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View Full Version : 6 sp crashes going into 2nd gear



kevinharrop
10-23-2017, 09:25 PM
So I may have figured out why the PO put this up for sale: the trans crunches going from 1st to 2nd (137,000 miles). Now I have in the past had sports cars with this issue and learned to shift them just so, such that I beat the crunch.

The trans on my Miata tends to crunch less or not at all after warming up.

Possibly I should try some magical mystery oil?

Under the car for the first time today (at the mechanic's lift) and confirmed PO's claim of no rust, yes! and the boots on the CVs are good. Yes to that too. And that the exhaust is new and stainless steel, very good.

kung fu jesus
10-24-2017, 07:17 AM
Mine does it as well when cold between 1-2. Warm, it's fine. Maybe inspect the clutch hydraulics, bleed them, replace the fluid in the transmission.

RotorNutFD3S
10-24-2017, 07:54 AM
This is unfortunately pretty normal behavior on most Miata 6-speeds. A common recommendation (for 6-speeds) is flushing the current trans. fluid and replacing it with Ford Motorcraft trans. fluid (XT-M5-QS), quite a lot of people found that the 6-speeds behave much better with that fluid, especially at cold temps.

RustRat
10-24-2017, 09:45 AM
I had the same thing happen to both my 5sp, always making a metal clunk in 1-2 change. Thought it was normal for Miatas in general.


Sent from my iPhone using Tapatalk

kevinharrop
10-25-2017, 12:49 AM
A common recommendation (for 6-speeds) is flushing the current trans. fluid and replacing it with Ford Motorcraft trans. fluid (XT-M5-QS),

That stuff is $23 per qt. Does the 6 sp take two or (braces himself) three? Or better yet, 2.1.

kevinharrop
10-25-2017, 01:19 AM
I had the same thing happen to both my 5sp, always making a metal clunk in 1-2 change. Thought it was normal for Miatas in general.


Sent from my iPhone using Tapatalk

Normal in the sense that 2nd gear synchros wear out first on a transmission, I can't tell you why. I suppose it gets the most use.

You have choices: rebuild ($$$) or try RotorNut's magical fluids ($) or learn to shift thru the sweet spot, although there may be no sweet spot. Or live with it. I personally cannot stand the damned crunching, I think I am spending money on magic fluids.

RotorNutFD3S
10-25-2017, 08:00 AM
That stuff is $23 per qt. Does the 6 sp take two or (braces himself) three? Or better yet, 2.1.

Yeah, it's not exactly the least expensive option for fluids, but a lot of people swear by it. I've noticed an improvement on the 6-speed equipped cars I've worked on, with only one car showing no real change. NB 6-speeds take 2 qts.

tsingson
10-25-2017, 08:32 AM
I swear the price of that stuff changes by the dealer. I don't remember paying that much. Might want to call around.

kevinharrop
10-25-2017, 08:52 PM
Well, I have ordered three qts (my shop could not guarantee getting every drop of 2 qts from the bottle to the trans) at $17 per, ground shipping, should see it in a week or so, and then I'll give you a report.

chiefmg
10-26-2017, 06:07 AM
The drain and fill plugs for a 6 speed are on the left (driver's) side of the transmission. DO NOT remove any plug from the right side or you will regret it. Easiest way is to remove both plugs, once drained replace the drain plug and then fill from the top until fluid comes out of the fill plug. Oh yeah, and make sure your car is level (seems obvious I know, but I've read stories of people who didn't understand that).

tsingson
10-26-2017, 06:36 AM
You may want to try removing the top one first. That way if you can't, you don't drain it all and not have a way to fill it.

RotorNutFD3S
10-26-2017, 09:37 AM
You may want to try removing the top one first. That way if you can't, you don't drain it all and not have a way to fill it.

Always a good idea! Fortunately if that does happen, you can fill it from the shifter turret (6-speeds only). In which case you use two qts and be done with it.

kevinharrop
10-26-2017, 05:35 PM
Always a good idea! Fortunately if that does happen, you can fill it from the shifter turret (6-speeds only). In which case you use two qts and be done with it.

That's IF you can get your Nardi shift nob off the shift rod.

kevinharrop
11-08-2017, 08:36 PM
Well, I have finally got a couple of quarts of Rotornut's XT-M5-QS fully synthetic transmission gear oil into the tranny. I THINK it is an improvement. Shifting seems easier, and the crashing noise of grinding the 2nd gear synchronizer to a fine powder is less pronounced. But I need to evaluate it over a number of days, yes?

