Possible Trans Issue - Chevelle Tech
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post #1 of 6 (permalink) Old Jul 15th, 19, 10:42 PM Thread Starter
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Possible Trans Issue

My car has recently developed a slight bucking when slowly pulling away from a stop. It only happens after the car has been driven for 25 to 30 minutes, when it's warming up I do not feel the bucking. The trans is a TCI TH400 with a 10" ATI converter. The rest of the combo is the typical 454 with a roller cam and a 12 bolt posi with 4.11's. I have the vacuum line for the trans and pcv valve plumbed into the same port, could this cause my issue? Fluid level looks good.

'70 Malibu, 454 w/Brodix Ovals, TH400 w/10" ATI, 12 bolt with 4:11's
2013 ZL1 Camaro, Ashen Gray Metallic, No Mods YET
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post #2 of 6 (permalink) Old Jul 15th, 19, 11:02 PM
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Rame
 
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Re: Possible Trans Issue

Seems plausible , right when you take off I think it would loose vacuum in the line due to the pcv, plug the pcv line and see if it improves. I recall some others have problems with the brake booster plumbed in with the pcv so don't tie in there either.

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post #3 of 6 (permalink) Old Jul 15th, 19, 11:06 PM Thread Starter
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Re: Possible Trans Issue

Quote:
Originally Posted by sampoerna415 View Post
Seems plausible , right when you take off I think it would loose vacuum in the line due to the pcv, plug the pcv line and see if it improves. I recall some others have problems with the brake booster plumbed in with the pcv so don't tie in there either.
Okay, I will give that a try. Fortunately I have hydro boost for the brakes so I don't have to worry about a vacuum source for the brake booster.

'70 Malibu, 454 w/Brodix Ovals, TH400 w/10" ATI, 12 bolt with 4:11's
2013 ZL1 Camaro, Ashen Gray Metallic, No Mods YET
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post #4 of 6 (permalink) Old Jul 16th, 19, 12:11 AM
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Rame
 
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Re: Possible Trans Issue

Also they have vacuum restriction/check valves that you can play around with, GM had that stuff from the factory to fix weird stuff, might be worth looking into if nothing else works.

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post #5 of 6 (permalink) Old Jul 16th, 19, 3:32 AM
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Re: Possible Trans Issue

The modulator should only affect shift points. You could try starting in manual 1st, or in reverse to see if any change. Sounds more like an engine miss.

You can also try holding the brake while putting a light load on engine in drive to replicate the symptom.
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post #6 of 6 (permalink) Old Jul 16th, 19, 4:08 PM
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Re: Possible Trans Issue

try it in a turn , if its worse....maybe posi clutches sticking

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