MGB 78 MGB cannot shift into reverse

[Svcmangler]

I am unable to shift into reverse when the car is running. It just grinds. If I turn the car off, I can then shift into reverse. I have just replaced the clutch, throwout bearing, pilot shaft bushing as well as the clutch master, clutch slave, and clutch hose. The hydraulics have been bled, so no air in the lines. All other gears shift perfectly. thoughts as to what can be causing this?

 

[YakkoWarner]

It sounds like the flywheel and clutch disc are not 100% disengaging, and there is some drag causing the input shaft of the trans to be spinning even with the clutch fully pressed. Do you notice any noise or reluctance going from N to 1st with the engine running? Thats the only other place you'd notice it, since changing between 2-3-4 doesn't happen from a dead stop. It COULD just be the brand new components need to wear in a little, but its odd if it happens going from N to R but not N to 1...

 

[Svcmangler]

Yeah neutral to first is fine. Just trying to shift into reverse is where the grinding starts. I also noticed that when I am shifting thru the gears the engine almost seems to be revving too high, almost like the clutch is slipping. I am not sure.
Would the slave cylinder piston rod cause that if it was too short?
What about if the clutch disc was installed backwards? I'm just pulling at straws now.

 

[YakkoWarner]

This has me confused. A too-short slave piston could cause the clutch to not fully disengage and keep the input shaft turning, but the fact that it only happens in reverse is whats throwing me. And a slipping clutch would be almost the polar opposite - not fully engaging.