$120 later....

Agent☣Orange
11-08-2017, 11:44 PM
Crashing and crunching are very harsh words. Yes, see how your new fluid reacts and it may take a couple thousand miles.

kevinharrop
11-09-2017, 12:37 AM
Crashing and crunching are very harsh words. Yes, see how your new fluid reacts and it may take a couple thousand miles.

Thousands of mile? Let's hope not. And yes, it has been easy to have a very violent response to shifting from 1st to 2nd. Think good thoughts.

kevinharrop
11-09-2017, 12:41 AM
My wife is bugging me to take her for a long road trip in the Miata. She's a good girl.

I think a stop at Moss Motors in Goleta will be a part of the excursion.......

We'll see how the gear box responds to the new oil then, now won't we?

Agent☣Orange
11-09-2017, 01:07 AM
This hyperbole is starting to feel kind of creepy. We’ve gone from tranny fluid to an objectified wife.

kevinharrop
11-09-2017, 07:45 PM
This hyperbole is starting to feel kind of creepy. We’ve gone from tranny fluid to an objectified wife.

I don't know what you are talking about. Objectified wife my ass. Shall we avoid getting personal here? I would have expected more from a moderator.

And there was no hyperbole in my description of the noises my trans made with the old oil.

For those who care, I think the synthetic magic oil is a significant improvement. Early days, still.

Agent☣Orange
11-10-2017, 11:21 PM
I know, right? It’s like they let anybody in here nowadays.

kevinharrop
11-19-2017, 10:11 PM
Sorry, it sounds like crashing to me!

No, the new oil has not cured the trans.

The only way to have a near silent 1st to 2nd shift, and no sound going into 3rd, is to hold the clutch hard against the floor for way too long, and slowly draw the lever back. And that is not always successful. It certainly is not behaving as it should.

In my past experience with sporty cars and manual transmissions, it seems to me that the clutch pedal need not be all the way down to release the clutch and to perform a smooth shift. I had three MR2s and each could be shifted as fast as my foot and hand could do it.

There is adjustment on the shift pedal under the dash? I stuck my head down there and swore a blue streak; that is mighty inaccessible. I foresee having to pull the driver's seat out so that I can lie on my back to do the work.

I have viewed a few youtube videos ostensibly on the subject, but they were not good examples of the type.

Has anyone here got good experience adjusting the rod between the pedal and master cylinder that resulted in more complete disengagement of the clutch?

I'm starting to worry....

Agent☣Orange
11-19-2017, 10:38 PM
Kevin, between worrying about the perfect shift compared to your previous cars, I’ve often found it less stressful to lower my expectations, pay for new synchros or move to a different platform.

A good tranny oil needs a few thousand miles to work but regardless, I think you should sell your Miata, buy another Toyota and work from your base of experience.

kevinharrop
11-19-2017, 10:47 PM
Thanks for the advice, I'll stick with the Miata. This 6 sp is simply not performing as it should, and I'll continue to look for a good solution.

Are you suggesting that replacing the synchros is the solution?

And does it really take thousands of miles for the oil to make a difference? I have trouble seeing that.

Agent☣Orange
11-19-2017, 11:00 PM
Well, no. Not the first thing I’d do. I’m preaching acceptance more than solutions. For instance, every morning, when I start my current car, it shakes the whole car and sputters to life like I have an obnoxious cam which I don’t. Even my dentures fall out and I don’t even wear dentures. It takes a few miles before it smooths out. From a nostalgic perspective, I enjoy every moment of that obnoxiousness because I love its character.

Fill your tranny with some good Amsoil, RedLine or Motorcraft and be patient. If you’re seeking Formula 1 performance a minute later, you’ll be disappointed but if you are patient, your Miata will reward you.

*after new synchros.

kevinharrop
11-19-2017, 11:16 PM
And you don't think the clutch is out of adjustment? Because that now seems a likely villain to me.

HarryB
11-20-2017, 03:24 AM
Clutch master cylinder rod/pedal can be adjusted. Stick your head under the dash; pretty straightforward to do so. Also look for possible clutch cylinder leaks

kung fu jesus
11-20-2017, 09:19 AM
Clutch hydraulics. Replace them.

