Alfa Romeo Forums banner

1 - 20 of 36 Posts

·
Registered
Joined
·
8,982 Posts
Discussion Starter #1
i have been reading in the 'gt' forums on this subject..i am coming to think the most cost effective solution is to lightin the flywheel. that seams to carry the most spun up weight.. to make the flywheel lighter, less mass moving durring the shift..i.e. the flywheel slow down quicker...easyer shift.. am i on the right tract here...
 

·
Registered
Joined
·
1,566 Posts
When you depress the clutch pedal you disconnect the gearbox input shaft from the engine, so that will, IMO, not have any impact on the inertia inside the box.
You lighten the flywheel to make the engine more responsive to opening and closing of the speeder.
Lightning of the gearwheels remove some of the wheels inertia and their rotation speed will drop off or pick up more quickly, thus making the life of the synchromesh rings easier.
Erik
 

·
Registered
Joined
·
6,087 Posts
Gear lightening and flywheel lightening are two entirely different things. One must also be careful about lightening a stock flywheel. Three to four lbs. is safe to take off. If you want to remove more, the maximum you could go with is five, but you better make sure that after it is properly balanced, no more than that has been removed.

Best regards,
 

·
Registered
Joined
·
1,056 Posts
i have been reading in the 'gt' forums on this subject..i am coming to think the most cost effective solution is to lightin the flywheel. that seams to carry the most spun up weight.. to make the flywheel lighter, less mass moving durring the shift..i.e. the flywheel slow down quicker...easyer shift.. am i on the right tract here...
I know that there has been a lot of discussion about lightening gears to "save" 2nd gear synchro. Though success has been reported I feel that it's a wives tale and that success was achieved by just fixing the trans and using a proper oil. The only way that a true improvement can be accomplished is to reduce the rotating mass of the clutch disc.

I know that I am going to get a lot of heat for this.

The affect of the mass of the clutch disc is multiplied through the gear train of the trans. In 1st gear the disc mass has it's greatest affect while in 5th gear the disc has the least affect. That's why 2nd gear synchro fails 1st cuz that synchro has the toughest job to do.

For street use gear lightening won't harm anything except to weaken the gear. In competetion every pound counts so gear lightening makes sence.

Perhaps this is a job for Myth Busters.
 

·
Registered
Joined
·
6,087 Posts
Hey Geezer,

My Grandpa use to say; he who tells the truth better have one foot in the stirrup. :D:D:D
Well, then I hope he does have one foot in the stirrup because he is telling the truth. :) Nonetheless, there are outfits (many which also perform track prep work) than can also lighten the gears for safe street use. In all cases not much material is removed (and 5th is too small to have anything removed), and the "savings" in real benefit is very small and could be almost negligible. I say "could be" because if you know how to shift properly, and have just had the transmission rebuilt to stock specs, it will last you just as long as if you had had the gears lightened. I'm not saying that gears shouldn't be lightened. If the transmission is being rebuilt, it is an opportunity to do so. (Certainly I would never open up a perfectly working tranny to fit lightened gears.) It is rather cool to have race type components in your car. Just make sure that this is done properly for street use, and don't expect any "seat of the pants" feeling that is better than a stock tranny in terms of performance. If you feel something different, it's in your head. If you're going to place the track on the car, then that's very different..,

Best regards,
 

·
Registered
Joined
·
2,513 Posts
I know that there has been a lot of discussion about lightening gears to "save" 2nd gear synchro. Though success has been reported I feel that it's a wives tale and that success was achieved by just fixing the trans and using a proper oil. The only way that a true improvement can be accomplished is to reduce the rotating mass of the clutch disc.
Not a wives tale, it is simple really. When an object is spinning, the weight of it increases (E=MC2-the mass has kinetic energy, so it's spinning weight increases). Look at what the "typical" drivetrain power loss is and you'll understand this more, along with lighter pistons, crank, rods, flywheel, clutch, etc... The more weight you save in these parts increase the power your rear wheel gets to see. Removing a pound of stationary weight can equal 10 pounds or more of rotational rate-given the rpm. Aluminum rods, undercut and cross drilled cranks are a great mod, but given the fact the you've only lost a pound or maybe a little more, wouldn't that like be saying if you put a lighter battery into your car it would perform just the same? I don't think so.

