8HP70 Thermostatic Valve

PNUTLT1 · Sep 14, 2017

I was searching for Ram parts and look what I came across.

HP70 HP90 A8 160 Degree Thermostatic Valve by Paramount Performance

I wonder if this would really help us with our 8 speeds and our high transmission temps.

Trapinator · Sep 14, 2017

PNUTLT1 said:
I was searching for Ram parts and look what I came across.

HP70 HP90 A8 160 Degree Thermostatic Valve by Paramount Performance

I wonder if this would really help us with our 8 speeds and our high transmission temps.

Check description. Only available for the A8 upgrade

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crazykid1994 · Sep 14, 2017

I wonder how much power the A8 upgrade holds for people running boost and strokers. I didn't find much info on their website

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shane1981 · Sep 14, 2017

8 speed is good for 513 ft lbs of constant torque in stock form. They are supposed to run warm hell they have a heater in them

tuned by Jay Greene

tsielski · Sep 14, 2017

The thermostatic bypass valve on our Ram's is located within the transmission heater assembly. It unfortunately is not installed closer to the ATF cooler, like it is on cars equipped with the 8HP70 or 90. Were it in a similar position, I'd have bypassed it long ago.

There really are only two options, in my view, to lower the transmission temps on our 8HP70's. One, you can remove the TBV from the transmission heater. It is located on the lower left end of the heater assembly, facing the front of the vehicle. It is held in place by an internal snap ring. Remove the snap ring, grab the little protrusion on the black plastic cap and with pliers, ease it out. The TBV easily separates from the o-ringed black plastic cap, which then can be re-inserted and the snap ring re-attached.
Doing this will allow ATF to flow unrestricted from the cooler back into the transmission. The ATF will still mix with "heated" ATF from the heater assembly, but the overall temperature should be lower than with the TBV in place.
Only issue with doing this is access. On 4x4 Rams, the front driveshaft needs to be removed, and a rigid cable right above it, whose purpose is unknown to me at least, also needs to be partially detached/moved. Even doing the above, access to the snap ring is dicey; there isn't much room to maneuver.
You also could disconnect the engine coolant lines feeding the trans heater and connect them to each other, keeping that circuit intact, but those lines are on the very top of the transmission and difficult to access even if the vehicle were on a lift.

The other option would be to remove the trans heater assembly entirely. It then can be separated by removing 4 bolts, into two pieces; the heater, and a cast aluminum manifold that houses the TBV and also has the attachment points for the lines to the trans cooler. Remove the TBV from it's bore as described above, and drill/tap the two ~3/8" ports that move ATF into and out of the heater, for 1/8 NPT pipe plugs. Then re-attach the modified manifold to the transmission and re-connect the cooler lines, and connect the two engine coolant lines to each other.

I'm at the point of doing one of the above, but access to the trans heater/TBV is a little daunting.

wink · Sep 14, 2017

Bill recommends NEVER removing the valve. I'd listen. At least get his advice before doing anything. He's a really nice guy and you can trust what he says!

For those considering one of his trannies, I can vouch for the quality of his products. My Jeep has been throwing a whole lot of power at one of his built NAG1's for the past 3 years. I couldn't hurt it. However the new build is gonna be too much for it, so I sent it in for his Super Pro NAG1 upgrade, and his matching Dominator converter. The SP has a larger shaft, so the FTI I was running wouldn't work anymore.

wink

tsielski · Sep 14, 2017

Here are a few pics of the TBV, it's bore in the cast aluminum manifold, the back of the assembly facing the transmission itself, and a diagram showing the fluid flow.

Wild one · Sep 14, 2017

I don't know anybody who'd still be running the stock 203 thermostat and one of Bills trannies,so he's got a bit of a scare tactic going on with his claims of 197F at the starting line.I run 185 T-stats in both my wifes un-tuned 2016 Challenger and my tuned 2014 truck,and both get the **** run out of them on Fridays at the local track,and neither car or truck get much above 185F on tranny temps.

tsielski · Sep 14, 2017

Who is "Bill"? I'd be curious hearing his thoughts. The person whose advice I'd been listening to frequents the Eco Diesel and normal forum sections of the Turbo Diesel Register forum whose screen name is "transengineer". According to him, bypassing the TBV will net longer life for the 8HP70. He had no idea by how much, but although the fluid can handle the higher temperatures, the life of the internal solenoids and clutch packs will clearly be longer at somewhat lower temperatures.

Wild one · Sep 14, 2017

tsielski said:
Who is "Bill"? I'd be curious hearing his thoughts. The person whose advice I'd been listening to frequents the Eco Diesel and normal forum sections of the Turbo Diesel Register forum whose screen name is "transengineer". According to him, bypassing the TBV will net longer life for the 8HP70. He had no idea by how much, but although the fluid can handle the higher temperatures, the life of the internal solenoids and clutch packs will clearly be longer at somewhat lower temperatures.

Bill is Paramount Transmissions.Transengineer is a great resource for info on the 8speeds that's for sure.I've picked his brain a few times myself,lol.

