New clutch w/ 4sp top loader shifting problem

Just installed a Centerforce DFX clutch w/ new flywheel on a Ford 427 and 4sp top loader. Shifting nicely up to 20mph, getting over 30 and a grind starts going into 3rd gear. Down shifting into 3rd not going to happen, down to 2 and 1 no problem. Clutch is hydraulic and have adjusted pushrod out as far as it will go. Pedal grab is about 1/2 way up and put Royal Purple synthetic gear oil(75-90) which is good for GL5 and GL4 applications. The shifting forks are solid and tight. I'm stuck, any suggestions? Lou

 

Couple of issues. I assume the gearbox did not have the grinding issues that you refer to prior to installing the new clutch etc.

If that is correct then it sounds like the clutch is not fully releasing. However, your description of when the clutch engages suggests the pressure plate , pedal and linkage is doing its job and adjusted appropriately.

Something that is sometimes over looked when fitting a new clutch plate is to trial fit the plate to the front shaft of the gearbox before installing the plate. If the splines are tight then even though the pressure plate is fully releasing , the plate can still drag against the flywheel and give the impression that the pressure plate is not letting go.

Unfortunately that means pulling the box to check this out.

 

2X- down under

 

Try a true GL4 oil, not a GL4/GL5. The EP additives necessary to meet GL5 can make it hard for a brass synchro to grab the gear.

Some things that can cause the clutch to not fully release...
...disc w/ a bent center
...too tight pilot bushing
...disc installed backwards
...disc binding on the input shaft splines

New components also take a bit more travel to fully release due to machine marks and the rougher surface of the new lining. When it gets broken in w/ a slight glaze you might be OK.

 

Thanks for the replys, one of the tech guys at Summit also suggested the true GL4 oil. Did make sure the disc moved smoothly on the input splines and gave it a dose of white grease before installing. Centerforce suggests a 100 mile break in period, guess I'll just take it easy before dropping the box again.