sgroenink

Figured i'd try here, I've got a t56 magnum trans behind a turbo toyota v8 engine and Im at my wits end,

relevant measurements:

-Bellhousing run-out measured at 0.001-0.002" with dial indicator
-driveline angle <1.5"
-Pilot bearing is a 13mm thick and input shaft spigot is 11mm engaged into pilot bearing

The Symptoms:

1. regardless of any gear or speed, under acceleration load I get a VERY loud growl from 1500-2500rpm then it goes away, we're talking a >100db growl (not a bearing whine like a bad rear-gear but a low growl)

2. when in neutral with the clutch pedal released if i blip the throttle i get a very distinct and loud metal on metal knocking sound. it sounds very much like rod knock but i've stethoscoped it to the back half of the trans case where the tail housing meets the main case area. If i push in the clutch and blip the throttle all noise is gone

3. Im running a 2002 camaro hydraulic slave cylinder and after a few km I can see where the input shaft has been moving and contacting the slave cylinder guide sleeve. ie the input shaft is moving around and gouging aluminum out of the sleeve

All of these symptoms have been present since brand new and i've spent over 6 months fighting to get this fixed, i've measured, double checked, measured and checked every component of the transmission system at least 3-4 times. ive put 3 different brand new clutch slave cylinders in it, two different pilot bearings, two different adapter plates (one was a custom laser scanned and CNC'd 1 piece billet plate to 0.0001" tolerance $$$$)

The place i bought the transmission through sent it to tremec who promptly "functionally checked it on their dyno" and there was nothing wrong with it even though when I requested them to open it up and check the thrust clearances on the input shaft etc they refused and told me to come pick up my transmission.

Basically I've got a very expensive transmission sitting here that I need to find someone who is knowledgeable on these transmissions who can figure out what is wrong with it for me and fix it :-(

steve

Steveg1@telus.net

thesource

iTrader: (60)

I doubt its in the transmission. Where are you located?

jmd

iTrader: (4)

This happens if a pilot bearing is missing and the clutch is walking around when disengaged.[/quote]Your issue lies with this problem.

You've stated enough and pictures should be posted at this point.

sgroenink

Here's the slave cylinder and input shaft





And yes that is what has me so confused is that I KNOW the input shaft is engaging into the pilot bearing so that can't be moving so it has to be on the transmission side

thesource

iTrader: (60)

Definitely an alignment issue or the input shaft is walking. Does the mid plate have both dowel pins on it at 3 and 9 o'clock? Back of the block have both dowel pins as well?

sgroenink

Yes all the dowel pins are there and aligned etc etc

Pulled the front cover off and found this on the cluster shaft front bearing



You can see the scoring on the cage leading edge


I know this is a result and not the cause, I am assuming its a bearing pre-load issue but what I need now is a way to measure and correct it?

Steve

thesource

iTrader: (60)

Thats interesting but I don't see how its forcing the input shaft to rub the inside of the slave cylinder. You didn't happen to start the engine prior to filling the unit with fluid did you?

sgroenink

nope, had 4.3qts of ATFIII in it.

Im assuming this is a bearing pre-load issue that caused this scoring and if there is one on the cluster shaft then there could also be one on the input/main shaft.

anyone have a link to the manual/procedure to inspect the preload? all the rebuild links i find dont go over it "cause it shouldnt ever change"

Steve

thesource

iTrader: (60)

The T56 had a access hole you could use to check end play. Since the Magnum doesn't about the only way you can check it is to disassemble the unit, reinstall the cluster gear by itself and check it from the back with the tail housing off.

Where did you get the unit from?

sgroenink

I purchased it locally here in southern alberta but they purchased it from hurst driveline, have any link to how to check it on the magnum with the tailhousing off?

thesource

iTrader: (60)

No. You will need to isolate the cluster gear by itself which means completely disassembling it. Install the cluster gear and tighten down the mid plate. Set up a dial indicator to touch the rear most part of the cluster gear and use a flat blade screw driver or small pry bar to rock the gear up and down. If its too tight, the cluster gear will be hard to turn which you would then remove shims until it gets smoother.

sgroenink

I don't know if it matters but I found this gear to be very loose and have lots of play in it in the back half of the case



I found some better instructions with pictures on how to check the input shaft preload so I'll replace that one scored bearing on the cluster shaft as well as check the input shaft and go from there I guess

If that fails I'll need to find someone more knowledgeable on these transmissions than me to open it up and have a look