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  #1  
Old 01-09-2005, 11:31 PM
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eckertt@epri.co eckertt@epri.co is offline
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Confused Hi Stall TQ converter overheating the Tranny???

Our 72 Cuda has a 360 motor with a big cam (I could provide more details but I am not sure we need that for this question). Behind it is a 904 with a manual valve body and a 9" torque converter that has a 3500 rpm stall speed.

The 3rd member is a 8 3/4 sure grip with 3.55 ratio.

The guy that built this engine says that this combo sounds ok for the strip, but for the street maybe I might overheat the tranny.

His hypothesis: crusing at any speed where the engine / TQ converter is rotating at less than 3500 rpm, then it will be "slipping" and thus building up heat; possibly more than the trans cooler can disipate. He recommends a 10" converter with a stall in the 2500 to 3000 range.

My understanding of stall speed is that torque multiplying is occuring at rpms under the stall number. Does this infer more wasted heat?

Please know that we have NO experience with this vehicle. We drove it home and into the garage 3 years ago when it was a 318 car. And we have been restoring it extensively. We expect to be cruising (and some 1/8 mile stuff) this coming spring-summer.

What say all you TQ converter experts with experience?? I am all ears.

Thanks,

Tim Eckert
Concord NC
72 Cuda 360/904
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  #2  
Old 01-09-2005, 11:43 PM
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rumblefish360 rumblefish360 is offline
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4spd guy here that knows a little something.

His hypothesis is correct. The converter doesn't grab till it's rating. It's stalling until it grabs where it makes a better connection, so to speak.
Another way to look at it is it's slippage is very high and it's wasting energy. This allows it to slip until 3000 where the main power comes in. At that point the converter grabs and sends the power through with little slippage.

Cam duration is the major player here and should be provided. It is important info as well as weight of the car, tranny used, gear ratio selection,engine size, carb size, intake type and intended useage of the car.

Cruising around while having alot of slippage or below stall of the converter will cause extra heat. Heat is an enemy of trannys. Extra cooling is recomended.

Smaller the converter the less fluid inside of it and easier to heat up and get rid of. Smaller converters belong on the track. The larger the converter, the better it is on the street. A smaller converter has less fluid to send into the tranny for it's Hyd. link up with the tranny. This low fluid amount makes it easier for the tranny to reach that stall speed because theres less fluid to push through. That also makes it easier to rev up to stall speeds.

From here, I myself being in the same understanding boat as you would call Frank Lupo @ Dynamic.
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  #3  
Old 01-10-2005, 06:58 PM
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Any good converter builder can build you a converter that will be "tight" enough at lower rpm's not to over heat your tranny and still stall where you want it to. For a price of course.
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Old 01-11-2005, 03:45 AM
DartGT66 DartGT66 is offline
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I have driven with 3500+ stall speed converters for over 10 years. Five years with a 6300 stall, and currently with a little over 4000 and 3.23 gears. No problems with the trans, but my converters have been tight below the stall. With the 6300 stall 8" I had about 200 rpm more on teh highway than with a 10" street converter. The key is to have a good oil cooler, quality parts in the trans and a deep pan that holds more oil than stock. I think with a good trans cooler you should do pretty well.
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Old 01-11-2005, 09:58 AM
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Default Trans cooler

OK, I am hearing 2 things:

Lesson 1) Not all high stall TQ convertors are built the same. Some are tight (less internal leakage and thus less heat buildup) and some are loose (more leakage-more heat). The converter I have is a PTC 9” 3500 rpm stall speed torque converter. Is PTC a good brand?? Should I consider this as a tight one or as a loose one? Or does one only tell by driving it around?

Lesson 2) An trans cooler should be added. Unfortuantly, this car has the narrow (22"?) radiator support frame, not the large (26"?) one, so I bought a brand new 4 row radiator that looks like a stock unit (don't know the vendor name.) Of course it has a trans cooler. Yoy guys are recommending I add another air cooled trans cooler. Which cooler should the hot tranny fluid go thru first? The one in the radiator? or the add-on one? Any recomendations on vendor for the add-on trans cooler and size?

Also, Rumblefish said the cam specs are pertainent here so:

Camshaft:
Comp Cam, part# 20-243-4, Hydraulic, grind 292H
292° intake 292° exhaust duration
244° intake 244° exhaust duration (at 0.050” lift)
0.501” intake 0.501” exhaust lift (with 1.5 rocker ratio)
110° lobe separation angle


Thanks, Tim Eckert
72 Cuda 360/904
904 has manual valve body and sits behind a PTC 9" 3500 stall converter
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  #6  
Old 01-11-2005, 10:58 AM
DartGT66 DartGT66 is offline
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I have a 9.5" PTC now, I think it's a good one. B&M's stacked plate style coolers are propably the most efficient. I'm using one out of an old big refridgerator though The trans fluid really can't be too cols, so I would just pass the bottom tank and use only an external cooler in front of the radiator.
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  #7  
Old 01-11-2005, 11:28 AM
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Thanks Tim, for the cam specs. Now it's up to the auto trans guys to go the rest of the way. (I believe a 4spd guy, like myself, should not be giving exacting specs or advice like on a converter. It's a lack of exper. thing for me. I'd rather not give the advice on a specific unit. General is another thing.)

