727 Question

[65 3 times]

Gentlemen: Saturday on my second pass (1/8th) 7.50 @ 92mph during shutdown as I approached the turn around I ratcheted down to second (at about 15 mph) and the rear wheels locked up. I ratcheted to first and it free wheels as always. On return road I accelerate as always and ratchet to 2nd and it shifts fine then to third fine. Stopping for ticket I could tell 2nd was different. Back to pit and checked fluid level (OK) smelled fine was hot as expected. Cooled car and made 5 more passes. Up shifts were all fine and I braked into turn around before I down shifted.
727 is '70's vintage with a cheeta reverse pattern manual valve body , 2 qt deeper pan and 3200 stall. rear is 4.88 with strange spool in 8.75. I'm going to drop pan and check for residue and adjust bands. Any other ideas. Thanks in advance. Dave

 

[d fark]

Let us know what you find

 

[Roughbird72]

Wow! i've never have had that happen.
Hope you find out what it is.

 

[BBody360]

Cheetah always said down shifting in manual valve bodies was a "no no"

Any difference on the ET with the 5 other passes as compared tho the 1st?


Worst case scenario pull the pan and fear for sparkly things :icon_eek:

 

[dvw]

The only way it can lock the wheels in 2nd gear is if either the high gear clutch didn't release (which I doubt) or if the low roller clutch was bound, holding the rear drum. Which I suspect. If the low roller is damaged the rollers can be wedged out of position dragging the drum. Has it rattled the tires lately or shuddered on the launch? If so I'd be looking inside.
Doug

 

[65 3 times]

Thanks everyone. Dropped the pan and smelled bad. Fluid looked nice and red and clear. Did not smell til I dropped pan. Lots of band material in pan (red). Took pan and filter down to friends shop. (Old & lots of trans) Said to look up inside and see if you can see band material (red) still lining bands. Front band shows material and can not see rear band. I loosened jam nut on adjuster and counted turns in and it only went in 3 sides. I set at 6 sides about 30 passes ago. He thought it could have been band material jammed up between band and drum. I reset adjuster, changed filter,got some Lucas conditioner and fresh fluid, drank some beer and left it sit to think about and post.. Planning on about six quarter mile passes at Cedar Falls Mopar Max this weekend and am stumped on whether to proceed.... Thanks Dave

 

[partmopar]

I would take it out and have it looked over. If it breaks it may take a lot more than just the transmission. Do you have a bolt in sprag.

 

[65 3 times]

Not a bolt in sprag. Did not find any metal in pan or filter.

 

[dvw]

The standard bolt in sprag (low roller) is not an upgrade. Only the Super Sprag ($200 from A&A, Coan, Etc) is stronger. I ran 1000's of passes on stock low rollers. Even 200 passes on my 9.1 ET 64 Plymouth. The rear band is only applied in Reverse with a T/A valve body. Never seen a rear band wear out or shed material. I have seen front bands go down to metal, but never with a T/A valve body. Also seen low rollers damaged that you couldn't tell until it was disassembled. Remove the drive shaft and see if you can rotate the output shaft. It will be stiffer in one direction but it should turn smoothly.
Doug

 

[65 3 times]

Doug: Thank You. The output shaft rotates smooth and easy forward. It is stiff and smooth when turned backward (reverse rotation on driveshaft) Is it possible that the trans could have applied reverse when I downshifted ? I can not believe it locked as I thought initially. But maybe reversed for a second ? I also checked my log and the pan and filter had about 45 1/8th mile passes. When pan dropped I was surprised at volume of residue. Maybe 8 or 10 tablespoons of course red , looked like band material , residue. Maybe that is normal for that many runs. It has not rattled the tires or shook. Feels like I get some tire slip at launch. Converter is pretty tight (3000) for this engine. It's a 2nd and 3rd gear car. Thank You again Dave

