cold, the 5 speed can be the same, especially as they age.

However, from what you tell us the key to your issue is that it's only a problem when cold, i.e. ok when warmed up. This suggests the issue is likely within the GB, as has been indicated, so if it makes you feel better, i.e. the placebo effect, then focus on the GB & try a few cheap & easy things. Some owners note some improvement, at least initially, after trying some fixes, but the fixes don't always stick.

Btw, from memory the clutch slave cylinder pushrod isn't adjustable so, if you haven't already during your brief ownership, change the clutch fluid, in the process checking the slave cylinder isn't slowly leaking fluid into it's rubber boot. Then, if you haven't already, change the GB oil & maybe include an additive with it.

Again, if you haven't already, it's also worth while doing a visual inspection (& replace if necessary) of the inner & outer GB turret shifter boots. While you're there remove the shifter from the GB turret to check (& replace if necessary) the white plastic cap/ bush.

The only other thing is checking clutch pedal height (NA8 should be 175-185mm) & free play (NA8 should be 5-13mm), but if these haven't been touched then they should be within tolerances.

NitroDann wrote:Useless thread is useless.

Dann

Bit cranky of you old son, lighten up, don't you think his worry is justified seeing the car is only 80K old. That said you are correct in that it has been covered many many times and there is no easy answer. I love my 6 speed but it can always get better.

The OP may seek some relief with a miata roadster short shifter. See Lokiel's garage thread as it amongst others is awesome.

Thanks for the help, particularly 93 clubman's detailed hints. I wish I'd known about this before I purchased the car, I would have been more selective perhaps, though the rest of the car is in excellent condition. If the MX5 epitomises the "rider and horse as one", I guess the gearshift is the saddle - the connecting thing, and to me , if I'm going to do all that 6-speed shifting all the time ,it would be excellent if the shift is a delight rather than the cause of tension as it is now. And tension does not make for smooth shifts at the best of time.
BTW though it's worst at cold, there is still some baulking and uncertainty when hot....
I've bought some Nulon additive and will try that first. A $14 try is worthwhile. If things, like different oils can make a difference it must be pretty fine tolerances involved.... Had a look at the clutch pushrod and that seems ok. I noticed that the clutch pedal rubber is totally worn through on the left, so perhaps that indicates some bad driving habits previously...?

Let me be uber blunt.

They all do it.
Yours is no different.
Its just a little clack noise every now and then, it wont hurt you.
No one has EVER found a cure, its because there isnt one.
Get used to it, it wont hurt you, and it doesnt take anything from the driving experience, gear selection is still short and sharp, gear changes are still easy, its just some noise, and there isnt anything you can do about it.

Just stop stressing and enjoy your car.

Dann

Silvia wrote:BTW though it's worst at cold, there is still some baulking and uncertainty when hot....
I've bought some Nulon additive and will try that first. A $14 try is worthwhile.

The NA6 (5 speed GB) had/ has the best gear change - it was perfect IMHO. The NA8 (5 speed GB) gear change wasn't as good as the NA6, & the NB8A (10AE & Heritage) & NB8B=> were a little less perfect again.

Only put the Nulon in if you've already changed the GB oil, otherwise change the GB oil. Also, if you haven't changed the clutch fluid then change it, so that you base-line the vehicle in terms of service certainty.

Only other suggestion is, as a former Alfa owner, allow your vehicle to warm up just a little in the mornings before driving off. Now I'm only talking 1 or 2 minutes maximum, but in that time depress the clutch & engage 4th, 5th, reverse, 3rd & 2nd a couple of times. You might find you need to release & depress the clutch a couple of times as you do this because engaging a particular gear might feel a bit tight. The other Alfa trick is to change 1st to 3rd for those first couple of changes & avoid 3rd to 2nd changes until fully warmed up.

Btw, the early (2000-2001) NB8B had a clutch issue which could be replaced under waranty with a Mazda revised clutch &/ or pressure plate, but this shouldn't be a problem on yours as it's the later NB8B & you indicate clutch &/ or flywheel work was done less than a year ago.

Wouldn't worry about the clutch pedal rubber wear as it's much the same as how we wear our shoes, i.e. where emphasis is placed.

Thanks 93, I'll try the tips - I do a bit of a warm up in the morning, so the extra bits will fit in.
You're probably right and I will change the GB oil too and clutch fluid - that will cover every fluid it has. Does the clutch slave cylinder feed from the clutch?
I bought it from a 73 yr. old who did 5000km in the 2 years he had it!
...and I refuse to accept that the gear box issue can't be solved - or at least I'll give it a damn good go!

Silvia wrote:Does the clutch slave cylinder feed from the clutch?

...and I refuse to accept that the gear box issue can't be solved - or at least I'll give it a damn good go!

Yes, clutch slave is feed by clutch master. If it makes you feel better, fill your boots - it's your car - it's your prerogative.

Slight baulking into 2nd when cold is normal in all MX-5 manual gearboxes - 5 or 6 speed, NA to NC. It's even normal in our Astina 5 speed and BMW 6 speed. Try changing s l o w l y (maybe with a double de-clutch or short pause in neutral) for the first few km.

Try a GB oil change to Penrite light gear oil or equivalent and. as others have indicated, flush the clutch hydraulics. Don't waste your money on GB oil addatives and "liquid gold" transmission oils.

As others have said there is no easy fix.
Mine is an early NB8B 6 speed box (yes there are 2 types fitted to the NB8B)

Fix 1
After 3 oil changes in fairly quick succession, I settled on Redline Lightweight Shockproof Gear Oil.
General improvement to shift quality and a lot smoother when cold.

Fix 2
I fitted the short shift kit from MiataRoadster
http://mx5cartalk.com/forum/viewtopic.php?f=29&t=47730
This makes the shift feel much better and more accurate.
It has a very short throw and notchy which takes a while to get use to, might want to try one before you buy.

Fix 3
Keep the OEM gearknob or purchase a leather one from MX5 Parts
http://www.mx5parts.co.uk/product_info.php/products_id/654 It looks OEM and a lot better than the photo.
I have tried a Voodoo Magnum but didn't like it on the stock length short shifter.

I'm happy with the result I have achieved with the above changes.