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1949 Ford Coupe RESURRECTION
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Discussion Starter · #1 ·
I installed a Transgo shift kit some time ago, and noticed at the time that the 2-4 servo seemed a bit sloppy but I used it anyway (see the video link below).. From the numbers on it and the dimensions, I'm 99% sure it is/was a Corvette servo assembly. The Transgo instructions say to discard the cushion spring, etc... Lately, as temperatures around here have risen (90 degrees a couple of days ago), my 4th gear shift speed go way up to 65 mph. I can always tell that the shift point to 4th is a function of the fluid temperature (viscosity). When it's cold, it shifts like a dream, and the warmer it is, the higher 4th shift point.

So, about a year ago, I bought a Sonnax Super Hold servo (with both 2nd and 4th booster configuration, the complete set of parts). Since I can't find the original cushion spring (I never throw anything away), and it appears that there are TWO different OEM cushion springs, I don't know which one to buy to install in the Sonnax, as it says "use OE cushion spring". then add the "OE Corvette Cushion spring, which I'm sure that it's the 08681195(??) spring that is meant to soften the 1-2 shift and soften the 3-2 downshift....

Problem is, there are two cushion springs as listed on Rock Auto, 08642539 (Pink) and 08642273 (Orange). I've googled the crap out of those numbers and have not been able to find out what the difference is between those springs.

By the way, anybody know what the color/dimensions the OE 2nd Gear Release Spring???

I have not taken the Transgo/Corvette/modified servo out yet ..as it's my daily driver and need to have everything I need before taking it apart...

Too bad Sonnax doesn't include all parts so as not to have to use "OE parts" to reinstall the servo.

Thanks in advance for the help !

Here are some links...

The second time I rebuilt the transmission, I SHOULD NOT have put the servo back in... shoot me..here is a short video, most likely my problem
 

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8642539 cushion spring was used with most servos including the Vette from factory.The 8681195 spring I’ve only only seen in C5 corvettes that I can remember.The servo piston return spring is 8642273 and I think most were orange,but in the Transgo instructions it tells You to reuse the original,so you should have it.You will also need the retainer snap ring 8642105 if you don’t have it. This is the info I have,hope it helps.
 

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1949 Ford Coupe RESURRECTION
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1,049 Posts
Discussion Starter · #3 · (Edited)
THAAANKS, Coupe !.. you are correct.. I had forgotten about that snap ring (and it's not in my "pile" either).... surely seems weird that such a radical modification to the servo like leaving out the cushion spring and the snap ring would work at all.. but then, I've not fully understood how / why the servo needs to have two different functions / gear signals to do the same thing... squeeze the band.. oh well, I guess some things we just have to accept ... except that Epstein didn't kill himself..........ahahahah

And by the way, I DO have a what looks like red or orange spring that is 1.00" in ht., OD is 1.50", and spring diameter of 0.115". Would that be the cushion spring? I suspect its not, as it is brand new, not greasy, etc. looks like it may have been in the kit, (WHICH, by the way, there is NO listing of parts and what they are.. you just have to go by the pictures... these trans parts guys could all do better... the assume that "you just have to know", I guess....

Another question regarding sloppy instructions.. the Sonnax sheet shows the supplied washer against the 4th gear dual servo assembly (cover), and use the OE washer and clip (BUT the OE washer is mislabeled as "OE 4th gear RETURN spring", with the arrow going to the WASHER, and another label with the label "OE 4th gear RELEASE spring"..pointing to the spring. So you have stacked on the pin in this order -----spring then OE washer, then E-clip, then Sonnax washer, then cover....I suppose that is correct but ........
Schematic Rectangle Line Handwriting Font


By the way since you surely seem to know what you are talkin' about, have you seen the problem with the rise in 4th gear shift point as a function of viscosity/temperature?

Thanks again..
 

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THAAANKS, Coupe !.. you are correct.. I had forgotten about that snap ring (and it's not in my "pile" either).... surely seems weird that such a radical modification to the servo like leaving out the cushion spring and the snap ring would work at all.. but then, I've not fully understood how / why the servo needs to have two different functions / gear signals to do the same thing... squeeze the band.. oh well, I guess some things we just have to accept ... except that Epstein didn't kill himself..........ahahahah

And by the way, I DO have a what looks like red or orange spring that is 1.00" in ht., OD is 1.50", and spring diameter of 0.115". Would that be the cushion spring? I suspect its not, as it is brand new, not greasy, etc. looks like it may have been in the kit, (WHICH, by the way, there is NO listing of parts and what they are.. you just have to go by the pictures... these trans parts guys could all do better... the assume that "you just have to know", I guess....

Another question regarding sloppy instructions.. the Sonnax sheet shows the supplied washer against the 4th gear dual servo assembly (cover), and use the OE washer and clip (BUT the OE washer is mislabeled as "OE 4th gear RETURN spring", with the arrow going to the WASHER, and another label with the label "OE 4th gear RELEASE spring"..pointing to the spring. So you have stacked on the pin in this order -----spring then OE washer, then E-clip, then Sonnax washer, then cover....I suppose that is correct but ........ View attachment 615626

By the way since you surely seem to know what you are talkin' about, have you seen the problem with the rise in 4th gear shift point as a function of viscosity/temperature?

Thanks again..
I don’t have a cushion spring here to measure,but it only has about 3 coils and is wider than it is high and a thick wire.It looks just like the picture in the Transgo instructions.The Sonnax servo assembles like a stock one.The small return spring,washer and E clip in that order,than the gold washer sits on the E clip and than the 4th gear super hold servo. I can’t recall of a specific complaint of rise in the 4th gear shift point,but when your dealing with hydraulics anything is possible. Valvebody bore wear and valve wear,governor circuit leaks,pressure regulator valve and pump wear can create some noticeable problems. Also when the fluid gets hotter it gets thinner. Pressure tests when cold and at operating temp will be different. Quality of oil could make a difference.
 
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