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Thread: powerglide

  1. #1
    Senior Member MASTER BUILDER
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    powerglide

    Been battling tranny problems all year long....last time blew out front seal and the tranny brake is still not holding......also my 60 foot times have been going into the toilet all year at the start of the year they were 1.41 now they r at 1.63....it will rev up to my 2 step setting but decided to send it in to get checked out anyways....the tranny is at my tranny guy and he phoned me and told me that he can not find anything wrong with the front pump tolerances r all perfect.....had a gauge on it and had 230 psi....so anyways he is trying to pressure test the valve body but he cannot find any leaks....i am losing my patient on this and going to replace the valve body with a new one....is there something else i am missing and also does anyone else have any ideas........thanks in advance

  2. #2
    Senior Member DYNO OPERATOR
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    GET RID OF IT! SO MANY GOOD BUILDERERS OUT THERE! OR MAYBE TALK TO THEM! David.

  3. #3
    Senior Member MASTER BUILDER
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    The guy that i took the tranny to phoned me tonight and told me that he found that my tci standard brake only had a 1/4 inch passage(not like the pro brake which is alot bigger) to the reverse passage going to the tranny case, and the jw case has a 3/8 inch opening...he figures that the hole is to small in the valve body and causing a prssure drop going into the case for the brake causing it to be lazy....he is going make the hole in the brake the same size as the case..............what do you guys think will it work and could this be my problem all along.............thanks

  4. #4
    Senior Member MASTER BUILDER
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    Sorry about your additionial problesm. Your test pressure sounds to be at a good number, but it will change in the different gears. So, it will be different in 1st, 2nd, neutral, reverse, and 1st gear with the transbracke applied. There are several different things that could be causing your problems. For it to blow out the front seal, it is getting too much pressure built up behind the seal. I drill the hole beside the stator out to 1/4" and this helps fill the converter faster and helps on the excessive pressure behind the seal. This can be seen in the articles done in the DragRacingOnline article http://www.dragracingonline.com/tech.../viii_1-1.html
    http://www.dragracingonline.com/tech.../viii_2-1.html
    JW also sells a powerglide repair manual that I have used for several years with some benificial tricks.
    The reverse clutches could be too tight. I set them up with 0.060"-0.095" clearance and all of the springs. The reverse dump in the case may need to be enlarged to allow a quick release. If reverse doesn't release quickly it can cause your 60ft times to be real sluggish. On the JW case, I was told that there is an adjustable bleed dump to allow it to be quicker or slower on the release.
    If the high gear clutches are too tight or partially being applied it can cause a drag, also. I set their clearance to about 0.050". I use the double ring servo in the case. When low is applied it pushes on the apply of the band and the release of high gear. Then when high gear is applied it pushes for the high gear clutches and pushes on the release of the band. This is through the little steel tube that goes from the transbrake/valve body to the transmission case.
    If your trans cooler is too small or it is stopped up, it can cause a back up and cause a problem with the release and cause problems with the front seal.
    If the front drum has been machined for a roller bearing the end play can be tightened up to about 0.010".
    I use all straight steels and no wave plates in the clutch packs for racing.

    When you have problems with the Transbrake not holding, what RPM are you at and what does it do (rock backward or rock forward, or drive forward)?

    Thanks

  5. #5
    Senior Member MASTER BUILDER
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    Is your transbrake valve body for the Pro-tree or is it for the Full-tree? The pro-tree usually has two dumps for releasing reverse, so it is applying more fluid to counteract the amount that is being bled off and the passage would probably need to be a little larger. A usual sign of the pro-tree brake is that you have to apply the transbrake button to back up. If it is the full tree brake, it doesn't try to release as quickly and therefore doesn't have as much volume of fluid applying reverse. That would be the determining factor of whether I drilled additional holes.
    It doesn't sound like your transmission guy has the expertise with this racing glide, so you should probably get a few of the books and start again with a different set of eyes.
    One thing to keep in mind, is that when you increase the oil feed hole diameter, you can sometimes decrease the pressure but increase the volume.

