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JHEARD

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I just put 3:73s and had a new diff put in. Im alil concerned about the trans, its working good now but any suggestions?
 
Possibly a driveshaft. I notice at 75ish with my 373s My rear view mirror shakes. A 93 driveshaft or a steel tbird shaft may help you.
 
DieselDan said:
Possibly a driveshaft. I notice at 75ish with my 373s My rear view mirror shakes. A 93 driveshaft or a steel tbird shaft may help you.
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My driveshaft shook with 3.27 gears, bought a 93 shaft, shook again. Bought a dynotech shaft with the 4.10s, still shakes. Put 4.30s in it, now it shakes forever. I see no cure. If someone could give me the magical cure, I'd love to hear it.
 
KStromberg said:
My driveshaft shook with 3.27 gears, bought a 93 shaft, shook again. Bought a dynotech shaft with the 4.10s, still shakes. Put 4.30s in it, now it shakes forever. I see no cure. If someone could give me the magical cure, I'd love to hear it.
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Have you tried clocking the driveshaft on the diff? If that doesn't help it could be a bad cv joint, differential carrier bearing, or even a bad mount somewhere in the drivetrain, engine mount, trans mount, front pumpkin mount, rear pumpkin mount, etc. It could also be a bad tire, or bad wheel bearing, etc. If your using a dynotech shaft I doubt that's the cause. I'd look at other moving parts, especially if clocking the driveshaft makes no difference.
 
DieselDan said:
Possibly a driveshaft. I notice at 75ish with my 373s My rear view mirror shakes. A 93 driveshaft or a steel tbird shaft may help you.
Click to expand...

Tbird shafts are all two piece rubber crimped garbage, that's why the tbird crowd loves the 93 mark shaft
 
Chris_Murder said:
Tbird shafts are all two piece rubber crimped garbage, that's why the tbird crowd loves the 93 mark shaft
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Ah, I know Jamie (bad97LSC) uses a t bird shaft and I thought he said it was a 1 piece shaft, I must have been mistaken.
 
Jamie has a Dennys shaft I thought?


Anyway, a J-mod wont really help the trans to last but a trans cooler will make a big difference. The biggest killer of auto trans is heat.
Also the tail shafts and seals break with vibrating driveshafts so a good balanced shaft is important with the steeper gears.
 
LaserSVT said:
Also the tail shafts and seals break with vibrating driveshafts so a good balanced shaft is important with the steeper gears.
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To KStromberg:

With that being said, I'm not sure if 4R70W's have them, but if the tailshaft has a bushing in it, a worn bushing may also cause a vibration.

My dad's work van had a bad vibration, caused by a worn tailshaft bushing. It was a Chevy van, so it's apples to oranges, but might want to check it.

Is the front yoke of the driveshaft worn/scratched?
 
I'll dig mine out of the pile (I've got several shafts floating about) and take a closer look at it. I could have sworn that it is one piece from yoke to yoke.

EDIT: Damn, correct, two piece.
 
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Chris_Murder said:
Have you tried clocking the driveshaft on the diff? If that doesn't help it could be a bad cv joint, differential carrier bearing, or even a bad mount somewhere in the drivetrain, engine mount, trans mount, front pumpkin mount, rear pumpkin mount, etc. It could also be a bad tire, or bad wheel bearing, etc. If your using a dynotech shaft I doubt that's the cause. I'd look at other moving parts, especially if clocking the driveshaft makes no difference.
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Ditto on the clocking, even try doing it on the output shaft. PITA but I heard good things.
 
LaserSVT said:
Jamie has a Dennys shaft I thought?


Anyway, a J-mod wont really help the trans to last
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Seriously?:p Yes, a cooler helps a great deal but we both know that the j-mod, when done correctly and all springs left in, does pro-long the life of our transmissions. Adding a cooler just makes it all even better. Oh, that little deal that Dan said about Jamie's shaft.... He's just trying to get him started. :shifty:
 
NoLimit95 said:
Seriously?:p Yes, a cooler helps a great deal but we both know that the j-mod, when done correctly and all springs left in, does pro-long the life of our transmissions. Adding a cooler just makes it all even better. Oh, that little deal that Dan said about Jamie's shaft.... He's just trying to get him started. :shifty:
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I still have a hard time wraping my head around that. I understand it makes the trans shift firmer and quicker and I understand how it does it but I dont see how thats any better for a trans. I wont say its worse but how can putting more stress on the trans clutches and gears help it last longer?
 