Geezer said:
The affect of the mass of the clutch disc is multiplied through the gear train of the trans. In 1st gear the disc mass has it's greatest affect while in 5th gear the disc has the least affect. That's why 2nd gear synchro fails 1st cuz that synchro has the toughest job to do.
Have you seen how big your 5th gear is on the layshaft???!!! Sucker is huge-that is a lot of constantly spinning weight-even if your not even using that gear!

Geezer said:
For street use gear lightening won't harm anything except to weaken the gear. In competetion every pound counts so gear lightening makes sence.
Did you think that over? In racing your stressing out every component of the vehicle and yes, racers for many years used lightened gears without failure even under the duress of racing. Street use is of very little wear and tear, you don't need extra strength to pick up a pack of cigs from the gas station on the corner.
 

·
Registered
Joined
·
4,046 Posts
I had my gears lighten and I can speed shift up and down from and to 2nd gear without any grinding but to say that the gear lighting is the reason I don't know?

But Pat Braden said this about the 2nd gear synchronizer failure (Owner's Bible on page 155);

There are two fixes for this problem. For short-term satisfaction replace the synchros, for a permant fix, the individual gears must be drilled to reduce their mass.

IMO it's worth every penny of the cost's and highly recommend it if your doing tranny work anyway.
 

·
Trained (ex)Professional, , 1953-2018 RIP,
Joined
·
16,232 Posts
...and that success was achieved by just ... using a proper oil.
I hear ya there, Geezer.
I recall reading a discussion (don't know if this BB or another forum) where many posters did not know of, nor experienced, bad 2nd gear syncros. Of those that did respond saying the syncros went bad, most were from the USA.
In 35+ years of driving Alfas, I've never personally had one syncro go bad (although if I bought a car that had a 2nd gear grind, changing to a non-hypoid oil usually solved the problem).
So I chalk up bad/grinding 2nd gear syncros to two things;
1) incorrect lubricant
2) driving technique
Although lightening the gears has the potential for a positive effect on the syncros, I think it is FAR less effective than the root causes; #1 & 2 listed above (ie lightened gears + incorrect lubricant = grinding).
 

·
Registered
Joined
·
6,087 Posts
I hear ya there, Geezer.
I recall reading a discussion (don't know if this BB or another forum) where many posters did not know of, nor experienced, bad 2nd gear syncros. Of those that did respond saying the syncros went bad, most were from the USA.
In 35+ years of driving Alfas, I've never personally had one syncro go bad (although if I bought a car that had a 2nd gear grind, changing to a non-hypoid oil usually solved the problem).
So I chalk up bad/grinding 2nd gear syncros to two things;
1) incorrect lubricant
2) driving technique
Although lightening the gears has the potential for a positive effect on the syncros, I think it is FAR less effective than the root causes; #1 & 2 listed above (ie lightened gears + incorrect lubricant = grinding).
Interesting post... I wrote this today, in another post of a different topic:

My "favorite" is the infamous second gear crunch. I see descriptions that state how a car is original, well-cared for, etc., etc. but has a second gear crunch and how these cars are known for weak synchros. .... If you replace the synchros, and shift properly, you can go 20+ years without a synchro issue. (My '74 Spider, by the way, has never had it's transmission opened, and there is no crunch in any gear. I really don't think that it is the only Spider with "strong" synchros.)

Best regards,
 

·
Registered
Joined
·
1,085 Posts
Lightened gears vs freshening syncros

Geezer and Jim: we are in agreement. Here is my thoughts I posted some time ago. (When can we educate the newbees how to use the search feature on the AlfaBB?)


I had an Auto Delta GTA close ratio gear set that had the lightened gears, and I rebuilt it and put it in my car (#108), for one of the 2.5 races. Kevin Mckee drove the car to test the gearbox during the test and tune day, we changed the gearbox to one of my close ratio gear ones, and Kevin re-drove the car. His evaluation was that he could not feel any difference in the shifting effort, nor was there any lap time differences.

The amount of weight that is removed from the gears amounts to only a few ounces in comparison to the 30(?) pounds of gears that you are synchronizing. And the weight is so close to the center of the gearset axis that it will make little or no difference. Any lightening improvement depends on the distance from the center of rotation.

