Thanks - I own an RX8 R3 now (and questions about gearbox/clutch)

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Re: Thanks - I own an RX8 R3 now (and questions about gearbox/clutch)

Post by New Duke » Wed May 13, 2020 10:28 pm

I've been told that the RPM difference is precisely why the gearbox (usually) lasts longer on the MX5. I also think it's reasonable to assume that RX8 gearboxes are, in general, likely to be abused more than MX5 ones. I certainly know of plenty of MX5 gearboxes to fail though. The 'bulletproof MX5' rep is a bit of a myth IMO. My MX5 certainly wasn't more reliable than my RX8.

I wouldn't give too much pause to how quickly YouTubers can change from 1st to 2nd. Video can't convey whether they're simply smashing the gear in and damaging the box, or if their insides are already smashed to mush. Nuances you can feel in your own car.

Might help not to think of the gearbox (or the RX8) in normal terms. It's a high revving real sports car, in a world where 'sports car' is applied much too often. 10ish years and tens of thousands of miles is a very reasonable life span for a sports car gearbox, IMO.

I think of the gearbox as a consumable, just like tyres, brakes, ignition components etc. I appreciate that you'd prefer not to have a S1 gearbox, but when I can have a S1 gearbox fitted for less than the price of a set of new tyres... it's really not too bad and I focus on other things.

(The S1 gearbox is tougher than the one used in the R3 and the NC MX5, but has weaknesses too. When you combine this performance and low price point then there are bound to be compromises)

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Re: Thanks - I own an RX8 R3 now (and questions about gearbox/clutch)

Post by R1DSO » Sat May 16, 2020 12:22 am

Interesting to hear the RPM is the biggest stress point here. Instinctively, I would have thought that torque would have been more of a factor, however I’m no gearbox tech :lol:.

I personally wouldn’t rule out an S1 box, although I’d prefer to rebuild the R3 tranny with uprated parts if such a thing could be done for sensible money. Amusingly, I couldn’t help noticing a load of threads on the US OC forum about failing S1 boxes, reporting that the S2 was better. In fairness, most of these seem to be from around the time the S2 was coming out, so too early to judge. And ‘driving stick’ doesn’t always come naturally to our American friends :lol:.

Compared to some of the reports on here, my gearbox still seems to be in pretty good shape for now. I took the car out for it’s first long drive today since the maintenance I’ve been doing on it. It’s only had the odd 20-30 minute outing to date, but today it got a good 1 hour 30.

Gear shifts are consistently stiff and notchy for the first 5-10 minutes before the Redline MT-90 warms up. I’d come to expect that as normal and continued 2nd to 3rd notchiness after that. However, interestingly, I guess the oil must have benefited from the additional warm-up time as after 40mins, all the notchniess had gone :shock:.

The car was still sometimes hanging on to 1st under heavy load, though. Even with my best mechanically sympathetic changes, it often feels like it doesn’t want to come out of 1st, then, with enough shifting pressure, it sort of pops out. This means that I end up changing so slowly that the car’s revs have dropped, which counter-productively makes me want to put more stress on the box by hangIng on to the beeps in 1st before changing, to maintain some momentum.

The drag race shifts at 6:20 in this old video from bonkers Japanese channel Best MOTORing is an example of the 1st to 2nd shift speed I’ve seen. Even if I was being mechanically unsympathetic, I don’t think I’d be able to physically change gears that quickly in my car due to its hanging 1st gear thing:



I’ve also noticed an occasional slight thud and some movement when depressing my clutch when the car is warm and stationary (or almost stationary) and I’m about to put it in 1st. Given I’ve replaced and bled the clutch fluid, this makes me wonder whether the hanging 1st symptom is something clutch or clutch cylinder related :-k.
Last edited by R1DSO on Sat May 16, 2020 9:06 am, edited 4 times in total.

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Re: Thanks - I own an RX8 R3 now (and questions about gearbox/clutch)

Post by V8 Power » Sat May 16, 2020 8:22 am

The general stiffness/notchy action when cold is normal for R3’s (well it was for mine) but the sticking in 1st is not so sounds like something is amiss.
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Re: Thanks - I own an RX8 R3 now (and questions about gearbox/clutch)

Post by New Duke » Sat May 16, 2020 3:09 pm

:whathesaid: It's normal when cold for the gearbox to be really stiff and unpleasant. It can take longer than you might expect to warm up too depending what driving is being done.