    Good luck

  6. #6
    Senior Member MASTER BUILDER
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    The jw case i am usuing has the bigger holes in the case 3/8 inch for the pro brake and i am usuing the full tree brake and it is usuing a 1/4 inch feed out to feed the case. He told me the stock case uses a smaller hole like the one in the full tree brake and that is why i had no problem with the brake holding when i was usuing the stock case ....i have all the problems since i changed to the jw case......so does this make sense by him making the hole bigger in the valve body on my full tree brake to match the same size as the case, it will pressure up and fill the the reverse port quicker..thus holding the trnasbrake....i have 220 psi spring in the tranny and when in gear it goes up over 230 psi and when the brake was applied the pressure didn't drop......i did not have a gauge on the reverse side though....when i put it back in i am going to warm up the tranny good as it seems to hold when it is cold and not when it is hot and put a guage on the reverse side....also i am going to blow out the cooler lines and change the filter....blowing out of the front seal is the first time i had thaT HAPPEN i think that my line from the vent to my can was kinked....i am going to replace with a braided line.......the tranny guy told me if it doesn't work this time i have to take it to someone else and he also told me he is going to charge me for this...well i have spent alot of money all year and have no results with the tranny being taken out 6 times and going to the races and only making one pass and putting it on the trailer is enough pain for me to mention pulling it in and out and all the fluid.so on.u know what i mean............so i do appreciate u replying to my problems.......and i am hoping that making the hole bigger in the transbrake valve body to match the jw case will solve the problem let me know what u think.................thanks alot

  7. #7
    Senior Member MASTER BUILDER
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    I do not think that opening up the passage on the valve body will help. JW designed that case to work with a full-tree or pro-tree brake, by adjusting the amount of fluid allowed to dump. This is their website with a phone number http://www.racewithjw.com/about.php Why don't you give them a call?
    If I were you, I would not let this guy touch my transmission any more. It has been 5 or 6 times and it is still not right and he says that he is going to charge you for this and that it might not still work, while he is experimenting on your valve body and case. He doesn't know what is going on.

    Bill Mitchell

  8. #8
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    Quote Originally Posted by sp2816
    I do not think that opening up the passage on the valve body will help. JW designed that case to work with a full-tree or pro-tree brake, by adjusting the amount of fluid allowed to dump. This is their website with a phone number http://www.racewithjw.com/about.php Why don't you give them a call?
    If I were you, I would not let this guy touch my transmission any more. It has been 5 or 6 times and it is still not right and he says that he is going to charge you for this and that it might not still work, while he is experimenting on your valve body and case. He doesn't know what is going on.

    Bill Mitchell
    Yup, I think I'd have to agree! If he hasn't gotten it right to this point, then I'd say it's a pretty safe bet he won't get it this time either! Sounds like it's time to learn to do them yourself, that's what I did years ago! :wink:

  9. #9
    Senior Member MASTER BUILDER
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    This is the following specs on what he found and did

    reverse clutches set at .060 a little tight
    pump clearnace between the driven gear is .005 in spec
    driven gear to pump .006 in spec
    gear and housing .001 in spec

    I phoned jw today and he told me that all there brakes have 3/8 outlet to match the case so they recommend all brakes have at least 3/8 outlet to match case, to work proberly.

    I phoned cti who make the brake, they told me that all there brakes have a 5/16 outlet and see no problem with that...i told him mine is not even 1/4 opening...he said no way i think it has to be a old brake....the hole is maybe 3/16 in size to go to a 6/16 hole that is half the size, i can see where it would make it lazy.

    he is going to drill it to 3/8 and see if that works if it doesn't i am going to put in a new brake

    Yes i agree i have to learn how to do my own glides and all this has educated me

  10. #10
    Junior Member SHOW GUEST
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    If you need help from someone who's done Glides since the late '70's and is willing to share knowledge.... give me a shout. I'd gladly run through some things with you to get things back on track for you!
    http://www.oldanimotorsports.20megsfree.com Oldani Motorsports
    TCI, BTE, JW, ATD/Hipster, Jesel, Impact, Stef's/B&B, Nitroplate, Comp Cams/Powerhouse, Jomar, Isky, Crane, Crower, AFR, Jager, etc.....


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