, Weigh everything in the transmission that a synchro slows down, (essentially everything except the main shaft, including the clutch disc), and you will see what I mean.

And so why are people selling lightened gear sets? "Because people buy what they want, not what they need".

The secret to improved shifting comes from the condition, and modification, of the clutch disk!!!! An old disk will not break the suction from the flywheel or pressure plate on release, and adds to the drag of the gearset, increasing the task on the synchronizers. A fresh disk with radial groves cut in the facing, will do the job!!

And, you ask, why did Auto Delta lighten the gears???????? For the same reason that they tried to put aluminum floor boards in the cars, and use magnesium in components that were stronger made out of aluminum, and so on. The FIA rules formula was CCs to weight, and Alfa was fighting to get comparable horsepower, because of the hemi combustion chamber, and the long stroke, as opposed to the competition, who had short stroke, modern combustion chambers. Alfa also couldn't increase the displacement, liners were already on the thin side, and they had already increased the stroke.

So to make the Alfas competitive to the 1600CC Datsuns that weighed hundreds of pounds less, and were getting close to comparable horsepower, They HAD to lighten EVERYTHING, including the gears, to keep the cars competitive.

That is my story, and I'm sticking to it!
 

·
Registered
Joined
·
302 Posts
Not sure about the spiders but the milano transaxle design is faulty. All the syncro gears are on the output shaft, this means that when a gear is engaged it much "sync" the mass of all other non-engaged gears as they are all coupled to the input shaft(constant mesh). Most other designs have some syncros on input shaft and some on output shaft reducing the work done by any particular syncro. This is why lightening alfa gears is so benificial. And that should include all gears and input shaft. of course super light clutch disk helps a lot too.
TomP.
 

·
Registered
Joined
·
1,085 Posts
Tomp: The gear placement set up is the same for the spider/gtv and the alfetta transaxle. (As are some of the gears and the syncros.)

The syncros stop the same mass in both.
 

·
Registered
Joined
·
2,513 Posts
I hear ya there, Geezer.
I recall reading a discussion (don't know if this BB or another forum) where many posters did not know of, nor experienced, bad 2nd gear syncros. Of those that did respond saying the syncros went bad, most were from the USA.
In 35+ years of driving Alfas, I've never personally had one syncro go bad (although if I bought a car that had a 2nd gear grind, changing to a non-hypoid oil usually solved the problem).
So I chalk up bad/grinding 2nd gear syncros to two things;
1) incorrect lubricant
2) driving technique
Although lightening the gears has the potential for a positive effect on the syncros, I think it is FAR less effective than the root causes; #1 & 2 listed above (ie lightened gears + incorrect lubricant = grinding).
Hi Jim! Not to argue, just mentioning my own personal experience: I use the incorrect fluid (hypoid type) and have lightened gears and have no grinding, no problems, whatsoever.
 

·
Premium Member
Joined
·
13,494 Posts
I am covering all the bases. Lightened gears, lightweight (1lb4oz) clutch disc and lightened flywheel. All work done by Richard Jemison, who knows a bit about these things.
Ed Prytherch
79 Spider
2 x 88 Verde's
 

·
Registered
Joined
·
2,513 Posts
Almost forgot, not only do I use the wrong fluid, but I also never double clutch. Drive it like it is stolen, every minute, every day.
 

·
Registered
Joined
·
6,087 Posts
I am covering all the bases. Lightened gears, ... All work done by Richard Jemison, who knows a bit about these things.
Hmmm,....

I`ll bet I`ve built as many lightened transmissions & transaxles as anyone. I would suggest that it`s really not worth the money. This is another Alfa myth that never ends. .... When you take the amount of rotating weight on both shafts, and measure the loss by lightening (and serious lightening see pics, serious backcuts on each side and serious drilling) you only loose about 24 oz. all of this very close to the rotational center of the shaft. What you get at that point is really not a factor in the acceleration & deceleration forces on the syncronisers.
But during that modification and renewal of the syncro assemblies including dogs on the gears that need them, using a conventional syncro on 1st and replacing the sliders, along with centering the sliders correctly you get effectively a new shifting box. Actually 1st will be better. But for those reasons, not gear lightening.
The reason that all of the gears are not lightened is primarily that they are too small, and some too small to make the effort & time worth doing.
...
Best regards,
 
1 - 20 of 36 Posts
Top