Pull Ya · Sep 14, 2017

tsielski said:
Who is "Bill"? I'd be curious hearing his thoughts. The person whose advice I'd been listening to frequents the Eco Diesel and normal forum sections of the Turbo Diesel Register forum whose screen name is "transengineer". According to him, bypassing the TBV will net longer life for the 8HP70. He had no idea by how much, but although the fluid can handle the higher temperatures, the life of the internal solenoids and clutch packs will clearly be longer at somewhat lower temperatures.

"Transengineer" has a pretty stellar reputation based on the information he has shared on TDR regarding transmissions.
Jay

wink · Sep 14, 2017

Wild one said:
I don't know anybody who'd still be running the stock 203 thermostat and one of Bills trannies,so he's got a bit of a scare tactic going on with his claims of 197F at the starting line.I run 185 T-stats in both my wifes un-tuned 2016 Challenger and my tuned 2014 truck,and both get the **** run out of them on Fridays at the local track,and neither car or truck get much above 185F on tranny temps.

Are we talking the same thing? Yeah I run a 180 T-Stat in the Jeep, but it had nothing to do with the tranny. Just curious what kind of power you're making in those vehicles.

wink

Wild one · Sep 14, 2017

wink said:
Are we talking the same thing? Yeah I run a 180 T-Stat in the Jeep, but it had nothing to do with the tranny. Just curious what kind of power you're making in those vehicles.

wink

The 8 speed uses engine coolent to heat the tranny,bring the coolent temp down,and the tranny temp goes down. Read the link close,and you'll see Bill is claiming 197F sitting on the starting line.Nobody running any amount of horsepower is going to be running the stock 203F thermostat,and that's the only way you're going to sit on the starting pad with a tranny temp of 197F.

wink · Sep 14, 2017

Wild one said:
The 8 speed uses engine coolent to heat the tranny,bring the coolent temp down,and the tranny temp goes down. Read the link close,and you'll see Bill is claiming 197F sitting on the starting line.Nobody running any amount of horsepower is going to be running the stock 203F thermostat,and that's the only way you're going to sit on the starting pad with a tranny temp of 197F.

Gotcha! Didn't know about the 8 speed connection. However I know Bill, and he's as honest as the day is long. I'm sure there's a reason he posted that temp. It's definitely not to hawk his wares through scare tactics. That's just not his style. He'd rather recommend another product than sell you the wrong thing.

Here's a personal experience I had a few years back. I was trying to save $1k over Bill's tranny and went with a SHR. Total POS that was defective before it shipped. Eddie is a crook! Not only would he not stand behind it, he said he wasn't gonna take my core. Well my vendor called Bill and he said tell him to send it to me, I'll cover the core for him. And he did. When he went through it he said there wasn't a usable part in the whole tranny. It had less than 5k on it. So he sent it back. It's been sitting in my garage since then. Still comped the core fee. So I bought the Paramount I should've in the first place. In my book that's going above and beyond...

I think everyone in the 6.1 world swaps their t-stat right away, so I'd assume the serious 8-speeders would as well. But mea culpa, I've not changed the one in my Ram yet. Just haven't got around to it. But then I've only got 3k miles. It'll happen.

But I'd still like to know about your rides. Just interested in what other go fast folks have mod, power, and ET wise. I don't know anything about your Challenger, so interested in it as well. I've been at the track every week for the past 7 years beating the hell out of my Jeep, yet I still enjoy this stuff off-track too.

wink

PNUTLT1 · Sep 14, 2017

Well I always see that high tranny temps kill transmissions.
So the goal would be to keep it low, but these 8 speeds are meant to be running high so it's kinda confusing.
I have a 180 stat and since the coolant is cooler than transmission is cooler somewhat but I wouldn't mind it being lower. Even the rams with 6 speeds run a lot cooler.

I think before I get trans Tuning in a month or so, I'm going to put a new filter on my 8 speed and top it off with redline fluid.

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tsielski · Sep 15, 2017

Originally I had thought that installing a cooler engine thermostat would in turn allow the 8-speed to run cooler, but unfortunately that doesn't happen. Engine coolant is used to get the transmission hot in the transmission heater (or up to operating temperature to use Mopar's propaganda) quickly. It works in conjunction with the TBV to keep the temps hot.

When I still was running the OEM T-stat (203 degrees), my trans temperatures were 185 - 188 while cruising on the highway. After installing a 180 degree T-stat, the trans temps are exactly the same. After an aggressive pass, I've seen trans temps spike to over 195, and then take a long time to drop back to the 188-185 range thanks to the TBV, because even when open, it doesn't allow full flow of cooled ATF.

The TBV is the little device that keeps the trans temps artificially hot. It does not allow any ATF, after being cooled in the trans cooler, to return to the transmission, until the ATF is at least 180 degrees. Once at that temp, the TBV opens a little, letting some cooled ATF mingle with the hotter fluid. A few times I've seen trans temps drop to 179 for a second or two, then it jumps right back to 185+ when the TBV closes. The engine thermostat really has no effect on transmission temperatures once everything is warmed up.

Bottom line is the TBV is a thermal management device that Mopar uses to make the 8-speed run at temperatures which yield slightly better fuel economy, in my view, at the expense of some transmission life. How much of a fuel economy improvement is unknown compared to a transmission running at say 160 degrees.

