Rebuilt Transmission Knocks ... Help

R

rkatk

Senior Member
Just started up the new engine and transmision and Houston WE Have a Knock. I thought it was in the engine but when I depressed the clutch the knock stoped. The knock speeds up and slows down with the idle speed. I can feel the knock on the bottom rear half of the transmission case. I took the shift tower off and drained the transmission and did not see anything in the case out of place.
The transmission has all new gears, shafts bearings yadda yadda.
The only things turning in the transmission when out of gear and at idle are the input shaft, custer gear and the reverse idler. I turned the gears by hand with the shift tower off and did not hear or feel anything unusual.
I am at a loss as to what could cause a knock from the few parts that are turning. Anyone out there have a thought?
Thanks,
Randy
 
Could be a wrong starter bolt. Some times a longer one is installed and it hits or rubs the flywheel. Good Luck!
 
Did they drop a bolt in the flywheel housing when putting the thing together??? Is it consistent or off and on??
 
I just went through a transmission rebuild and haven't taken mine out for a drive yet but could it be the U JOINT bolt not tightened?
 
I put everything together myself. The sound isnt coming from the flywheel, no stray bolts. The knock is constant. Everything is tight no endplay in the cluster shaft. The U joint does not turn when the transmission is in neutral.
 
Ok so we narrowed it down then... When the car is in neutral you should be able to turn the U JOINT... So lets look at that. when you take the top of the transmission off can you slide the 2 sleeved gears forward and backwards so they aren't touching the lower gears? (hence, neutral state for the transmission) Wonder if the shaft is binding up for some reason?
 
The two gears slide freely and can be positioned in neutral. You cant turn the U joint in neutral without pushing the car since it is attached to the drive shaft.
 
Did you check for clearance between the shaft retainer bolt and any moving interior parts? I once rebuilt an early ****** with the thick retainer bar and replaced it with new shafts and the associated thin retainer bar. Problem was that the older bolt was then too long and made contact with a gear (cluster end or reverse, can't remember) and this caused an annoying knock.
 
I did that today thinking I may have movement in the reverse idler shaft. I had one of the seal kits on it. I removed it and went back to the original bar. No play in either shaft. I went back to the original bolt too but I will check that tomorrow.
 
The parts turning during idle in neutral:
Input shaft, sealed bearing, needle bearing
Cluster gear, short needle bearing, spacer, long needle bearing
Reverse idler gear, Idler shaft
What could possibly be knocking??
 
Have a look at the clearance between the 1st and rev sliding gear on the mainshaft and the rev idler gear.
This is what I found after fitting all new gears except the rev idler.
In neutral the 1st and rev mainshaft gear ONLY had about .005 clearance before touching the rev idler.
when the oil heated up it just contacted it and made a noise.
And yes ,the rev idler was the correct way,and the selectors were good.(I tried another top )
I found the problem by running the engine ,and without using the clutch gently pushed the gear lever towards rev gear,it only moved about 1/8 at the knob before trying to get rev,where as to try for 1st gear it was 2ins.
I rectified the problem by machining the 1st rev mainshaft gear to give it more clearance to the rev idler,
I also noted it was different to the dimensions on the original ford gear.
Lawrie
 
Lawrie said:
Have a look at the clearance between the 1st and rev sliding gear on the mainshaft and the rev idler gear.
This is what I found after fitting all new gears except the rev idler.
In neutral the 1st and rev mainshaft gear ONLY had about .005 clearance before touching the rev idler.
when the oil heated up it just contacted it and made a noise.
And yes ,the rev idler was the correct way,and the selectors were good.(I tried another top )
I found the problem by running the engine ,and without using the clutch gently pushed the gear lever towards rev gear,it only moved about 1/8 at the knob before trying to get rev,where as to try for 1st gear it was 2ins.
I rectified the problem by machining the 1st rev mainshaft gear to give it more clearance to the rev idler,
I also noted it was different to the dimensions on the original ford gear.
Lawrie
Click to expand...
Lawrie,
The shortest shifter movement is fron neutral to high. Are you sure you didn't mix up the two shift tower shafts? Bill W.
 
Check the thrust at the crank. If the crank moves forward and backwards enough it will knock and probably leak oil. Takes a while to start leaking but it will if this is the problem. I know, you said it is a new motor but, never say never. Anyone can screw up and cut the thrust too small for the crank.
 
TrannyNoise.jpg


When I first bought my 28, and let the clutch out in neutral, the ****** sounded like a bucket of gears being tumbled in a cement mixer. When I took the ****** apart, every part inside was like NOS, except for the bearing between the input and output shafts. It had a couple of crunched rollers, and you wouldn't believe the racket it made.

To check this out you could put the rear on jack stands, shift to 3rd gear and let the clutch out. Now the input and output shafts will be turning as one straight shaft and that little bearing will not be moving in relation to the shaft.
 
rkatk said:
Spacer is in at the needle bearing.
Will the crank thrust make the transmission knock?
Click to expand...
Definately,. Pushing in on the clutch will stabilize it with pressure and stop the knock. Any engine knock can sound like it is coming from different and sometimes remote spots.
 
Put it up on jack stands and started it up. Same knock as I had in 1st, 2nd and 3rd. The knock was twice as loud if not more when I shifted into reverse.
How do you check the crank thrust with engine installed?
Thanks
 
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