Will only shift out of 1st to 2nd at 5000 RPM same for 3rd and stays there till full stop and then repeat.

 

How is the fluid level?

 

Good.

 

Sounds like the vacuum modulator, it's on the right side of the transmission down low, make sure the rubber vacuum line is connected and that it is getting vacuum. You probably won't be able to see the line unless you get under the car, but look for a vac line hanging down and if you have longish arms you can reach it to put the vac line back on.

 

TH400 trans also has a electric kick-down circuit. To diag, disconnect electrical connection from side of trand and re-road test.

 

I put a new modulator on and hose connected, has vacuum.

 

I have looked and cannot find it.

 

The switch should be mounted at the throttle pedestal. Should be a green and Light green/white wire. Or, in the left fuse panel pull fuse #2. Should be a 3A fuse.

 

Is that the same 2 wires that plug in at the throttle cable on top of the motor, if so I have unplugged those wires and no effect.

 

Well that sorted the easy stuff.

Now the governor nylon driven gear sounds like its lost its teeth.

Access is via a tin cover on the RH side of the rear section of the trans unit, 5?? bolts from memory.

Simple to get at in fact, and the gov unit simply slides out, local trans parts supplier will have a gear, just forget Jaguar, simply drop it on the counter and ask for the nylon gear.for a TH400.

 

I will put it on ramps tomorrow and take the gear out.

Also when it is stuck in 3rd gear, if you are going 20 mph the trans is like it is in neutral till you reach 4,000 rpm then it catches and will speed up, when you let off the gas rpm goes down to 700 rpm.

 

Next is the o/ring in the TOP of the filter suction tube. They split, and the pump will suck air, its easier than sucking fluid.

Eventually it all catches up, and away you go, sort of, until next time.

 

You lost me, how do I get to the O ring ?

 

You remove the tranny sump pan, then one bolt undoes the filter, and the suction tube comes down into the filter from above. This is a quite wide plastic tube that fits into the metal body above the filter and is sealed with an O ring.

 

Thank you, I might mention if I manual put in 1st or 2nd the tranny stays engaged all the time, no high rpm's, when it shifts to 3rd is where I get high rpm's at low speed, it stays in 3rd until dead stop then goes to 1st, then shifts to 2nd at 5000 rpm then to 3rd at 5000 rpm.

If that gear that Grant mentioned earlier is striped will the peices be in the tranny and cause a problem.

 

They could be anywhere, and the trans will not care at all.

The bits are no bigger than a cut finger nail, and the Dacron filter will NOT allow them into the innards anyway.

That last post suggests the gov is the problem more than the filter o/ring.

Just to make your weekend, I had one of mine where the actual vac modulator piston (inside the valve body) STUCK, and that sucker was all over the place withchanges. EASY fix, modulator out, you know where it is, pair of tweezers poked up the hole and withdraw that piston.

Some have a light spring behind that piston, some dont??????, this one did not, so I found one that would do, and slid it in the hole, and that kept the piston hard up against the modulator and took the guess work out of the gear changes.

 

Thanks Grant, I will check the piston first and go from there.

 

Would almost bet the vacuum hose going to the modulator valve is 28 years old so might as well replace it, where does that hose connect on the motor ?
While there I will check the piston and then the gear.

There are the 2 wires that go to a switch on throttle cable and 2 more wires that go to a switch where the throttle cable wraps around a round cylinder, would like to replace those 2 switches but I don't know what they are called.

Checked the tranny fluid cold and it and it goes all the way up the indented part of the plastic, way over full, could this be my problem ?

 

I did not mean for this to be on this thread but can't remove it. I found what was causing the passenger side clunk. Is this an easy job ? What is this called and what do I need.

 

Well, when I checked the vacuum on the hose from modulator valve I inserted a plastic tube into the end of it so it would be long enough to suck on it and held vac, , I disconnected the hose from the big L shaped hose as that hose was new, so I took the new hose off and on the back side it had rubbed a hole in it, replaced hose and all is good.

Now I have to replace the bushings that are causing the clunk but I don't know what that part is called or what part # or if it has to be a jag only part. With help from you guys I will finally be able to get it running and driving right.