TH 350 Trans - linkage ?

[K5_Fla]

I have a newly rebuilt Turbo 350 trans. Everything with the trans has been great. For fun the other day, I put the shifter into 1st gear ( never tried this before) hit the gas and drove around. I noticed that the trans will shift into 2nd gear on its own after around 2K RPM.

If I manually hold the shifter down… it stays in 1st gear the entire time. Guessing it has something to do with the linkage? I looks underneath.. but not sure exactly what to adjust. Any help?

 

[diesel4me]

A TH400 will upshift itself if its put in manual low around 5200 rpms...not sure if a TH350 is the same way--seeing yours upshifted at 2500 rpms or so I'd say your not fully engauging first gear with the linkage...to adjust it you take off the linkage at the colum and put the tranny shift lever in drive,then adjust the slider pinch bolt at the colum on the linkage so that it shows it in "drive" on the indicator,then it should be adjusted right....the detent cable must be adjusted properly also,to prevent it from downshifting too early ,it also changes the amount of line pressure to the clutches I believe..

 

[K5_Fla]

you have any pictures of the adjustment bolt? I know my issue is linkage adjustment ...as it holds fine in all RPM if I hold it in 1st gear. just not sure exactly what to adjust.

 

[blazerz]

350's wiil hold in first gear at any rpm..... the linkage on a column shift has a plastic insert that wear's out and let's the linkage get sloppy...it's a whole lot better feel when you replace it......a 400 turbo will shift on it's own into second, if it's stock... some shift kit's are designed to fix that....

 

[K5_Fla]

are far into the column? what is the process to change the plastic insert?

 

[diesel4me]

The adjustment is located where the shifter linkage rod goes into the lever on the steering colum,the pinch bolt there can be loosened and the linkage slid up or down as needed to align it...sorry I cant post a photo,but its easily seen from under the hood..

 

[K5_Fla]

ok.. so no need to take apart the steering column... all the adjustments needed are under the hood where it all comes through the fire wall correct?

 

[blazerz]

the plastic piece i am talking about is on the linkage under the truck, on a bracket bolted to the frame......

 

[4X4HIGH]

350's wiil hold in first gear at any rpm..... the linkage on a column shift has a plastic insert that wear's out and let's the linkage get sloppy...it's a whole lot better feel when you replace it......a 400 turbo will shift on it's own into second, if it's stock... some shift kit's are designed to fix that....

This is not true of all TH350's or most others for that matter. There were different valve bodies which allowed the trans to stay in the gear that was manually selected (factory valve bodies).

 

[blazerz]

i don't know of any 350 that is valved that way....375's maybe, 400's for sure......

 

[K5_Fla]

my TH350 will run up to 6K RPM ( or until it blows up) in 1st gear... the issue is I have to hold the shifter down.. otherwise it will slip into 2nd at around 1500-2000rpm. issue with mine is 110% linkage....just not sure exactly what / where to adjust. Im going to take some pics under it soon... so you all can help.

 

[4X4HIGH]

i don't know of any 350 that is valved that way....375's maybe, 400's for sure......

I've had many over the years that will hold the gear that was manually selected and then i've also had many others that will upshift at a high rpm regardless of manually selected gear.