overrun clutch (4l60e)
I've got Overrun applied in all shifter positions, even reverse, with 4 gear oil shuttling the overruns off.
Just like the sonnax deal, but without a bulky add on...all self contained in the VB
I'm 99% sure I am the first to do this without a valve body add on like sonnax

I think it has been 11 years for me...

We ended up discussing two different Transmission Models.

I brought up the THM700-R4 again, because @tayto was going to work on his own Deign for the THM700-R4...
I wanted to check on his progress...
And maybe give him some clues based on the Design that I use.
You then made your Post that I quoted above... because you have a Design also.
I have a feeling that we are doing the same thing.
Just like the 4L60E, the THM700-R4 releases the Overrun Clutch using the 4-3 Sequence Valve-Train (same Valve-Train used in both the 4L60E and THM700-R4).
Where we may differ is: Which fluid are you stealing and from what location.
Also with the 1982 - 1986 and Early 1987 Cores (No Auxiliary Valve-Body) There are 2 different ways that I have accomplished a Full-Time Overrun Circuit (ONLY Off in OD/ D4 once Up-shifted into 4th-Gear).
The Late 1987 - 1992 Cores, I only have 1 Method.
However the Diagram/ Images that I Posted were in regard to the 4L80E...
This is what Maroon Monster was also referring to.

We were talking about Full-Time Overrun without using an addition Valve (Like Sonnax produces).
He is definitely doing this differently, as he has the Overrun Clutch on in Reverse.
My Design does not work that way.
I am very curious as to what he did differently.

It's the whole reason there is even a sprag and a clutch pack there in the first place...beacuse it HAS to overrun for you to get 4th (and reverse)
The overruns don't add to the capacity of the FORWARD clutch either.
It just supports the input sprag. So it does make the transmission as a unit more durable, but it's not making the fwd clutch itself any better
now you say: "The overruns don't add to the capacity of the FORWARD clutch either."
so do they, like 7 clutches vs. 5 clutches, as has been mentione above, something like 40% more capacity or do they not? i really would like to be sure of how it is.
NO
The overruns to NOT add to the capacity of the FWD clutch
The are on separate splines of the hub
The overruns ONLY add value in supporting the input sprag. That's it.
Hydraulically they add no value to the fwd
Clutch surface they do not add either
I can't make it any more plain
We ended up discussing two different Transmission Models.

I brought up the THM700-R4 again, because @tayto was going to work on his own Deign for the THM700-R4...
I wanted to check on his progress...
And maybe give him some clues based on the Design that I use.
You then made your Post that I quoted above... because you have a Design also.
I have a feeling that we are doing the same thing.
Just like the 4L60E, the THM700-R4 releases the Overrun Clutch using the 4-3 Sequence Valve-Train (same Valve-Train used in both the 4L60E and THM700-R4).
Where we may differ is: Which fluid are you stealing and from what location.
Also with the 1982 - 1986 and Early 1987 Cores (No Auxiliary Valve-Body) There are 2 different ways that I have accomplished a Full-Time Overrun Circuit (ONLY Off in OD/ D4 once Up-shifted into 4th-Gear).
The Late 1987 - 1992 Cores, I only have 1 Method.
However the Diagram/ Images that I Posted were in regard to the 4L80E...
This is what Maroon Monster was also referring to.

We were talking about Full-Time Overrun without using an addition Valve (Like Sonnax produces).
He is definitely doing this differently, as he has the Overrun Clutch on in Reverse.
My Design does not work that way.
I am very curious as to what he did differently.

I have this done in my transbrake 4l80e valve bodies and my non-transbrake valve bodies also.
Don't want to share with the world how it's done. It's more involved than the 60e method. And it's a neat design I don't think needs to be given free.
But it works to feed the overruns with oil in all gears and shifter positions (except 4th gear)
Exactly like the sonnax does
We ended up discussing two different Transmission Models.

