[tazzco]

I installed a used 400 turbo, but it will not shift. I have checked the govener, and installed a new modulator, that I have adjusted 2 times so far, but it still does not shift. Any help will be nice

[TexasT]

Is this a known good unit? You saw it shift before? Or is is used and no telling what could be wrong?

[tazzco]

This is a known good unit. from a running vehicle. The only thing that I have not done is pull the pan and gear box. I think that maybe next on the list. I have read a few other things for trouble shooting in the Chilton manual.

[Crosley]

Do you have proper manifold vacuum to the modulator? Checked at the modulator to verify vacuum?

[tazzco]

I thought a vacum is a vaum, but I made sure new hose was new and small clams to ensure they did not slip off. The vacum I have is located just behind the carb, I would say half way between the carb and distributor. There is no obstructions in the vacume, should there be??

[Crosley]

Originally Posted by tazzco

I thought a vacum is a vaum, but I made sure new hose was new and small clams to ensure they did not slip off. The vacum I have is located just behind the carb, I would say half way between the carb and distributor. There is no obstructions in the vacume, should there be??

nope. Vacuum is not vacuum,

The Vacuum feed to the trans modulator must be direct manifold vacuum. It needs to raise and fall with engine load (throttle opening) so the modulator receives the proper signal to control pressure inside the transmission.

One side effect of low or no vacuum is ''no upshifts''

[cobalt327]

Originally Posted by tazzco

I thought a vacum is a vaum, but I made sure new hose was new and small clams to ensure they did not slip off. The vacum I have is located just behind the carb, I would say half way between the carb and distributor. There is no obstructions in the vacume, should there be??

If you are taking the vacuum from the intake, you are OK. The vacuum line need no restriction in it.

After reinstalling the trans have you rechecked the fluid level in Park w/the engine running?

Be careful using clamps on small diameter rubber tubing. Many of the small hose clamps will actually distort the tubing because they don't go that small, so if you use a clamp, use one like:


And NOT like:

The line has to fit tightly onto the nipples at both ends and there can be no splits or cracks in the rubber or steel lines at all. If you plug one end of the modulator line and pull a vacuum w/your mouth or a vacuum pump on the other end, the vacuum should hold for as long as you apply the vacuum. Same for the modulator itself- it has to hold a vacuum and the plunger has to retract when vacuum is applied to it.

[tazzco]

Yes, I did ensure that proper amount of fluid was in the transmission. I put the rear end up on jacks and shifted to reverse and drive. Then I made sure the kick down switch is working, by listening to the click inside the tranny. The hose goes from he manifold stright to the modulator, the small clamps shown above were use. I have checked and rechecked twice, so it seems that I will need to pull the pan and gear box for a cleaning. Any other ideas before, I get to this sloppy job, LOL

[cobalt327]

Originally Posted by tazzco

Yes, I did ensure that proper amount of fluid was in the transmission. I put the rear end up on jacks and shifted to reverse and drive. Then I made sure the kick down switch is working, by listening to the click inside the tranny. The hose goes from he manifold stright to the modulator, the small clamps shown above were use. I have checked and rechecked twice, so it seems that I will need to pull the pan and gear box for a cleaning. Any other ideas before, I get to this sloppy job, LOL

The term "gear box" usually refers to a manual transmission in its entirety. If you are taking off the tranny pan the next thing you will see is the filter (which should be changed while its apart) and the valve body and associated shift linkages, kick down solenoid, etc.

If you take the VB off, pay attention to the check balls- don't lose any. Removing the valve body (VB) will also mean replacing the gaskets. One way of getting the gaskets is to but a shift kit like from TransGo (B&M are more expensive and not as good IMO- ymmv). If you have a tranny shop in your area or a good guy at the NAPA counter you can buy them separately. There's a page on the TH400 here for reference. It's based on a thread originally posted by a good tranny guy, jakeshoe.

Use plenty of kitty litter under the tranny for any spillage. Remove the pan bolts in such a way that one side will tip down to drain about half the fluid before you take the pan all the way off. I'd suggest you wear goggles and old clothes. But unless you have a lift or are very careful, you're bound to get old ATF all over the place.

[SSedan64]

Are you using Rubber Hose all the way from the Manifold to the Trans Modulator?
It may be collapsing. Should have Metal line with short Rubber Hose at each end.

[tazzco]

Thanks to all that replied. In the end there was a very small hair line crack at the rear of the tranny on the passenger side. I rebuilt a 350 turbo, put a shift kit in it and on the rack it is shifting into all gears, so i will keep all of you posted. Thanks for all the help. Hipe I can repay