Grinding Sound WHen Shifting

Viper96

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Hello everyone.I am new to this forum and Viper ownership. I have a 96 GTS with 32,000 miles and have loved every minute but I have developed a problem during shifting. Sometimes when I shift from 1st to 2nd I hear a grinding noise when it goes in. This happens when the RPM is high or low but it happens mainly if I shift fast into the gear. It never happens when down shifting from 3rd to 2nd. I had the trans and diff oils changed at the dealer and I had the mechanic test drive it but he could not reproduce the condition and told me it is fine. This only happens with 2nd gear and I can go days without this happening. Does this sound like a very serious problem or can the fix be a simple one. What are some possible causes ? This has me bummed out. Thanks guys.
 

Russ Oasis

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Does it happen more when the car is cold or the same both hot and cold. When you downshift from 3rd to 2nd, are you double clutching or no?
 

Russ Oasis

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If you know how to double clutch, try matching engine and driveshaft speed as closely as possible when you shift. If that fixes the problem, you probably have worn synchros.
 
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Viper96

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If it is worn sybchros is the fix significant I don't know how to double clutch so is there another way of determining what is happening. If it is the syncros is the fix only for 2nd gear ? Sorry for the basic questions. Thanks.
 

Viper Specialty

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Viper96- Sounds like Synchros to me. However, the NOT doing it while downshifting sounds fishy- a bad synchro is more likely to come to light while downshifting. One explanation is that you're downshifting much slower than you are upshifting. If that is the case, everything points to a synchro.

It is possible to change JUST the 2nd gear synchro, but your nuts to not change at least the first 4 while you're in there.

If you get stuck or have any questions, let me know. I can also rebuild the trans for you if you need. My standard charge is 400+ parts. Expect approx 100-150 in parts if you do 4 gears' synchros. (I could be wrong, as I am working off 3000GT Twin Turbo Synchro prices, they range from 20-40 each)
 

Paolo Castellano

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I would try some Redline D4 ATF before you do anything. It is about $8.00/qt and can be bought from Bobby Archer. If you have the wrong fluid in there with the wrong slip coefficient ie too slippery, it will grind. The Redline product has the proper slip coefficient(not as slippery} so the synchros have time to match properly. I am sure the synchros are worn, but for $32.00 and an hour at the most of your time you can't go wrong!
 

sbkim

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I also noticed that it's difficult to shift from 1st to 2nd when the car is cold - sometimes grinding. Is this really normal or something that needs to be fixed? All is well, once warmed up though...

Thanks
 

Russ Oasis

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A little grinding when the car is cold is more acceptable than all the time. It's because the oil in the tranny is thick and won't allow the synchros to work well until it thins out and heats up. I'd take it VERY slow shifting while cold to avoid the grind.
 

TomMiriViper

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I have the same grind when my car is cold. When the fluid gets hot it thins and the grind goes away. It's done it for a while so I haven't worried about it. Tom
 

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