SB 727 band lever help needed

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340sport

340sport

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Hey guys. I'm hoping someone can help out and get us back on the track. So, last night at test and tune I told my kid to do his burnout in second gear, but it was his first pass ever in the car and I guess he was nervous and was in first instead. So, he launches and part way down the track he has no forward gear after shifting. He pulls off and has nothing. No forward or reverse gear, only park. Pulled back to the pits and I check and adjust the linkage to make sure it's accurate and check the fluid level. Still nothing. Pull the pan and there's a slight amount of clutch dust, nothing major. However, the front band lever is hanging down. That doesn't seem right. So, now what? I really don't know much about transmissions, but want to seek help to find out if it needs to come out or if it's a possibility to fix it in the car. Combo is 360, 727 no brake, manual valve body and winters shifter. Unknown convertor, but I think it's 10" and supposedly fresh trans.

Where do I begin?
 
340sport said:
Hey guys. I'm hoping someone can help out and get us back on the track. So, last night at test and tune I told my kid to do his burnout in second gear, but it was his first pass ever in the car and I guess he was nervous and was in first instead. So, he launches and part way down the track he has no forward gear after shifting. He pulls off and has nothing. No forward or reverse gear, only park. Pulled back to the pits and I check and adjust the linkage to make sure it's accurate and check the fluid level. Still nothing. Pull the pan and there's a slight amount of clutch dust, nothing major. However, the front band lever is hanging down. That doesn't seem right. So, now what? I really don't know much about transmissions, but want to seek help to find out if it needs to come out or if it's a possibility to fix it in the car. Combo is 360, 727 no brake, manual valve body and winters shifter. Unknown convertor, but I think it's 10" and supposedly fresh trans.

Where do I begin?
Click to expand...

Everything with that band apply can be serviced without pulling the trans except changing the band.
Sometimes the lug on the end of the band tears off and that means it comes out.

It might have just trashed the strut between the lever and the band lug.(this is a common failure point.)
Also, when it does this the strut sometimes ends up laying on top of the valve body.
If both ends of the band are intact it’s an easy fix.
 
Do I remove the valve body and search for the strut and go from there? Is there anything I need to know about removing the valve body (any linkages or easily lost parts, etc.)?
 
340sport said:
Hey guys. I'm hoping someone can help out and get us back on the track. So, last night at test and tune I told my kid to do his burnout in second gear, but it was his first pass ever in the car and I guess he was nervous and was in first instead. So, he launches and part way down the track he has no forward gear after shifting. He pulls off and has nothing. No forward or reverse gear, only park. Pulled back to the pits and I check and adjust the linkage to make sure it's accurate and check the fluid level. Still nothing. Pull the pan and there's a slight amount of clutch dust, nothing major. However, the front band lever is hanging down. That doesn't seem right. So, now what? I really don't know much about transmissions, but want to seek help to find out if it needs to come out or if it's a possibility to fix it in the car. Combo is 360, 727 no brake, manual valve body and winters shifter. Unknown convertor, but I think it's 10" and supposedly fresh trans.

Where do I begin?
Click to expand...
Here you can see the parts involved.
You will probably find the strut and the small lug for the band adjuster on top of the valve body.

IMG_4504.png
 
Thanks for your help. I will report back with my findings. Fingers are crossed!
 
340sport said:
Do I remove the valve body and search for the strut and go from there? Is there anything I need to know about removing the valve body (any linkages or easily lost parts, etc.)?
Click to expand...
When you pull the VB the park rod will probably fight you just a bit.
Turn the driveshaft back and forth a little with your hand and it should come out by pulling the VB forward.
Sometimes it takes a light yank.
Same going back in.
Make sure your linkage tab goes back in the manual valve when putting the VB back in.
Other than that it’s cake.
 
