GT4: a sticky SHIFTuation

1) Clean the bottom of your shift lever out. There could be anything up to dinosaur bones in there (it IS an old car).

2) Worn motor mounts in some situations can cause it.

3) Worn silent blocks in the shift shaft.

4) Not enough oil in the tranny.


I am sure there are more reasons.

 

Open the trans fill hole and see if any oil comes out. The symptom you describe can occur when the trans is overfilled meaning oil from the engine sump is leaking to the trans sump due to a failing shift shaft o-ring.

 

Definitely check the oil. The gearbox on these cars will generally shift easier and smoother as it warms up.

cheers

 

Just moving the shifter side to side it shouldn't be "sticky". When everything is correct the spring pressure in the shifter centers it (I think). Could be the shifter is just binding up and needs lubing ... things would have to be way way out of alignment for that to bind side to side if I'm understanding that correctly.

If the shifter feels smooth side to side and it's tough going into gear definitely check the gear oil level before you drive again (low oil or oil that is way over due for a change will cause this symptom) ... maybe even drain and change it. It'll give you a chance to look at the magnets that catch debris. Don't get scared if you see build up ... there's always some ... it's the size and/or type of metal that matters.

cheers

 

When you say hot ... how hot it is the car ... does this happen in 5 minutes of driving only when it's hot out or when you've got the car hot and it's hot out? ... when it's cold out it just never happens? ... I know you can't test that today but tonight you could test that.

Check the oil level ... that's a painful thought thinking the shaft is binding as you rotate it because the gearbox is hot because of lack of oil! Hopefully it's just heat inside the car binding up the shift linkage ... lint and all kinds of debris falls in there ... the coolant tubes are just like a 308 right underneath the shifter also yes?

cheers

 

My GT4 sometimes did this. It had all the right oil in the trans. Never did work out what it was.

You wanna have a go of my 360 stick - not much better...

Lee

 

I struggled with this all throughout my 4 years with the car. Got worse in the 90deg July heat, but was great in the fall. Never was able to figure it out. The shifter and shift linkage is all clean, with new silentblock bushings. The only thing that I did not do is replace the motor mounts.
Good luck. I'll be interested to see what you find.....

JIM

 

Have you opened the trans fill hole yet to see if any oil comes out?

 

Wonder if it would be a water hose pressing against the shift linkage and as the water temp rises so to does the pressure in the hoses and one may be fouling the shift linkage.
I know on my car that there is a hose pressing on the linkage but my gear change seems OK at all times.

 

+1.

My transmission started shifting harder and harder over about 2 months, and when I checked it I drained about 8 quarts out (!!), which apparently included about 4 quarts of motor oil. My shift shaft seal was leaking between the engine oil sump and the transmission, allowing the mix. Interestingly, the other seal was not leaking, so no engine oil was leaking onto the garage floor.

With new seals from Verell and Redline NS, it shifts perfectly now, even cold.

Forrest

 

19 and 5 on this drawing. The check is to see if you have motor oil in your tranny. If you do, then replace them.
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I should have been more specific: the rear 19 and 5 keep the motor oil out of the tranny. The front 19 and 5 keep the motor oil off the ground.

 

Hmm. I just reread this.

My shifter would move easily side-to-side when it was over-full with engine oil; onlymoving into gear was stiff. I don't actually see how oil level could affect the side-to-side motion, since that is only shifter shaft rotation. The shaft rotates within the oil seals (Part #5) normally, centered within the bore, and is not normally in contact with the metal case of the transmission. And the shift selector fork should move freely with rotation unless it is out of adjustment, in which case I suspect that it would feel noticeably clunky.

The self-centering springiness of the shift lever is provided by a spring-loaded piston in the shifter (11 and 12 in the lower drawing) which bears against a flat face on the side of the otherwise-spherical shifter ball, such that the spring is compressed when the shifter is moved to either side from the center position. If this piston were binding, then side to side stiffness would probably be present, but forward and back should be OK, at least into second and third gears, I would think.

So if it's getting stiff both side-to side and forward and back, perhaps there is some misalignment issue with the shift rod, but I am at a loss as to how temperature could make such a big difference. Maybe a motor mount issue?

You could pull bolt number 32 out of the rearmost SilentBlock and separate the lever from the transmission if you want to narrow down the possibilities, but I guess you'd have to do it while the car was still hot...

 

I think the important clue is that it gets stiff side to side!!!

This tells me that something is expanding & binding on something in the shift linkage when things get hot, opposing linkage rotation!!!

To the best of my knowledge, there are are only 4 places where something could bind on the shift linkage opposing linkage rotation:

The 2 housing openings for the front shaft that's actuated by the shift lever. The shifter housing does get heated by the coolant lines that are routed under it. Possibly the housing openings were machined slightly undersize & bind under expansion.

The shift shaft opening on the front of the engine sump

The shift shaft opening on the casting web between the engine & tranny sumps.

Again, for either of the sump openings to be the problem it would have to be undersize, or have been damaged somehow.

 

On my car the aluminum shield on the headers was resting on the shift shaft. I think the motor mounts would have to be really far gone to put real pressure on the shaft but I guess it is possible. Plus they might get gooey-er with heat?

 

I developed some resistance in the shifter throw side to side.
Took the shifter gate off and placed the shifter into 1st gear. Squirted some Pro21 lube in between the centering spring coils and then moved the shifter into 4th gear and did the same.

Feels 200% better.