Transmission kick under accel - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

SCharged · 03-17-2014, 02:52 PM

Anyone experiencing transmission knocking under wheel spin off a start?? I get the usual shifter shake, but also some ''dry'' knocking of the tranny underneath..

anyone else?? fixes?? tranny support/mount maybe?

Thanks

7thgear · 03-17-2014, 03:08 PM

auto or manual?

SCharged · 03-17-2014, 03:23 PM

Sorry, should've specified... it's manual

Travisty75 · 03-17-2014, 03:38 PM

Quote:

Originally Posted by SCharged

Anyone experiencing transmission knocking under wheel spin off a start?? I get the usual shifter shake, but also some ''dry'' knocking of the tranny underneath..

anyone else?? fixes?? tranny support/mount maybe?

Thanks

If it's what I and a couple others have experienced then it's actually "wheel hop." I say that because I'm not sure the wheels are actually hopping, but that's what it feels like. If you watch some Whiteline videos on YouTube the entire rear subframe of the car moves an incredible amount. What I think actually happens is that the whole system moves, binds/unloads the wheels, then wheels stop spinning/system moves again.

Based on my hunch, I've bought diff outrigger bushings, diff mount bushings, and subframe bushing inserts. I'm hoping that's enough to keep everything where it should be.

SCharged · 03-17-2014, 04:23 PM

Quote:

Originally Posted by Travisty75

If it's what I and a couple others have experienced then it's actually "wheel hop." I say that because I'm not sure the wheels are actually hopping, but that's what it feels like. If you watch some Whiteline videos on YouTube the entire rear subframe of the car moves an incredible amount. What I think actually happens is that the whole system moves, binds/unloads the wheels, then wheels stop spinning/system moves again.

Based on my hunch, I've bought diff outrigger bushings, diff mount bushings, and subframe bushing inserts. I'm hoping that's enough to keep everything where it should be.

Makes sense.. Although I 've had this on the wet too.. I've never seen wheel hop on wet i think..

Travisty75 · 03-17-2014, 05:51 PM

Quote:

Originally Posted by SCharged

Makes sense.. Although I 've had this on the wet too.. I've never seen wheel hop on wet i think..

I've experienced it in wet and dry. Dry was under spirited acceleration at the start of an AutoX, wet happened leaving stop lights with a bit if a clutch side-step.

Guff · 03-17-2014, 05:57 PM

Yup, it's wheel hop. It's pretty intermittent in our cars and it really isn't too bad compared to some other cars I've launched in. Like@Travisty75 said, there's a few things you can get to alleviate it, but it's really just something you gotta live with when you have IRS.

GotMunchies? · 03-17-2014, 05:59 PM

This is likely wheep hop if it felt like a juddering from the rear end with vertical vibrations. Its a common issue with RWD cars with many different types of suspension set ups. I get it in my Mustang with a stick axle - its worse in the wet. Older CTS-V's could axle hop so badly they would blow up differentials. Fixes range from driving adjustments to adjusting suspension geometry.

SCharged · 03-18-2014, 10:53 AM

Thanks for input everyone. I'm kind of relieved... will still keep an eye open and update thread if it ends up being something that may be of interest to the community.

OrbitalEllipses · 03-18-2014, 11:09 AM

There are mounting points you can stiffen to prevent slop (engine mounts, trans mount, rear diff mount, rear subframe inserts, 1pc driveshaft) and minimize wheel hop, but as others have said it's the nature of the beast.

Mikem53 · 03-18-2014, 12:20 PM

Quote:

Originally Posted by OrbitalEllipses

There are mounting points you can stiffen to prevent slop (engine mounts, trans mount, rear diff mount, rear subframe inserts, 1pc driveshaft) and minimize wheel hop, but as others have said it's the nature of the beast.

How is this car with wheel hop..? My old age mentally prevents me from doing too many abusive launches.. My last car was a C6 vette, I had terrible wheel hop issues.. I aliveiated most of the wheel hop issues by replacing the stock GY Runflats with some non-runflat pilot sports.
IRS set ups aren't good for abrupt hard burnouts. At least in my experiences..

OrbitalEllipses · 03-18-2014, 12:24 PM

Quote:

Originally Posted by Mikem53

How is this car with wheel hop..? My old age mentally prevents me from doing too many abusive launches.. My last car was a C6 vette, I had terrible wheel hop issues.. I aliveiated most of the wheel hop issues by replacing the stock GY Runflats with some non-runflat pilot sports.
IRS set ups aren't good for abrupt hard burnouts. At least in my experiences..

I haven't addressed it, but this thread might have good information: http://www.ft86club.com/forums/showthread.php?t=29020

Short search link (LMGTFY, forgive me): http://bit.ly/1ooDBaL

03-17-2014, 02:52 PM	#1
SCharged Senior Member Join Date: Jun 2013 Drives: asphalt fr-s Location: ottawa, on Posts: 151 Thanks: 52 Thanked 112 Times in 41 Posts Mentioned: 0 Post(s) Tagged: 2 Thread(s)	Transmission kick under accel Anyone experiencing transmission knocking under wheel spin off a start?? I get the usual shifter shake, but also some ''dry'' knocking of the tranny underneath.. anyone else?? fixes?? tranny support/mount maybe? Thanks

03-17-2014, 03:08 PM	#2
7thgear i'm sorry, what? Join Date: Jan 2012 Drives: Canada Location: I rock a beat harder than you can beat it with rocks Posts: 4,399 Thanks: 357 Thanked 2,508 Times in 1,268 Posts Mentioned: 40 Post(s) Tagged: 3 Thread(s)	auto or manual? __________________ don't you think if I was wrong, I'd know it?

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03-17-2014, 03:23 PM	#3
SCharged Senior Member Join Date: Jun 2013 Drives: asphalt fr-s Location: ottawa, on Posts: 151 Thanks: 52 Thanked 112 Times in 41 Posts Mentioned: 0 Post(s) Tagged: 2 Thread(s)	Sorry, should've specified... it's manual

03-17-2014, 05:59 PM	#8
GotMunchies? Senior Member Join Date: Feb 2014 Drives: '14 WRB BRZ 6MT Limited Location: United States Posts: 105 Thanks: 4 Thanked 75 Times in 39 Posts Mentioned: 4 Post(s) Tagged: 0 Thread(s)	This is likely wheep hop if it felt like a juddering from the rear end with vertical vibrations. Its a common issue with RWD cars with many different types of suspension set ups. I get it in my Mustang with a stick axle - its worse in the wet. Older CTS-V's could axle hop so badly they would blow up differentials. Fixes range from driving adjustments to adjusting suspension geometry.

03-18-2014, 10:53 AM	#9
SCharged Senior Member Join Date: Jun 2013 Drives: asphalt fr-s Location: ottawa, on Posts: 151 Thanks: 52 Thanked 112 Times in 41 Posts Mentioned: 0 Post(s) Tagged: 2 Thread(s)	Thanks for input everyone. I'm kind of relieved... will still keep an eye open and update thread if it ends up being something that may be of interest to the community.

03-18-2014, 11:09 AM	#10
OrbitalEllipses Banned Join Date: Jan 2012 Drives: Attitude Location: MD Posts: 10,046 Thanks: 884 Thanked 4,890 Times in 2,903 Posts Mentioned: 123 Post(s) Tagged: 4 Thread(s)	There are mounting points you can stiffen to prevent slop (engine mounts, trans mount, rear diff mount, rear subframe inserts, 1pc driveshaft) and minimize wheel hop, but as others have said it's the nature of the beast.

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