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Discussion Starter · #1 · (Edited)
Hard Shifting MOD

This thread was posted elsewhere but really want feed back on this mod. I have had two crappy warranty trans repairs and the shift quality has deminished to scarey. In my hunt for fixing it(covering it up) I installed a B&M Short Throw Sport Shifter and shimmed the detent on the side of the transmission. The shimming is a test in progress. It feels good with a .070 copper washer installed but may reduce it to .050. I don't need it popping out of gear. Has anybody tried this "fix"?
 

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Discussion Starter · #3 ·
Feels good

I have driven this car for 45 miles all city and some quick sprints to third gear and have not had any problems. I will try the .050 this weekend (if I can find one). I am still going to lean towards the notchy feel a hair for the security. Cars equiped with factory length shifters would probably need to go .030 or .040 since they would have more leverage than I.
 

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What's involved with shimming the detent? When you try the .050 shim, please take pictures of where you place this shim and post it.
 

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Discussion Starter · #5 ·
Not changing .070 shim

Here is a digram of the M12. Part number 9 is the detent. The shim I used is .070 thick, .780 inside dia., .125 from inside to outside edge. You can get these almost anywhere. It's a popular sized drain plug gasket.
I am going to leave the .070 in it feels good and haven't had any concerns. I can't believe there isn't any more interest in the mod. There is many complaints on this topic.
 

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Discussion Starter · #6 ·
Still doing good

I have had great success with this MOD. It makes the shifting really smooth and can be done in about 15 minutes. You just need the correct size (above) drain plug copper washer. You will also need a floor jack, jack stands and a 15/16 socket. I drive this car daily in heavy traffic along with a little canyon fun when I can. I have not had one reason to remove this mod.
 

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JMFND said:
Here is a digram of the M12. Part number 9 is the detent. The shim I used is .070 thick, .780 inside dia., .125 from inside to outside edge. You can get these almost anywhere. It's a popular sized drain plug gasket.
I am going to leave the .070 in it feels good and haven't had any concerns. I can't believe there isn't any more interest in the mod. There is many complaints on this topic.

I wonder if this is the mod that Antivenom does to make the shifting smoother?
Thanks for the info! :thumb:
 

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a little more info

1) is the M12 shown in the diagram the same thing as the T56?
2) What exactly is the detent for, what does it control and how does adding various sizes of shims change is function?
3) Does the shim (washer) have to be brass? Is there a reason for this?
4) Does this mod have any adverse effects on the durability/life span of the transmission? (ex. more heat etc...)

Thanks for your help.
Noel.

PS. $60 for a brass washer? Come on.
 

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I've got a question. Does this mod address the problem of "notchiness" when shifting through the neutral gate? I have a BPP shifter, and the gear placement is just about perfect with the stiffest side load springs, but there's that same old "hangup", or hesitation when going through the neutral gate. Stock shifter had it, and the aftermarket one does too, but with the BPP, I've got a much shorter throw, and positive gear placement. Does this shim specifically deal with the notch feel in the neutral gate area? Thanks.
 

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exSSer said:
I've got a question. Does this mod address the problem of "notchiness" when shifting through the neutral gate? I have a BPP shifter, and the gear placement is just about perfect with the stiffest side load springs, but there's that same old "hangup", or hesitation when going through the neutral gate. Stock shifter had it, and the aftermarket one does too, but with the BPP, I've got a much shorter throw, and positive gear placement. Does this shim specifically deal with the notch feel in the neutral gate area? Thanks.
:yeadog:
 

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A good read.
 

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Copper shim

Is this from an oil drain plug, transmission, or rear differential. What did you ask for at the autoparts store or dealer to get this shim.

Randy
 

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Discussion Starter · #16 ·
No way. I'm selling it for 1 million dollars each.