LaserSVT said:
I still have a hard time wraping my head around that. I understand it makes the trans shift firmer and quicker and I understand how it does it but I dont see how thats any better for a trans. I wont say its worse but how can putting more stress on the trans clutches and gears help it last longer?
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Idk how it works either, but everything I have been told by every one is that the firmer it shifts the better it is for the trans....
 
LaserSVT said:
I still have a hard time wraping my head around that. I understand it makes the trans shift firmer and quicker and I understand how it does it but I dont see how thats any better for a trans. I wont say its worse but how can putting more stress on the trans clutches and gears help it last longer?
Click to expand...

Just normal driving, more fluid flow is allowed through the semi restricted holes in the plate, which in turn will help out a little on cooling. Opening the valve body passages helps with the shifts and lengthens the life of the junk pre-98 TC. An alteration to the flow path of fluid derived from "un-modifying" closed passages from the factory is more like it. These trannies were designed to shift firm, and were 'toned down' to suit the buyers. All the j-mod is doing, is putting it back to the performance level it was designed for.

trans cooler + j-mod = win win but it's not hurting the trans, especially if the springs are left in and not removed for the extra firm 2nd gear.
 
LaserSVT said:
I still have a hard time wraping my head around that. I understand it makes the trans shift firmer and quicker and I understand how it does it but I dont see how thats any better for a trans. I wont say its worse but how can putting more stress on the trans clutches and gears help it last longer?
Click to expand...

firmer shifts are an old hot rodders trick since day one, and it's always helped the trans out.

With Auto's, usually when they go out, it's the clutches...when a trans has to shift smoothly, you're slipping the clutches...similar to what you would do in a manual car. Quicker shifts slips the clutches less, and makes them last longer.

Now, I assume there is a point where you can go to far, just like you can install too much clutch and damage your trans in a manual setup, but from my jmod research, there are a couple of different stages you can perform so that you can match your power level.

I currently just got an xcal 3 today...love it so far. I've increased my line pressure (no j mod) 5% and it slips a lot less under heavy throttle, which is perfect, but is still smooth at low rpm's...I'll experiment with line pressure through my xcal before i perform the jmod...as I like adjustability...jmod is permanent.
 
v8only said:
I'll experiment with line pressure through my xcal before i perform the jmod...as I like adjustability...jmod is permanent.
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You can always pull the valve body back out and install a stock plate and go back to the smooth shift. The W3Z3 from a 93 that I put in mine raised my trans fluid pressure 15 psi higher. So.... the jmod will be done very soon to accommodate for that.
 
v8only said:
firmer shifts are an old hot rodders trick since day one, and it's always helped the trans out.

With Auto's, usually when they go out, it's the clutches...when a trans has to shift smoothly, you're slipping the clutches...similar to what you would do in a manual car. Quicker shifts slips the clutches less, and makes them last longer.

Now, I assume there is a point where you can go to far, just like you can install too much clutch and damage your trans in a manual setup, but from my jmod research, there are a couple of different stages you can perform so that you can match your power level.

I currently just got an xcal 3 today...love it so far. I've increased my line pressure (no j mod) 5% and it slips a lot less under heavy throttle, which is perfect, but is still smooth at low rpm's...I'll experiment with line pressure through my xcal before i perform the jmod...as I like adjustability...jmod is permanent.
Click to expand...
That makes more sense. Never thought about longer clutch slippage time with the slower shifts. Thanks.

I was going to J-mod my last Mark but ended up getting the shift tune so perfect in the SCT software that I didnt want to screw it up with a J-mod. The couple cars with J-mods I was in I didnt like. At heavy load they were gret but I hated the light load shifting. With the software you can command a nice smooth partial throttle shift and a neck snapping WOT shift.
 
yea I agree and that's what I'm seeing now with my xcal....at only 5% it's still smooth as can be at low rpms I want to try bumping it up quite a bit, but I'm reading now that increasing the line pressure will overheat the trans.....so a trans cooler is needed now.

Have either of you bought a trans cooler yet? Laser, how much increase in line pressure are you running?
 
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