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Discussion Starter #1
I recently have heard some people saying having the gears lightened during a transmission overhall makes a really big difference. Does anyone have any solid opinions on this?
I'm wary, because it's expensive. And most people who overhall a transmission do it for a reason. I mean, if your synchros are shot and the box has 300k miles on it, and you rebuild it: It will feel great whether you lightened the gears or not!
In theory lightening the gears *could* make a real difference, making the gears alot easier for the synchros to spin up. I might guess that this could really help the synchro longevity. Might also make shifts smoother. But I'm not buying any 'it revs quicker' stuff yet ;-).
Have any of the experts out there tried building gearboxes both ways and comparing? Is it worth the bucks? Any recommendations on where to have it done?
Carl
 

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The pundits say it gives a quicker change, because as you mention the lighter gears having less inertia are easier for the synchros to adjust. So if you are looking for that extra tenth in every change ......

If it is for a less than ultimate competition car then I don't think it will add much extra value, especially if its only a std set of ratios

Cheers

MikeB
 

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gearbox lightening

I have both a Spider and a GTV that have had the gears lightened by Mr Merritt Carden (as well as carefully assembled)and can honestly say that there is a remarkable improvement. Ease of shifting , no crunching on 2nd upshift etc. Of course , the synchros, sleeves,bearings, forks are also in top shape. As one of the guys who experimented (without much success ) with all the oil combinations mentioned in on ths BB ,I am now running regular Valvoline 80/90 in both boxes and I am quite happy with that. To sum up, our gearboxes, once the state of the art in the industry,can really benefit from some massaging . Whether that's worth the dough,its up to to the Alfisti to decide.Cheers.
 

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I just put a tranny with lightened gears in my '67 GTV. There was nothing wrong with the old one; I wanted the best possible transmission to go with a new engine.

Having shifted Alfas the old way for more than 30 years, I feel reasonably well qualified to second the comment that lightened is better ... by a lot.

By the by, Tom Sahines, Tech Wizard for the ARA, requires that the later model transmissions he builds -- like my 1984 gearbox -- use only Shell Spirax 80W-90 oil.

Pundit Gary
aka Pedant Gary
 

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MichaelB said:
If it is for a less than ultimate competition car then I don't think it will add much extra value, especially if its only a std set of ratios
Well, I think you have to define "value" here. Even if it didn't make the gearbox shift better (and in my experience it does), it makes a rebuild last MUCH longer by putting less stress on the synchros.

To me, that's value.

Joe
 

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Discussion Starter #6
Hmm... it's sounding like the lightening is well worth the effort.
I had also heard some rumor of different and better lasting synchro materials being available. Has anyone heard anything about this, or are they all the same?
Carl
 

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in addition to lightening, does it add a lot of expense to change the gearing slightly
to help those of us w/ 4.56 rears? a longer draw in 1st, and slightly higher 5th would sure be nice.

john
 

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Hi John,

You can also get essentially the same results by exchanging your 4.56 ratio differential for a 4.11:1 version. This is pretty easy; the spiders changed to 4.11 ratio in the mid-80's (?) so there should be plenty of axles available. You can change the entire axle or split the axle and substitute the new diff. No adjustment of the ring & pinion spacing is necessary.

roller said:
in addition to lightening, does it add a lot of expense to change the gearing slightly
to help those of us w/ 4.56 rears? a longer draw in 1st, and slightly higher 5th would sure be nice.

john
Regards,
 

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Hi there,I am about to rebuild a guilia gearbox to put in my 1750.Could someone post some photos of lightened gears?How much are they actually lightened?Nobody here in Jakarta has lightened any before.....I have an old 1750 box to experiment on first.Also is 5th gear in the guilia box lower than in a 1750 box?
Cheers,Fletch.
 

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Here is a picture of the lightened gears we had at Centerline. Unfortunately, we are sold out and will not be producing any more in the near future.

They had approximately 25% less rotating mass. Please note, others lighten the gears even more by back-cutting them in addition to drilling them.
 

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My two cents worth....

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, (without lightened gears, but same ratios) 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 the synchros slow down, (that is essentially everything except the output 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.

I'm interested in others opinions. Thanks
 

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Question @ Joe.....

Do you know if the lightened gear sets included new synchro sleeve engagement rings pressed onto the lightened gear sets? Or are the lightened gears coming out come with tired rings still in place?

