Billet servo

[stovebolt 34]

Need some opinions , comments , corrections , scoldings or whatever . Just replaced the 692 servo with a billet servo . It appears to be a brand new unused Sonnax . Used my stock servo pin with the stock inner piston , cushion spring , cushion spring retainer and stock return spring . They tell you to remove the seal from the inner piston and discard . I question why you would remove the inner piston seal as it appears to be nothing but a spacer now . Like I said it appears to be a Sonnax but but I got it off "Flea Bay ". The machining appears to be really good . The outer piston and cover seem to be close tolerance .

What gets me is it uses pfte ( teflon ) ? seals on the piston . One solid and one scarf cut . I always thought lip seals would be better ???

Bottom line > > > It doesn't shift as hard as my 692 . Why ? ? ? ? ?

Thanks for any comments .

 

[TexasT]

If it didn't come with lip seals I doubt it is a sonnax. I just received a sonnax from sonnax in a sonnax box and it came with the lip seals and a new pin. Also had sonnax on the instructions.

I'll take some pix if you are interested. Mine came from amazon.com. do a search it was quite the bargain.

 

[stovebolt 34]

Thanks Tex
I pulled it up on Amazon . That is a really good deal . From what I see my servo appears to be a "knock off " of the Sonnax minus the pin and the lip seals . Sales hype being what it is . . " OE style PTFE seals create a positive seal without causing band drag " . Really ?

I just drove it a short diatance at light throttle . I'm going to try some full throttle upshifts and see what it does before passing final judgement .

 

[TexasT]

If you feel it is leaking past the seal you could try wrapping them with Teflon tape to help them seal better. Or get a lip seal kit and replace the Teflon rings.

 

[stovebolt 34]

Thanks , I might just try the lip seal kit . I might lightly scotch brite the servo case bore . Since I used my stock pin I didn't check band clearance . after I got the servo cover retaining ring on The drive shaft turned in both directions . When I pressed on the cover the driveshaft only turned one way . When I do it over I'll see how much clearance I actually have . I got a lot to learn .

 

[TexasT]

That clearance could have changed a lot with the different servo. I would definately check that.

I do know the sonnax one I got has a different pin than the stock one. The attachment is different.

 

[stovebolt 34]

Just a follow up . I got a seal kit and servo pin for the Sonnax servo . Neither will fit this servo . The lands on this servo are too narrow and the Sonnax pin is way too short . Not complaning , just never know . Part of the learning process . I did tighten the band clearance a little bit . It does seem to help . You have to pull the transmission to do a number on the servo as the 34 frame K member is super close . I'm getting good at pulling the transmission but it's something I wouldn't do very often .

 

[clusolynn]

If you are still having a problem, try a local hydraulic shop, they probably have a seal that will fit.

 

[TexasT]

How are you checking clearance?
I was told that if you assemble it up without seals and put it in you should be able to get a 60 thousands feeler between snap ring and cover. If too much weld a little on the tip, too little, grind some off.

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[clusolynn]

That's why its adjustable! You don't have to add and subtract shims, or weld and grind until its 'CLOSE'. If installed with transmission in vehicle, turn the output shaft and 'feel' for drag. If installed when building, install servo ONCE, and adjust to tighter more accurate clearances without removing the servo.

 

[clusolynn]

Uh, I, uh, well, duh, I just posted something that will seem totally out of place, because it is! This post sent an alert to my email, and I thought the last post was asking about my adjustable servo? So, I just answered without reading the other post before it! Ding! Ding! Ding!
Sorry!

 

[TexasT]

No prob, clue us in on this adjustable servo. How's it work, price, where to get it. Pix if you have some.

 

[stovebolt 34]

Tex , I did it like you mention , without the seals . I used one stainless washer and rechecked with a bent piece solid copper wire that I ground down to approximately .060 . It seems to be better . The old 692 servo might have had a little bit of slip before it grabbed hard. I used the stock width band that came with the overhaul kit . This billet servo does not seem to slip . Using manual low to second it shifts pretty solid . Second to third is pretty solid . Since this is not a pro build I might be expecting too much but all help and comments appreciated .

 

[TexasT]

On your direct clutches in the drum, how much clearance did you set them too? I like .045-060 . I ended up with an extra steel in there to get it tight.
I am searching a bigger/thicker selective for the front. I was told this is the mickey mouse washer as it looks like three mickey ears.
Did you drill out the spacer plate on any of the shifting holes? Not too much at at a time as small changes make big difference. Whose shift kit are you using? I have directions to several so I can try different things.
I am using a stock width carbon fiber band. I think there is a wide one but I didn't have access to a lathe so I went stock this time.

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[clusolynn]

Hello, if you are interested in the adjustable servo, checkout my TurboBuick profile page, it has a link to my homepage. There is information about the servo and a contact form you can use to contact me. I am currently out of TH200-4R billet Adjustable Servos, will have more made within the next 2 months, but you can see pictures and brief description. Thanks for asking, John.

 

[clusolynn]

It looks like there are alot of views, so here are a few pictures. The bottom one on the left is the TH200-4R, the other is a TH700-R4 with Corvette piston.

 

[olds403]

Nice yellow head parrot John. Send me a pm when you get servos in stock.

 

[bison]

There's a lot more to it than putting a servo in. I'd tighten the clearance on the band till you feel drag. The 2nd oil feed in the plate has a lot to do with 1-2. Increased line pressure and rapid throttle transition can stroke the accumulator valve prematurely and accumulate too much 2nd oil. You need more spring on the servo for a larger apply area.


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[TexasT]

Care to elaborate on the spring and feed hole sizing for us? I'm just trying to get it done on a budget like most. Thanks for any additional input.
So tightening until drag might be tighter or looser than .060. The trans oil will provide a layer to keep it from dragging during operation? I guess this is a "feel" sort of thing?

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[stovebolt 34]

Confession is good for the soul , I guess . I used the much maligned B&M Transpak . At the time I didn't know any better . Just drilled the spacer plate like they instructed ( street/strip ) . used the spacers they provided for the accumulators . I followed their instruction on the 4th accumulator which I found out later is the wrong way to do it . 10 vane pump with bigger boost valves . I didn't mess with the clearances on the direct drum .