Rear diff clunk after a hard upshift?
Yep Did it in the STi that I had and the 06 MR that I have now. I did it a lot more in the STi seeing it was @ 30k miles... Now I just baby my car until it is broken in right.
I have a JDM Evo7 and a USDM 03 Evo8, the clunk happen to me on Evo7 whenever I make a quick shift on 1 to 2. However never happen on my USDM Evo. I think most of the people have this clunk. So I am not too worry about it.
just to let you guys know, when i installed a polyurethane lower front engine mount, i never got the clunk again. put the stock one back in since i'm going to stock for trade, it clunks again on hard shifts.
This sound is pretty normal, it may be those bushings, but more likely it's drivetrain lash. Warrtalon said it, but not everyone knows the insides of their drivetrain. Basically, there's some play within the gears on the rear diff. Since Evo's predominantly are FWD, the center diff only locks up when it has to - accelerating hard does this, especially in the lower gears. So when the center diff locks up, the rear differential suddenly gets power, but there is some play in there and the gears slam together. That's what the "thud" is from. You can alleviate that by shifting smoothly and loading up the drivetrain gradually, instead of slamming it.
You can also get the similar thing happening if you are in gear (especially first) and stepping on the throttle and abruptly lifting it. There is a bit of play or lash in the drivetrains of all vehicles. If you've had a sportbike, you'll know what I mean even more.
Keep in mind this is a simplification, there are many mechanisms that cause slop, but this helps with figuring it out.
Oh, and it isn't good for the car, but won't kill it as far as I know.
You can also get the similar thing happening if you are in gear (especially first) and stepping on the throttle and abruptly lifting it. There is a bit of play or lash in the drivetrains of all vehicles. If you've had a sportbike, you'll know what I mean even more.
Keep in mind this is a simplification, there are many mechanisms that cause slop, but this helps with figuring it out.
Oh, and it isn't good for the car, but won't kill it as far as I know.
Last edited by EVOcuda; Sep 8, 2007 at 06:07 PM.
Which bushing replacements stop this?
There are the ones in the rear mustache bar, and the chassis/diff mount bushings. I'm assuming the ones where the diff mounts to the chassis. Do these come in the ES master kit? Thinking about doing it all in one shot.
I get this anytime I go thru the gears quickly. I've tried shifting like a pu*** as was mentioned, but its simply not within my capabilities. I never fully lift, and although adding some throttle before wot was mentioned as a solution... its not one.
The term, "banging gears" was used in this thread but that is not what I am doing. Hardly any physical effort is required to shift these gear boxes like lightning. I've found (which is a scary thing to get used to transitioning to another car that isn't so shifting friendly) that it only requires a half push, it "falls" the rest of the way into gear. This enables some seriously quick shifting. My instant transition back to full power I think is what sends the drivetrain lag backlash down to the rear diff.
Either way, the thump has to go. Loud noises should signify horrific failure, not my rear diff saying "omghi2u"
There are the ones in the rear mustache bar, and the chassis/diff mount bushings. I'm assuming the ones where the diff mounts to the chassis. Do these come in the ES master kit? Thinking about doing it all in one shot.
I get this anytime I go thru the gears quickly. I've tried shifting like a pu*** as was mentioned, but its simply not within my capabilities. I never fully lift, and although adding some throttle before wot was mentioned as a solution... its not one.
The term, "banging gears" was used in this thread but that is not what I am doing. Hardly any physical effort is required to shift these gear boxes like lightning. I've found (which is a scary thing to get used to transitioning to another car that isn't so shifting friendly) that it only requires a half push, it "falls" the rest of the way into gear. This enables some seriously quick shifting. My instant transition back to full power I think is what sends the drivetrain lag backlash down to the rear diff.
Either way, the thump has to go. Loud noises should signify horrific failure, not my rear diff saying "omghi2u"
thank u have a nice day
Evolving Member
Joined: Jan 2006
Posts: 269
Likes: 0
From: Houston
Try this
Hope you find it helpful. My understanding is, its neglagible but over all, try not to shift so quick if you care for your car. I don't know if the above piece of hardware is a good band-aid for the issue or not, I'd like to know from others who have bought the product.
the clunk is the rear diff where it connects to the drive shaft hitting the bottom of the car..
when you replace the bushings and see the super soft rubber pieces of **** mitsu used you'll understand.
when you replace the bushings and see the super soft rubber pieces of **** mitsu used you'll understand.
