It’s been happening more and more on the Miata. At 200k miles, it’s not surprising. My question is motor mounts or diff bushings? Or both? I want the 2-5 shift problem solved, but I don’t need a ton of nvh. The Miata shakes, rattles, and rolls enough as it is.
I feel like 5th to 2nd may make you sadder.
Transmission mounts, engine mounts, rear end mount then shifter bushing is my go for inspection.
In reply to wearymicrobe :
Quite true! But the Miata doesn’t have trans mounts due to the PPF. The motor mounts seem the easy button. The diff bushings are supposedly a PITA.
In reply to wearymicrobe :
Trans mounts should never affect it, especially on a Miata which doesn't have them.
Engine roll is controlled by the engine mounts, engine pitch is controlled by the trans mount on vehicles that have them, the PPF on things that don't. I would THINK that the PPF is flexible enough in twist that the diff mounts would not affect engine/trans roll to any significant degree, since it's an open C channel with holes in it.
Mostly the smoothcase shifter setup kinda sucks. RX-7 guys have long had lots of issues with 2-5 shifts, or rather 2-balk shifts as the shift rod tries to find a home between the 3-4 and 5-R fingers. I'm shocked that Miatas shift as well as they do given that it's the same design, I've never 2-balk shifted a Miata.
Now I wonder if there were contour updates made to the Miata shift fingers, and they wear out to look like RX-7 fingers...
5th to 2nd makes you explodier.
In reply to Appleseed :
Ah yes, there was an RX-7 mailing list post where someone lamented destroying an E36 M3 engine. Someone else's E36 M3. A NEW one. At a track day.
"Around and around the Firebird track
The engine was really revvin'
Shifted to second when I wanted fourth
Pop! goes the engine"
They had pretty mushy engine mounts, this was kind of a problem people had with the cars. And he was trying to UPshift from 3rd to 4th.
IIRC he was on the hook for $10k thanks to that oops.
I had the same problem in a specmiata with a higher mileage transmission. You may need to adjust your shifting technique a bit. I let the shifter centering springs do the work for 2-3 shifts. I use the bottom of my palm on the shift knob and push slightly diagonally from 2nd to 3rd but don't force it. I haven't had a problem in any Miata since.
This was my experience at least. Bushings may help but it was more technique for me.
wearymicrobe said:I feel like 5th to 2nd may make you sadder.
Try going from 5th to 6th...in a transmission that doesn't have 6 gears.
Will said:wearymicrobe said:I feel like 5th to 2nd may make you sadder.
Try going from 5th to 6th...in a transmission that doesn't have 6 gears.
Did you hit R for Race?
On the Miata, do the motor mounts. The PPF does indeed twist, so the diff bushings won't make any difference. I've seen stock engine mounts broken at 60k miles. It may be worth rebuilding the shifter in case there's some slop in there.
It's also a timing issue. What's happening is you're trying to slot 3rd right when the engine unwinds from the cut in power, and all of a sudden 5th is where 3rd used to be. The fairly tight gates in the Miata don't help. It's most likely to happen on an aggressive shift when the engine movement is greatest and you're rushing your timing a bit.
Appleseed said:5th to 2nd makes you explodier.
The 3rd to 2nd accelerating was the only thing I could do to take out my leaning 225. I’d tried everything else...
Keith Tanner said:Will said:wearymicrobe said:I feel like 5th to 2nd may make you sadder.
Try going from 5th to 6th...in a transmission that doesn't have 6 gears.
Did you hit R for Race?
You hit "Honda built a lockout to prevent a 5-R shift but apparently Ford didn't and oh my god I can feel the rattle from the shift lever in my teeth" gear.
In reply to Keith Tanner :
That is exactly when it happens. Aggressive shifting near redline. If I shift slow it’s fine, if I shift at General cruising speed it’s fine.
Just need to get this tackled before autocross season. Off to buy competition mounts.
Will said:wearymicrobe said:I feel like 5th to 2nd may make you sadder.
Try going from 5th to 6th...in a transmission that doesn't have 6 gears.
The ultimate money shift
Keith, ordered some comp mounts just now. Website wouldn’t take my Apple Pay, kept saying address isn’t real. Just used PayPal instead. Not sure if that’s my end or you guys. But throwing it out FWIW.
A little off topic but kind of relevant.
Can one use wedge shims of some description to rotate an engine and gearbox a couple of degrees? The bell housing I used to mate a ribcase to my f2 doesn't clock the gear box as far as it should meaning I've got preload on my engine mounts and transmission mount and I'm picking up an occasional 2-5 shift myself.
Also for the 2-5 shift problem if it's not engine mounts, pull the shifter out and see if the little bush on the end of the shifter is still there or if it's shattered and gone AWOL. I agree with others that it's more a mount issue, but a self destructed bush has given me dramas finding the right gear in the past.
Fun fact, smooth case and rib case shifters are interchangeable.
Thanks for letting me know, I'll look into it.
wae and I did this multiple times at the $2017 Challenge drags. Didn’t even think about motor mounts being a possible issue. One more thing to check on when I resurrect the Miata in the spring.
In reply to daeman :
Depending on which way you needed to go, you could put spacers under one of the engine mounts, or you could put a pinion angle shim designed for leaf spring axles under the trans mount. They're generally available in several sizes like 3 degree, 7 degree.
I recently fixed the engine mounts on my RX-7 (FB chassis, FC engine mounts, with an HB style engine as a base - which was a chassis not sold here...) and found that my shifter now runs hard into the handbrake when in 1st and 2nd. It's not falling over to the exhaust side anymore, you see.
In reply to Knurled. :
Sweet, I was thinking truck alignment shims or leaf spring shims might be a goer! I had to drill a second set of holes for the trans mount and pie cut and weld a shifter to get enough space to shift 5th-R without it fouling on the floorpan and dust boot. but that's only a short term fix, I'll end up tearing mounts if I can't get the load off them.
In reply to daeman :
My shifter is the stock RX-7 shift lever, with the top rubber-bushed half removed and a bent over piece of Ford inner tie rod end welded in its place. (Might have been from a US-version Mk3 Escort, might have been from a Tempo, which was sort of based on that and I don't think had ever infected any other continent) I'm pretty sure it was a Ford because almost everybody in the world uses 14x1.5 tie rod ends and this one was an M12 thread, which was easily retapped to take the Mazda shift knob. It sits much further back and to the left, to match the extended steering wheel...
It was all well and good when I constructed it, before when the engine mounts were off.
In reply to Knurled. :
Don't you love when you find a parts bin solution only to be foiled by some minor issue because they were never intended to be used in that configuration....
Yes of course I can bolt the transmission I want to this engine, so long as I feel like making a mishmash clutch kit and don't mind not being able to get 5th or reverse without vehicular surgery.... Why do we do this to ourselves? And we're mental enough to call it fun....sick individuals the lot of us.
The diff bushings are supposedly a PITA.
That's only true if you don't know how to swing a hammer. I just put a bigass socket over it that fit it well and smacked the E36 M3 out of it and it pretty much flew out. I did take some care in how i braced the diff arms so as not to crack them off when doing this. Also there's ball joint press, shop press, blah blah. I like hammers and rarely use my press.
Yup, hammer blows and a socket make it easy. But you have to pull the diff to do it, so it is more involved than the motor mounts.
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