RevMax 8 speed thermostat bypass

[Bigskyroadglide]

If you're not living on the edge you take up too much space

 

[crazykid1994]

Might be me,but it looks like the only change that i can see is the newer one comes with the transfer tubes,which were updated.Maybe i'm missing something though.Alot of times the suffix change relates to a price change to,from what i've gathered up from my local parts department,but don't quote me on that,that's just what my local partsmen has told me,lol

My tubes were the older style with the o rings. Not the newer encased tubes. It’s weird because I bought my truck dec 2016. It’s a 2017 model

 

[Wild one]

My tubes were the older style with the o rings. Not the newer encased tubes. It’s weird because I bought my truck dec 2016. It’s a 2017 model

From what i've gathered up,it looks like the tube change occurred in the 18's ,i thought it was earlier then that. I replaced my tranny in the spring of 18 and at that time the new style transfer tubes were available through my local parts department.
That might be the reason for the part number change from 18 on though

 

[Different Drummer]

Today's run temps

View attachment 236774

That's Nashville to Knoxville

That looks about perfect. IMO

 

[Different Drummer]

I don't want to muddy Caulks thread so I am going to put this here. Plenty of minds have been weighing in on the subject so all please feel to comment. My question is, what do you think would be the results if I did the following.
1) Place a valve in the line that runs between the 3 way diverter and the heater on the transmission. Thus allowing hot fluid from the cooling system to be shut off. Same principle as in the heater core in the cabin area. Valve off = no fluid flow and no heat, Valve open = fluid flow and heat.
2) remove the spring and thermostat that is under the plastic cap . This would eliminate the 180 degrees required to get fluid to flow to the cooler. There would be two paths for fluid to follow, one to the cooler and one to the heater. However, unlike the #2 option with RevMax the fluid going to the heater would not be heated because you can stop the hot coolant flow with the valve under the hood.
In fact if you were traveling through a very cold area you could open the valve and allow some of the fluid to be heated. When in a very hot area close the valve.
This seems kind of simple and straight forward to me. What am I overlooking?
Does that plastic cap require spring pressure to hold it against the c-clip for a seal?
And somebody please tell me why my font gets smaller as my post gets longer. What the hell causes that?

 

[Wild one]

I don't want to muddy Caulks thread so I am going to put this here. Plenty of minds have been weighing in on the subject so all please feel to comment. My question is, what do you think would be the results if I did the following.
1) Place a valve in the line that runs between the 3 way diverter and the heater on the transmission. Thus allowing hot fluid from the cooling system to be shut off. Same principle as in the heater core in the cabin area. Valve off = no fluid flow and no heat, Valve open = fluid flow and heat.
2) remove the spring and thermostat that is under the plastic cap . This would eliminate the 180 degrees required to get fluid to flow to the cooler. There would be two paths for fluid to follow, one to the cooler and one to the heater. However, unlike the #2 option with RevMax the fluid going to the heater would not be heated because you can stop the hot coolant flow with the valve under the hood.
In fact if you were traveling through a very cold area you could open the valve and allow some of the fluid to be heated. When in a very hot area close the valve.
This seems kind of simple and straight forward to me. What am I overlooking?
Does that plastic cap require spring pressure to hold it against the c-clip for a seal?
And somebody please tell me why my font gets smaller as my post gets longer. What the hell causes that?

Personally i think you're over thinking this,lol. You're adding more leak points to a system that already has a few. Why are you wanting to heat the fluid,when the HD trucks and the cars don't heat the fluid. I think you'd be farther ahead adapting the HD trucks thermostat block into place.From what i've gathered up talking to a few HD owners,the 8 speeds in the HD's are running right around the 160/165 range when the trucks are running down the road unloaded.

 

[Different Drummer]

Personally i think you're over thinking this,lol. You're adding more leak points to a system that already has a few. Why are you wanting to heat the fluid,when the HD trucks and the cars don't heat the fluid. I think you'd be farther ahead adapting the HD trucks thermostat block into place.From what i've gathered up talking to a few HD owners,the 8 speeds in the HD's are running right around the 160/165 range when the trucks are running down the road unloaded.

