Differential clunk under sudden acceleration.

[Siajoon]

Originally Posted by roastbeef

driveshaft is an easier and potentially cheaper fix than the diff. plus, you could easily upgrade to the carbon one piece for just a few dollars more.

Well, that's atleast good to know...

[amrazM]

Originally Posted by roastbeef

driveshaft is an easier and potentially cheaper fix than the diff. plus, you could easily upgrade to the carbon one piece for just a few dollars more.

Mfactory carbon shaft costed me less than a new one would run, if it does need a DS you can buy slicer’s

[Siajoon]

https://www.m3post.com/forums/attach...hmentid=418833

Came across this SIB trying to figure out if maybe this is what I am experiencing and it could possibly just be the nature of the vehicle?

Anyone else see this?

Although it says noise when going from 1st to 2nd not really what I'm experiencing. Interesting nonetheless

[atopa2002]

it's the gear lash in the diff and its normal, made worse with stiffer bushings

[pbonsalb]

I have seen that TIS. Makes sense as a possible fix for the driveline clunk that some have complained about. I had a little clunk before I did the subframe and diff bushings and after. I notice mine only at very low speed, like backing out of the garage or maybe changing from 1 to 2 when going slowly. I later changed the driveshaft to a CF one and there is still some noise. It’s not bad and does not bother me, but since I have taken up the rest of the slop in my 95k mile drivetrain (motor and trans mounts have also been replaced), the diff input is a possibility and I will probably get to that project eventually.

[Siajoon]

After taking a ride with Malek he told me to immediately stop driving the car as I could cause a lot of damage to the diff.

We're going to install reinforced subframe bushing and oem diff bushings.

The clunk from accelerating hard and suddenly should be gone after this.

Will check back in after I get the car back!

[MikeyG]

Engine mounts?

[Siajoon]

Originally Posted by MikeyG

Engine mounts?

Motor mounts were done 2k miles ago

[Siajoon]

Update:

The good the bad and the ugly... looks like the diff bolts were cut clean.... very very happy I got to this before it was to late..

Malek informed me that my subframe was free of any damage or cracks... will do another update once I drive the car and do some pulls to see if the clunking I was hearing from the rear end is gone!

[Bartledoo]

You didn't push on the diff very hard then because it should've moved substantially. My bolt was sheared the same and the diff was loose as a goose.

[Siajoon]

Originally Posted by Bartledoo

You didn't push on the diff very hard then because it should've moved substantially. My bolt was sheared the same and the diff was loose as a goose.

what did you end up doing? just replacing the bolt or did you replace the subframe bushings and diff bushings?

[Bartledoo]

Originally Posted by Siajoon

what did you end up doing? just replacing the bolt or did you replace the subframe bushings and diff bushings?

Nah it would've just broken again, and possibly wrecked the subframe. I upgraded to aluminum subframe bushings, powerflex purple diff bushings, and all new bolts.

[Siajoon]

Originally Posted by Bartledoo

Nah it would've just broken again, and possibly wrecked the subframe. I upgraded to aluminum subframe bushings, powerflex purple diff bushings, and all new bolts.

sweet! also what I am doing as well.

im excited to punch the throttle without worrying about my Rear end destroying itself... for god sake we have ITB's for a reason!! instant throttle response. But with an issue like this it paralyzes you from enjoying its full potential

[pbonsalb]

Naturally aspirated? Any drag racing? R compound tires? I was worried about this possibility so I changed to stiffer subframe and diff bushings a few years ago to reduce movement. There have been a few posts here over the years of damaged subframes and diffs. The only downside from the stiffer diff bushings is a little diff whine that is noticeable at certain speeds.

[tdott]

Originally Posted by Bartledoo

Nah it would've just broken again, and possibly wrecked the subframe. I upgraded to aluminum subframe bushings, powerflex purple diff bushings, and all new bolts.

You should stop posting. You clearly don't know anything. The diff has several other bolts hold it up, plus the drive shaft and output shalfs, it will not be easy to move around with that one bolt sheered, it takes a lot of force.

Please stop giving advise you aren't helping, the best advise is always to get it inspected rather than making up stupid guesses.

[Siajoon]

Originally Posted by tdott

You should stop posting. You clearly don't know anything. The diff has several other bolts hold it up, plus the drive shaft and output shalfs, it will not be easy to move around with that one bolt sheered, it takes a lot of force.

Please stop giving advise you aren't helping, the best advise is always to get it inspected rather than making up stupid guesses.

Actually,

He is right.. this is what Malek a very very credible source said. He told me the choice is completely mine.. he could change the bolt out and I could be on my way but I'd be back again because the bolt is not the issue it is the subframe bushings that we're the cause to begin with.

[pbonsalb]

There are 3 diff bolts, 2 front and one rear. They hold the diff. The driveshaft and axles will not hold the diff in place.

[dparm]

Originally Posted by Siajoon

I suppose that makes sense, Maybe I should just try getting the diff bushings replaced regardless.

Only reason I haven't is because I was told they last atleast until 100k. Currently at 68k.

Bushings don't have a set lifespan. It will depend on how hard you drive the car and the kind of conditions they are exposed to. Cruising on the highway for most of its life will not put as much stress on them as a car that goes from stoplight to stoplight.

[F87_M2SH]

Your problem is the driveshaft for sure had the same problem

[SAMM3Y]

I'm interested to hear how the car performs with the new subframe bushings. I changed out my diff a while back and replaced the diff bushings with purple powerflex, didn't change the subframe bushings. When I hard launch the car the back end starts bouncing up and down a little which makes me have to pedal the car a bit, I was wondering whether it's subframe bushing related or I had the suspension setup with too much rebound, it's like it didn't want to sit. I guess either makes sense. I'm glad you figured your issue out OP, das gonna be nice!

[Siajoon]

Originally Posted by SAMM3Y

I'm interested to hear how the car performs with the new subframe bushings. I changed out my diff a while back and replaced the diff bushings with purple powerflex, didn't change the subframe bushings. When I hard launch the car the back end starts bouncing up and down a little which makes me have to pedal the car a bit, I was wondering whether it's subframe bushing related or I had the suspension setup with too much rebound, it's like it didn't want to sit. I guess either makes sense. I'm glad you figured your issue out OP, das gonna be nice!

Right off the bat, the rear end feels extremely planted like it should be. And the powerband feels much more linear and progressive as it should be.

I would recommend getting solid subframe bushings, I think it will help tremendously with the wheel hop you're experiencing

[SAMM3Y]

Originally Posted by Siajoon

Right off the bat, the rear end feels extremely planted like it should be. And the powerband feels much more linear and progressive as it should be.

I would recommend getting solid subframe bushings, I think it will help tremendously with the wheel hop you're experiencing

What brand/model solid bush did you go for? I think I'm gonna go for that for my next mod. It's not wheel hop I'm experiencing, it's like the potential energy on a wound spring that's fighting back. Like that of a compressed bush, I'd like to think the suspension would stay sat under load so maybe it is bush related. I don't launch my car to much really, that's why I haven't been too worried about it. But when the time comes that I need it, I want it to be there.. cheers,

I believe the f8x m's are all solid subframe mounted from the factory should be a good e9x upgrade.