904 slipping

-
mopardemon340

mopardemon340

Well-Known Member
Joined
Aug 10, 2015
Messages
553
Reaction score
37
Location
WI
today we took the car out for a short drive and found a flat straight road. we stoped and took off like we are on a track..at about 55 to 60 it felt like the trans slipped so we let off the gas.. went back to the house and checked the the oil and it was just a little below the full line.. during normal driving it drives great no issue before we put this trans back into the car we took it to a trans shop and had them look at it and everything checked out so we put it back in.. we rebuilt the trans a few years ago and jut want to make sure it was proper still. what would cause the trans to feel like it slips. it 3500 stall 904 trans. want to figure this out before we take it to the track
 
Last edited:
its a lokar kick down so yes it is.. it acts normal when driven normally. but hard acceleration is when it slips or flashes.. tomorrow i will try to get a video so it can be heard and gauges seen.
 
At WOT is the Lokar cable pulling the kickdown lever all the way back? Or only part way?
 
this trans has not been built at all.. its behind 472ph 525tq magnum 360.
 
toolmanmike said:
Geez, it's probably sipping. It was originally built for 290 horses.. have you adjusted the bands?
Click to expand...
we havent adjusted anything. the trans shop would of adjusted it back to stock when they took it apart and looked at it all
 
what would i need to do to beef it up to handle the power
 
mopardemon340 said:
what would i need to do to beef it up to handle the power
Click to expand...
mopardemon340 said:
today we took the car out for a short drive and found a flat straight road. we stoped and took off like we are on a track..at about 55 to 60 it felt like the trans slipped so we let off the gas.. went back to the house and checked the the oil and it was just a little below the full line.. during normal driving it drives great no issue before we put this trans back into the car we took it to a trans shop and had them look at it and everything checked out so we put it back in.. we rebuilt the trans a few years ago and jut want to make sure it was proper still. what would cause the trans to feel like it slips. it 3500 stall 904 trans. want to figure this out before we take it to the track
Click to expand...
when you say "we rebuilt the trans a few years ago" do you mean YOU rebuilt it?
 
j par said:
when you say "we rebuilt the trans a few years ago" do you mean YOU rebuilt it?
Click to expand...
neighbor and I rebuilt it a few years ago.. but a few months ago i took it to a trans shop to make sure it was still good.we had issues with it before and turned out to be bad VB so it was replaced and everything else was still well with in spec.
 
I'm going to reiterate what kiss said real quick here I'd like to maybe clarify this in my own head that since you've had this problem you have definitely verified that the kickdown linkage which is actually as you know since you've rebuilt this is the valve pressure lever. And obviously if you don't have all the valve pressure when you're at maximum torque there will be likely slippage. All I've heard you definitely say so far is that you verified there's enough oil in it. That's why I asked. When you answered kiss it seemed as if you were speaking from knowledge of it being correct at one time.

mopardemon340 said:
neighbor and I rebuilt it a few years ago.. but a few months ago i took it to a trans shop to make sure it was still good.we had issues with it before and turned out to be bad VB so it was replaced and everything else was still well with in spec.
Click to expand...
 
i know for a fact the KD is proper. if it wasnt proper wouldnt it have issues during normal driving and not just during hard acceleration.
 
isnt the KD so you down shift into a lower gear. how would that affect the up shift when you have it wot from the start
 
Okay this is why I started the whole conversation by asking you if you actually rebuilt this transmission yourself or not. That is not a kickdown like in a Chevy transmission that's vacuum operated. It's a pressure valve the more pressure that's needed to hold the clutches. If that pressure is overridden then it kicks down. At least that's the way I understand it.

mopardemon340 said:
isnt the KD so you down shift into a lower gear. how would that affect the up shift when you have it wot from the start
Click to expand...
 
ijust double checked the KD and i found a 3/16 of play so i tightened it up. but would that much cause an issue..
 
And you have "472hp, 525tq" . If you juice up the power plant you need to toughen up the tranny. (and the rest of the drive train for that matter) My buddy went from a stock 383 to a 500 horse 440 in his 70 Bee. He blew the planetaries out of the stock 72 a few weeks ago. It's beefier now!
 
I just double checked the KD and i found a 3/16 of play so i tightened it up. but would that much cause an issue..
Click to expand...


Yes, and no
At 55/60 you were probably already in second gear, and the engine was just on top of the torque peak. The engine is putting a hurt on the tranny and the chassis is starting to push wind. It needed all the throttle pressure available, and it still wasn't enough.
Your 904trans will need a lots of up-grades to survive that engine; the least of which is more throttle pressure.
 
Last edited:
You must log in or register to reply here.
-

Back
Top