I brought up the THM700-R4 again, because @tayto was going to work on his own Deign for the THM700-R4...
I wanted to check on his progress...
And maybe give him some clues based on the Design that I use.
You then made your Post that I quoted above... because you have a Design also.
I have a feeling that we are doing the same thing.
Just like the 4L60E, the THM700-R4 releases the Overrun Clutch using the 4-3 Sequence Valve-Train (same Valve-Train used in both the 4L60E and THM700-R4).
Where we may differ is: Which fluid are you stealing and from what location.
Also with the 1982 - 1986 and Early 1987 Cores (No Auxiliary Valve-Body) There are 2 different ways that I have accomplished a Full-Time Overrun Circuit (ONLY Off in OD/ D4 once Up-shifted into 4th-Gear).
The Late 1987 - 1992 Cores, I only have 1 Method.
However the Diagram/ Images that I Posted were in regard to the 4L80E...
This is what Maroon Monster was also referring to.

We were talking about Full-Time Overrun without using an addition Valve (Like Sonnax produces).
He is definitely doing this differently, as he has the Overrun Clutch on in Reverse.
My Design does not work that way.
I am very curious as to what he did differently.

I have this done in my transbrake 4l80e valve bodies and my non-transbrake valve bodies also.
Don't want to share with the world how it's done. It's more involved than the 60e method. And it's a neat design I don't think needs to be given free.
But it works to feed the overruns with oil in all gears and shifter positions (except 4th gear)
Exactly like the sonnax does
The Best V8 Stories One Small Block at Time
I have this done in my transbrake 4l80e valve bodies and my non-transbrake valve bodies also.
Don't want to share with the world how it's done. It's more involved than the 60e method. And it's a neat design I don't think needs to be given free.
But it works to feed the overruns with oil in all gears and shifter positions (except 4th gear)
Exactly like the sonnax does

My Shop is Completely closed.
I will not be building Transmissions anymore.
I have scaled everything back to a small home shop in my 3-Bay Garage.
Once I stop having Strokes (had a few more this past week)...
I will ONLY be offering GM Electrical Services (Connector Parts, Pig-Tails, and Harnesses).
I will need to turn to you or Frank for any of my Transmission needs.

I would also like to purchase a Separator Plate for a 4L60E and a 4L80E, as well as anything else cool that you have.
Thank you for continuing to contribute here, I know it can be very difficult at times (I experience it here too)...
But honestly we have some amazing Moderators also!!!
so in the end, was i correct when saying: "in my imagination the sprag and forward clutch are "in series" (where the weakes link would set torque capability)."? the forward clutch strenghttens the sprag, so it doesnt fail first and now the forward clutch is the weaker link? (or another element in the trans.)
but then, what does sonnax mean by:
Prevents input sprag and Forward clutch failure by engaging overrun clutch in D4 1st, 2nd and 3rd Gears and D3 1st and 2nd Gears. (sonnax)
does sprag failure automatically make the forward clutch fail as well? if so, why?
(sorry for being so clueless about auto internals.)
edit: seems i also misunderstood "I would estimate that the overrun clutch can hold about 40% of the torque capability" (mrverdit). i quickly assumed the 40% was added to the foreward clutch capability.
Last edited by Dian; Oct 30, 2023 at 01:21 AM.

My Shop is Completely closed.
I will not be building Transmissions anymore.
I have scaled everything back to a small home shop in my 3-Bay Garage.
Once I stop having Strokes (had a few more this past week)...
I will ONLY be offering GM Electrical Services (Connector Parts, Pig-Tails, and Harnesses).
I will need to turn to you or Frank for any of my Transmission needs.

I would also like to purchase a Separator Plate for a 4L60E and a 4L80E, as well as anything else cool that you have.
Thank you for continuing to contribute here, I know it can be very difficult at times (I experience it here too)...
But honestly we have some amazing Moderators also!!!

