Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community - FT86CLUB - View Single Post - Root Cause Found?... short shifter RATTLE

grumpysnapper · 03-16-2022, 11:14 AM

That gear stick rattle has bugged me for years.
I've fitted 4 different short shifts, the latest being the IRPv3.
The only one that didn't have some degree of rattle was the TRD version.
I loved the KartBoy, but it was bad...and I really love the IRPv3...but it is bad.

So I've recently decided to spend (many) hours and hours under the car, under friends cars, looking, playing, padding, insulating, greasing, installing, uninstalling, changing bushes, tightening, loosening, pushing, pulling, prodding....you name it.

I think rattle has nothing to do with the shifters themselves (although they transfer the effects differently). It also has nothing to do with the shifter being body mounted or on its original gearbox mount (ie. KartBoy and IRP both rattle)

I believe the rattle comes from the gear selector shaft after it passes through the oil seal into the rear gearbox extension. There is up to a millimetre (and maybe more) of "play" or "wobble" in the shaft, which then vibrates passing along the selector shaft then up to the shifter lever.

This "play" has been evident in pretty much every 86/BRZ that I've now crawled under. There is no bearing holding the shaft in place, it simply sits in a flexible oil seal that allows easy movement, and transfer of internal vibration from inside the box.

To test my theory I took a (large) zip tie, looped it up over the selector shaft near its entry point at the oil seal, and zipped it up as tightly as I could around the bottom of the rear gearbox extension.... securely holding the shaft down. Not practical, and not a real solution.

BUT it worked...no rattle at all in 3rd ( but because it is such an agricultural solution, then 4th worked less well until I changed the position of the zip tie along the shaft.... and of course 3rd started getting noisy again...and vica versa)

Could the oil seal be replaced by a bearing? If not, is there a way of holding the selector shaft firmly, centred in its action, in place (without forcing it downwards)?

Sadly, if I'm right, this is not good news as far as I'm concerned, as it indicates a fundamental design flaw.

03-16-2022, 11:14 AM	#1
grumpysnapper Senior Member Join Date: Jan 2020 Drives: BRZ Location: Brisbane, Australia Posts: 352 Thanks: 309 Thanked 608 Times in 209 Posts Mentioned: 6 Post(s) Tagged: 0 Thread(s)	Root Cause Found?... short shifter RATTLE That gear stick rattle has bugged me for years. I've fitted 4 different short shifts, the latest being the IRPv3. The only one that didn't have some degree of rattle was the TRD version. I loved the KartBoy, but it was bad...and I really love the IRPv3...but it is bad. So I've recently decided to spend (many) hours and hours under the car, under friends cars, looking, playing, padding, insulating, greasing, installing, uninstalling, changing bushes, tightening, loosening, pushing, pulling, prodding....you name it. I think rattle has nothing to do with the shifters themselves (although they transfer the effects differently). It also has nothing to do with the shifter being body mounted or on its original gearbox mount (ie. KartBoy and IRP both rattle) I believe the rattle comes from the gear selector shaft after it passes through the oil seal into the rear gearbox extension. There is up to a millimetre (and maybe more) of "play" or "wobble" in the shaft, which then vibrates passing along the selector shaft then up to the shifter lever. This "play" has been evident in pretty much every 86/BRZ that I've now crawled under. There is no bearing holding the shaft in place, it simply sits in a flexible oil seal that allows easy movement, and transfer of internal vibration from inside the box. To test my theory I took a (large) zip tie, looped it up over the selector shaft near its entry point at the oil seal, and zipped it up as tightly as I could around the bottom of the rear gearbox extension.... securely holding the shaft down. Not practical, and not a real solution. BUT it worked...no rattle at all in 3rd ( but because it is such an agricultural solution, then 4th worked less well until I changed the position of the zip tie along the shaft.... and of course 3rd started getting noisy again...and vica versa) Could the oil seal be replaced by a bearing? If not, is there a way of holding the selector shaft firmly, centred in its action, in place (without forcing it downwards)? Sadly, if I'm right, this is not good news as far as I'm concerned, as it indicates a fundamental design flaw.