The idea of opening the valve and allowing heated fluid to flow was an after thought that came to mind while I was typing. So lets toss that thought aside.
Now I think you may be over thinking Wild one? To suggest that simply taking a ball valve and adding a short piece of 3/4 hose to it, removing the original hose from the diverter valve , install the preprepared valve and hose onto the diverter valve and then reattaching the original hose to the down flow side of the valve is going to be leak prone seems more like over thinking. You don't even have to cut the original hose.
That is all of maybe a 15 minute procedure up top where it is easily accessible. There are millions of cars with heater hoses running under the hood and through the firewall without leaks.
Removing the plastic cap at the transmission and replacing after removal of the thermostat is nothing more than what every procedure suggested or performed so far has called for.
Remove the heat source, remove the 180 degree thermostat so fluid will not be impeded to the cooler and let it flow. I will have to give it a try in the Spring when I hopefully do the transmission service and report results.

 

[caulk04]

By simply removing the thermostat, you'll get little too no flow through the cooler. It's a much shorter path for it to go through the heat exchanger. Likely fine in cold weather, but in warm weather you won't be able to cool it down, even with the coolant turned off from the exchanger.

 

[Wild one]

I honestly don't think DD has caught onto how the system operates,as he seems to be hung up on pre-heating the fluid. The fluid is only pre-heated to meet the trucks milege numbers.I've tried to get it across to him,that if pre-heating the fluid was beneficial to the life of the tranny,the cars and the HD trucks would also be pre-heating the fluid.I'm not saying you haven't got some good ideas DD,but you have to realize only the 1500's pre-heat the fluid,while the vehicles with the most factory horsepower ahead of the 8HP70 don't pre-heat the fluid,ie: the 6.4 SRT Challenger/Chargers,and the vehicles that put the most torque stress on the tranny don't pre-heat the fluid ie: the 2500's and 3500's.That should make you question why the 1500's have to pre-heat the fluid,it's not done for the life expectancy of the transmission,it's done strictly to meet cafe/epa milege numbers.

 

[Different Drummer]

By simply removing the thermostat, you'll get little too no flow through the cooler. It's a much shorter path for it to go through the heat exchanger. Likely fine in cold weather, but in warm weather you won't be able to cool it down, even with the coolant turned off from the exchanger.

Thank you. This was one of the things I was hoping you folks that have had a close look at the system might answer. The unknown to me was what is the path of least resistance to flow if the thermostat chamber is left entirely open? Will there be equal flow to the cooler and the heater? Will there be more flow to the cooler than the heater? Will there be more flow to the heater? You have answered what I did not know. Apparently the internal design of the thermostat chamber is such that more flow will enter the heater if the controlling device is removed.
My mistake to try to ferret out the information without asking directly.

Can anyone describe the exact path the transmission fluid travels? The only diagram I see is not doing it for me.
I ask because if the fluid arrives at the Thermal control unit from the cooler it would make no difference if it passed through the heater core if the heat supply to the core was removed. i.e. blocking the flow from the 3 way diverting valve under the hood on the frame rail.
I guess there is some fluid path I must not be getting a grasp of.

I know I am in the minority on this but I just don't want to get my transmission Temp. down to the 120's. Caulk04 you obviously have the equipment available to you and the capability and experience to use it to make the device you have come up with. I like it a lot and in fact it is similar to what I had originally envisioned. If it brought Temps into the 150 range I would have already grabbed one from you.
Please keep updating your Temps. once in a while.

 

[Different Drummer]

I honestly don't think DD has caught onto how the system operates,as he seems to be hung up on pre-heating the fluid. The fluid is only pre-heated to meet the trucks milege numbers.I've tried to get it across to him,that if pre-heating the fluid was beneficial to the life of the tranny,the cars and the HD trucks would also be pre-heating the fluid.I'm not saying you haven't got some good ideas DD,but you have to realize only the 1500's pre-heat the fluid,while the vehicles with the most factory horsepower ahead of the 8HP70 don't pre-heat the fluid,ie: the 6.4 SRT Challenger/Chargers,and the vehicles that put the most torque stress on the tranny don't pre-heat the fluid ie: the 2500's and 3500's.That should make you question why the 1500's have to pre-heat the fluid,it's not done for the life expectancy of the transmission,it's done strictly to meet cafe/epa milege numbers.