We ALL hope you can still find the time and motivation to keep sharing your authoritative knowledge of GM transmissions here and especially your wonderful diagrams which have taught us so much.
so in the end, was i correct when saying: "in my imagination the sprag and forward clutch are "in series" (where the weakes link would set torque capability)."? the forward clutch strenghttens the sprag, so it doesnt fail first and now the forward clutch is the weaker link? (or another element in the trans.)
but then, what does sonnax mean by:
Prevents input sprag and Forward clutch failure by engaging overrun clutch in D4 1st, 2nd and 3rd Gears and D3 1st and 2nd Gears. (sonnax)
does sprag failure automatically make the forward clutch fail as well? if so, why?
(sorry for being so clueless about auto internals.)
edit: seems i also misunderstood "I would estimate that the overrun clutch can hold about 40% of the torque capability" (mrverdit). i quickly assumed the 40% was added to the foreward clutch capability.
Here is an analogy
Your truck is the fwd clutch
The chain hooked to it is the input sprag
The rest of the trans is a big load you're trying to pull
A stronger input sprag would be a beefier chain.
turning on the overrun clutch is like adding a tow strap with a bit of elastic to the chain. It will absorb some shock. And help support some of the load of the chain
That doesn't in itself make the truck any stronger or weaker.
You need the truck to work
And the chain to work
To have any fwd movement.
So, yes they both have to work
But no...a stronger input sprag, or turning on the overrun clutch...will not make the fwd clutch itself stronger.
If you were going to slip the fwd clutch aka if your truck was bound to get a flat tire...that will still happen regardless of how strong your chain is
If your chain breaks...it doesn't matter how much hp your truck has...you aren't pulling the load
That's about as good as I can do here without having an analogy so ridiculous it doesn't work at all
still confusing sonnax saying it prevents foward clutch failure.
edit: so to wrap it up, i was asking how much fluid would come out if you remove the plug. the corvertte only has a fill/check plug. so if the engine is running thats the level. if engine is not running, i assume the pan fills more. by how much?
Last edited by Dian; Oct 31, 2023 at 05:26 AM.
still confusing sonnax saying it prevents foward clutch failure.
edit: so to wrap it up, i was asking how much fluid would come out if you remove the plug. the corvertte only has a fill/check plug. so if the engine is running thats the level. if engine is not running, i assume the pan fills more. by how much?
I played around with this on the dyno and you can add considerably more with this method.
We ALL hope you can still find the time and motivation to keep sharing your authoritative knowledge of GM transmissions here and especially your wonderful diagrams which have taught us so much.

I have been severely Mentally affected...
My mind does not want to cooperate with what I need it to do.
I feel like someone removed the portion of my Brain where Creativity, Design, Processing, and Complex Understanding would be.
Everyday of my life, I have wanted to learn something new...
For the most part, I have been able to do so.
Now I have the same desire, but I am struggling to understand anything that I do not already Know or have a general understanding of.
I am very frustrated day to day as I feel Mentally Broken.
I have more free time now to contribute here...
However I am afraid that my declining mental status will render my being here as completely valueless.

I have been severely Mentally affected...
My mind does not want to cooperate with what I need it to do.
I feel like someone removed the portion of my Brain where Creativity, Design, Processing, and Complex Understanding would be.
Everyday of my life, I have wanted to learn something new...
For the most part, I have been able to do so.
Now I have the same desire, but I am struggling to understand anything that I do not already Know or have a general understanding of.
I am very frustrated day to day as I feel Mentally Broken.
I have more free time now to contribute here...
However I am afraid that my declining mental status will render my being here as completely valueless.
When I check onto this place every day, I look at the latest comments, and there are several members that I ALWAYS read, regardless of the sub-forum. You are one of them.
The most important thing is that you are safe/ healthy. We all appreciate your contributions, and wish you the best.
This is probably just a rough patch, and things will get better soon.