Good to hear that the longer drive helped a bit. I wonder if what it needed was a long, hot drive to properly re-lube all the internal components. Long (like an hour +) drives and being driven hard once warm really is what these cars like (and IMO need). Maybe the car was driven mostly on short drives by the previous owner/dealer too before you got it. I spent years slowly fixing the neglect of previous owners.

It does sound like you have some gearbox wear though sadly. I had similar symptoms on mine. The next phase for me was losing 4th gear. But that was on track under stress that you won't reach on the road... so I don't want to be alarmist.

In case you want a reference for the change speed of a healthy gearbox, yesterday I uploaded some audio to the first post of this thread: viewtopic.php?f=5&t=81839
If you skip to 01:15 then you'll hear a pull away from 1st, then shifts into 2nd and 3rd. So you can compare that with how yours is doing and how much/if it's slower than normal.
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Re: Thanks - I own an RX8 R3 now (and questions about gearbox/clutch)

Post by Mpv2k3 » Sat May 16, 2020 7:09 pm

Since late last year I found that I had trouble getting into some gears to the point that it just felt like the gear just didnt want to budge even with quite some force behind it.

There was an occasion at Brandshatch last December when it happened on track with Ian mothersole in the passenger seat.

Naturally I thought it was my syncro rings failing again as I had these replaced around 2015.

Forward to this year after I had some car work done, my mechanic drove my car to collect me from the station and commented on the gearbox.

He suggested it may be my clutch slave cylinder or master cylinder and should replace both as it could be either. He was only able to get the clutch slave cylinder as the lockdown kicked in and the other part was still at the dealership.

We replaced this part and lucky enough it seemed this was the part failing by sticking.

The gear changing is perfect now. :thumleft:
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Re: Thanks - I own an RX8 R3 now (and questions about gearbox/clutch)

Post by warpc0il » Sat May 16, 2020 8:15 pm

Sometimes the issue is just the clutch hydraulic line, still filled with old and tired fluid.

Many garages/dealers/owners ignore the clutch line when replacing the brake fluid, despite it sharing the same reservoir.

The clutch line can also be awkward to bleed, both for access and the lack of pedal resistance, which means that it often gets left with some air in the line.

I'm sure that many have gone to the trouble of replacing the slave cylinder and/or line, which has solved the problem, but was bit of an overkill.

Note that early 2004/05 cars did have an issue with the slave cylinders, as fitted in production, that causes the clutch to drag when the powertrain is really hot, e.g. stuck in traffic. This does require replacement to resolve.
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R1DSO (Sun May 17, 2020 10:44 pm)
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Re: Thanks - I own an RX8 R3 now (and questions about gearbox/clutch)

Post by R1DSO » Sun May 17, 2020 11:07 pm

New Duke wrote:
Sat May 16, 2020 3:09 pm
:whathesaid: It's normal when cold for the gearbox to be really stiff and unpleasant. It can take longer than you might expect to warm up too depending what driving is being done.

Good to hear that the longer drive helped a bit. I wonder if what it needed was a long, hot drive to properly re-lube all the internal components. Long (like an hour +) drives and being driven hard once warm really is what these cars like (and IMO need). Maybe the car was driven mostly on short drives by the previous owner/dealer too before you got it. I spent years slowly fixing the neglect of previous owners.

It does sound like you have some gearbox wear though sadly. I had similar symptoms on mine. The next phase for me was losing 4th gear. But that was on track under stress that you won't reach on the road... so I don't want to be alarmist.

In case you want a reference for the change speed of a healthy gearbox, yesterday I uploaded some audio to the first post of this thread: viewtopic.php?f=5&t=81839
If you skip to 01:15 then you'll hear a pull away from 1st, then shifts into 2nd and 3rd. So you can compare that with how yours is doing and how much/if it's slower than normal.
That sound recording sounds great =D>. I think I read that you’re running an un-resonated decat, which I’m assume gives the sound you’re getting with a stock exhaust. My still resonated stock ghetto decat sounds subdued in comparison, albeit I know a mic at the exhaust end picks up more than you get in the cabin.