Then open another thread about the same subject. Again. :|

Martin
11-20-2017, 09:27 AM
949 has an inexpensive kit http://949racing.com/miata-clutch-HOK.aspx

kung fu jesus
11-20-2017, 11:49 AM
Our site's sponsor, Goodwin Racing, also offers a comprehensive kit for clutch hydraulics. It is on sale!

http://www.good-win-racing.com/Mazda-Performance-Part/61-1836.html

Martin
11-20-2017, 12:27 PM
Ah, I didn't know Goodwin has a kit :)

kevinharrop
11-20-2017, 09:42 PM
Our site's sponsor, Goodwin Racing, also offers a comprehensive kit for clutch hydraulics. It is on sale!

http://www.good-win-racing.com/Mazda-Performance-Part/61-1836.html

Well, that certainly is a keen price. Given that the system has 17 years and 134,000 miles on it, (I think, I need to check the receipts that I have) I can well imagine that it is funky. But I do wonder if it could all be cured by adjusting the pedal. I was looking for someone who has done that and found improvement in his shifting to perhaps throw me a tip or two.

kevinharrop
11-20-2017, 09:47 PM
Clutch master cylinder rod/pedal can be adjusted. Stick your head under the dash; pretty straightforward to do so. Also look for possible clutch cylinder leaks

Yes, as I wrote above, I know that. What I am asking for is someone with similar symptoms as mine finding the solution in adjusting the clutch, and hopefully, some comments on how to do so.

kung fu jesus
11-20-2017, 10:12 PM
Kevin, in 17 years of ownership, 4 Miatas, the issue you describe, it is more often failing clutch hydraulics. Usually the clutch slave, but it is cheap enough and easy enough (and highly advisable) to replace both the slave and master at this point. It will eliminate two failure points at the same time and reset that system in terms of maintenance.

Many people try to fix the issue with fresh transmission fluid, bleeding the hydraulics, messing with the clutch pedal adjustment, or rebuilding the shifter. My experience has been the hydraulics are likely the resolution.

Because you describe the pedal needing to be held deep and longer, that is a key sign to the hydraulic components weakening.

The braided line in those kits is worth every penny. It makes replacing the slave considerably easier and eliminates the failure of an aging, OE rubber line. My 10ae, a California car it’s entire life, had the rubber clutch line rupture after 13 year and 160k miles of use.

The other possibilities to crashing gears are worn synchos, bad engine mounts, or broken shifter bushings.

Good luck.

kevinharrop
11-20-2017, 10:27 PM
I knew I had seen something about the clutch in the PO's records: The switch has been replaced. That must be a pig to get at.

kevinharrop
11-20-2017, 10:34 PM
Kevin, in 17 years of ownership, 4 Miatas, the issue you describe, it is more often failing clutch hydraulics. Usually the clutch slave, ...................

The other possibilities to crashing gears are worn synchos, bad engine mounts, or broken shifter bushings.

Good luck.

Thanks. I know the shifter bushing is still tight, and that makes me happy. Not as happy as finding no rust when the car went up on the grease rack, but happy.

OK, I'll read the repair manual on replacing the clutch system. I'm not wild about replacing the whole pipe system with one braided hose, just because I like a original looking engine bay (but I will be polishing the valve cover in time!).

If you think the symptoms say replace the clutch hydraulics, I suppose I will.

kung fu jesus
11-20-2017, 10:42 PM
There are lines that just replace the rubber, but the only people who see you removed the lower pipe will have to be under the car.

They made a lot of these cars. An NB with 13x k miles and stock engine bay impresses no one, especially Mazda.

kevinharrop
11-21-2017, 10:07 AM
There are lines that just replace the rubber, but the only people who see you removed the lower pipe will have to be under the car.

They made a lot of these cars. An NB with 13x k miles and stock engine bay impresses no one, especially Mazda.

Wasn't trying to impress anyone. I just like a tidy engine bay. And damned right they made a lot of them. I rarely noticed them until I bought one, now they seem to be all over the place.

kevinharrop
12-23-2017, 09:28 PM
Well, it has been about 6 weeks and the oil DID improve the shift somewhat. The tranny can now be said to snick rather than crash, and that is an improvement. I am learning to shift slowly (which is unsatisfactory) and can feel the stress whenever I can hear it. About half the time there is no negative indication. That is an improvement.

I bought from Goodwin the cylinder replacement kit and installed them yesterday. One thing that was a nuisance was that I could not separate the flex line from the top of the lower hard line. I could not even remove the spring clip that holds that junction to the chassis. So at this moment both the original flex line and the lower hard line are still on the car, the hydraulics by pass them with the stainless flex line that came with the kit.

