I am putting a hydro stick in my 31 Olds coupe. It is an Nos slant pan with an original competition shifter. The shifter has spaces for reverse/park then 1-4 speeds and then neutral however the transmission only has 5 detentes on the bracket. It goes into reverse park, trans locks up, then first through 4 but no detente on the transmission for neutral. Any ideas. Based on the numbers on transmission it is an unblown completion model. Any ideas?
Seems only 5 detents are required. 5 detents separate 6 positions. Neutral is the last position in the gate.
So you're starting in one position, let's say Neutral, then moving the shifter 5 times to get to Reverse. That's 5 detents. The detents in the transmission have to be synchronized with the shifter gates so that would have to explain both.
I don't think so. If you are in neutral, that's one detent. And then 5 more detents (as you said) to go through the four gears and reverse. So that's 6 detents total that should be needed in the transmission. The B & M catalog even shows where the detents will appear if you use the stock column shifter. I guess the question is did B & M make a competition hydro that wasn't a full manual transmission? A modified transmission that kept the stock shift pattern?
I don't think the reverse position is really a detent. Just one end of the quadrant which I believe is also the park position with the engine off. I would think the two competition Hydro's (Blown/Unblown) would be manual valve bodies and use their gated competition shifters. All the B&M Hydro stick shift "patterns" are the same.
(Working from memory here). There are 5 detents in the transmission. N, D, S, L, R. N detent is pretty self explanatory. R detent is as well. One of the modifications that B&M (as well as others) made, was a modification to the valve body to allow the transmission to stay in 1st gear, instead of automatically upshifting 1-2. In the second and third pictures that @31olds posted at the start of this thread, the 't' shaped piece below/behind the gold detent is the modification. Stock, in D, the transmission will automatically make the 1-2 upshift on the first band, and then the 3-4 upshift on the second band. Stock, in S, the transmission will automatically up shift 1, 2, 3 as speed increases. Stock, in L, the transmission will only make the 1-2 upshift. There's no '6th' detent, because there is no provision for holding first. In application, putting the shifter in 1 is putting the transmission in L. Due to the modification, the transmission will hold in 1st gear. Putting the shifter in 2 is putting the transmission in S. Allowing the transmission to shift to 2nd. Putting the shifter in 3, the transmission is going to continue the 2-3 upshift. Putting the shifter in 4 is putting the transmission in D, allowing the upshift to 4th gear. I've never drag raced a Hydro Stick. However, I've read lots about racers actually not using 1, because the 1-2 upshift needed to happen so quickly that it was too 'busy' coming off the line to make the 1-2 manual shift. So instead, racers started in 2, letting the transmission made the 1-2 upshift itself as designed. Ironically, the modification that made B&M synonymous with these transmissions during that time, was fairly impractical for actual racing application.
Not quite. Nice explanation of how the hydro stick works, but as Speedy says, he's never raced one. So can anyone explain how you can have the transmission go through 6 gear changes with only 5 detents. IE a stock hydro trans has Reverse/Park (R) and Neutral (N) fixed. That's 2 positions. Then there are 3 left (L), (S), and (D). That's a TOTAL of 5 positions as is shown in the OP's original pictures. Count them, there are only 5 detents in the pictures. And you can't go past the (R) and (N) end points. The B & M Hydro Stick also has Reverse/Park (R) and Neutral (N) fixed. That's 2 positions. Then you should be able to put it in any one of 4 gears and hold it in that gear. That is 4 additional positions for a TOTAL of 6 positions. The OP states that the transmission he has a B & M competition tag. If it is truly a full manual Hydro Stick, how can you hold the trans in any one of 4 forward gears with only 3 positions (L), (S), and (D) available. Or is the OP's trans a fake and just a stocker with a 1st gear hold valve but bogus B & M tag? Anyone have a real known Hydro Stick to open up and compare with? Or anyone with real experience using one?
No, the OP's transmission is not fake . Here is a stock 1955 GM Hydromatic valve body. It only has and only needs 4 detents. Here is a great thread on the Hydro stick https://www.jalopyjournal.com/forum/threads/b-m-hydro-stick-hydrostick.1246713/
FYI in a stock transmission it appears that there are actually 5 detents. Reverse/Park detent is around the corner. That's what was confusing - didn't realize that the shifter arm rotated that much. I was only looking at the notches. That also answers the OP's original question. He is not actually in (R/P) in the first position. If he moves the shifter arm all the way to (R/P) there are then 5 additional notches to move through for a total of 6 notches. Thanks everyone for helping me clear this up in my own head.
Glad you watched the video. Yes the detent plate rotates further than what is shown in the OP's second picture. I guess I'm wrong but to me you don't hit the first detent until you pull it out of R. It looks like the OP needs to clear the parking bracket in order to get to the R position.
If you had read my full explanation, including the part about the modification B&M makes, you would understand why there isn't a detent for 1st. And I said that I hadn't raced one. Which is different than not having one, or having driven one. Either way, seems you've made sense in your own head, which I guess is good enough. Hopefully @31olds got what he needed from this thread as well.
Thanks to all for writing. I haven’t been back here for awhile. I think I also figured out that reverse park detent is around the corner as show in picture with the detents labeled. My question is now this . Is there a lock out in first as well since my transmission seems to lock up won’t turn in both the reverse/ park position and the next position which is first. All of this is with the transmission on the bench with no oil so it may change when operating I guess. Any thoughts on that? Thanks for all the help with this. Want to get it to the track next year.
You can bench test with an air compressor. I'd need to dig through my notes and refresh myself on the steps involved with that however.
That would be great. It would be great to be able to do that with out all the work of putting it in the car. Let me know. Thanks!
On another issue. Does anyone know the value the furnace brazed torus. Is it that the vanes would come loose at higher rpm? How worth is it to have the furnace brazing? Just wondering since my NOS hydro stick came with out that feature is it worth it to find a furnace brazed pair? Have a chance to buy one set.
You can use air to test the operation of the clutches and servos, but you can't really test transmission operation without driving the pump.
According to the B&M technical info I have from 1971, the crimped fins in the stock torus have a 50% fatality rate and were not included in their guarantee. The brazed fin torus were recommended for all applications and were included in C-5, CF5, F9, and F-10 kits. They were guaranteed and were said to be virtually indestructible. Since you have a "competition" Hydro Stick if the Torus you have came with it, I would think you may have the brazed assembly unless you have already determined it is not. It should be easy to tell if you take it apart. You will probably need new gaskets though. jaracer is correct and there are actually 2 pumps.
Thanks I figured it was something like that. Apparently the person who bought this originally was a cheapskate and would pay the up cost for the brazed option. I have located a brazed torus to use. Thankfully. Proceeding ahead with the project. Just learned that there are at least two flywheels one with 5/16” bolts and one with 3/8” bolts. Fortunately I had both so am going with the 3/8” bolts . Also have discovered the Chevy option used only half the bolts. Interesting stuff.
If you change flywheel check to see that it matches your starter. Different years different starters.
Thanks I did they are the same. I am assuming the smaller torus bolts were for a lower horse power application? But 30 bolts of the 5/16” should have been enough for almost any engine.
Who knows. My 49 transmission used 5/16” and my 56 used 3/8”. Which I’m assuming means that the tanks equipped with Hydramatics in ww2 had the smaller bolts.
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