1-2 shift grinding status

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klystron

klystron

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After the new transmission went in and nothing changed, the fixed operations manager at Premier Chevrolet in Morgantown, WV drove a brand new Sonic in sales and was unable to reproduce the problem. He talked to engineering and they have sent a whole new shifter assembly with new cables and everything as well as a new "custom spec" transmission whatever that means.

Hopefully more news to report next week.
 
brandon1239

brandon1239

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klystron said:
After the new transmission went in and nothing changed, the fixed operations manager at Premier Chevrolet in Morgantown, WV drove a brand new Sonic in sales and was unable to reproduce the problem. He talked to engineering and they have sent a whole new shifter assembly with new cables and everything as well as a new "custom spec" transmission whatever that means.

Hopefully more news to report next week.
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:popcorn: sounds just like my problem. I ended up getting a new car because no matter what they did it still would grind from 1-2. 4 transmissions later...
 
klystron

klystron

Banned
BrianH said:
I have the same issues. There's a sticky thread in the Transmission forum here: http://www.sonicownersforum.com/for...sion/2626-second-gear-grinding-remedy-35.html
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So far they are replacing the clutch, presure plate, shifter, linkage, and hydraulics. The "hand-built transmission" that was ordered was put on hold. The good news is that my dealership is working with a GM engineer who is very much interested in solving this problem. This could mean that a solution for others who have this issue is on the way. I will know in the next day or so if I am going to get a 3rd transmission. It's unlikely, however.

I am very lucky my dealer was willing to test drive two new cars to check for this issue. I know normally you don't do a hard shift on a new car but they wanted to see if they had an issue and they did not. Mine did this from day one. I am really happy with Premier in Morgantown, WV.

I have a phat Impala until Wednesday.:blankface:
 
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rcmn0022

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Mine went away but I had this issue when my car was new.

It seems like this was the transmission maybe breaking in the synchros or something but it hard shifts like a dream. I was even able to NLS through all the gears, the 1-2 shift works perfectly now.

Try quickly shifting and see if this slowly solves itself, at least that was my case. It could be a different cause of the issue for the two of us.
 
klystron

klystron

Banned
rcmn0022 said:
Mine went away but I had this issue when my car was new.

It seems like this was the transmission maybe breaking in the synchros or something but it hard shifts like a dream. I was even able to NLS through all the gears, the 1-2 shift works perfectly now.

Try quickly shifting and see if this slowly solves itself, at least that was my case. It could be a different cause of the issue for the two of us.
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I'm not sure I want to grind my gears into submission. :) Thanks for the info, though.
 
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rcmn0022

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I highly doubt that the grinding sound is the gears at all. I believe it is the selectors that are not tolerances are too tight. Or the friction material is too grabby and needs a different oil
 
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OD3X1

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rcmn0022 said:
I highly doubt that the grinding sound is the gears at all. I believe it is the selectors that are not tolerances are too tight. Or the friction material is too grabby and needs a different oil
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The only friction material in a manual is the cutch and there should never be oil on it.
 
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rcmn0022

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OD3X1 said:
The only friction material in a manual is the cutch and there should never be oil on it.
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There is friction materials in the synchronisers in all modern manual transmissions. Or we would all have to learn how to revmatch every gear
 
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RaceThisLTZ

New member
^^^ this is very much the truth. I would like to try a different weight oil as mine grinds as well. Im not about to risk a shot in the dark though.
 
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OD3X1

New member
You are aware that synchros are typically made of brass? If anything else is in widespread use I am curious to know about it.
 
Preloader

Preloader

The M32 Martyr
Word is that an updated M32 has arrived. Any new M32s will have cooling fins in the casing.

I haven't heard that they specifically addressed the 2nd gear grind, but it not impossible.
 
theenico

theenico

New member
rcmn0022 said:
There is friction materials in the synchronisers in all modern manual transmissions. Or we would all have to learn how to revmatch every gear
Click to expand...

No there isn't.

The synchronizers are just metal (brass, steel, and some trans' even use phenolic) cones with tiny teeth on the face. The teeth lock the shift hub/balking ring to the mating teeth on the face of the desired gear. These teeth are not to be confused with the helical teeth on the OD of the gear.

During a shift, the cone shape on the ID of the syncro starts to engage the cone on the OD of the gear you are going to. The oil drag (friction) that happens as the cones come together is what speeds up or slows down the shaft of the mating gear so that the syncros don't crunch.

Changing the viscosity of the oil and/or using friction modifying additives can change how the cones interact.

I'll go look for some pictures.
 
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