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727 - pulls motor down on 2-3 shift

Posted By: boscosis

727 - pulls motor down on 2-3 shift - 03/28/11 06:19 PM

On jack stands you can tell that the motor lugs a little on the 2-3 shift; you almost see the tires stop turning briefly also. On the track the shift is lazy and the mph/et are not what they should be. This is a race-only 727 with a billet drum, bolt-in sprag, and a non low band apply A&A manual valve body.
What should we look for? This valve body has worked fine in a different tranny.

THanks
Posted By: 68valiant68

Re: 727 - pulls motor down on 2-3 shift - 03/28/11 06:22 PM

what was the clearance in the high gear clutch pack? maybe to tight?
Posted By: dOc …

Re: 727 - pulls motor down on 2-3 shift - 03/28/11 06:24 PM

Shift timing is waaay off.

What are the critical specs?
Posted By: boscosis

Re: 727 - pulls motor down on 2-3 shift - 03/28/11 06:27 PM

I'm afraid that I didn't personally build the tranny so I don't know the clearances. Do you guys think it's a valvebody issue?
Posted By: dOc …

Re: 727 - pulls motor down on 2-3 shift - 03/28/11 06:30 PM

Can you at least check line pressure ?
Posted By: dartman366

Re: 727 - pulls motor down on 2-3 shift - 03/28/11 06:35 PM

Quote:

Shift timing is waaay off.

What are the critical specs?


some time's you have to fudge the band adjustment a little to get it where it want's to be, is the band lever ratio the same as before? try backing off the band adjustment 1/4 to 1/2 turn and see if that help's,,if you tightened up the clutch running clearance then it engages before the band has released fully.
Posted By: dartman366

Re: 727 - pulls motor down on 2-3 shift - 03/28/11 06:39 PM

Quote:

Do you guys think it's a valvebody issue?


probably not,like I said before, band adjustment.
Posted By: JohnRR

Re: 727 - pulls motor down on 2-3 shift - 03/28/11 07:21 PM

Quote:

Do you guys think it's a valvebody issue?




It's an issue CAUSED by the valvebody.

The 727 walks a very fine line on overlap , which is what you are seeing. The factory went to pains to make it as small as possible, when you increase line pressure, change clutch front pack clearance, change the lever ratio, change band adjustment and change spring count in the front drum you change that oh so delicate shift timing from the factory setting.

Now you have to deal with it. Playing with the band adjustemnt is the easiest way to try to fix it.
Posted By: John_Kunkel

Re: 727 - pulls motor down on 2-3 shift - 03/28/11 07:43 PM

Easiest way to cure severe overlap is to place an orifice restrictor in the front clutch feed passage in the case. (circled in red below)

Remove the VB, tap the passage in the case to 1/8"-27 NPT and place a pipe plug with a drilled orifice in the case. I'd start with a .140" orifice.

Attached picture 6554324-Orifice.jpg
Posted By: boscosis

Re: 727 - pulls motor down on 2-3 shift - 03/28/11 08:54 PM

Thanks for the help guys; I'm considering finally building my own 727 along with my brother this time around. I've pulled them apart before but only to salvage parts like drums or planetaries.
What manual/book do you guys recommend that I buy as a first-time "builder"?
Posted By: Cab_Burge

Re: 727 - pulls motor down on 2-3 shift - 03/28/11 09:58 PM

Quote:

Thanks for the help guys; I'm considering finally building my own 727 along with my brother this time around. I've pulled them apart before but only to salvage parts like drums or planetaries.
What manual/book do you guys recommend that I buy as a first-time "builder"?


The problems your describing are common when the shifter linkage is not adjusted correctly Make sure the shifter cable end drops into the shifter arm attached to the valve body easily in all three forward gears as well as nuetral Put the car up on jackstands and disconnect the shifter cable, start the car and shift the tranny manually from underneath the car at 1500 to 2500 RPM and see if it does the same as before, if not it is the linkage Let us know what you find out
Posted By: boscosis

Re: 727 - pulls motor down on 2-3 shift - 03/28/11 10:07 PM

Shifter alignment is perfect so I'm pretty confident that isn't the problem.
Posted By: 440Jim

Re: 727 - pulls motor down on 2-3 shift - 03/28/11 10:10 PM

Just to add to the good advice given,
if that trans has a 5.0 front band lever, take it out and put a 3.8 or 4.2 ratio lever in.
Posted By: Sixpak

Re: 727 - pulls motor down on 2-3 shift - 03/28/11 10:15 PM

Quote:

Thanks for the help guys; I'm considering finally building my own 727 along with my brother this time around. I've pulled them apart before but only to salvage parts like drums or planetaries.
What manual/book do you guys recommend that I buy as a first-time "builder"?



One of the best 'books' I ever got came with a complete rebuild kit from Fairbanks transmissions - the instruction manual. Similar kits from B&M, etc. had virtually identical steps in them. I still refer to them when doing my 727's. Go to Mancini's - I think they sell one or more of the popular TF mod books...

http://chucker54.stores.yahoo.net/toatrha.html
Posted By: maximum entropy

Re: 727 - pulls motor down on 2-3 shift - 03/28/11 10:28 PM

Quote:

Just to add to the good advice given,
if that trans has a 5.0 front band lever, take it out and put a 3.8 or 4.2 ratio lever in.



yeah, that 5.0 lever is a killer. anything you can do to speed up the release of the intermediate band, is going to make it easier to nail down the 2-3 shift timing. a billet servo with heavy duty release springs is a good step.
Posted By: theman440

Re: 727 - pulls motor down on 2-3 shift - 03/29/11 12:14 AM

How does it shift at WOT ?
Posted By: dartman366

Re: 727 - pulls motor down on 2-3 shift - 03/29/11 12:40 AM

Quote:

Quote:

Thanks for the help guys; I'm considering finally building my own 727 along with my brother this time around. I've pulled them apart before but only to salvage parts like drums or planetaries.
What manual/book do you guys recommend that I buy as a first-time "builder"?



