Noise under deceleration while in gear

[beefajita]

So for many years now I have had a noise under deceleration at about 3000rpm that sounded like metal on metal bolts in a washing machine. Other people on this forum and other DSM forums have reported the same thing. Some turned out to be clutches, others were the "wob-wob" noise from a worn carrier bearing, and still others took all the suggestions from other users and reported that the noise still persists. I remember reading a post from one person that his car had been doing it for years and he simply drove around the noise by not engine breaking and kicking it into neutral when slowing down. I talked to Shep years ago (he built my tranny)and his over the phone diagnosis was an out of balance flywheel and pressure plate assembly. I too, like many others replaced carrier bearings, balanced my clutch assembly, balanced my aluminum driveshaft, changed motor mounts, ect. But the noise kept persisting.

Then, last week I noticed a spacer in the assembly diagram that goes in between the bracket for the intermediate shaft and the engine block. I had taken my transmission on and off dozens of times and I knew that no such spacers ever came with my car. It should be noted that previous owners of my car were horrible mechanics and I have spent years undoing the damage they have done; from rewiring the harness under the hood and under the dash because it was so hacked up, to finding grounds that had just been deleted, to replacing home depot hardware that was used in place of suspension bolts. It was no surprise to me that these spacers were missing. Without the spacers the intermediate shaft, or half shaft as I like to can it, sat cock-eyed coming out of the transmission, barley noticeable unless you line your eye up so you can compare the angle of the shaft with the angle the block and oil pan sit at, the shaft and edge of the block should be parallel. Without the spacers, the half shaft had a decreasing angle moving out to the CV joint, thus sat cock-eyed. The noise under decel turned out to be the half-shaft's bracket resonating against the engine block. I ordered all factory hardware for the intermediate shaft's bracket, and botta-boom-botta-bing, no more noise under decel.

Here is a picture of the spacer I speak of:

 

[JNR]

Thanks for the heads up and this should go into the archives, IMO as I doubt most people are aware of this, or bother to look at the manual.

I'm going to see if my spacer is there now, as I get a little decel noise that I hadn't bothered to investigate deeply.

BTW - would you happen to know the dimensions and/or material? This would be something simple to fabricate rather than messing with the dealer/parts...Also, is it pretty easy to get to once everything is already buttoned up?

EDIT - also judging by that diagram, seems there is only one spacer that goes on the the 'left' "bolt area", or should there be one each on either of those "bolt areas"? That would seem odd though to only have one unless the mating piece is staggered, etc.

 

[alansupra94]

Definitely interested in this. I believe that the previous owner to this car cut the A/C bracket to make it work? Not 100% sure about this.

 

[iceman69510]

I think that spacer only applies if the A/C mounting bracket is gone. Otherwise the bracket is behind one of the two mounting points.

There is not a spacer or anything else at the other location.

 

[beefajita]

You are probably correct iceman, my buddy in Texas just checked his car and it has no spacers, we both have A/C. but, for whatever reason (bent bracket or maybe not a VR4 half-shaft) this fix made my noise go completely away and now i can decel without my car sounding like it is coming apart...

 

[beefajita]

JNR: the material is steel and is ~8mm thick, in retrospect I could of done it with washers or even a poly swaybar bushing cut to an 8mm thickness. It is relatively easy to access the two bolts but it is a lot easier if you remove the driverside longitudinal subframe brace.

 

[iceman69510]

Interesting. I have never seen the spacer. I will have to investigate further.

 

[JNR]

Thanks for the info and personally I don't like stacking washers for anything (kind of a crude jimmy rig fix), but rather would just cut something off thick wall tube, or make something from a 'billet' piece of rod, to ~5/16" thick (8 mm) then. I'll have to see if mine is there first before doing it though.

Hmmm, judging by it being shown in the FSM, it should be there on all vehicles from the factory, I would think, although I am simply going from the pic posted and don't see the rest of it. Going to check my FSM when I get home though, just for curiosity.

What is confusing to me still though is they show the bolt and the first item (washer?) going into both holes there and show that spacer on only one on the backside...being the bolt/"washer" is a typical, does that mean the spacer is too? Would make more sense when I see this, I suppose.

 

[iceman69510]

CAPS shows quantity of 1 for the spacer, 2 for the bolts.

 

[CutlassJim]

I don't know how all you old timmers can be so confused by this. The ac bracket takes up that space and there is only a spacer if the car didn't have AC, like %1 of DSMs, All gvr4 had it. Tidbit: If the car came from the factory with no AC it also had a crank pully with only one set of grooves on it for the front belt. The back of it is smooth.

I agree washers is a shitty fix and if the thickness is off it will put pressure on that bearing.

