3 spd 86 shifts 1-2 fine, wants to stop when it shifts to third.

[lbrowne]

Happened this morning when it was taking a little timbit hockey player to 6am practice. Wasn't going fast at all, there was a hard sounding shift when going to third gear and if you give throttle it just revs, but if you let off the gas completely it really tries to stop like you're gearing down in first or got the brakes on.

No the handbrake ain't on lol

If I manually put it in first or second she drives fine. Tries to hit third and she wants to stop.

Torque converter? High speed lock up? Or the transmission itself?

[lbrowne]

No one?

[ont_guy_38]

If clinebarger doesn't chime in shortly you could pm him , He is the tranny guru on this site.

[notyo_cheez]

Check simple and cheap first. Check your vacuum line to the modulator for connection/leaks.

Adjust the TV cable, with engine off slide up clip open throttle wide, snap clip down and return.

[clinebarger]

What transmission? TH350 or TH400?

I would check the shift linkage first.

[lbrowne]

Originally Posted by clinebarger

What transmission? TH350 or TH400?

I would check the shift linkage first.

I feel ashamed that I don't know, other than it's a 3speed and apparently a heavier duty trans? Apparently my 2wd truck is optioned out to have a snow plow - according to the glove box codes.

We got dumped on by snow last night, so it might not be till the weekend till I confirm.

If the shift linkage was broke, wouldn't that affect 1-2 shifts as well?

[lbrowne]

Fluid is good, lots of it and it's still red. A bit darker than fresh but not black.

I thought for sure the trans code would be on the pan but it just says Hydramatic Div of GMC on it. I thought I seen it somewhere but it's pretty dirty out there now.

Can I get it from looking up the codes on the glove box door?

[clinebarger]

Originally Posted by lbrowne

I feel ashamed that I don't know, other than it's a 3speed and apparently a heavier duty trans? Apparently my 2wd truck is optioned out to have a snow plow - according to the glove box codes.

We got dumped on by snow last night, so it might not be till the weekend till I confirm.

If the shift linkage was broke, wouldn't that affect 1-2 shifts as well?

Check adjustment, If the detent is between D2 & D3 it can cause wierd issues.

Originally Posted by lbrowne

Fluid is good, lots of it and it's still red. A bit darker than fresh but not black.

I thought for sure the trans code would be on the pan but it just says Hydramatic Div of GMC on it. I thought I seen it somewhere but it's pretty dirty out there now.

Can I get it from looking up the codes on the glove box door?

M40....TH400/TH375
M33....TH350/TH350C

With HydraMatic on the pan....Most likely a TH400, HydraMatic didnt design the TH350, Chevy & Buick divisions did.


Pan ID chart....

[Car'n'Guitars]

This should help you determine.

[lbrowne]

TH400 by the looks of it.

[lbrowne]

I checked the fluid last week after the truck had been running for a while, it's at the proper levels.

Took it for a boot and it just doesn't want to grab that 3rd gear. Almost like a lockup converter or something is toast. Next is to haul her in and check the linkages.