No, I am not hung up on pre-heating the fluid. I do not have a desire to heat the fluid at all. I suggested cutting off the heat supply to the heat exchanger by putting a valve in the line that carries hot fluid from the radiator to the thermal unit or heater. You cannot transfer heat if you do not have a source of heat to transfer from.
I share your beliefs on all that you say in regards to comparing our 1500's to other vehicles. I do understand why the engineers heat the fluid and I do agree with your explanation on how and why the system does what it does.
Recall that I suggested that it might be plausible to use the thermostatic control block from the HD trucks on the 1500's. I would love to see the Temps. that the HD guys are posting.
I learned the hard way long ago that I should always be open to new information and willing to learn new things. In searching for Information I keep coming upon statements that put forth 175*F as the ideal transmission Temp. I know we have always felt lower is better when it comes to transmission Temps. Recall the statement I made about cooling the THM400 in my 3500 GMC.
With that transmission I would have and still will say that I can't get the Temp. low enough.
However, on the ZF transmission I just don't feel good about taking it down into the 120's.
I realize that I stand alone on that but thats what I am comfortable with.

 

[caulk04]

Can anyone indicate the fluid flow direction on these ports? I'm curious on the in/out and flow direction.

View attachment 235514

In this picture, port A is fluid into the trans, port B is fluid leaving the trans.



Red arrows are fluid leaving the trans, going towards the cooler and heat exchanger.

Blue arrow is fluid coming back from the cooler.

Multi color are the ports between the heat exchanger and manifold.

Because it's such a short path, fluid will flow through the heat exchanger much more easily than it will through all the lines to the front of the truck unless forced to do so by an open (hot) thermostat or my valve.

Fluid flows into the thermostat housing from either end, toward the middle of it where it reenters the trans.

 

[Wild one]

No, I am not hung up on pre-heating the fluid. I do not have a desire to heat the fluid at all. I suggested cutting off the heat supply to the heat exchanger by putting a valve in the line that carries hot fluid from the radiator to the thermal unit or heater. You cannot transfer heat if you do not have a source of heat to transfer from.
I share your beliefs on all that you say in regards to comparing our 1500's to other vehicles. I do understand why the engineers heat the fluid and I do agree with your explanation on how and why the system does what it does.
Recall that I suggested that it might be plausible to use the thermostatic control block from the HD trucks on the 1500's. I would love to see the Temps. that the HD guys are posting.
I learned the hard way long ago that I should always be open to new information and willing to learn new things. In searching for Information I keep coming upon statements that put forth 175*F as the ideal transmission Temp. I know we have always felt lower is better when it comes to transmission Temps. Recall the statement I made about cooling the THM400 in my 3500 GMC.
With that transmission I would have and still will say that I can't get the Temp. low enough.
However, on the ZF transmission I just don't feel good about taking it down into the 120's.
I realize that I stand alone on that but thats what I am comfortable with.

I'm pretty comfortable with the tranny running at 140F,as my wifes last two 8 speed Challengers run right around those temps if you're driving them in the neighbourhood of 50/55 mph,and at those speeds they both will take upwards of a 100 miles to get to 140. We'll go out for an evening drive in the country in the summer,and it'll take us over 2 hours to make a 100 mile tour,and we're almost back home by the time the tranny hits 140F.We have lots of wide open country side up here,to tour through checking out wheat fields etc.i grew up farming,so i like slow drives in the country side,lol. Even at 75mph the tranny in her 1320 Challenger will run no more then 165 on a 75F day,and that's a car that comes from the factory with a 2600 rpm high stall torque convertor and tranny brake factory installed.The only time the tranny in her 1320 will get up to 175,is if you're standing on the tranny brake for close to minute with the engine rpm at 2600. There's also a pile of oil field in Alberta,with a fair amount of 6.4 HD trucks,and those guys beat the living hell out of a 3/4 ton HD truck when it's cold,and the 8 speed has a pretty good rep for surviving even the young guys driving a company truck,and some of those trucks have more air time then driving time,lol. I also work on the idea that ZF has you check the fluid level at 122F,which leads me to think as long as the tranny runs over that 122F temp,it'll be perfectly fine.Like i stated earlier,i've never seen an automatic transmission blow up or scatter parts from being to cold,but i've seen lots blow up from being to hot.

 

[Wild one]

In this picture, port A is fluid into the trans, port B is fluid leaving the trans.