- - - Updated - - -

Doug: Thank You. The output shaft rotates smooth and easy forward. It is stiff and smooth when turned backward (reverse rotation on driveshaft) Is it possible that the trans could have applied reverse when I downshifted ? I can not believe it locked as I thought initially. But maybe reversed for a second ? I also checked my log and the pan and filter had about 45 1/8th mile passes. When pan dropped I was surprised at volume of residue. Maybe 8 or 10 tablespoons of course red , looked like band material , residue. Maybe that is normal for that many runs. It has not rattled the tires or shook. Feels like I get some tire slip at launch. Converter is pretty tight (3000) for this engine. It's a 2nd and 3rd gear car. Thank You again Dave

 

[Bubba C]

I think you might have a valve sticking in the valve body.Its possible that its sticking between 2 gears at one time...

 

[65 3 times]

[video]https://youtu.be/LzeGLHzaMMY[/video]

This video demonstrates problem. Watch as I slow for turn around and down to second. I can't tell if it locks or reverses... Thanks for looking Dave

 

[dvw]

OK now that I watch the video I don't think it's the low roller. It appears that it was in 2nd/3rd at the same time.You should not be seeing much material in the pan at your power level and number of runs. How is the shifter adjustment? Test it in 2nd and 3rd by removing the clevis pin to make sure there is no bind. I'd be taking it apart and doing an inspection.The really isn't any valve to stick in a T/A valve body to cause this issue. It could be possible that the valve body has a crossfeed, crack loose halfs, etc. Pretty unlikely though. The question is why didn't it come out of 3rd gear. The only thing that occurs on a 3/2 downshiftt is the high/revese clutch dumps pressure and the intermediate band is applied. Unless you really did bang the shifter into reverse. Is it possible to hit reverse with your shifter? Does it have reverse lockout?

 

[65 3 times]

Doug: Thanks for thoughts. I'm listening and respect what your saying. It's a B&M ratchet shifter and reverse is locked out. I did about 4 more test & tune passes after this one with no issue but I think I better pull it and refresh. I looked at and read about A&A Coan Super Sprag. Was not familiar with these guys yet but will look close. Thanks again & also to all that looked and thought about. I'll let you know what I find for the files.... Dave

 

[383man]

I agree with what Doug is saying also. I thought Turbo Action does sell low band apply valve bodies now ? Is yours a low band apply V/B ? Ron

 

[65 3 times]

Ron: I am not sure about valve body. It was installed in '99 so it likely is not a low band apply. After listening I think I damaged the sprag on a downshift from higher speed on an earlier run. With 4.10 gears I finished the 1/8th at about 5200. rpm. When I installed 4.88's I cross about 62-6300. I would let up and brake and downshift to help and have learned this is a NO-NO. The sprag is trying to catch up with the rear end and over speeding. I love running this car & hope there is enough years left for me to learn to do it correctly. Thanks for your help and thoughts. I will post this fall when I tear it down. Dave

 

[65 3 times]

Last Word. Against better judgement I reset band and filled with type F and Lucas conditioner. I wanted to race Mopa Max @ Cedar Falls Ia last Sat. Trans acted fine on warm up. First pass shifted normal. Second pass best 60 ft ever @ 1.64. Ran 11.72 @ 119.0. Won first round. On second round (4th pass) I ended my weekend in a cloud of smoke at the finish line and lost oil pressure. Loaded when we could not locate problem and took car home. Sunday unloaded and studied path of oil and discovered a new way to loose pressure quickly. The plug on the rear of the oil pump along with the spring and relief valve was gone. Yikes!! Replaced parts , removed distributor and spun pump to bring up pressure. Oiled to 60 lbs. and started. Seemed to be OK but will pull pan and check rod and mains. I think I will call myself lucky (purchased lottery ticket) and quit for year. Plan to renew trans. (Coan Super sprag and related parts. ) Also building 543 stroker. If I can edit videos I will post here. THANK YOU ALL..... Dave

 

[65 3 times]

[video=youtube;AzKat9JKfmw]https://www.youtube.com/watch?v=AzKat9JKfmw[/video]

Mopar Max - Cedar Falls raceway - 9-26-15 11.72 @ 119.0 mph.