MT Accumulator Delete Mod (ADM) and BS Thread

You are likely right. I pulled the spring off a long time ago when some one noted that it helped with feel and didn't change the force much. I found both of those to be untrue.

 

I might try this out with my old pedal just to see....

 

Hey, Folks.

I updated the 1st Post to add the attached TSB. It really helps reduce the clunk noises in 1st gear for me.

 

how prevalent is this? my 17 doesn't have it and i haven't heard much about this.

you had the whine in 5th, 6th, or both? and that's odd but it really resolved your 1st clunk?

 

No whining except a subtle one from the diff. This was just that clunk that we get from driveline lash. I was skeptical that it would work, but someone said that it did. So, when I redid the ADM to use @Shellshock 's accumulator, I whipped on some Noico. Just covered as much of the inner surface as I could.


I have since added Noico to the rear wall and rear doors. That shit is amazing.

 

I'm curious how a different heat shield will resolve any of this. I mean, other than the fact that the new one is double the price of the original....

Is it a heat thing, or a vibration thing?

Is the whine/clunk still present with the accumulator removed? Do you even still need the heat shield? I assume it's providing some protection to the slave, but is the heat really that bad? Would adding some fiberglass shielding do a better job?

Just having trouble understanding how a thin metal shield can cause this problem. Or maybe it's the bolts? Wouldn't explain why you would need a new shield too.

 

Like I said, I was surprised when someone noted the TSB and that it helped with the clunks related to the driveline lash. I believe it is from the cushdrive springs on the friction plate being a bit soft and it twangs around when unloaded?


My only guess is that the bare shield echoes / amplifies the noises from the area. The sound insulation muffles that.


A lot of folks do leave the heat shield off when doing the ADM. The cat is there and Toyota might have felt that it degrades the fluid over time? I have no idea, but I tend to put mechanical protections back into place.

Mainly I bought some Noice for the interior and thought about it when I was dremeling the accumulator.

 

You make a solid point. Mine is a 2018 and the plate doesn't have any kind of sound absorption on it. I think I will probably add some that I have lying around. Granted my secondary cats are gone so the heat is already less severe than normal, plus I use DOT 4 in my clutch.... Still you make a good point and it wouldn't hurt to add some material in there.

 

Thanks!

I would be interested to hear what you find.

 

Finally got this done using a milled out accumulator. It's very subtle, but definitely improves shifting. Gone are pulses & oscillations, overly difficult shifts and inconsistent bite point.

 

Another observation:

While we focus our accumulator hate on the clutch release, I feel there is a significant benefit when engaging the clutch too. I think my shifting has improved and I can now shift more quickly (as done in past vehicles) because the accumulator is not buffering/slowing the engagement side of the clutch either. I'm getting the full engagement of the clutch when I want it while I'm in the process of shifting versus it lagging slightly behind me.

 

The 2nd Gen folks noted that they got a bit more travel with the ADM.

Myself, I have not noticed anything on the disengagement side. The accumulator doesn't (shouldn't) restrict the flow under positive pressure / disengagement as brake fluid does not compress. The diaphragm can only move under negative pressure when the fluid is flowing back to the master cylinder and restricts and dampens the flow.


IMHO, the direct control of the clutch gives consistency and predictability, so that contributes to generally good feelings all around?

 

Would it not stand to reason that when you push the clutch pedal in, that the diaphragm would flex allowing brake fluid to accumulate under the plate, slowing down the action being applied by the pedal? I figured it would have an impact on both directions of pedal movement. Alas, I don't know if this is true; I only have my subjective impressions.

 

I don't believe that the diaphragm itself flexes. The clutch fluid pressure is not that high. It is just that square seal that compresses just a bit.

 

<shrug>

 

I felt your pain reading this. I've been curious about the feel of this mod, I think getting a tune to remove the rev hang would be more noticeable. Eventually I'd like to do both

 

Did the mod this weekend. It was definitely a struggle to get everything unhooked and put back together.

I would recommend taking the extra 5 minutes to remove the driveshaft. It is right in the way.
It would have been nice to have ratcheting tube wrenches as well, most of the bolts are just hard to get to.

I went with the Dremel method. Mainly to keep it looking OEM.


Besides the struggle of threading the mounting bolts blindly, I did somehow booger the threads in the accumulator. Had to essentially "retap" them with the hose fittings.
This might lead me to suggest going with the brake line method.
Crossing my fingers that it doesn't leak. Its been good so far.

The most notable difference for me is the shift from 1st to 2nd. It is much improved and has no more clunking. Can shift much faster and smoother. Don't have to hold 1st gear out to keep up with traffic.

The bite point is more consistent and more defined.
Still can't figure out why Toyota though it was necessary to add the accumulator.

 

I agree.
I would bet that the 'diaphragm' does not flex. It is very thick, probably 1/8 inch thick.

I can tell a difference with the disengagement. It seems much easier to get into gears from a stop. Can also get the shifter into 1st while rolling a little better

 

I am glad that you like it. It sounds like it was quite the effort.