M1009 TH400 shift points

[Pirate Ed]

Hi,

Newbie here. Recently acquired a M1009 that needed a new trans. I purchased and installed a nice used TH400 from another from hillbillywizard.com in Halifax PA. I just took it for a test spin and it seems to me that the truck shifts awfully hard and the 1st to second is particularly high rpms when it upshifts. It has been awhile since I have driven an older vehicle. My Duramax has spoiled me maybe.

Comments?

Thanks in advance.

Ed

 

[porkysplace]

[h=1]What are normal shift points?[/h]

 

[cpf240]

Vacuum lines - hard and soft lines, vacuum pump, vacuum regulator valve. Start there.

edit: Forgot to add modulator valve on side of trans if the others things check out...

 

[joshuak]

Greetings and welcome to the site Pirate Ed.

Are you familiar with the Technical Manuals available for your truck? Available for download here, amongst other places.

TM9-2320-289-20, troubleshooting section, Transmission, Will Not Shift Properly, page 2-55.

The TM's in general and this section in particular have helped me out quite a bit, along with a healthy doses of the advanced search function here on SS.

Hope you enjoy your new truck and please post pics or it didn't happen!!!

 

[Warthog]

As stated earlier, make sure all you vacuum lines are install and in good condition. With replacing the tranny you may have missed one.

 

[Assel]

welcome from south germany, did you make sure it has the right torque converter on it? you said its from another m1009, so should be right one but are you 100% sure? if its a th400 from a Gas engine it will run higher rpm until shift...diesel deadline is 3600rpm I think... Gas engines go much more...

 

[cucvrus]

Gas engine does not have a 6 bolt torque converter that I know of. That would be a dead giveaway. I just had this issue and spent $20.US at the transmission shop. I had the 2 vacuum lines at the IP shift controller switched. All is well now. The top goes to the transmission and the bottom to the vacuum pump. Am I right about that? Check your vacuum pump and your modulator on the transmission. Hose should be new and tight on the connections.

 

[llong66]

You can also adj. shift points by adj. the vacuum regulator valve on the pass. side of the injection pump. If you loosen the two bolts holding it in position, rotating it forward will make the tranny sshift sooner/softer. I believe some of the modulators on the side of the tranny can be adj. also with a small allen wrench located inside of the hose inlet. I have not had any experience with that though, just what I have read and I dont believe all of them are adjustable.