727 transmission tuning advice

[dshockley]

Well,



I finally found a transmission guy that I am confident in and I have an appointment on Friday to have the transmission serviced and adjusted. That will work out great because I will have the CTD all tuned up (new HX35 with a 16 housing and some more pump tweaks). However, I don't want to leave it up to him how I adjust the transmission. I would like to adjust the bands and increase the line pressure, etc. What kind of exprerience have you guys had tweaking the 727 transmission behind the CTD. What line pressures should I specify? What other advice do you have for me? The transmission has 50K on it and is in great shape. I have a transmission temp gauge to keep an eye on things!



Thanks alot for the help.



Dan

 

[Withers]

Try www.dieseltrans.com , lot's of free advise in the discussion, tech tips forum.

 

[dshockley]

I searched all the old posts there, but did not really see what I was looking for. I have seen people post what they have done here before and was really looking to get some feedback on people's personal experiences.



Thanks,

Dan

 

[dshockley]

Research synapsis

Well,



Here is what my research has yielded as far as information. I am looking for anyone to confirm these items and maybe share their experiences, mileage, etc. with the forum.



Fluid: manual recommends 7176 or Mopar Dextron II but the forum consensus is Dextron III with some recommending up to 6 qts of all different kinds of motor oil.



Line pressure: My 1991 manual recommends setting the adjustment to 1 5/16", but does not give a corresponding pressure. One forum member says 1 3/8" will give 100psi full throttle pressure. Others say that manual says 52 psi and the practical max is 60psi with an optimum around 57psi. Is this the idle pressure?



Front servo: Manual says 72 in lbs then back off 2. 5 turns (but I have heard up to 4) In addition it has been recommended to set the gap between the K/D servo push rod and the rocker arm to 3/16 or 5/16.



Rear servo: Manual says 72 in lbs then back off 2 turns. (but have heard as many as 4)



Please help to clear the murky water!!

I appreciate all of your input.



Thanks

Dan

 

[jbolt]

Dan-



Give Bill Kondolay at DTT a call. He is extreamly helpful and will take the time to answer all your questions. I've chatted with him a few times and he is a no nonsese person. No pressure, no BS he just tells it as it is. He will tell you what to do and how to do it right. No purchase required.



Let us know what you come up with.



Jay

 

[hdm48]

Somewhere in here you should be able to find a couple of posts related to trans adjustments. I know, I replied to them. And in these replies I made some detailed instructions on how to adjust everything you can without pulling the unit out.

But just for fun, here are some highlites.

Line pressure: 1. 125" from valvebody to spring retainer

KD band: 5/16" spacer between srevo piston and rocker arm. Take the adjuster to zero, don't crush it in.

Rear band: per factory spec

Now the goodie: find an aluminum accumulator piston, pull the valve body and replace the plastic one with it. And when you put it back together, leave out the accumulator spring. This REALLY helps your 2-3 shift.

And to protect your unit when it gets hot, replace 2-3 quarts of transmission fluid with 30wt engine oil. DO NOT use shift improver fluids!

The engine oil will not effect cold weather performance, but it will help at temp.

And make darn sure your KD cable is adjusted.

And when first started in the morning, let it idle in "neutral" for about 30 seconds before going anywhere. This will fill the TQ and lube everything.



Hows that?





-dave-

 

[hdm48]

Oh, and I forgot to mention, too much line pressure will eat it alive in short order. Stay away from shift kits.

And have a transmission shop clean the cooler. They can do it on the truck and it is a good thing to do.

And by the way, I use dexron 3 and Castrol gtx 30wt

 

[DPKetchum]

I p. m. you

 

[BushWakr - RIP]

With your throttle vavle cable fully returned to the idle position you can set your 'idle line pressure' to a max of 60 psi, however that begins to get rough on the front lip seal (?) so, it was recommended to me, that 58psi was a good compromise.

As for WOT pressure that should be approx. 103 psi max.

Again, double check with Bill K.

