Short shifter rattle

[davekmoore]

Had a short shifter on the car for 80,000 kms. It rattled from day one although installed by a mechanic rather than me (the latter would have caused more than just a rattle).

There have been a couple of helpful suggestions such as replacing the bottom bush or the whole turret kit from a standard car but it doesn't seem logical that either of these would solve a rattle that was there from day one - and on a non-standard piece of kit.

So I built up some courage today and dismantled the fippin thing. Everything appeared to be tight and intact and complete. The only issue seems to be some upward and downward movement on the bottom bush. It's a green poly bush. Please see the pics as a guide to hopefully suggesting a solution?


Short shifter with extended lever and Voodoo knob. It rattled with the standard short short shifter. Still rattles with the long lever. Still rattles with the piece of rubber pipe added to the extender to make it fit the gaiter better. Pretty isn't it? The pipe seems to cut down some of the extra heat from the gearbox though.


Intact upper boot. All bolts were fairly tight. Needs a clean (spilt beer on it).


Side pic of upper boot showing attachments.


Intact lower boot. All bolts were tight.


Fitting below lower boot upside down. Gasket intact.


All seems good apart from the up and down movement on that green bottom bush. Other ones I've seen are white, not green, I think?




Final pic

Sorry this is so long winded but I really am ready to be rid of this damned rattle, if only so I can start work on getting rid of all the other less annoying ones.

By the way, it's surprising how much more gearbox, engine and road noise and heat there is driving the car around with just the bottom boot attached. Yes, this does mean I managed a partial reassembly! I might treat myself to a replacement for the previously discarded sound proofing when I finally reassemble it with the solution you can hopefully provide.

[tescoking]

Could be the bushing smaller than the OEM one. Is it metal or plastic/rubber?

[davekmoore]

Plastic.

After all this, do you think the supplier maybe provided the wrong sized bush?

If so, that'll make me grumpy on the one hand and delighted on the other that there's a simple fix http://www.mx5mania.com.au/product1653.htm Hopefully the fact that Mania's one is white and mine is green means there are different sizes and the white one will solve the problem.

[tescoking]

Plastic.

After all this, do you think the supplier maybe provided the wrong sized bush?

If so, that'll make me grumpy on the one hand and delighted on the other that there's a simple fix http://www.mx5mania.com.au/product1653.htm Hopefully the fact that Mania's one is white and mine is green means there are different sizes and the white one will solve the problem.

Mine is white

[Nevyn72]

I suspect the bushing is the wrong size, the Miata Roadster short shifter kit supplies a different bushing depending on what box you have and from memory the later model NB 6-speed uses a slightly larger bushing than all earlier boxes....

From the MR site in this link;
http://miataroadster.com/miataroadster/ ... 63251.aspx

HISTORY OF MIATA SHIFTERS:

For NB2 6-speeds, Mazda enlarged the OD of the tip of the shaft (from 15mm to 17mm) and the ID of the hole in the turret (from 19mm to 21mm) vs. all NA/NB 5-speeds and NB1 6-speeds which share the smaller dimensions.

To complicate matters, all NB1/NB2 6-speed shafts have the same shorter distance between the axes of the fulcrum balls and tip balls vs. all NA/NB 5-speeds.

To economize on manufacturing our kits, MiataRoadster uses the same 15mm size tip on all shafts and uses proprietary thicker-walled bushings for NB2 6-speeds.

If you’re swapping a tranny, the VIN riveted onto the side of its case will confirm its source.

To the best of my knowledge, the breaking point between the NB1 and NB2 6-speeds is the VIN ending in -220738. This should apply worldwide.

Mazda:

NA/NB 5-speed
&
NB1 6-speed:
shaft tip 15mm D
turret hole 19mm D

NB2 6-speed:
shaft tip 17mm D
turret hole 21mm D

MiataRoadster:

NA/NB 5-speed
&
NB1 6-speed:
shaft tip 15mm D
turret hole 19mm D

NB2 6-speed:
shaft tip 15mm D
turret hole 21mm D

So measure your shifter tip, bushing size and inside diameter of the turret hole while you have things apart and see if you have the right size one!

Then check to see if the one supplied in the Mania kit will solve the problem if it's the wrong size.
It may not as the kit from Mania is designed to refurbish the factory shifter and you shift lever isn't factory......

If you need a different size to Mania offers then get in contact with Bill at MR and see if he can help you with one of the options he uses in his kit....

[de Bounce]

Replace the metal gear knob with the OEM leather and plastic knob

[davekmoore]

Replace the metal gear knob with the OEM leather and plastic knob

Thanks for the suggestion. These options have been eliminated as the source of the rattle.

[davekmoore]

Thanks Nevyn. I've ordered a replacement standard bush. Fingers crossed!

[tescoking]

Thanks Nevyn. I've ordered a replacement standard bush. Fingers crossed!

If that was their mistake then tell them to give the new one to you for free

[davekmoore]

Thanks Nevyn. I've ordered a replacement standard bush. Fingers crossed!

If that was their mistake then tell them to give the new one to you for free

Yup, I'd normally do that, except I've had the shifter for years and cant be sure who I got it from. The bush is only $10 in any case. Hopefully it will solve the problem.

[tescoking]

Thanks Nevyn. I've ordered a replacement standard bush. Fingers crossed!

If that was their mistake then tell them to give the new one to you for free

Yup, I'd normally do that, except I've had the shifter for years and cant be sure who I got it from. The bush is only $10 in any case. Hopefully it will solve the problem.

Hopefully is the bushing size problem, otherwise, you might need too look into the clutch and the transmission.

[davekmoore]

Hopefully is the bushing size problem, otherwise, you might need to look into the clutch and the transmission.

Thanks for the thought. Already eliminated from my enquiries. The problem is defo somewhere in the gearshift mechanism. It will be great if the bushing, which will arrive on Tuesday, solves it. If not, I'll be looking for other solutions within the gearshift assembly only.

[de Bounce]

Replace the metal gear knob with the OEM leather and plastic knob

Thanks for the suggestion. These options have been eliminated as the source of the rattle.

The gear shifter shaft is the source of the rattle as the shaft has no internal damping, therefore any noise is transmits into the cabin.
The big metal ball (gear knob) acts as a amplifier.
The OEM knob is made of plastic and leather and should absorbs some of the noise making it quieter.

Mine went from a continuous rattle to a rattle at about 6500 rpm and up.
Makes for a good rev limit indicator.

If you want to eliminate the rattle, replace the SSK with the stock shifter!

[davekmoore]

Turns out Mazda replacement part, although bigger, has a thinner wall so the ball at the bottom of the shifter wobbles about even more.

Hopefully this will solve it http://www.miataroadster.com/miataroads ... 63717.aspx

Will report.

[Nevyn72]

Did you make sure you got this sized bushing?

shaft tip 15mm D
turret hole 21mm D

Come to think of it, you never mentioned whether you actually measured the shaft tip and turret hole?