One of the best 'books' I ever got came with a complete rebuild kit from Fairbanks transmissions - the instruction manual. Similar kits from B&M, etc. had virtually identical steps in them. I still refer to them when doing my 727's. Go to Mancini's - I think they sell one or more of the popular TF mod books...

http://chucker54.stores.yahoo.net/toatrha.html


the two best book's to have and will tell you a boat load of info and they are Torqueflite A-727 Transmission Handbook by Carl H, Munroe and the ATSG manual(automatic transmission service guide), I have both and they are indespensable. I do 904's but the 727 book still has a lot of pertinate info.
Posted By: A727Tflite

Re: 727 - pulls motor down on 2-3 shift - 03/29/11 01:55 AM

You're not real clear with the problem at hand. You state that the trans almost locks up on the stands on the 2-3 shift, then you state it is lazy on the track. It's not uncommon to get overlap on the stands. What does it do on the track, run away on the 2-3 or overlap on the 2-3. What's lazy mean, it feels like it is slipping or not very quick to respond to the shifter movement? Watch the tach, if it jumps up on the 2-3 that's runaway, if the tach immediately drops and the car noses down on the shift that's overlap. Over lap means the front band hasn't come fully off before the front clutch has come on. Runaway means the band came off before the front clutch came on with sufficient capacity to pull the motor down. Any good valve body (A & A, Turbo Action, etc) out of the box installed in a properly built trans will not be off the mark, the rest is all timing. The number of front clutch springs vs. front band operating ratio and the front band release spring/s makes up the timing. Just the correct combination of parts. Believe it or not, go to the old Direct Connection manual, pick out the front clutch spring combination for your engine size, and match to the front servo release spring stack. You won't be disappointed. Remember, those packages were done by the engineers with only one motivation - make the Mopars as fast as possible.
Posted By: dOc …

Re: 727 - pulls motor down on 2-3 shift - 03/29/11 02:09 AM

Lucian Mancini

..... part of that Highland Park and CTC "family" ? ..
Posted By: BradH

Re: 727 - pulls motor down on 2-3 shift - 03/29/11 02:20 AM

Quote:

Easiest way to cure severe overlap is to place an orifice restrictor in the front clutch feed passage in the case. (circled in red below)

Remove the VB, tap the passage in the case to 1/8"-27 NPT and place a pipe plug with a drilled orifice in the case. I'd start with a .140" orifice.



I think this is what "LAR 414" mentioned doing to help fine tune the 2-3 shift, too. I think I need to try something like this...
Posted By: Cab_Burge

Re: 727 - pulls motor down on 2-3 shift - 03/29/11 04:22 AM

Quote:

Shifter alignment is perfect so I'm pretty confident that isn't the problem.


I've seen long time mopar drag racers get the adjustment off two turns of the cable end and not have a clue what was wrong, these are long time racers that have been around the block several times Think about how the bolt holes in the valve body are all (10)slotted so you can seat it with all the stock servo springs and such, move it 1/8 inch from one valve body to the next and your in trouble on the shifter adjustmenst on most aftermarket cable shifters I hate to see your freinds foot blown off because it is overlapping on the one to two shift
Posted By: boscosis

Re: 727 - pulls motor down on 2-3 shift - 03/29/11 12:32 PM

The 2-3 under WOT? Really nothing special - it seems to shift late (after the lever is pulled) and not quite as quick to change gears as it should be.
CAB - point taken and I appreciate the concern. We had just installed a new cable and my brother went to great lengths to check that its exactly where it should be. When we're ready to try again we'll check it very carefully for alignment.
Posted By: High Impact

Re: 727 - pulls motor down on 2-3 shift - 03/29/11 02:27 PM

Quote:

Quote:

Just to add to the good advice given,
if that trans has a 5.0 front band lever, take it out and put a 3.8 or 4.2 ratio lever in.



yeah, that 5.0 lever is a killer. anything you can do to speed up the release of the intermediate band, is going to make it easier to nail down the 2-3 shift timing. a billet servo with heavy duty release springs is a good step.
--------------------------------------------------

I too put that 5.0 lever in my trans thinking it would make it a "killer shifting, tire chirping machine" It did that very thing where it bogged down going into 3rd gear, it just didnt shift right. I asked on here and was told to take that 5.0 lever back out and put in a 3.8. I did and it was perfect Then I cranked up my line pressure about 4 more turns and it shifts super. The best shifting mopar trans I've EVER had.
Posted By: 65_gt_rag_402

Re: 727 - pulls motor down on 2-3 shift - 03/29/11 04:56 PM

You are correct about the 5.0 lever. My dart has it in there and it shifts like that . trans is now 7 years old and never had a issue with it. Still shifts hard! That is the symptom you will get with a 5.0 lever. When you have it on the jack stands running , its more obvious .Nothing to worry about !
Darty

Attached picture 6555922-raggiefrt.tina7-25-10pix487.jpg
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