727 manual low to 2nd shift problem

[Scout-It-Out]

I installed a b+m shift kit a couple months ago. I just finished a complete rebuild a few days ago. The valve body was not touched since I just did it, and it worked! I adjusted both bands 2 turns out after 72" lbs.

Now, on to my problem. When I shift from manual low to 2nd it acts like low isn't releasing quick enough. It kind of slows down for 1/2 a second. It doesn't do it in "d" or if I shift at low rpm. I did readjust the int. Band to 2 1/4 turns out after reading on here. No difference. I haven't loosened the low/rev. Band yet. Any thoughts??? Thanks!!

 

[jauringer]

I installed a b+m shift kit a couple months ago. I just finished a complete rebuild a few days ago. The valve body was not touched since I just did it, and it worked! I adjusted both bands 2 turns out after 72" lbs.

Now, on to my problem. When I shift from manual low to 2nd it acts like low isn't releasing quick enough. It kind of slows down for 1/2 a second. It doesn't do it in "d" or if I shift at low rpm. I did readjust the int. Band to 2 1/4 turns out after reading on here. No difference. I haven't loosened the low/rev. Band yet. Any thoughts??? Thanks!!

The low/revers band is the only difference between manual low and breakaway low so that's what I'd check first. Sounds like it May be too tight.

The kickdown band is applied in the upshift regardless of which low you're coming from. We know it's working fine in drive so that's not it.

Good luck,
jason

 

[jauringer]

Thought of one more thing. Never installed the B&M, does it inlcude the shim for the rear servo piston?

You increased your pressure with the kit so if the rear servo is not shimmed it will delay your manual 1-2 shift. Not used in d.

Jason

 

[Scout-It-Out]

I didn't see anything about shimming. This is the first I've heard of it! I adjusted the low/rev band to 2 1/4 out... No change. I searched online and only found one guy with this same problem. Only thing is, no one answered him!

 

[jauringer]

Yeah, the rear servo mod is apart of the transgo kit. I put a billet unit in mine which already has the moded piston but you don't have to go that far, especially considering your trouble shooting at the moment.

The real nice thing about the 727 is there are mopars all over the planet still running them so there's a ton of info and aftermarket support. Of course most of it is regarding a 2-3 bind up, not the 1-2 manual shift bind.

Here's a pic I borrowed from google imgs of the cheap washer method. It makes it one solid unit and releases instantly. When the servo is activate, it applies pressure to the band. The pressure also slightly compresses the piston and inner spring which is now compressed even more with the added pressure of the shift kit. So now when the servo releases the tension in the spring has to release too, causing the band to hang on a little bit longer.

I hope this helps. Good luck!
Jason

 

[Scout-It-Out]

Thanks for help jason! I May give that a try. I installed a kevlar rear band when I rebuilt it. Does that make any difference? It just seems odd that it didn't do this with the shift kit before I rebuilt it.

 

[jauringer]

thanks for help jason! I May give that a try. I installed a kevlar rear band when I rebuilt it. Does that make any difference? It just seems odd that it didn't do this with the shift kit before I rebuilt it.

Yes, kevlar makes a big difference. It's creates much more friction and holding power over the stock band. The monroe book does not recomend kevlar in a shifting band. (which is what you turn the rear band into on a manual 1-2 shift.)

I personaly don't think shimming the rear servo is even an option considering the build. It's cheap, easy and at the very minimum will reduce your current 1-2 manual shift bind if not eliminate it completely.

The 727 build is not very dificult but one things for sure, it's all about the combonation, you have to get that right. Preferably using one that's proven to be effective time and time again. (ie:monroe book)

edit: if I were you, with the current testing that has been done. I would adjust both bands back to the B&M shift kit recomendation, shim the rear servo and go from there. (unless backing off the kickdown band helped the "d" 1-2 shift. If it cleaned that up any, I would leave that one as is.)



jason

 

[Scout-It-Out]

The b+m instructions don't have you adjust the bands for the "heavy duty" version. For the off road only, it says "tighten snug and back off 3 turns" also the kit comes with a new rear servo spring, but again the hd version doesn't say to put it in. It seems to me that putting it in would help my problem! Any down sides to trying that??

 

[jauringer]

the b+m instructions don't have you adjust the bands for the "heavy duty" version. For the off road only, it says "tighten snug and back off 3 turns" also the kit comes with a new rear servo spring, but again the hd version doesn't say to put it in. It seems to me that putting it in would help my problem! Any down sides to trying that??

Well one things for sure, the B&M kit is not the the transgo tf2! I do agree, the hd spring will help just as much as the shim kit. Again though, considering the build, I would still do both, giving you complete control over the rear servo @ the band adjustment. Honestly, I assumed the hd spring was already in place...shouldn't have done that.

Here's some of my setup.

Rear band is 2 turns back from 72 in/lbs with a billet rear servo (equal to you shimming yours), the hd large servo spring, and hd spring retainer. Running a performance solid rear band (not kevlar thought)

my kd band is 2 1/2 turns back from 72 in/lbs with a billet servo and a 3.8:1 ratio apply lever. Running a solid performance band (red lined)

running a 100% stock rear servo with all your mods.....I bet that bind up is pretty darn noticeable. I guess the good news is that you now have even more room to improve that shift!

Take the rear servo out and make it right. Or better yet, talk to Jeff about getting a nice replacement!

The billet unit I run has a larger piston with two seals that are better quality. Part of it rides in a new area of the bore providing a seal that is far superior to stock. No shimming is required and it won't cock or crack like the oe one can. Lastly, clearances between the piston and piston pin will increase from wear over time creating a leak point in the servo. A new unit will solve that as well.

Good luck
jason

 

[Scout-It-Out]

Well, it's fixed!! I didn't drive it very much yet but it is definitely a lot better! I kind of did the mods one at a time hoping each would work. I did the hd servo spring, no difference. Then I tried backing the adjuster off to the b+m 3 turns, still nothing. Today I did the shim on the servo, bingo! The b+m kit did have a shim in it. Again it was in the off road racing only version. I still have the adjuster at 3 turns out. I'll never buy a kevlar band again!! I'm about ready to put dzus fasteners on my tranny pan

thank you so much for all your help jason!!

 

[jauringer]

Great news brother! Once that kevlar takes hold, I guess it doesn't like to let go! Dzus fasteners, lol. It sounds like you've become a stud at dropping the tranny pan and vb. Maybe you can take a part time job @ the drag strip.


Jason