View attachment 237194

Red arrows are fluid leaving the trans, going towards the cooler and heat exchanger.

Blue arrow is fluid coming back from the cooler.

Multi color are the ports between the heat exchanger and manifold.

Because it's such a short path, fluid will flow through the heat exchanger much more easily than it will through all the lines to the front of the truck unless forced to do so by an open (hot) thermostat or my valve.

Fluid flows into the thermostat housing from either end, toward the middle of it where it reenters the trans.

You might be able to keep some heat from the heat exchanger,by using the Rev Max kit,and turning the block off plate into a restrictor plate instead.It'd take some trial and error to figure out the size of holes you'd need in the plate for it be used successfully as a restrictor plate though.If somebody decides to try that idea out,i'd start with no more then 1/16" holes and work up from there.Used as a restrictor plate,will keep the majority of fluid to be forced through the cooler,but still allow some fluid to run to the heat exchanger and warm up.It'd take some trial and error to find that fine line to where the restrictor plate idea would work though

 

[caulk04]

You might be able to keep some heat from the heat exchanger,by using the Rev Max kit,and turning the block off plate into a restrictor plate instead.It'd take some trial and error to figure out the size of holes you'd need in the plate for it be used successfully as a restrictor plate though.If somebody decides to try that idea out,i'd start with no more then 1/16" holes and work up from there.Used as a restrictor plate,will keep the majority of fluid to be forced through the cooler,but still allow some fluid to run to the heat exchanger and warm up.It'd take some trial and error to find that fine line to where the restrictor plate idea would work though

I've already considered that as an option with my part. Would be very simple to drill a hole in the other end and another to cross it which would allow metered flow through my valve. Still keeps the simplicity of not splitting the thermal unit for the revmax plate.

 

[Wild one]

If anybody in Southern Alberta wants a duplicate of the Rev Max block off plate give me a holler. I had 4 made up,and they set me back 60 bucks each which is what i want for them.I'll deliver them to Calgary or Red Deer or any where in between those 2 centers.No paypal account,so it's cash deals only,lol
Rick

 

[Different Drummer]

In this picture, port A is fluid into the trans, port B is fluid leaving the trans.

View attachment 237194

Red arrows are fluid leaving the trans, going towards the cooler and heat exchanger.

Blue arrow is fluid coming back from the cooler.

Multi color are the ports between the heat exchanger and manifold.

Because it's such a short path, fluid will flow through the heat exchanger much more easily than it will through all the lines to the front of the truck unless forced to do so by an open (hot) thermostat or my valve.

Fluid flows into the thermostat housing from either end, toward the middle of it where it reenters the trans.

I see the thermostat in the photo. Have you placed it there to indicate its position relative to flow? Where the blue line make a 90 degree turn is where the thermostat enters the unit ?

 

[caulk04]

That isn't my picture, just a Google search. The 90 turn in the blue line is where the fluid returning from the cooler enters the outside of plastic plug and passes through those fluted ports to the center. If the stat is cold, it cannot go any further. Once it opens, the fluid can pass and reenter the trans.

 

[Wild one]

I see the thermostat in the photo. Have you placed it there to indicate its position relative to flow? Where the blue line make a 90 degree turn is where the thermostat enters the unit ?

This pic might help a bit to ,you can see how the flow path is inside the thermostat housing.

 

[Different Drummer]

That isn't my picture, just a Google search. The 90 turn in the blue line is where the fluid returning from the cooler enters the outside of plastic plug and passes through those fluted ports to the center. If the stat is cold, it cannot go any further. Once it opens, the fluid can pass and reenter the trans.

If you extend the blue line past the 0-ring nipple toward the multicolored circle, that is the path that your device blocks, correct? Preventing already cooled fluid from getting into the heater.
Bear with me now, I know I am frustrating you guys. If I am correct in my understanding, what you are saying is that even though there is not any heat exchanging taking place ( because the source of heat was removed by either the blocking plate being installed or by a valve in the supply line ), this robs fluid from getting to the cooler. I thought that fluid when it exited the heater was destined for the transmission and when it exited the transmission it was headed for the cooler. I think what you want me to grasp is that with a totally open chamber ( where your device sits ) there will be starvation of volume heading out to the cooler.
Be kind guy's, don't shoot me!