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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 1979cheyenne on January 27, 2015, 01:48:22 am

Title: Figured out why my t350 clunks in all gears
Post by: 1979cheyenne on January 27, 2015, 01:48:22 am
ive been doing lots of research as I am new to auto transmissions, and couldn't find a reason why mine was shifting hard and clunking in all 3 forward gears and reverse then I read about the differences about a i-6 stock turbo350 and a v8 t350. Seeing as my truck were originally a I-6 truck with a 94 crate 350, the shift points are higher in the I-6 and lower in the v8 so it is shifting well into the torq range I'm guessing as it has loads of low end torq. There's probably a casting number to tell differences but I figured someone might be able to use this. The trans mounts are good btw.
Title: Re: Figured out why my t350 clunks in all gears
Post by: Irish_Alley on January 27, 2015, 02:03:56 am
The clunking might be slop in the read or a bad u joint or a bad trans mount
Title: Re: Figured out why my t350 clunks in all gears
Post by: 1979cheyenne on January 27, 2015, 02:06:52 am
I had a suspicion about u joints I was going to jack the truck up and check tomorrow but good idea I'll check the rear end play. I bought a new trans mount thinking that would fix it and mine was practically new so that wasn't it
Title: Re: Figured out why my t350 clunks in all gears
Post by: roundhouse on January 27, 2015, 06:47:05 am
Shift points should be adjustable with the vacuum modulator and the governor


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Title: Re: Figured out why my t350 clunks in all gears
Post by: 1979cheyenne on January 27, 2015, 03:23:05 pm
I couldn't find a vacuum modulator on mine when I looked a while back. Is it possible I over looked it?
Title: Re: Figured out why my t350 clunks in all gears
Post by: LTZ C20 on January 27, 2015, 03:55:56 pm
Should be at the back, right hand side, right above the back of the pan with a vacuum line goin to it.
Title: Re: Figured out why my t350 clunks in all gears
Post by: 1979cheyenne on January 31, 2015, 06:14:55 am
Sorry I've been busy, I'll check later today most likely. Just gotta try to squeeze under my truck haha
Title: Re: Figured out why my t350 clunks in all gears
Post by: enaberif on January 31, 2015, 12:17:01 pm
Sorry I've been busy, I'll check later today most likely. Just gotta try to squeeze under my truck haha

Vacuum modulator has a vacuum line attached which feeds up to the manifold for vacuum.

Red circle: http://s90.photobucket.com/user/esmykm13/media/Olds%20pics/IMG_125420Custom20Custom_zps1b3e6cb1.jpg.html
Title: Re: Figured out why my t350 clunks in all gears
Post by: 1979cheyenne on February 02, 2015, 01:11:50 am
I found it and it's connected. I crawled under and tried to shake the driveline at rear end and transmission and there is some play and a noise in the trans not u joints I'm not sure if that's normal or not. But next time it's running I'll try to adjust the screw inside
Title: Re: Figured out why my t350 clunks in all gears
Post by: Irish_Alley on February 02, 2015, 01:46:48 am
can you spin the driveshaft by hand?
Title: Re: Figured out why my t350 clunks in all gears
Post by: 1979cheyenne on February 02, 2015, 06:57:36 am
It rotates back and forth inside the rear of the trans, no noticeable slop in the u joints or rear end
Title: Re: Figured out why my t350 clunks in all gears
Post by: rich weyand on February 02, 2015, 09:48:08 am
Moving the shift points with the governor is really easy.  You just need a heavier weight or two.  They're about an inch square, and you can buy them in kits so you can try different ones.  Takes about 5 minutes to get the governor out.  There's a cap on the side of the transmission with a bail holding it on.  You pop the cap off, and then the governor just slides out.
Title: Re: Figured out why my t350 clunks in all gears
Post by: 1979cheyenne on February 04, 2015, 11:53:04 pm
I've heard of people installing corvette trans gov if I'm not mistaken to replace stock ones
Title: Re: Figured out why my t350 clunks in all gears
Post by: 1979cheyenne on February 14, 2015, 06:03:30 pm
Could it be a shift kit and vacuum modulator? It kicks you into seat when it shifts every gear and shifts pretty high rpm part throttle