rebuilt entire trans and still have a rattle on decel?

[97grnrs]

my 95 tsi has a weird rattle noise from the trans on decel or if i hold the idle around 3k sitting still, the noise goes away if i push the clutch in , i thought TOB so i replaced it. still same noise. then i thought input/intermed gear cluster bearings so i rebuilt the whole trans and replaced any bearing that was out of spec. everything has proper clearance , the main diff has a hair more endplay than oem spec but that should not effect anything, the trans shifts great but i still hear this annoying rattle from the end case area. maybe its just vibration from solid mounts and act 2600 causing things to vibrate inside the trans but no other car i had ever rattled like this. i also put in a spare trans in the mean time and it too had the exact same rattle but the gears were shot in it so i took it back out. does anyone elses awd trans do this? i went over the internals numerous times and found nothing wrong and it still has this annoying rattle.

 

[bastarddsm]

Joys of having a modified performance car. They all do this.

 

[hotrodssnova]

Have you checked your engine mounts?
Edit. I just noticed you had solid mounts. Those will vibrate the crap out of everything, and cause rattles. Switch to poly mounts and save yourself some headaches.

 

[Hal]

Joys of having a modified performance car. They all do this.

Uh, no they don't

 

[bastarddsm]

Lol then what is the trick? Everyone I've seen with a clutch that would take some power rattled like hell. Even with a new trans.

 

[97grnrs]

i do have poly mounts. not completely solid metal but it does cause alot of vibration. im just concerned something is wrong in the trans but i see absolutely nothing out of place besides the few bearings that were worn out of spec which i replaced. the car runs so nice but this noise has constantly got me worrying whats gonna blow apart , who knows , hopefully all it is is just vibration rattling the trans internals at certain rpms.. if you would put a marble or stone in the end case and shake it around real fast thats basically the type of noise i hear on decel or any time the car is vibrating

 

[donniekak]

Does it go away if you press in the clutch, or take the car out of gear?

 

[Hal]

Lol then what is the trick? Everyone I've seen with a clutch that would take some power rattled like hell. Even with a new trans.

Noise on decel might be the clutch (depends on disc hub style), it could also be worn drive line bushings or the use of solid bushing on the rear diff and/or drive shaft.

Noise sitting still has zip to do with the drive line and is most likely some other harmonic (say a exhaust bracket other some other part that is vibrating).

None of them are the transmission itself.

I have SOLID steel mounts in mine and an unsprung hub on a twin disc.

I get a decel harmonic and the floaters rattle when the clutch is disengaged.

I never get a rattle with the clutch engaged and the car sitting still.

But not "all modified performance cars" have the problems described by the O/P.

Hal

 

[97grnrs]

if i sit at idle in neutral and hold the revs around 3k i can make it rattle. its def coming from trans , my rear diff does have rattle because of solid bushings also but thats a different noise. this comes from the trans internally, if i make it rattle while in neutral by revving the engine to a certain rpm and then i press the clutch it will go away. which doesnt make sense to me cause everything in the trans is within spec. if you ever take the center diff out of a trans and spin it in your hand the rattle/ vibrating noise it makes is similar to what im hearing.it doesnt matter if its in gear or out. but once clutch is pressed in it stops. the springs still seem to fit tightly in the act disc also so i doubt its that. i hear it from the end case region of trans with my stethascope

 

[Hal]

Then every thing doesn't "have the proper clearance".

It could be the reverse brake cone, it could be a chipped gear tooth, it could be a shift fork rattling on a slider, it could be any number of different things.

 

[97grnrs]

I've inspected all internal parts multiple times. Nothing is broken or chipped and all bearing preloads are ok. It does sound like rev brake cone area that rattles though .

 

[bastarddsm]

I don't know how your twin doesn't rattle, but mine sure does. My trans was silent untill I put a puck clutch in it. Worn out, or rebuilt didn't matter still rattles with the 6 puck. Even worse with the twin. My galant with a 100k mi trans that's well worn is completely silent with a stock clutch on it.

 

[97grnrs]

ya ive pretty much come to the conclusion the excessive vibration from solid mounts etc is going through my gear cluster and internals of the trans and just rattling the hell out of the rev synchro and stuff in the end case. theres really no other explanation for it. another trans i was using made the exact same rattle when i had it in so guess ill have to just live with it.

 

[donniekak]

I would get a stethoscope and verify its coming from the reverse synchro area.

 

[Boostdriven]

Damn dude that sucks. I run poly mounts but only on the sides, my front and back are good stock ones. Honestly I don't see a point in running all poly mounts on a daily driver. Every time you push on the gas or let off the gas something has to absorb the shock. In my opinion solid mounts are hard on everything, any vibration from the engine is not absorbed by the solid mounts its all absorbed by your drive train so more unnecessary wear and tear on the drive train. I would switch to stock front and back mounts and the side ones will still keep the front of the car stiffer kind of like a strut tower bar.

 

[97grnrs]

ive verified with a stethascope like 10 times.. i work at a shop , i put it in the air like every day trying to figure out the source of the noise. def the reverse synchro area is where its coming from . oh well ill just deal with it. if something blows apart then i guess ill find the problem. but i dont think it will

 

[big_d]

5th gear synchro rattling in the hub? I've only heard it on early transmissions though (90's). Jack from Jack's Transmissions did have a thread on it somewhere.

 

[97grnrs]

ya i saw that , its actually the reverse synchro that goes over the rev brake cone. 5th synchro is farther down on the gear stack, i dunno. ill prob trade the car for a bike soon anyway if i find a trade worth the money ive spent on this car...