Gearbox whine but trouble finding the issue.

I noticed a slight whine which was most noticeable in 2nd/3rd while decelerating. My car has no cats or mufflers so it's possible it whines in other conditions but just not audible over the exhaust.

I noticed the TOB has a slight noise to it while at idle until the clutch pedal is pressed as well.

So I dropped the gearbox (thanks for the tech support Ernie!) fearing a loose ring nut but after checking all the ring nuts they are still staked and "appear" tight. The bevel gear has some very small marks beginning in the face of the teeth with a corresponding marks on it's mating gear. It appears very minor but is noticeable on careful inspection. My assumption is that the bearing is bad causing play in the (layshaft ?) 1st gear has a slight bit of play. If it isn't supposed to have play then that give credibility to my idea that the bearing is in fact bad allowing the play in the shaft which allows the bevel gear to not align right with it's mating gear causing the slight markings on the face of the teeth.

So replace the outer bearing on the drivers side of the layshaft? Should I check anything else? All the other visible gears around the box appear okay and all the ring nuts (including the ring nut under the throw out bearing) are all staked and appear to be tight.

 

How are you guys locking the box so that the ring nuts can be removed to replace bearings? I've tried putting it in reverse and 2nd but with reverse engaged I cannot get any other gear.

Also, are there any cheaper variations to the 4 outer bearings on the gearbox? I'm replacing mine as preventative maintenance. I assume the ring nuts can be reused?

 

Totally understandable to take it to folks who know what they are doing. In my case, I wrench on my race cars and street cars alike. I've just never dug this far into a street gearbox because most racing boxes have a 5th-reverse shift position ( sequential dog ring box ) so I'd rather be safe and ask than sorry and broke.

In my case the gears look fine other than some very small and very light pitting on the face of the teeth on the bevel gear. Being that it's over $3k to replace and it is in perfectly usable condition I'm sure it will be fine once I replace the bearings and tighten the ring nuts correctly so there is no more play.

Ernie actually texted me a little bit ago after chatting with FBB so I should be good to go on getting the ring nuts off. Getting them torqued back on for installation might require some more thinking though.

 

About to try right now. Impact gun and a shop rag wedged in the bevel gear.

 

Really struggling to find a bearing puller that can get the bearings out by the outside of the inner race. None are fitting and after grinding the teeth of a 3 jaw puller one of the arms cracked when trying to pull the bearing. Anybody have a picture of the setup they used to pull the bearings on the oil pump side?

SIDE NOTE: I think I'm just going to pull the outer bearings on the oil pump side and tighten the ring nuts correctly with lots of 271. I am pulling the engine this winter anyways so we will see if this fixes the problem and if not I will just address the other bearings during the engine out service.

 

Okay, the bearings look perfectly fine and I'm not going to pull them. I had a local transmission shop actually take a look at them for me and they could find no visible issues with them. I'm actually curious if just re torquing the ring nuts and using some red thread locker will do the job to get rid of the whine. If not, I'll address it when I do the engine out in a couple months.

I am, however, having one hell of a time trying to get reverse and 2nd gears engaged so I can torque the ring nuts. I can get every single gear by itself engaged but once a gear is engaged I can't get any other gear to go into place. Has anybody else had this issue?

Also, I was thinking of torquing to 160 ft-lbs which is a little over the 154 ft-lbs (210nm) Ferrari calls for just to make sure the nut is nice and tight.

 

That is an interesting notion. I'm trying to find a way that 2 gears not engaging at the same time might be tied to another part of the gearbox yet still allow each gear to engage at a time. Somebody more knowledgeable about synchro's would have to chime in for that one. Too top it off, like a dope I got the rag stuck behind the bevel gear. Ernie sure got a laugh out of it when I told him, haha.

 

Andy, after looking at the bearings I agree with your guess on the gearbox. They were all in very good condition. The very slight marks on the bevel gear indicate there was some slack between the two and I now believe the layshaft ring nut was not fully tightened when the box was last rebuilt. Also, when I changed the gear oil from whatever was last in there to the Red Line 75w90NS the whine was more apparent.

I will try again to get the gears engaged so I can tighten the ring nut

 

Are you saying to engage reverse, then align a forward gear, then disengage reverse, then engage the already aligned forward gear, then re-engage the reverse gear (which should already be aligned from before). Correct?

I will try this. I have yet to get reverse and any forward gear engaged together still!

 

Are the shafts indexed to make it easy to return the fork back to proper position?

 

Okay, thanks for the heads up. Was able to get the two gears engaged after loosening the fork.

I got both the drivers side ring nuts tightened plus 10% over spec with plenty of red threadlocker. There is still the same amount of play in the layshaft which allows a small amount of clearance between the bevel and mating gear. I would think there would need to be a small amount of clearance designed into the gears correct? I can't detect any lateral play in the shafts themselves so perhaps it's the clutch shaft not being tight? All the gears have a very small amount of movement but I assume this has to be designed into the box. I've never seen a gearbox with gears that didn't rock ever so slightly from designed tolerances.

The whine is definitely a mechanical noise of a bearing or gear. It can't be a wheel bearing because when I press the clutch pedal in the noise goes away immediately. Could this be the throw out bearing afterall? I know these clutches are very strangely designed creatures. Heck, there were arguments from some pretty smart folks on what the grub screw on the flywheel ring nut even does!

 

Thanks FBB. Yup, I qualified 13th which was much further back than I should have been. I got up to 11th in just a couple laps but spun going over the rumble strips exiting turn 4. After 29 seconds!!!! I was finally back on track and was 26th but finished 12th. It was very cool taking the checkered flag at the most storied race track in the world and seeing my name and position on the tower as I passed the pagoda each time.

 

So, what about shimming the bevel gear? It really looks like the bevel gear and mating gear on the layshaft have play which should not be there. I can move the cv flange back and forth and see the bevel and mating gear just barely clank together through the motion. Surely there shouldn't be play there? It also is aligned with the marks on the bevel gear and mating gear.

I also noticed the main bolt holding the CV flange to the diff had a ton of sealant behind the large washer I assume to stop a previous leak. Plus, there is a little movement in the CV flanges so perhaps the bearings are toast. I'm going to check it out. Feels good to put this beautiful car back to great condition but definitely a learning curve on some of the eccentricities. Can't wait to drop the motor this winter...

 

Okay, after the last post a light bulb went off in my head. Went out to the garage and pulled the passenger side CV flange outward to see if that took up the slack in the bevel/mating gear mesh. Yup, I think that's the problem with the whine and marks on the face of the teeth. With the outward force applied to the passenger CV flange it brings the bevel gear in full contact with the mating gear and the play is completely gone. I caught this JUST in time before any damage occurred. So either the bearing behind the CV flange has started to fail and is out of spec or the bevel gear is not shimmed correctly.

 

So the spacers with varying thickness (#12) are what is used to pull the diff from one side to another? How much play (if any) should I allow between bevel and mating gear?

Also, is the bearing pressed into the diff side cover? The cover is being a total PITA to get off and I'm worried about applying any more force to it for fear it may crack.
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