Best Regards,
John M
 

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John,

Even though they were in the photo, the "Dog Rings" were not included with the gearsets. Our machinist needed them pressed off to do the lightening. We have good used rings available.

These have always been a bit of a problem - Alfa doesn't sell new ones, to get new ones you need to buy a brand new gear!

Joe
 

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JoeCab said:
John,

Alfa doesn't sell new ones, to get new ones you need to buy a brand new gear!

Joe

Thanks Joe. That's what I thought.....cha ching!

Best Regards,
John M
 

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Fletch said:
...Also is 5th gear in the guilia box lower than in a 1750 box?
Only if it's from a GT Junior or a Spider Junior which have an 0.85:1 fifth gear. All others have an 0.79:1.
 

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As far as gear lightening goes, I have to believe it helps the trans shift better and feel better. I haven't driven a lightened gearbox for a while, BUT I do recall driving my friends Bertone Giulietta spider prototype for the first time and I was REALLY impress at how the gearbox felt. It shifted SO smooth and effortlessly I couldn't believe it. Then I realized it was a four speed. If I recall correctly from a 'guide to gear lightening' written in the late 70's or early 80's, the four speed had about 10% less inertia due to the lack (obviously) of fifth gear. I believe the article said lightening a five speed would result in about 7% less inertia - just enough for the synchros to work better. My second experience with less inertia was a Giulietta veloce with a stuck clutch. I warmed up the car and kinda beat on it in first gear, but it just wasn't working. I probably closed my eyes for a second when I shifted to second, fully expecting an awful sound, but I got a PERFECT shift. I thought 'WOW' and wondered if it was a fluke. I got the clutch unstuck and then tried third gear WITHOUT using the clutch and got another perfect shift. Did you ever try that with a five speed??? Good luck! I don't believe I EVER got a nice shift in a 5 speed Alfa without the clutch, I had a few where it barely ground, but NOTHING like shifting the four speed. And for what it's worth I used to drive my Fiesta (great car!) without using the clutch once I got moving and it was very easy to do - upshifting or downshifting. I am sending out some gears for a gearbox for my junior that will be lightened... I think I will get a new clutch disc with the groves as well.

1166
 

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It is said that Porsche transmisions are similar to Alfas or vice a vera.

Synchro hubs or dog plates are sold separate at $120,for their transmissions and they appear very similar to the Alfa ones.

See at Automotion web page,

http://automotion.com/ProductPage.aspx?pid=106046&name=Synchro+Hubs&type=20

I don't think they are identical but maybe their source could source the Alfa rings

Any ideas regarding this out there.

Regards

Ken Geiger
 

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

George, you are a knowledgeable guy and normally I wouldn't comment when you give your learned opinion on matters mechanical. In this case, however, I think it's important to know that there is a difference between a good stock gearbox and a good gearbox with lightened gears. Everyone will have to define "need" as it applies to their own situation.

My understanding from talking to you is that your Alfa experience is primarily on the track, driving a dedicated race car. My experience over the past almost 40 years is driving Alfas on a regular basis, with a lot of foolishness on winding mountain roads thrown in. Obviously, your perspective will be different than mine because we drive under very different circumstances.

When shifting up or down at higher engine speeds, I don't notice as much difference between lightened and unlightened gears. On the other hand, those of us who aren't doing full-throttle race shifts know about the "pause-one-two" hesitation between gears that makes shifts smoother in normal driving. Lightened gear sets do not require the Alfa pause. You just shift, quickly, slowly, or inbetween, but always smoothly. Eliminating that pause wasn't so much a need as a desire. There is another benefit, though.

The person I bought the tranny from is a friend. Mechanic is not his day job, but he has rebuilt many transmissions in his long Alfa history, for himself, friends, friends of friends, etc. He's a long-time enthusiast who drives his Alfas on the street and who has a long history racing (his Giulietta Spider race car is rather well known). He says my synchros will last longer with the lightened gears. Because I plan to keep the car until one of us -- it or me -- becomes a lawn ornament, anything that will enhance its mechanical condition over time is a good thing.

GW
 

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viewpoint/lawn ornament

Gary, thanks for your viewpoint, and when can you send your beautiful car for my lawn ornament? (It would be there only when I wasn't driving it). Or are you saving it for your new place on the Olympic Pensuila?

GW (also)
 
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