6 Speed Miss-shifts - fixes

The American · Postby **The American** » Sat Jun 11, 2016 6:52 pm

Hi All,

I've got an NB2 6 speed, with Miata Roadster shifter. The shifter improved shifts but I still regularly struggle with finding third on track. Today at the Wondai Sprints I fumbled a downshift coming into a chicane and the extra time I spent wrestling with the shifter meant I muffed the chicane and ran off the track. No damage fortunately!

Watching my videos, I can see that the shifter moves around a lot under power, braking and in corners.

I have new standard engine mounts and rubber/standard diff mount bushes. I am thinking that solid or polyurethane bushes will stop some or all of this movement.

Has anyone got before and after experiences to share, or another way you fixed this issue?

ManiacLachy · Postby **ManiacLachy** » Sat Jun 11, 2016 7:26 pm

No first hand experience, but as soon as you mentioned the shifter movement my first thoughts were engine and diff mounts. You could probably go delrin diff mounts, and some poly engine mounts as NVH shouldn't be a deterant to you like it would for many.

See thecarpassionchannel videos for installs on both, and the differnces he's experienced.

rascal · Postby **rascal** » Sat Jun 11, 2016 7:32 pm

Defintely go stiffer engine mounts. You notice it even when adding hp to a nat asp car, so a turbo one definitely needs them..

Steampunk · Postby **Steampunk** » Sat Jun 11, 2016 7:53 pm

Be careful RE how stiff the mounts are. First hand experience that polyurethane diff mounts are a no-no if you use your car regularly as a regular street car as NVH increase is massive. Never experienced stiffer engine mounts but from other forums, the word is, once again, go too stiff and NVH increases dramatically. Worse case I've heard is interior components getting shaken apart/loose and nausea inducing even on short trips.

I can't see how stiffer diff bushes will improve shifting, especially since you've got new rubber ones.

First thing to check is the bushes on the short shifter.

Postby **NitroDann** » Sat Jun 11, 2016 8:00 pm

You want this style of combo.

The American · Postby **The American** » Sat Jun 11, 2016 9:00 pm

NitroDann wrote:You want this style of combo.

Sorry Dann, which?

Postby **NitroDann** » Sat Jun 11, 2016 9:09 pm

http://www.good-win-racing.com/Mazda-Pe ... 08478.html

like that, stock coldside poly hotside.

90% of the benefits of stock, 90% of the benefits of aftermarket.

Dann

ManiacLachy · Postby **ManiacLachy** » Sat Jun 11, 2016 10:14 pm

I have a set of these 949 Hyrbids on my shelf awaiting install some day http://949racing.com/Supermiata-hybrid-motor-mount.aspx, they consist of a mazdaspeed rubber mount and a poly mount, which is what I think Dann is describing.

But you only use your car in competition these days, don't you? So, I'd think a full set of polys would be the ticket for you. I can't imagine you care too much if you induce a little extra vibration at idle.

davekmoore · Postby **davekmoore** » Sat Jun 11, 2016 10:30 pm

ManiacLachy wrote:But you only use your car in competition these days, don't you? So, I'd think a full set of polys would be the ticket for you. I can't imagine you care too much if you induce a little extra vibration at idle.

2 x poly engine mounts is a lot more vibration at idle, but you might not care, bearing in mind the benefits..

The American · Postby **The American** » Sun Jun 12, 2016 7:21 am

Thank you everyone

I put poly diff mounts in my last car when I installed a TorSen. At first I thought the diff was shot, but I soon got used to the hum. I only had stock power in that car, and it was the 5sp - no problems shifting ever.

I'll put engine mounts on the shopping list!

chops · Postby **chops** » Sun Jun 12, 2016 4:46 pm

That hybrid combo looks like an excellent idea for a car that sees the street. I have just installed super Miata competition mounts on my track car and don't reckon they would be a lot of fun on the street

pezchops · Postby **pezchops** » Sun Jun 12, 2016 5:29 pm

probably something you already checked, but my nb8b had excess stick movement and gear selection going crap.
i found the 4 bolts holding the shifter housing to the gearbox where not tight.
the housing is not dowelled, and the bolts are not a fitted size, so you end up with a lot of play.
torquing the bolts fixed the problem.

davekmoore · Postby **davekmoore** » Sun Jun 12, 2016 6:33 pm

.... plus Loctite.

The American · Postby **The American** » Tue Oct 18, 2016 10:32 pm

So, after exchanging emails with Blackbird Fabworx for about a month, I can't get them to actually issue me with any details so I can pay for a set of their engine mounts. Who knows why - they seem super keen whenever I can get a response.

Does any one else have a recommended supplier?

madjak · Postby **madjak** » Tue Oct 18, 2016 11:11 pm

I have finally fixed my mis shift issues once and for all.

I already had poly engine mounts, MR short shifter and Energy Suspension bushings in the diff but I still had movement during big sweepers. So I bought two m10 rod ends, tapped them into an ally bar and bolted a solid brace from the chassis to the head. Now the engine can't move at all and you can feel it in the shifting. It's great.

Of course the car shakes lots now. At least you know if anything is loose cause it falls off in a couple of mins of idling!