5th gear issue

Sound like some linkage adjustment will be needed. I had the same issues with my 360 when shifting from 2-3 and down from
3-2 or 5-6. Should not be to hard to do. I hope you have a good mechanic.

 

Probably a shifter adjustment. What gear oil are you using, and when was it last changed?

 

I too have a problem when changing from 4th to 5th when driving say at high speed / red line revs,no crunching but a fair amount of reluctance to shift smoothly, but no probs when changing from 4th to 5th lowish speed revs, will be interested in what you find.
cheers
Mark.
p.s. I run an 86 328

 

Are your current bushings really old or known to be bad? I also have Delrin bushings but I'm reluctant to put them in. The car was designed with a rubber bushing to allow a certain amount of compliance. Ferrari easily could have made it solid or could have used some plastic or other bushing but they chose not to. Also, they could have stayed with rubber and made the bushing bigger (more rubber) or even a little smaller (less rubber) to change stiffness. You might even increase shifting difficulty with a stiffer/harder material when you have engine movement under acceleration etc.

I'm sure there are people that have used them with success but every engine and shifter rod is aligned a little differently.

 

It can be your synchro.
When you going to change the bushings you can also easily check the synchro on your 5th gear. If you want I can take a picture to show you where the 5th gear synchro is and how to measure it.

 

A couple of things can effect syncro operation. Since their job is to match input and output shaft speeds, a dragging clutch or wrong viscosity gear oil is more likely than a bushing or adjustment since it is related to road speed. At higher speed the syncro has a bigger job in matching your gear speeds. Since no other gear changes are mentioned, I'd say the 5th gear syncro is the weakest and showing up when put to the test. Sounds like this is the first real test with the RedLine oil too. If that is synthetic, I'd test with the good old orig style oil before I took anything apart.

 

In most cases I'd think 5th sees the least wear of any of the synchros.

I experienced this symptom on my car with high miles and just shifted it carefully until I finally tore it down . .. . what I found was the nut had started to come loose that holds the 4-5 gear cluster on the shaft and unfotunately it's on the "input" side . . .. think you'd have to take the sandwich plate off to get to it but you might be able to rock the gear cluster back and forth from underneath with a screwdriver/prybar just to see if it's loose. If someone posts a pic of the exploded diagram I can point out the part I'm referring to.

Any chips stuck on the magnetic drain plugs? Nothing significant when I experienced this problem but just something to look at.

Hopefully it is just linkage alignment/engine movement.

edit: unfortunately it did damage the outer bearing and that gear cluster on the inside spline so just tightening it may not be an option if it has come loose.

 

Picture of my 308 gearbox. Let me know if you want a closer shot.
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If you press the shifting fork to the right (see last picture) and you don't have any clearance, you need to change your synchro.
The book say the clearance should be more than 0,4 mm
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I'm sure it does, and every other mechanic does as well. That's why there's an old trick of swapping the second or third gear synchro with the fifth gear synchro. Shifts to fifth are usually much easier than shifts down lower so a worn synchro will hardly be noticed in fifth. If synchros are not available or expensive or it is a quick and dirty job, a trans shop will sometimes just swap the worn synchro with fifth and call it good. Yes, they are not doing anyone a favor.

That said, I bet it is an alignment issue. I replaced my rubber bushing with an aluminum bearing and noticed better precision and no real downside, but that was over a shot rubber version, not against a new rubber bushing. If it was me I would use the Delrin.

 

Aren't these cars fun, Jim? Finish your steering rack and suspension project and a new project announces itself...

Imagine NOT being able to solve all this by doing things yourself.... no wonder people call these cars money pits.

Good luck with the gearbox. I'm sure you'll solve this one too...

Hans

 

Enjoy the summer driving her Jim.

You don't want to end up like me.

 

FWIW 4th and 5th synchros are different from 1st thru 3rd (well at least on 80 and newer 308's) . .. but yeah . . point taken that 4th and 5th could've been swapped . .. as fishing posted he'll be able to check this from underneath.

edit: thought worn synchro symptom would be more gradual . . thought this problem happened "all of a sudden" . . . was this the first high rpm shift into 5th in years/ever?

 

Have you checked clutch cable adjustment??

 

I have the exact same problem going into 5th.
Any good reference to the shift forks alignement ?
Couldn't find one using search ...