He will answer your phone call or posted question with specifics for your version of the 727.



Hope that is some help.



Bob.

 

[dshockley]

hdm48,



I had read all of the post that you made before about the adjustments. I also read everyone else's posts and the amount of contradiction led me to make this post. From my experience, all the folks on this board are really knowledgeable and helpful and that is why it is difficult to sort through conflicting opinions. I was hoping to get a little broader feedback to help me decide between the differing opinions instead of hearing from the same group of people.



DPK,



Thanks for the message. I read that info in one of the other posts and again, that topic also prompted this post. For now, I think that I will go with straight Dextron III until I get some more concrete information.



Bushwakr,



Thanks for the clarification. That was just what I was looking for.





Thanks for all the input on this subject, I really appreciate all the help,



Dan

 

[DPKetchum]

As well as dtt you can look up Transgo web page and they have a help line number. Only one guy takes calls and was very knowledeable with everthing from 6,000 horse drag cars to inports. I talk to him twice and I think he took the myth and stated straight testing and experiance facts.

 

[BushWakr - RIP]

I have also suggested Transgo once or twice myself.

However I'd like to add a caution here. If the primary function of that kit results in elevated internal pressures you MUST make sure that you do not get into the range were lip seals, etc are being over stressed.

Since higher pressures are used to hold clutch pacs tightly together, you must make sure that a "used" trans/VB can take the increase(s) you may inflict on the them.



All I'm saying is this,... when upping pressures in a stock (used) transmission, stay on the shy side of your max allowable ranges or you'll be doing a serious Re & Re before you know it.

If you have the transmission pressures diagnosed properly and fully, then you will have some idea of how far you may be able to 'stretch it' before you get into trouble.



Lastly, on my truck I had to add a "universal throttle return spring" to the throttle vavle arm on the transmission to make sure the throttle valve arm returned to full idle position.

To determine if you need this, lay under the truck, have someone depress the throttle pedal to WOT, then release it back to idle position. Watch the throttle valve arm move backwards during throttle opening, and also watch to see if it returns FULLY forward at idle setting. If not you should try the solution I mentiond.



bob.

 

[dshockley]

Thanks alot for all of your advice.



I just got back from the transmission shop and this is what we did.



front servo, 72 in/lbs back off 2 turns

rear servo, 72 in/lbs back off 2. 5 turns

line pressure to 58 psi

5 qts of dextron mercron III

installed the temp sender in the pan



These spec. were based on the cumulative advice of this board in addition to the information from a conversation yesterday with Bill K.



Now for the next question, since I put the sending unit in the pan, what should be the range of acceptable operating temperatures? I would have rather added it in the line, but Bill K suggested that there was not a good way of doing that.



Thanks

Dan

 

[Case500D]

Hi Dan,



I have been following this post and did the same adjustments that you had done. Philip came over and helped me. I didn't notice much difference in 1 to 2 shift, but 2 to 3 was a bit firmer. I went to put my 2nd gen pan on but the brazed in bung hit the valve body. Time to grind a bit. The only spot in the entire pan where the vlave body is even close and I put a sending unit there, whoops. Anyway, the adjustments for the 518A are the same as you just listed for the 727, so it sounds like you are good to go.



Jeremy

 

[BushWakr - RIP]

Dan,



Currently there is a bit of debate over the pan sensor method or the outlet line method.

I've run both, and currently have it in the pan for two reasons.

One I felt knowing what the temps were just as the oil entered the system was the way to go...

Second, with higher pressures in my setup the cooler line fitting would be prone to leaks.

Now your quetion, I almost never see my gauge come off the 240*F. Only when in very heavy stop and go does it move, and then I've never been above 255*F.

How that correlated to the cooler line temps at the time, I do not know.



Bob.

 

[dshockley]

Well,



So far the temp has not gone above 150 F. I haven't driven all that much, though.



Case500D,



That is just about exactly what I have expeinced so far. 1-2 could be a little better, but 2-3 has improved.



Thanks for all the help guys.

Dan