Really helpful to hear those 1st to 2nd shifts. I think these sound quicker than what I’m getting under load, but I’ll do an iPhone recording to compare once I’ve sorted out my CEL issue. The weird thing is that my sticky shift is just under load, though – 1st to 2nd shifts are fine when not flooring it. I’ve taken to quickly popping the stick from 1st to the gate space between 3rd and 4th before changing up to 2nd to help.

Interesting to hear the RX-8 like long hard runs. Even more of an excuse to use it :D. Maybe I’m being overly sensitive to the 1st/2nd issue, but I am planning to to track the car once my ignition coils turn up and I can get a ticket. So, in the back of my mind, I’m thinking that any existing issues have the potential to get work under the strain of track work.

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Re: Thanks - I own an RX8 R3 now (and questions about gearbox/clutch)

Post by R1DSO » Sun May 17, 2020 11:10 pm

Mpv2k3 wrote:
Sat May 16, 2020 7:09 pm
He suggested it may be my clutch slave cylinder or master cylinder and should replace both as it could be either. He was only able to get the clutch slave cylinder as the lockdown kicked in and the other part was still at the dealership.

We replaced this part and lucky enough it seemed this was the part failing by sticking.

The gear changing is perfect now. :thumleft:
Although it’s a relatively cheap part, I won’t be looking forward to a slave cylinder replacement if that becomes an area to investigate. Keeping the gearbox in place, it looks like even more of a PITA to get too than the clutch fluid bleed nipple #-o.

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Re: Thanks - I own an RX8 R3 now (and questions about gearbox/clutch)

Post by R1DSO » Sun May 17, 2020 11:22 pm

I’ve been watching some of this guy’s videos and the thing that has struck me is how logical gearbox internals are. To my (fairly amateur) eyes, it seems a lot simpler than a rotary engine rebuild:

https://www.youtube.com/user/GearWorldTV

He’s into US trannies, which may well be simpler than The Mazda equivalent. And, from reading one of Dave’s posts, I’m aware that there are minute tolerance considerations when replacing parts and Mazda issued a whole separate service manual for the box.

However, I’m still surprised how little there seems to be on DIY RX-8 gearbox rebuilds. Perhaps the abundance of cheap S1 replacement boxes negates the need, but I thought there would be more documented instances of DIY owners giving it a go out of interest, or to use uprated internals.

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Re: Thanks - I own an RX8 R3 now (and questions about gearbox/clutch)

Post by warpc0il » Mon May 18, 2020 1:01 am

I know of a few members that have stripped their S1 'boxes, to determine what was damaged; in all but one case it had been the 4th gear sychro due to GL-5 or GL-4 oil being used.

In the one exception the box was a complete mess after it appears that the oil had never been changed in over 80k miles. :shock:

The S1 6-speed gearbox repair manual is here viewtopic.php?f=58&t=60547
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R1DSO (Mon May 18, 2020 5:04 am)
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Re: Thanks - I own an RX8 R3 now (and questions about gearbox/clutch)

Post by R1DSO » Sat May 23, 2020 11:14 pm

warpc0il wrote:
Mon May 18, 2020 1:01 am
I know of a few members that have stripped their S1 'boxes, to determine what was damaged; in all but one case it had been the 4th gear sychro due to GL-5 or GL-4 oil being used.

In the one exception the box was a complete mess after it appears that the oil had never been changed in over 80k miles. :shock:

The S1 6-speed gearbox repair manual is here viewtopic.php?f=58&t=60547
Thanks Dave :thumleft:. I see the link also mentions a manual for the R3 transmission. Is that still available/shall I PM you regarding it? I wouldn’t mind some bedtime reading, even if only to familiarise myself with what’s going on in the box theoretically.

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Re: Thanks - I own an RX8 R3 now (and questions about gearbox/clutch)

Post by warpc0il » Sat May 23, 2020 11:21 pm

I'm still waiting for the R3 6-speed transmission manual to appear, so I can add it to the library
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R1DSO (Sun May 24, 2020 12:11 am)
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Re: Thanks - I own an RX8 R3 now (and questions about gearbox/clutch)

Post by R1DSO » Sun May 24, 2020 12:11 am

warpc0il wrote:
Sat May 23, 2020 11:21 pm
I'm still waiting for the R3 6-speed transmission manual to appear, so I can add it to the library
Got it, thanks :).

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