Whoa. I haven't been here for days.
OK I really don't know what the drain plug fits. But I do have the size .070 thick, .780 inside dia., .905 outside dia. (this measurement not real crucial) I used copper. It has to be drain plug quality metal or it will crush and not be affective. Napa is where I probably got mine they could look it by size. THE ONLY PROBLEMS YOU CAN HAVE IS SHIMMING IT OUT TO MUCH. I have a B&M sport short throw. A stock shifter would probably work better with a .040 or .050. A transmission detent is ball bearing under spring pressure (the M12 is a fully enclosed detent) that is pushed into a U shaped cut out in the shifter shaft. This is what a lot of people complain about "it's too notchy". You are just lessoning the spring pressure behind the ball bearing being pushing into a U shape cut out in a shaft. In turn not so notchy. This is where we could run into a problem. If the shim is to thick, no spring pressure and it will pop out of gear (NOT GOOD). I have read about another members mod on the same subject but don't know how they will "custom fit" for different shift length if in fact it is the same mod. The M12 is a T-56. I think that was all the question. I run a tune for 520 rwhp and have not had any concerns. Makes it shift close to what I would expect for 50K car.
 

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I hadn't seen this thread, saw the comments in the other thread though, wondered where they came from.
Thanks JMFND, I'm not going to say anything about anyone in particular but if this is indeed the part in question in the other thread it makes me mad that that someone would pro-port to have spent years in R&D on an item that seems fairly obvious what it will and will not do and the consequences. What makes me maddest is that, again if these parts are one in the same, that someone would be willing to further perpetuate the corvette tax and over charge people for what appears to be a washer. If you can sell it to people fine, make a profit fine but this is no different to the Skip shift resistor or the Home Depot lowering bolts. There was one comment made about nickel and diming on a $50k car, well these are nickel and dime parts and 1000x what something is worth is just stupid. Wonder how well a $.10 resistor works vs the $40.00 part, same thing. Again, thanks JMFND for shedding some light, I would have done the same thing, figured this out and shared with my buds.
 

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Shifter Mod

I just completed this mod. Hard to find in the dark even with a mag light! This part is much harder to find in my local than estimated. Copper Washer was 1.00. I had to buy two though. Mine was the .050 thick version. However I don't find that my car shifts any better than before. It still is quite notchy through the neutral gate from all gears, and may be somewhat harder to find reverse. For all of you who still want to attempt this mod the shifter detent assembly of located near the top of the transmission on the passengers side at the rear where it connects to the differential. It is just below a coolant line I believe. Mine was 15/16" but looked funny because it has a small flat circle 5/8" standing off of the center approximately 1/8 inch. I will probably attempt the other version of this mod from Antivenom.
 

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Z16South said:
I just completed this mod. Hard to find in the dark even with a mag light! This part is much harder to find in my local than estimated. Copper Washer was 1.00. I had to buy two though. Mine was the .050 thick version. However I don't find that my car shifts any better than before. It still is quite notchy through the neutral gate from all gears, and may be somewhat harder to find reverse. For all of you who still want to attempt this mod the shifter detent assembly of located near the top of the transmission on the passengers side at the rear where it connects to the differential. It is just below a coolant line I believe. Mine was 15/16" but looked funny because it has a small flat circle 5/8" standing off of the center approximately 1/8 inch. I will probably attempt the other version of this mod from Antivenom.
What shifter do you have and did you try the .70 washer.
 

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The reason you people are having to resort to a shim to "cure" notchiness is your aftermarket shifters. All aftermarket shifters increase shift effort. You feel that as notchiness.

I should add that there is more going on inside the transmission to make it notchy than just the ball-spring detents, however, it is true that you'll find that decreasing the ball-spring tension will decrease the shift effort to a certain extent, but decrease it too much, and you'll create a host of other problems.

For other than hard-core drag race applications, I've yet to see a Z06 which has a properly operating clutch and transmission operated by a good driver that needs an aftermarket shifter. I've also driven some aftermarket shifters which are way too high effort and too-close gated. In fact, IMO, the B&M Ripper is a disaster in this respect...though it a is good drag race shifter in the hands of a driver familiar (and comfortable) with it's very short fore/aft and crosscar throws.

I have an 04 and, with the clutch functioning properly, the trans with the right lube and proper "hand/foot" coordination, I've yet to want a shorter throw shifter and have no problem shifting so quick I bark the tires even on a shift with the clutch.
 
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