Fourth gear shudder-Sy

[86GN-862+2]

Just wondering what it could be. The shudder happens just as fourth gear(700r4) is about to kick in at around 42mph. So, what can it be? Once in OD, vibration goes away. Leaning toward a sticking governor valve but does the torque converter play a role here? Any help is appreciated.
109+ thousand miles and still pulling strong BTW.

 

[Boostedpimp]

There's this :

http://www.syty.net/forums/showthread.php?t=75906&highlight=shudder

But I'm betting its a shudder load issue and not a trans issue. The reason I say that is when you go into 4th gear, the parts that WERE spinning are now not spinning. In other words, you have LESS components spinning now than you did before. 2nd gear has a lot of the same components being held and your not vibrating in 2nd. That make sense? You should be shifting into 4th at about 44MPH with part throttle. If you take a stick shift and shift it into too high of a gear too soon and you'll put a TON of load on the engine and it'll shudder like crap. With an automatic, you get the added stress of the converter lockup. If throttle position is too low, line pressure will be too low to hold the TCC if it's locking up too soon. Then you get the TCC shudder

 

[86GN-862+2]

Thanks!
Maybe it's time to re-stall and re-build the torque converter. 2800 rpm stall sounds about right to me. Maybe 3K and get a stock turbo and have someone build me a 20G to go with the re-stall. Gotta love bolt- ons.

 

[Boostedpimp]

If it's a stock turbo truck I wouldn't up the stall or waste time with it until you pickout what turbo combo your going to upgrade with but that's me. 3k stall on a stock truck will be way over kill

 

[86GN-862+2]

Not if I get a 20g with a 14 cm which is what the post says up top. But you are right if stock turbo is kept, then just rebuild. I already installed the TT chip with 009's and liked how it feels.
I might just up the boost on the stock one to 16-17 and see. Thanks for the heads up!

 

[Boostedpimp]

Not if I get a 20g with a 14 cm which is what the post says up top. But you are right if stock turbo is kept, then just rebuild. I already installed the TT chip with 009's and liked how it feels.
I might just up the boost on the stock one to 16-17 and see. Thanks for the heads up!

3k stall would still be kind of on the high side for a 20g/14cm don't you think

16 to 17lbs of boost is not the limit of the stock turbo.. many have been able to squeeze low 20's out of the stocker before it became inefficient. This was of course without any kind of meth injection which I would assume could probably help squeeze another few psi out of it but at that point why bother.

 

[86GN-862+2]

Boostedpimp,
I'm a newby still when it comes to the sy/ty. Good info you are sharing. I was thinking of higher boost and came across a post about diesel Holset wastegate actuators and how well they hold boost. I think the lowest one offered is 20lbs. Ever tried that? I suppose for the money a manual boost controller is better and more versatile.
Thanks for the good info.

 

[Boostedpimp]

Boostedpimp,
I'm a newby still when it comes to the sy/ty. Good info you are sharing. I was thinking of higher boost and came across a post about diesel Holset wastegate actuators and how well they hold boost. I think the lowest one offered is 20lbs. Ever tried that? I suppose for the money a manual boost controller is better and more versatile.
Thanks for the good info.

Lowest boost meaning that would be base boost? These trucks have glass internals so unless the truck's tune spot on it would probably be best to stick with the stock turbo/stock adjustable waste gate actuator until you iron out the truck's tune and get a solid goal and budget in mind. Stock turbo has been known to go into the mid 11's I believe although allot of work went into that and the driver of the one truck i can remember ran stop fuel class normally. I know there's allot that can be done to 20g's to get some serious power out of them.

The common pitfall with these trucks are people want to slap on the largest turbo or stall and expect nothing but gains but you have to remember it's all about the right combination of parts. I've seen toss tons of money at there truck but never get it tuned and it runs slower then a stocker. Take these guys for example. They are north of the boarder but worth the time if you want the most out of what you'll have.

https://www.facebook.com/caracing
Check this thread out with there 20g setup for a customer they did and look at the dyno numbers out of it.. couple that with the correct stall and your running some serious numbers in your awd brick http://www.syty.net/forums/showthread.php?t=64336

 

[Boostedpimp]

and if you haven't already... register over on syty.net ask all your questions or at least read up over there nothing but knowledge over there for these rare vehicles