 

[iceman69510]

I see what you are saying Jim, but CAPS lists a spacer even for the E39 (which would have been 100% A/C equipped). So it should not list the spacer as applicable to that model.

I agree it is most likely not needed with the AC bracket, as I have never noted a problem before on any of my 3 cars, plus others have discussed how they cut up the bracket to make a spacer when they removed the AC. Just strange to have it listed, that's all.

 

[belize1334]

I've been filling the gap with a couple of lock washers which crush down to the appropriate width when tightened. But I've always wondered if maybe the bracket sat a little skewed. And I have terrible decel noises. I will be replacing with the non-A/C spacer to see if anything changes. Thanks for the heads up.

Edit: Just ordered from Mitsu, ~$5.00. P/N lb297732, assuming that we were looking at the same diagram. Time will tell.

 

[mitsuturbo]

Wouldn't a fajita full of bees sting your mouth?

 

[FlyingEagle]

I will take this thread one step further, with regards to the dimensions of the AC bracket spacing.
Are all the AC brackets the same thickness?
Reason I ask is because following a swap from an 89 4g61t to a ~91 4g63t and a used KM210 trans/new ACT clutch/new Fidanza 8lb flywheel swap at the same time, I have had a final drive/gear noise to some degree and a pronounced decel noise in 4th/5th - maybe just because road speed and trans heat is higher on the highway.
Changing from GL4 75-90 and 1/2 mix of Syncromesh to Redline MT90 has not changed things to any degree other than smoother shifting.
I swapped AC brackets from the 4g61t piece to the 4g63t piece, and reinstalled - no spacers obviously, same halfshaft from the original turbo Colt setup.
Curious to see where this thread goes.

 

[mitsuturbo]

Ok, guys. This is not rocket science. There are two bolts which hold that carrier bearing against the engine. The transmission bolts to the engine. Clearly this was engineered so that the axle stays straight in the front diff by way of alignment of the transmission and how it's bolted up, and these two bolts holding the carrier in a specific place on the block. If the bolt which is closest to the CV axle is in right, and tight, and the two mating surfaces are flat like they should be, then you should be able to tell if the 2nd bolt is going to need some "spacer" in order to keep things flat when it's torqued down. That bearing doesn't have a lot of "give" to it. It should be relatively simple to tell if something's a bit "off".

BTW, if you use a non turbo FWD block with equal length shafts, there's a stub cast into the block which has to be cut off in order for your axle to mount properly.

 

[Barnes]

Quoting beefajita:
You are probably correct iceman, my buddy in Texas just checked his car and it has no spacers, we both have A/C. but, for whatever reason (bent bracket or maybe not a VR4 half-shaft) this fix made my noise go completely away and now i can decel without my car sounding like it is coming apart...



The bolded section is why things are confusing here. If he A/C, he shouldn't need the spacer. Yet somehow putting the space in his car IN ADDITION TO having the A/C bracket his driveline noise improved. That doesn't make any sense to me.

 

[DynastyLCD]

Quoting alansupra94:
Definitely interested in this. I believe that the previous owner to this car cut the A/C bracket to make it work? Not 100% sure about this.



Barnes, did you ever think that the PO of beefajita's car had multiple GVR4's, or DSM's? maybe they took an A/C bracket and cut it to make a spacer for another project? just an idea. wouldn't be the first time i've seen really shoddy work like that.

i know my GVR4 had the bracket, and i left it there as opposed to cutting it or installing the spacer, and i had nothing additional to it.

did you get this car from CT by chance?

 

[beefajita]

Nope. It was Ken Inn's car. I couldn't even begin to list the atrocities he performed on this automobile. It was such a mess, the last GAVE it to me to get it out of storage because everything was trashed on it. Ken Inn is my nemesis.

Barnes, I am saying that both cars have A/C, mine had a horrible noise under decel for years, my buddies did not. I installed spacers, my decel noise went away. I asked my buddy to look under his car and see if he had spacers, because his car does not make noise under decel. He went out and looked and he has no spacers, it is bolted directly to the A/C bracket and block. Thats all bud.

 

[beefajita]

The lesson here: is make sure your intermediate shaft is parallel to the bottom edge of your block and at a 90 degree angle coming out of the transmission, otherwise horrible noises may occur. And yes mitsu a fajita full of bees does sting the mouth. /ubbthreads/images/graemlins/jawdrop.gif

 

[Ralli380Gvr4]

I know I'm digging this one up from the dead but...

Does anyone know the exact dimensions for this washer? I'm having the same symptoms (noise/rattling under deceleration)and would like to try this before I invest anymore $. Also the part # was not coming up when I searched JNZ's site.

Let me know if anyone can help me out. Thanks in advance.