The sorry news is that I discern no improvement.

I really don't want to wrestle with adjusting the clutch pedal. Does anyone have any actual experience in making that adjustment that they would like to share?

Meanwhile I'll be saving for a transmission rebuild. Drat.

MiataQuest
12-24-2017, 09:50 AM
Are you sure the transmission fluid level is correct?
A low fluid level will allow the transmission main-shaft gears to spin excessively making shifting slower for synchronization.

Next give us some feedback on the clutch engagement point.
Do this procedure on a flat surface in a safe location.
1. Push the clutch pedal to the floor.
2. Shift the transmission into 1st gear. Did it engage easily or do you need to slightly force it?
3. While paying attention to the clutch pedal location, VERY slowly start to release the clutch pedal.
4. At what point does the car start to move? Clutch pedal near the floor, midway, or near the top?
5. At what point does the clutch pedal become fully engaged with no slippage? Near the floor, midway, or near the top?

I can walk you though how I adjust the clutch next if we think adjusting the clutch engagement point is needed. To adjust the clutch is actually pretty easy even for my 62 year old body.

If the clutch adjustment/engagement point is good, it could also be the clutch pilot bearing causing the shifting problem. It can give similar symptoms as being low on fluid.

kevinharrop
12-24-2017, 02:00 PM
I need to assume that the trans is full. I had the fluids replaced with the Motorcraft synthetic by my shop. I'm pretty confident that they filled it up.

I'll run that test on the clutch soon and report back.

Possibly we will see if my 58 year old body can do what your 62 year old body can.

kung fu jesus
12-24-2017, 02:54 PM
If you can, find another 6 sp Miata owner and ask to drive their car and vice versa. It may help give you a baseline or least comparison to how it should feel.

kevinharrop
12-24-2017, 04:15 PM
If you can, find another 6 sp Miata owner and ask to drive their car and vice versa. It may help give you a baseline or least comparison to how it should feel.

Good idea. I attended my local enthusiasts' meet for the first time Friday. Not a large turnout due to the cold and Christmas. The vast majority of cars were NAs. There was a very crisp NB2 that I would have been afraid to drive, it was so nice. I could have asked him (assuming it was a 6 sp) to drive mine and tell me what he thought.

I'll hope there is a 6 sp the next time I attend.

kung fu jesus
12-24-2017, 04:24 PM
I have to reiterate, the 6 has never felt as fluid as the 5. Just my opinion.

If the ‘crashing’ is more pronounced at higher RPMs, try to observe how the engine rocks in the bay, perhaps side by side with another Miata with known fresher engine mounts. Worn engine mounts will pull the engine and transmission over, making the shift action chunky.

I don’t know I would recommend a trans rebuild. A known low-mileage donor would be a lot cheaper.

Agent☣Orange
12-24-2017, 06:14 PM
My ‘02 had a 6-speed while I was living in the Pacific Northwest. I initially had the grind on winter mornings. It’s just the nature of a mechanical beast when everything is cold. Motorcraft (German) was expensive but did help tremendously, especially over the years.

Now I look back on it nostalgically because we no longer have pull-out chokes and pumping the gas pedal but I did need to give my Miata a while to warm up and settle down. Six-speed was admittedly notchier than the 5-speed but supposedly stronger, a whole other debate. I did like being able to fill my 6-speed from the turret though.

kevinharrop
12-24-2017, 06:31 PM
I did like being able to fill my 6-speed from the turret though.

The start of that filling process is to remove the window switches. Which I tried to do and got nothing but damaged plastic. 17 year old plastic seems a bit brittle. I could not get my switches out.

Agent☣Orange
12-24-2017, 06:57 PM
There’s a lot of old “wisdom” on another forum such as the idiotic, yanking out ball vents with a shoe string that was relevant two decades ago before better methods were found. I’ve seen a few Miatas with ugly knife and screwdriver marks on the console from removing the center switches. Old, textured plastic is indeed hard to remove, even harder to replace. Get a set of nylon panel tools available everywhere and be patient.

chiefmg
12-24-2017, 07:27 PM
You DO NOT have to remove the window switches in an NB1 in order to pull the center console. There is no screw underneath holding it in like the NB2s. There are two screws inside the storage at the back, two more at the front and that's it. You do have to remove the wiring from the window switches but that's easy enough to do once you get the console into the air. FYI there are brand new switches available on eBay for around $70 (just be sure to get the right color).