Band adjustment

[flyinlow]

What effect does running the second gear band 1/2 turn tighter  have on the 1-2 shift on a 727/518 trans?

I installed a Transgo tfod-hd2 kit and now the free play on the servo arm seams less than before.  Band adjusted Snug with small wrench , then loosen 1 1/2 - 2 turns. I used 2 turns.

[RD]

band needs to be adjusted to 72" lbs then turned back the required number of turns as stated by your transgo kit.  it should not be snug, but rather to a specific torque specification.

make sure you check your kit to see what it requires.  the 72" lbs is the stock spec.

[flyinlow]

Thats what the Transgo instructions say. Snug with a small wrench ,then back off  1 1/2 - 2 turns.  My 73 service manual says tighten to 72 inch pounds , then back off 2 turns for a 440 with dual exhuast.

How critical is the adjustment ? Half turn to tight will the band burn? Half turn to loose will it slip?

The amount of movement of the second gear band apply lever from its relaxed position until it is applying the band seams a little less than before I changed the servo springs and adjusted the band.

I have an aftermarket manual for the 518 but I cannot find a spec for the band adjustment.  The trans came out of a 94 van 3500 ,5.9 L.

[John_Kunkel]

You won't feel the half-turn difference in the seat of your pants (the old buttmeter).

The "turns out" adjustment depends on the lever ratio, the 1 1/2 - 2 turns is a happy medium if the lever ratio isn't known. If you have the pan off, a good way to adjust the band is by the gap between the servo plunger and the lever; use the flats on a 3/8" or 5/16" Allen wrench as a feeler gauge.

[grdprx]

I'm trying to adjust the bands properly, borrowed a torque wrench that reads inches..  What sort of socket do you use on the adjusting screw?  It's square!!   

I called a transmission shop, they want $40 and freight!  Otherwise they suggested bringing it into the shop for some $...

[John_Kunkel]

The band adjustment stud has a 5/16" square head.

Forget the torque wrench, use a 4" Crescent wrench and tighten the stud just snug, then back it off the proper amount of turns.

[375instroke]

What sort of socket do you use on the adjusting screw?  It's square!!   

I called a transmission shop, they want $40 and freight!  Otherwise they suggested bringing it into the shop for some $...

Well, if it's square, use a square socket.    I've gotten away with the next size up 12pt. socket.  They also make 8pt. sockets.  They are readily available.  Are you saying the trans shop wanted $40 for a square drive socket?  I paid about $6 or $8 off the Snap-on truck many years ago.  Rebuilt 3 transmissions and now it sits.

Just looked at the Sears web site, and a 3/8" drive, 5/16" 8pt. socket is $2.99.

[grdprx]

Sounds like a plan!  Thanks for pointing the rookie in the right direction   

[flyinlow]

Thanks for the input on the free play(5/16-3/8 allenwrench).

After installing the transgo kit and about 3 hours of bending and changing length of the throttle preasure linkage ( welded in a section)

it shifts pretty well.

Light throttle 1-2 15mph,  2-3  25mph  positive shifts

W.o.T 1-2  5200 rpm  , 2-3 5000 rpm. firm shifts

Is there a way to raise the w.o.t shift to about 6000 ?


Dont forget to turn off lock up getting off the freeway. Voodoo cam gets unhappy at 800 rpm in overdrive .

[Lifsgrt]

I've found if you adjust your kickdown linkage to make it longer by turning the piece that attaches to the carb counterclockwise, the shift point goes up.  Otherwise, you may have to pull your tailshaft off and change the governor to a higher rpm version.

[John_Kunkel]

I was going to suggest a governor kit but the OP has a 518 so it's a little more complex than just removing the tailhousing.

[oldkimmer]

You won't feel the half-turn difference in the seat of your pants (the old buttmeter).

..........U sure will  when it binds up on either the 1-2 or 2-3 shift., trans go is notorious 4 that, u need the proper clearance, not only 4 the bands, but also internally......but as john says,with the lever ratio unknown that 2 turns is a good starting point , the higher # lever ratio, the less clearance u need..................kim........

[John_Kunkel]

Actually you want the free clearance between the band lever and the servo plunger to stay about the same regardless of the lever ratio, that's why there are different "turns out" adjustments for different lever ratios; that's why I recommended the 5/16"-3/8" clearance method when the ratio in unknown. Due to the basic nature of levers the 5-1 lever will require the most servo travel to apply the band and the 2.9-1 lever will require the least, thus the factory specified fewer turns out for the 5-1 lever and more turns out for the 2.9.

The idea is to keep the servo travel constant so that the volume of fluid used to apply/release the servo will be the same, this affects the shift timing on the 2-3 upshift.

[flyinlow]

The servo lever is the stock one for a 94 3500 series van with a 5.9L witha 518 trans.  Looks like the one in my 727. How do you determine the ratio?

Next winter I want to upgrade the transmission. New seals ,clutches,sprag, overdrive spring,converter and maybe the front drum. Guess I should look at the servo parts too. Want to put a few thousand miles on it this year and see how well it works. So far the overdrive trans is great.

[John_Kunkel]

The ratio is stamped in the lever, a '94 with a 5.8L would probably have a 3.2 lever.

[flyinlow]

What is the best trade off ? Does more leverage give a firmer 1-2 shift , but then slow the 2-3 shift?

[mally69]

 

[John_Kunkel]

The lever ratio has more to do with holding power (Archimedes) than shift firmness, the higher the lever ratio number the tighter it will apply the band around the drum so, indirectly, more squeeze will stop the drum more abruptly which makes the shift feel firmer.

It's really all about power, on the 1-2 upshift more power will tend to make the band apply slower (slip) for a given lever ratio and on the 2-3 upshift a higher ratio lever will be slower to release and will cause more overlap but if the motor has enough power it will "drive through" the dragging band and little or no overlap will be felt by the old buttmeter.

The 2-3 upshift needs to be a lot like a well-orchestrated dance routine, just the right amount of overlap (some overlap is necessary) to prevent rpm flareup without the "clunk" of excessive overlap.