On the cooler, yes, add one. I did to my (Seldom had) Auto trans cars. After the stock cooler is the way you want to do it. MoPar has a deep pan. Actualy 2 for ethier tranny that you (The reader) may be running.

I never heard of that performance converter company.
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  #8  
Old 01-11-2005, 12:19 PM
DartGT66 DartGT66 is offline
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I hadn't either, guess they are realtively new. Anyway, I have an angine putting out way over 700 hp and 700 ft-lbs, and I had problems with the 8" converters because they would never hold at teh rpm level my engine had. I tried several of them and finally found one that worked decently and is still in use in the '69 valiant. I got tired of trying to be quick in the 1/4, and decided to do a different kind fo car, mainly street oriented with good driveability. So I rebuilt our old family car and installed a smaller cam in to the engine, 10" TCI converter and 3.23 gears. Decided to try it in the 1/4, the results were decent but seemed like the converter was slipping pretty bad. That's when I decided to order a new one. Asked different companies but finally decided to go with PTC mainly because of the price. They promised me a good converter for 800$. So I ordered it through straightline performance and when the parts finally came there was a wrong converter! It cost only 400+$! So I started to ask what that means and they said that they had came in to different thoughts, and thought that this less expensive converter should work for me. The converter felt way better than the previous TCI, and was actually less expensive tahn a new super street fighter. But the 1/4 mile would tell the truth; the car was a little over tenth quicker, but the big thing was that I had 1000 rpm less going through the traps. Take in to account, that this means that the engine runs in lower rpm and makes less power there. Still the speed was better too. There is a pic of my valiant in the straightline perofrmances customer rides! http://www.straightline-perf.com/Cus...aceCars5.shtml
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  #9  
Old 01-15-2005, 07:42 PM
70 net440 70 net440 is offline
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I wouldn't bypass the cooler in the radiator. When I worked in a tranny shop, we always routed the fluid into the add-on cooler first, then to the rad. You can always install a trans temp. gauge if you have heat concerns.
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  #10  
Old 01-16-2005, 04:37 AM
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Ive ran 2800 stall in 3/4 ton truck with a 318 (290 mech roller)(no joke, sold car, kept engine, truck needed engine), never had a problem, use good fluid, royal purple is what I use
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  #11  
Old 01-16-2005, 05:12 AM
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A good syntetic fluid will help it run cooler. I first used syntetic oil in the tranny on my Peterbilt and it ran 20-25 degrees cooler on the hills. I then put it in the diffs and engine with simaler results. Its good stuff.
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  #12  
Old 01-16-2005, 07:09 AM
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DartGT66; WOW! Very cool. Theres a good vote in the PTC corner.
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  #13  
Old 01-19-2005, 12:26 AM
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Default Tranny coolers

70net 440 says to route the hot fluid first to the add on cooler, then to the cooler in the radiator.

OK, which of the 2 steel lines is the fluid output from the transmission? The rearward most line? or the forward most line?

Thanks for all the input guys!

Tim Eckert
72 Cuda 360/904
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  #14  
Old 01-19-2005, 03:07 AM
DartGT66 DartGT66 is offline
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The forward line goes to the cooler, the rear line is the return.
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  #15  
Old 01-19-2005, 11:33 AM
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I always read to route the line through the stock cooler first, then to the added cooler second. Theroy being that the external cooler will cool off the fluid more and better after the stock one does it's job.
The reverse wasn't recomended because the stock cooler could add heat back into the fluid from the rad.
The external cooler should be second IMO.
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  #16  
Old 01-20-2005, 11:05 PM
70 net440 70 net440 is offline
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It probobly doesn't matter which way you route it. If my memory serves me tranny fluid at normal operating temp. is about 300 degrees. I don't think that even the biggest add-on cooler will lower the temp. of the fluid below 180 degrees, the average temp. of the radiator. Like I said, the difference is probobly neglagable. By adding the cooler and a deep pan as suggested above you will increase the capacity of the system and you shouldn't have any problems.
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  #17  
Old 01-21-2005, 06:15 AM
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One thing I do in my Cuda is put the tranny in neutral when at stop lights. If your car moves forward when in gear and no brakes, and you hold it back with your brakes, that energy is turned into heat. Big cams usually mean higher idle speed which means more heat. Both tranny and engine will run much cooler when in traffic and around town.
And it looks kinda cool when you put it back in gear.
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  #18  
Old 01-21-2005, 10:45 PM
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Tim give these guys a try www.bteracing.com apparantly they can redo your converter to what you want. Take alook in the Drag racing forum there's a thread on converters that might help.
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  #19  
Old 01-28-2005, 06:32 PM
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Default 904 Tranny Pan

Thanks again for all the good input,

I am planning to buy a B&M stacked plate cooler, and a deep pan for the 904.

