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727 no reverse…. ?

LemonWedge

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Been a while since I’ve posted here at FBBO, but I’m in need of some help….
a buddy of mine has a gorgeous 65 B-Post street/strip HotRod. Pretty standard 440/727 setup. last year he had a shop replace the converter. When he got it back, the shifter (cable B&M unit) wasn’t adjusted properly. He talked to them but just never got it back to them. Then reverse went out. He didn’t want to argue with the shop, so I told him to bring it to me it probably just needed to be properly adjusted.

I got under it and sure enough, the cable was tense and bound when in each gear. Routing of the cable was a mess….. so I spent some time sorting things out and got it to where I was sure it was adjusted “correctly”. Everything felt and looked right, but still no reverse.

I then dropped the pan and turned My attention to the low/rear servo and strut. Everything looked to be still in place correctly. So I then dropped the valve body and put some air to the rear accumulator. The servo worked perfectly and the strut activated the band just as it should. Adjustment seems slightly on the loose side, but it binds down the band just fine.

Im at a loss…. What to check next? Could the valve body not be operating correctly?

everything else seems to be fine other than “no reverse”. It is a stock valve Body with a kit as far as I know. Currently, when left in D, he DOES have low. So the overrunning clutch would seem to be ok (???).

anything else I should check before I throw it back together for one last “check” before pulling the whole thing to go through?

Help…….

IMG_2828.jpeg
 
Need to figure out if it's a shifter problem or a trans problem. Good that you check inside the trans for broken band & parts.

Disconnect the cable at the trans. Move the lever one click away from park which is reverse. With a helper sitting in the car, jump the relay and start the engine and see if reverse is there.

those aftermarket shifters can be a potential problem especially with a shop working on it.
 
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" Currently, when left in D, he DOES have low. So the overrunning clutch would seem to be ok (???)."

But the over running clutch isn't used for reverse... The Low/Rev band is...
The Low/Rev band is also applied in manual low... So, put the trans in manual low and it should have engine braking... If you can accelerate normally in low but when you let of the throttle the car doesn't dramatically slow down but instead just coasts your looking at a band issue...

Since the pan is off I'd adjust the band to spec to see if it helps....
 
My bets are the front clutch pack. I will bet 3rd/high gear is also not right.
 
I agree move the trans lever manually with the shifter diconnected. Still doesn't have reverse? If 3rd gear functions correctly the forward clutch which is also used in reverse is functioning. If third slips that points to a forward (3rd/R) clutch problem. If it has manual braking in the L posistion of the shifter, the rear band is applying. So both items that apply to select reverse function. But are they commanded on in reverse? Next test would be to check for pressure at the rear servo test port. Should be 230-280psi. Let me know.
Doug
 
My bets are the front clutch pack. I will bet 3rd/high gear is also not right.
That's the other option... I say tighten the band & try it cause you have nothing to lose if it the front clutch the trans is coming out and apart...
 
I agree move the trans lever manually with the shifter diconnected. Still doesn't have reverse? If 3rd gear functions correctly the forward clutch which is also used in reverse is functioning. If third slips that points to a forward (3rd/R) clutch problem. If it has manual braking in the L posistion of the shifter, the rear band is applying. So both items that apply to select reverse function. But are they commanded on in reverse? Next test would be to check for pressure at the rear servo test port. Should be 230-280psi. Let me know.
Doug

Doug,
Can you go into more detail on how to perform this test and where the “rear servo test port” is?

I’ll run this test, and try to get it back together and fluid back in to run through the gears. We did not try shifting it by hand while running before hooking the shifter back up, but I can verify that moving the shifter slowly all the way from P back to D, and back to P again multiple times with the engine idling, there is no R engagement. I can feel the detent…. Shifter feels correct, but no engagement.
WITHOUT the car running, I did run the lever by hand, and again could / did identify each detent.
 
Doug,
Can you go into more detail on how to perform this test and where the “rear servo test port” is?

I’ll run this test, and try to get it back together and fluid back in to run through the gears. We did not try shifting it by hand while running before hooking the shifter back up, but I can verify that moving the shifter slowly all the way from P back to D, and back to P again multiple times with the engine idling, there is no R engagement. I can feel the detent…. Shifter feels correct, but no engagement.
WITHOUT the car running, I did run the lever by hand, and again could / did identify each detent.
Remove the 1/8" pipe plug located on the side of the rear servo. Screw in a 300 psi gauge. Put it in reverse and see what your pressure is. Also test in manual low.
Doug

TF_8_Tech_Info__Pressure_Ports.jpg
 
Been busy couple of weeks for me. Had to spend all last week and weekend moving my Mother in law into a home and taking care of all the details and legalities that go along with that. Then this week I’ve been in Dallas on a business trip. Haven’t had a moment to get into the garage. Im hopeful this weekend offers me some time.
 
Found the band adjustments were way loose somehow. Re-adjusted to spec (72”-lbs - 2 turns); and the lever extends about half of what it did prior. Front band also on the loose side, re-adjusted that while I was at it. I’ll button it back up today and see if that makes a difference, and run the line pressure test.
if still no reverse, out it comes.
 
Update: after the band adjustments, reverse works perfectly. In reverse, it must have been just free-wheeling the drum? Told the owner that loose bands to the point of not having reverse is likely a sign that the transmission is just plain worn out. Nothing broken, but probably needs new friction components sometime soon. Might not be the last time I’m in this transmission.

Backed it out of the garage and Test-drove the car around town before returning it to my buddy. All good. upon test drive, it seemed to me that the stock valve body, while working as it should, still felt very mushy between gears. I’m probably just used to my car which has a cheetah-body manual 727.
never did run the line pressure test, Doug. Probably should have, but it worked so I moved on. Thanks for the help, always good to learn.

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Funny story about adjusting bands. Right before my first rebuild my Volare Road Runner lost 2nd gear. A girl I worked with Husband was a trans guy. He told me how to adjust the band. But warned me if it needed more than 4 turns to get snug It could be worn out. I turned it in 4 1/2 or so and the backed it off. Shifted great. I though what does he know about Hot Rods? Drove it about 50 miles away from my house. Took a buddy for a thrill ride. It locked in 2nd gear. Car wouldn't even roll. Had to get my Dad and a tow bar. Pull the drive shaft and tow it home, 100 mile round trip. It welded the band to the drum. That's when I built my first trans. Converting from a 904 to a 727 in the process. Bottom line of the failure? Worn band due to incorrect KD linkage after converting to a 4 barrel from a 2 barrel. That was 1978
Doug
 
Funny story about adjusting bands. Right before my first rebuild my Volare Road Runner lost 2nd gear. A girl I worked with Husband was a trans guy. He told me how to adjust the band. But warned me if it needed more than 4 turns to get snug It could be worn out. I turned it in 4 1/2 or so and the backed it off. Shifted great. I though what does he know about Hot Rods? Drove it about 50 miles away from my house. Took a buddy for a thrill ride. It locked in 2nd gear. Car wouldn't even roll. Had to get my Dad and a tow bar. Pull the drive shaft and tow it home, 100 mile round trip. It welded the band to the drum. That's when I built my first trans. Converting from a 904 to a 727 in the process. Bottom line of the failure? Worn band due to incorrect KD linkage after converting to a 4 barrel from a 2 barrel. That was 1978
Doug

It does run a lokar kick down cable. Seems to shift and kick down on time, but I did not really check that component at all.
I’ll tell him to watch things closely.
thanks!
 
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