Since he has no forward gears, I would say there is problem in the rear clutch (forward gear drum). The band only applies when you shift from first to second gear, and then when you shift into third gear the band released and the front clutch (high gear clutch) is applied. So losing the band strut, or band lever shouldn't effect 1st gear or 3rd gear. But to have no forward gears at all, something else is wrong. When in reverse, the low/reverse band is applied and the front clutch is applied. Since it doesn't have reverse either, I would say you have more of an issue than just the band, or band lever. It could be a sealing ring, or lip seal.

When you drop the valve body, I would be doing an "air check" which will help you diagnose the problem. You can find online which holes activate which clutch, and same goes for the front band and low/reverse band. If you do an air check, and you hear clutch packs are leaking excessively, unfortunately the transmission will have to come out and be taken apart.

As far as him doing the burnout in first gear, the big risk there is hurting the sprag if the tires were to bite while under power. Then if the sprag is hurt, when in first gear on the starting line, he floors it, the sprag releases (breaks), and the front drum spins 2.45 times the engine RPM, which causes the stock front drum to explode. If you have a low band apply valve body, that is the best way to help protect the sprag.

Please keep us updated. I am curious to hear what happened but I think you have a bigger problem than the front band.
 
So....
Pulled the valve body down and no strut lever for the front band. Apparently when he was removing fittings to use AN fittings for the lines to the cooler he removed that adjuster it fell down. Got it hooked up and adjusted and nothing again. Nothing forward, nothing reverse. Didn't perform any air checks, no idea what that is. So, what's next?
 
340sport said:
So....
Pulled the valve body down and no strut lever for the front band. Apparently when he was removing fittings to use AN fittings for the lines to the cooler he removed that adjuster it fell down. Got it hooked up and adjusted and nothing again. Nothing forward, nothing reverse. Didn't perform any air checks, no idea what that is. So, what's next?
Click to expand...
I'm Not Qualified to give advice on this. But if You dig on the web, or here, you can find the PSI of air needed to move things to see if they function correctly. I Know I've ran across the info before, just never done it....
 
Have you checked line pressure in the low/reverse port in low gear?

If the reading is zero, you either:
- Broke the converter drive lugs out of the inner pump gear
- Broke the converter
 
No checks as I have no idea what or where to perform one. If you can elaborate I'll give it a shot when I'm able.
 
I would bet Duster346 hit the nail on the head with converter drive lug inner pump gears being broke, or converter being broke. Being that it was supposedly a fresehened trans, you may want to contact who freshened it and ask if they did anything to adjust the line pressure. Who's valve body is it? Since the car launched off the line and was moving forward til he shifted and then lost all movement, I would be willing to bet its what Duster346 said, either pump gear drive lug broke, or converter totally took a crap. I would send Duster346 a PM on how to check line pressure if you want to go that route. But if it was me, I would be taking the transmission out of the car. You will be able to see if the front pump inner drive lugs broke pretty easy.
 
Thanks for your reply. It's a Cheetah manual reverse valve body
 
340sport said:
No checks as I have no idea what or where to perform one. If you can elaborate I'll give it a shot when I'm able.
Click to expand...
You just need a 0-200psi pressure gauge in the L/R servo port with the vehicle running while in low gear. It's the furthest port back on the passenger side.

Would like to revise what I wrote.. if you have a zero reading you have a pump or inner gear failure, or the pump is not picking up any fluid (filter fell off, etc).

If you have a pressure reading (at least 100psi) and the car will not move backwards or forwards, you could've broken the turbine in the converter where the input shaft splines, or you have a shaft failure (unlikely at that power level) or other geartrain failure.

Was there a lot of debris in the pan, like a small bomb went off?
 
Nothing in the pan except a small amount of clutch dust and fresh fluid
 
Having had a “bunch of neutrals” at the track my first go to was to check the fluid level in park and then neutral. In my case there was zero difference so next we pulled the “output” line from the trans at the cooler. Started in N and zero flow. In our case the 727 pump gear lugs had given up.

let us know what you find! Sounds like it’s coming out though :)
 
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