I emailed Robert today, But for the rest of you here is the info:
Surprised to hear that there is a general problem with the syncros in Oz. With nearly 50 gearboxes built, I get feedback from racers using my gearboxes constantly, and there really seems to be no issues with syncros, but I will share a few insights on setup.
1- your comment on oils: There is no worse gearlube for these syncros and LSD units than any of the "No-Shock " oils. It is a never use concoction. In all my build data I only recommend RedLine 75-90 NS. The additives allow more bite between syncro band and sleeve improving the RPM matching necessary to engage correctly and reduce wear on the "dog teeth' of both gear and sleeve. Other Redline gear lube is both too light and without correct additives. Other Synthetics are too slipery to allow correct functioning. They might seem OK initially but they will result in rapid wear/syncro teeth damage.
2- Components: I agree that the aftermarket parts are inferior to the OE pieces. But they can be used on 4th/5th with no issues(as they are less stressed in these gears). They are a bit balky initially if both syncro band and sleeve are used together, however mating a new non OE band with a good used OE sleeve (sharp no lip teeth) resolves that initial resistance to engage. I always use a OE 5th gear syncro sliding sleeve between 4th/3rd gears and select good used OE syncro bands for 1st, 2nd., and 3rd gears. 4th and 5th gears get new aftermarket bands and 5th slider is typically a good OE used one. Critical to my raceboxes is removal of the 1st gear one directional syncro, and it is replaced by a assembly from a donor 5th gear (dog housing, band et al.so it works as all the gears allowing engagement up or down at speed)
I commonly dress all the dog teeth (on the gear assembly) to remove any "lip" that has formed and if new to make the fit in the slider easier to engage.
When the dog teeth develop a upward and downward lip at the tooth points (from engagement issues) but are still sharp pointed, that lip can be ground away to improve release and wear on the slider and bands. The development of those lips on the teeth points is commonly what causes the hard to engage balkness and binding that might cause a syncro assembly to be pulled outward from a gear.
3- lightening gears: Because the typical transaxle (and transmissions) I build are being raced, I have stopped drilling the gears after back-cutting both sides to lighten. Holes only enhance foaming of the gearlube. In reality lightening the 1st and 2nd gears are where most of the weight loss occurs. HOWEVER the most critical piece of lightening is not in the gearbox!
4- Clutch driven disk: This is the single most critical part involved with the syncros working. It in stock form is heavy and large in diameter and it must change speeds with every shift and that is a real burden on the syncros.
Both weight/diameter and construction is at fault. The spring centers are heavy and must go. There is no need for the torque springs as all the driveshafts have at least 2 rubber giubos, including my one piece steel or carbon fiber driveshafts. I use aluminum or single piece steel centers.
As well the wafer springs in stock driven disk compress under loading of the pressure plate. As well it also expands when released, and that causes drag making the syncro`s job impossible in race applications.
The proper material bonded and riveted directly to the plate resolves this expansion and enables quick release and good shifting. Critical in a racecar.
I do not use metalic pucs (too heavy) but use high temp full circle normal lining material on disk being used in stock type flywheel/PP assemblies. The aluminum versions are 1/3 the weight of a stock clutch disk. Steel ones 1/2 the weight.
5- clutch/flywheels: The front flywheels can all be lightened over 10 pounds (4 and 6 cyl) This must happen.
The greatest single thing to improve the performance of any car is reduction of weight in the rotating assembly, and with stock clutch assemblies weighing over 20 pounds the RJR 5.5 inch flywheel/input shaft assemblies, with twin disk or triple disk clutches are again 1/3 the weight of stock and only 6 inches OD for tremendous inertia losses.
Probably a little of all the above is why I don`t have gearbox comebacks for the issues you are experiencing.
Clutch disk are easy to build, and I`ve seen solid center clutches as I build offered by commercial builders.
See pics below and typical Build sheet data attached.
RJR7.25 and 5.5 flywheels/input shafts
RJR 5.5 clutch assemblt and dropped spindles
Aluminum Porsche PP and typical RJR alum center clutch
In a message dated 9/27/2011 12:14:42 A.M. Central Daylight Time, [email protected]
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I have read and heard about you on the BB and was wondering if you can help us Australian Alfa mechanics with grearbox problems we are all having in race cars.
The new syncros that are being sold world wide are giving us selection problems including no engagement.We have all tried various gearbox oils,like Redline 75-85 NS,,,.GL5 ,,Valvoline,Castrol and other brands.
We Alfa specialists are heavily involved in circuit racing with customers cars.
I am presuming the syncros are all made in 1 factory,and the yellow banded sydncros are all dried up.
We dont have problems with road car gearboxes.just race car gearboxes.
Robert Panetta Vin Sharp Corse Automotive
Manning Motors P.A.C.E Competition engines Alfa Specialist
Alfa 105 Specialist Melbourne Australia Sydney Australia
And many other Alfa Specialists,Australia wide, that are asking us for solutions
Vin Sharp has has old and new syncros analysed and there is a difference.
I have read your version on the BB about using NS as opposed to lightweight shockproof.
I personally dont think its an oil issue,as the dog teeth + sliding hubs are wearing out
Looking for your thoughts
On behalf or Australian alfa Specialists