Locked Shifts

[APWCU]

Just got my converter lockup switch wired in, I was doing some testing on locking the converter right after the 2nd gear shift and then leaving it locked through third and fourth, really makes a huge difference in acceleration but I have a couple questions. The trans is a full Goerend unit with a billet input and triple disc converter. Everything feels good when shifting but I don't want to hurt it if I can help it.

The truck is a QCSB 12v 2wd, so I'm not thinking it's too hard on the shafts and the trans, but wanted to get some opinions on how it's going to handle it. I'm not going to be doing it on a daily basis, but would like to be able to do it and not worry about it.

Thanks

 

[CREED1]

Locked shifts under power are way easier on trans and converter than unlocked shifts under power..

 

[gwhammy]

And why is that? Just asking as I'm looking to put a lockup switch on my twd. I don't have any billet parts but my truck doesn't make much power.

 

[mike_belben]

id also enjoy an explanation on how a fully coupled shift can be easier on a trans in any way than one with a fluid coupling that buffers the shafts from the full torque load by dissipating some of the engine output torque to the fluid being sheared in the convertor.

 

[ARbowhunter7]

id also enjoy an explanation on how a fully coupled shift can be easier on a trans in any way than one with a fluid coupling that buffers the shafts from the full torque load by dissipating some of the engine output torque to the fluid being sheared in the convertor.

Exponentially more efficient shift when locked, and it's common knowledge that "slipping into the next gear" wears out parts. Also, there's no need to buffer the OP's billet input shaft from full tq load...in fact, the ability to apply full torque load is exactly the point behind buying said shaft in the first place.


Sent from my iPad

 

[oilburnerr]

So if im at stock power level on a recently rebuilt 47rh and shift locked will it tear up my trans ?

 

[zstroken]

Exponentially more efficient shift when locked, and it's common knowledge that "slipping into the next gear" wears out parts. Also, there's no need to buffer the OP's billet input shaft from full tq load...in fact, the ability to apply full torque load is exactly the point behind buying said shaft in the first place.


Sent from my iPad

Not sure if I would say shifting unlocked, is "slipping into the next gear" .....

 

[ARbowhunter7]

Not sure if I would say shifting unlocked, is "slipping into the next gear" .....

LMAO...in Michigan, I'm sure you wouldn't! That's just a phrase some rednecks in my neck of the woods use to describe the feeling of an unlocked shift. Nothing technically accurate about it, but it conveys the feeling pretty well - especially to those who are used to locking up in 2nd and banging shifts from there on.

Geographical dialect aside, I do believe that a locked shift (in a properly equipped & set up trans, on a street truck) is better than an unlocked shift.


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[zstroken]

LMAO...in Michigan, I'm sure you wouldn't! That's just a phrase some rednecks in my neck of the woods use to describe the feeling of an unlocked shift. Nothing technically accurate about it, but it conveys the feeling pretty well - especially to those who are used to locking up in 2nd and banging shifts from there on.

Geographical dialect aside, I do believe that a locked shift (in a properly equipped & set up trans, on a street truck) is better than an unlocked shift.


Sent from my iPad

Better for ET perhaps, but no way that a locked shift is "better" for the transmission longevity. Let the transmission shift unlocked, the fluid coupling of the convertor will absorb the shock loads.

 

[ARbowhunter7]

Better for ET perhaps, but no way that a locked shift is "better" for the transmission longevity. Let the transmission shift unlocked, the fluid coupling of the convertor will absorb the shock loads.

I can see this going the direction of that awful, nitpicky, 22,000 page thread about how a 6BT will outlast any Vee motor because of the additional harmonic vibration that's inherent in that design, but I digress...

Back on topic, and to answer the OP's original question... NO, shifting while locked will not hurt your billet Goerend trans.

Also, Zstroken, while I don't know you personally, I know for a fact you know your chit. You've also helped me out personally with some of your wisdom, which I do appreciate. My replies have been tailored specifically to the OP's query, for all intents and purposes.


Sent from my iPad

 

[zstroken]

I can see this going the direction of that awful, nitpicky, 22,000 page thread about how a 6BT will outlast any Vee motor because of the additional harmonic vibration that's inherent in that design, but I digress...

Back on topic, and to answer the OP's original question... NO, shifting while locked will not hurt your billet Goerend trans.

Also, Zstroken, while I don't know you personally, I know for a fact you know your chit. You've also helped me out personally with some of your wisdom, which I do appreciate. My replies have been tailored specifically to the OP's query, for all intents and purposes.


Sent from my iPad

It is just my personal preference, have the convertor right for your application, and let it shift unlocked for normal driving, and if you want to drop the hammer shift it locked.

In my puller all of my shifts were unlocked, and I would just lockup in drive.

 

[ARbowhunter7]

It is just my personal preference, have the convertor right for your application, and let it shift unlocked for normal driving, and if you want to drop the hammer shift it locked.

In my puller all of my shifts were unlocked, and I would just lockup in drive.

Not to derail, but given a standard "performance build" (billet triple and input), what part are you most concerned with taking abuse under locked shifts?


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[duck_04]

Not to derail, but given a standard "performance build" (billet triple and input), what part are you most concerned with taking abuse under locked shifts?


Sent from my iPad

I was told 2 gear bands hate life under locked shifts.

 

[zstroken]

Not to derail, but given a standard "performance build" (billet triple and input), what part are you most concerned with taking abuse under locked shifts?


Sent from my iPad

Splines, planets, sunshell, shafts. However it is just like doing a neutral drop, or revving it to 4000 and dumping the clutch.
You are correct the trans will handle it, but I would say the unlocked shifts are easier on basically everything except for the convertor.

 

[ARbowhunter7]

I was told 2 gear bands hate life under locked shifts.

So you're thinking that, under lockup, the front band doesn't always release the 2nd gear clutches before the 3rd gear clutches engage?


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[duck_04]

So you're thinking that, under lockup, the front band doesn't always release the 2nd gear clutches before the 3rd gear clutches engage?


Sent from my iPad

Yep, my builder told me that binding could occur and destroy the front band. Doesn't always happen, but it's a possibilty. Only time my lockup switch is on is when I hit second gear off the launch and it's a risk I'm willing to take to gain a few tenths on my ET. Otherwise, my lockup switch is never touched.

 

[zstroken]

So you're thinking that, under lockup, the front band doesn't always release the 2nd gear clutches before the 3rd gear clutches engage?


Sent from my iPad

Not really, I am thinking more of the shock loads. Something has to give, figure engine is going from say 4000 rpm to 3000 rpm on a shift. Where if the convertor was unlocked it might go from 4000 rpm to 3500 rpm. So less torque is exerted on everything in the system.

A good example is if you shift a stock input locked there is a good chance it will break, yet shifting it unlocked the chances are much lower.

 

[Cummins41]

Not to derail, but given a standard "performance build" (billet triple and input), what part are you most concerned with taking abuse under locked shifts?


Sent from my iPad

This here is a prime example of what doing locked shifts under a hard load will do! And yes, that is a billet intermediate shaft!

Sent from my SM-G900V using Tapatalk

 

[TAftw]

Not to derail the thread, but will a lockup switch help when towing to reduce tranny temps? For instance, if I'm pulling up a steep grade the fluid coupling spinning in the converter creates heat. So if the converter is filled this would create less friction and therefore less heat?

 

[biggy238]

Help with towing, if used responsibly, yes.
It eliminates fluid coupling and thus reduces heat in the system.