But in my web searching, I am finding that most vendors only make deep tranny pans for 727, not for 904.

Do you guys know a specific vendor name and part number for a deep pan that fits the 904 (and of course the extended oil pickup piece?)

Thanks, Tim Eckert
72 Cuda, 360/904
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  #20  
Old 02-06-2005, 01:17 PM
70 net440 70 net440 is offline
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Hey, Tim found this in Summit. TCI deep aluminum pan for 904. PN. TCI-127900. $119.88
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  #21  
Old 02-07-2005, 10:59 PM
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Default 904 tranny pan

Thanks 70net440 for the pan info!

Tim
72 Cuda 360/904
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  #22  
Old 02-07-2005, 11:24 PM
HNB racing HNB racing is offline
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hey i ran a 3800 on the street for several years and i never had a problem i was using a b and m cooler for 28000 gvw me and the x used to take my belvedere on long trips sight seeing so i know if you run a good cooler everything will be fine
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  #23  
Old 02-07-2005, 11:50 PM
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[QUOTE=70 net440]It probobly doesn't matter which way you route it. If my memory serves me tranny fluid at normal operating temp. is about 300 degrees.

Another way to look at this, is would it be better for your engines cooling system to have the fluid cooled when it enters the radiator, or not?
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  #24  
Old 02-08-2005, 11:50 AM
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I don't think it would amount to anytihng toad. The rad. coolent is coolest at the bottom before it's taken into the engine. Or should be....
I stated to run the tranny line to the stock rad. cooler first and then into the extrenal unit second. This way it gets cooled like normal and then chilled in the added unit thats infront of the rad.
I think the effect of it in reverse is nil on the rad coolent.
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Old 02-11-2005, 11:12 PM
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Default Cooler 904 tranny

OK guys, Based on your expert advice, we now have a large B&M trans cooler and a extra deep aluminum TCI tranny pan with fins. We will bolt them on this weekend.

On this post, I have heard BOTH opinions on which cooler to run the hot fluid through first. So, I am planning to run the hot fluid thru the cooler in the radiator first, then thru the B&M cooler.

So any more opinions, I am still listening.

Thanks, Tim

Tim Eckert
72 Cuda 360/904
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  #26  
Old 02-13-2005, 01:30 AM
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Default Mopar's Answer to Which Cooler goes First

I finally decided to read the 72 Plymouth service manual. It shows that for some cars, an aux transmission cooler was added by the factory for the automatic transmission. The diagrams show exactly how they plumbed it.

1) Hot fluid from the front most line on the tranny enters the normal cooler in the lower rad tank on the driver's side.

2) The fluid then exits the normal cooler on the passenger side, and routes up and over the top of the radiator support frame. The line then drops down and connects to the aux (air cooled) cooler.

3) The fluid then exits the aux cooler, routes up and over the top of the rad support frame, then drops down and connects to the remaining line going back to the tranny.

Question: I am surprised that the factory routed the lines OVER the rad support frame, as opposed to drilling 2 holes thru the support frame. I guess it is just too hard to drill 2 holes and add rubber grommets while on the assembly line? Or is there some other reason for routing these extra lines this way?

Question 2: For those of you with a E body Cuda or Barracuda, if I route these two 5/16" dia steel lines over the radiator support frame, way over on the passenger side, will these lines interfere with the hood closing?

Tim Eckert
72 Cuda 360/904
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  #27  
Old 02-13-2005, 01:54 AM
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I think there might be two reasons for them not drilling holes and routing the lines thru them. First and probably the main reason, would be wear to the lines, it would only be a matter of time until they rubbed a hole in the lines. The other reason was probably ease of installation on the assembly line.

I can't help you on the hood, mine's fiberglass.
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  #28  
Old 02-13-2005, 03:15 PM
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Default Tranny cooling

Hey all,
Obviously I'm weighing in late on a well weighed in subject!

From what I found out prior to installing my tranny cooler. Do not bypass the lower radiator tank and route it through there first before the aux. cooler.

Part of the reason explained to me was counter-intuitve. The passing of fluid through the tank isn't just for cooling...it is also to help bring the fluid to normal operating temperature. Trans, fluid that is too cold isn't good either. Practically speaking I don't know how long the fluid would remain "too" cool, but I wasn't going to try and find out.

I used high pressure (300psi) rubber hose to route everything, as my stock lines were old and one had a kink. Minimal 90 degree turn fittings, I was told, help to keep good flow. Where I did plumb in fittings I used brass barbed and a hose clamp...hasn't leaked in 4 years. A forklift/industrial supply place hooked me up cheap with the $$ hose.

I used some hose separator/clamps that I got at the local speed shop to send the lines back to the trans...gotta' keep 'em organized and looking like I know what I'm doing! LOL!

And some advice that I still need to put into use: Get the deep pan with a drain plug. Every few motor oil changes...drain afew quarts out of the tranny and put in some new fluid. The idea being that the fluid is cheaper than a TF turned "Toast-Flite"

Hoping for a long life out of my 904!
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