Mopar, or any OEM for that matter, is really only concerned about component life for the duration of the standard warranty period. After that, it's not their problem. I'll also bet that the # of buyers who opt for the extended warranty is statistically small compared to the entire buyer population, and any "failures" in the extended period are regarded as a financially manageable risk. The transmission thermal management devices are a fuel economy ploy to improve their CAFE, however small, because improvements = $$, thanks to putative regulations from our government.

For those who never plan on keeping their trucks past 100K miles, or trade after several years, it's not an issue. For those who tend to use a vehicle up, it's something that bears addressing in my view.

Wild one · Sep 15, 2017

tsielski said:
Originally I had thought that installing a cooler engine thermostat would in turn allow the 8-speed to run cooler, but unfortunately that doesn't happen. Engine coolant is used to get the transmission hot in the transmission heater (or up to operating temperature to use Mopar's propaganda) quickly. It works in conjunction with the TBV to keep the temps hot.

When I still was running the OEM T-stat (203 degrees), my trans temperatures were 185 - 188 while cruising on the highway. After installing a 180 degree T-stat, the trans temps are exactly the same. After an aggressive pass, I've seen trans temps spike to over 195, and then take a long time to drop back to the 188-185 range thanks to the TBV, because even when open, it doesn't allow full flow of cooled ATF.

The TBV is the little device that keeps the trans temps artificially hot. It does not allow any ATF, after being cooled in the trans cooler, to return to the transmission, until the ATF is at least 180 degrees. Once at that temp, the TBV opens a little, letting some cooled ATF mingle with the hotter fluid. A few times I've seen trans temps drop to 179 for a second or two, then it jumps right back to 185+ when the TBV closes. The engine thermostat really has no effect on transmission temperatures once everything is warmed up.

Bottom line is the TBV is a thermal management device that Mopar uses to make the 8-speed run at temperatures which yield slightly better fuel economy, in my view, at the expense of some transmission life. How much of a fuel economy improvement is unknown compared to a transmission running at say 160 degrees.

Mopar, or any OEM for that matter, is really only concerned about component life for the duration of the standard warranty period. After that, it's not their problem. I'll also bet that the # of buyers who opt for the extended warranty is statistically small compared to the entire buyer population, and any "failures" in the extended period are regarded as a financially manageable risk. The transmission thermal management devices are a fuel economy ploy to improve their CAFE, however small, because improvements = $$, thanks to putative regulations from our government.

For those who never plan on keeping their trucks past 100K miles, or trade after several years, it's not an issue. For those who tend to use a vehicle up, it's something that bears addressing in my view.

With the stock T-stats,both my wifes 2016 Challenger and my 2014 truck both ran in the neighbourhood of 195 to 200F,with 185 t-stats,both run noticeably cooler at 180 to 185,even beating the **** out of both on back to back passes at the track neither one will get over 190F on tranny temps,engine oil temps will go up a lot though.Biggest change I found besides swapping T-stats was swapping grills in my truck,going from the Sport grill to the Honeycomb grill dropped my oil temps by a good 5 degrees. I've never got my tranny to run over 190F after going to a 185 T-stat,and that includes pushing the hell out of it in 3rd and 4th running upwards of 6,000 rpm for over 30 miles on mountain roads at 90+F outdoor temp,racing a WRX,lol.Truck runs 12.50's at 4600ft DA Wink,car is stock except for T-stat and catch can,it's her daily driver,and I kind of want one with some warrenty,lol.It runs 13.80's at the same elevation

wink · Sep 15, 2017

Wild one said:
With the stock T-stats,both my wifes 2016 Challenger and my 2014 truck both ran in the neighbourhood of 195 to 200F,with 185 t-stats,both run noticeably cooler at 180 to 185,even beating the **** out of both on back to back passes at the track neither one will get over 190F on tranny temps,engine oil temps will go up a lot though.Biggest change I found besides swapping T-stats was swapping grills in my truck,going from the Sport grill to the Honeycomb grill dropped my oil temps by a good 5 degrees. I've never got my tranny to run over 190F after going to a 185 T-stat,and that includes pushing the hell out of it in 3rd and 4th running upwards of 6,000 rpm for over 30 miles on mountain roads at 90+F outdoor temp,racing a WRX,lol.Truck runs 12.50's at 4600ft DA Wink,car is stock except for T-stat and catch can,it's her daily driver,and I kind of want one with some warrenty,lol.It runs 13.80's at the same elevation

Cool! Not bad for that DA. So are you running a shot? Can you check tranny temp on the Chally? On the Jeeps you can't do anything with the TCM. Only the LX crowd seems have that ability. I tried a MTCM, but wasn't happy, so I've got Bill's PTCM now. Works great! Probably gonna have to get him to reprogram it when I get the Jeep back. Have to see the powerband to know. But the Jeep is back on the lift and isn't coming off till it's done. About friggin' time!

wink

Edit: Oh yeah. The highest I've seen the tranny temp at the track is 177. That was after a round robin. When I let it cool between passes I was seeing around 165.

8HP70 Thermostatic Valve

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