Changing only 2 or all the synchromesh ring ?

Opinions(?) :
1. How many miles/kilometers since the last complete overhaul/rebuild including replacement of ALL bearings, synchro rings, etc. ?
2. If more than 15K-20K miles (25K-30K kms) or unknown, I would replace ALL wear items, probably bearings too.
3. Besides, if the transaxle/transmission is already out and apart, why wouldn't you replace ALL wear items ?

4. Replacing or reversing (only) some of the wear items is something I consider a band-aid/temporary solution and associate such tactics with (cheap) used car sales business or individuals not having enough money to get their daily driver fixed properly. Not something I would expect from any serious vintage car enthusiast/owner.
5. Also, if such band-aid/temporary solutions were to be initially or seriously suggested by a (vintage car) mechanic, I would recommend finding a better one, since if he/she thinks in such terms, I would worry what other band-aid/temporary fixes they perform on your car and perhaps not even tell you ?
6. And if an owner insists on these types of band-aid/temporary fixes, he/she is probably not the right kind of owner for the car he/she possesses.

All my above "opinions" apply to any and all collectible/hobby/vintage cars, regardless of make or model, be it an Alfa-Romeo, Dino, Model T Ford or Volkswagen Beetle.

 

My old buddy Dennis McCann said to throw as much new stuff in there as you can. Given the amount of work to remove, dismantle and replace the gearbox, I would replace as many of the wear items as possible. Synchro hubs and rings, bearings, seals and maybe even the limited slip discs if there is a lot of miles on the car. The reversible syncho ring should be good as new if it hasn't been flipped before.

 

P.S. All my earlier comments/opinions aren’t limited only to transaxle/transmission overhauls, but should apply to everything mechanical in any collectible/hobby/vintage car.
If you can’t afford to do things right by them, who are you trying to fool ? Yourself or the next buyer/owner ?

 

I think all of the synchros are available new from superfomance.uk.co.

Many moons ago, when we rebuilt my gearbox, we flipped the 1st/reverse and replaced the rest. (At least that's my recollection.) If you can get new, I'd replace them all in a, "While you're in there" approach. Looks to be about $2K USD worth of parts, so not cheap, but again, pulling the whole thing back out in a couple years isn't cheap either.

We replaced some bearings as well. I found them online at one of the bearing shops I've used in the past, most are standard bearings that cost 1/10th as much from a bearing shop than from any ferrari specific supplier.

D

 

It's a good strategy to be extreme thorough in your effort to obtain the correct size and quality components for your gearbox and differential. There are so many components that differs from one series to another and there are even differences within some of each series. I also doubt that there is many original NOS spare parts left anywhere, so scrapping all wear parts might not be so easy as it sounds. Sourcing the correct bits and pieces can be a job nearly as time consuming as fixing the box itself. I know of many Dino owners who have jo-jo'ed their Dino engine in and out countless time due to gearbox problems caused by wrong spare parts or sub machining quality. Pulling a Dino engine and tearing it down has quite a high start price and the cost for changing all wear parts out by default is not insignificant either! I selected to change out all the bearings and the complete differential due to pitting but I measured all the gear parts and only changed out parts that was either damaged or worn out of spec except for the synchro rings that was scrapped by default. I will recommend to run the overhauled gearbox in a test bench before you mate it with the engine if that is practical possible for you.

Best, Peter

 

i would inspect and keep good originals since many of the over seas repro stuff is crap.

 

Ed is correct, good used originals are almost always better than the current repros. We fight this problem all the time now, especially synchro rings.

 

When did these issues became common and how do they manifest themselves ? Do the rings break, have ill fit or wear out prematurely ?
Are the issues common in all (vintage, ZF ?) transaxles/-missions or only in some ?

 

They get them from Hill Engineering who also sells them at the same price. Hill's blurb on them sounds good but I have no experience with their parts. There are two different widths. 12 or 13mm.

https://www.hillengineering.co.uk/100739

 

I replaced all of my 246 synchro rings with parts bought from Superformance. Gearbox shifts perfectly with zero problems.

As for Hill Engineering parts they are outstanding. EVERYTHING I have ever gotten from Hill exceeds all expectations. Their parts and tools are second to none.

 

SF or Hill Eng are usually high quality parts, the synchro rings are well made but i have heard they recently changed the spec of the synchro rings (not the hubs)

Some recently fitted to one of my friends gearbox by a reputed ferrari main dealer has proved troublesome. They have recommended the car is run for at least 100 miles to bed them in, which i find odd.

Could be bad adjustment, not sure as yet.

Tony

 

Timo: See post #14. The repro synchro rings cause the car to very very difficult to get into a gear. We now, as a part of the regular process, hand-lap the rings on the bench to make sure they provide smooth engagement.

 

Interesting tell me more if you would be so kind

 

Tony: Not a lot more to say. Assemble the gearbox on the bench, select the various gears and then examine the synchro rings to see the contact points and make sure you have even contact all the way around the ring. If not, use valve lapping compound to make full contact. If the gears are hard to engage look for high points that are resisting the engagement.

 

Thanks, I didnt do the rebuild and its back in the car. 1st and Rev. are proving to be difficult, this leads me to suspect linkage adjustment may be the cause in this instance as all 5 rings were replaced and the others gears are fine.

One to watch in the future.

tony

 

Dyke: Thank you very much for your insight.
This is definitely something for me to pay attention on next rebuild.

Do you have an approximate recollection when this issue started to become “common” ?

It’s just that last two (Daytona) transaxles I rebuilt (both at the same time), included all new bearings & synchro rings, but that was several years ago.
Both exhibited slight “snugness”, especially on 1-2 up shifts (or down), during first 15-20(?) minutes of driving, but once everything was fully warmed, they became relatively smooth and precise.

 

Timo: These problems started within the last 5-8 years. Probably when a new batch of rings were produced (maybe in China or Eastern Europe).

 

Dyke: Thanks again for expanding.
So it seems my last sets might've still been "Old Stock", but I'll definitely pay close attention to next ones.