OS Giken GTA Close ratio gear set - Page 2 - Alfa Romeo Bulletin Board & Forums
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post #16 of 63 (permalink) Old 05-01-2011, 11:16 AM Thread Starter
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Do me a favor: when you see this guy ask him what makes him think he has an OSG gear set (other than what the owner told him)? When you get the answer post it on this thread.

Thanks,

B
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post #17 of 63 (permalink) Old 05-01-2011, 11:49 AM
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Fair enough.

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post #18 of 63 (permalink) Old 05-08-2011, 05:52 AM
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Are these OSG sets the same as the ones Spruell has ?
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post #19 of 63 (permalink) Old 05-08-2011, 11:32 AM Thread Starter
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"Are these OSG sets the same as the ones Spruell has ? "

The very same...

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post #20 of 63 (permalink) Old 06-15-2011, 03:36 AM
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So, how did this build go? Worth the investment? I ask because I will seriously look at this gear set in a few months.
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post #21 of 63 (permalink) Old 06-15-2011, 01:13 PM Thread Starter
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So, how did this build go? Worth the investment? I ask because I will seriously look at this gear set in a few months.
Hey Pancho,

The build went by the numbers. I put the gears in a 1967 Duetto gear box with a mechanical clutch. With all the gears on the main shaft running on roller bearings it makes a noticable difference in shifting and the sound. But the big thing is the 2.67 low close ratio's are infinitely nicer than the stock Alfa ratio's.

To me it was definitely worth the investement. It transforms the entire car. Not to mention the old gear box was hemmoraging gear oil from every place possible and I HATE oil leaks. My assembly procedure eliminated all of the leaks. I have about 500 miles on the GB now and it's completely dry. All problems solved.

Happy motoring:

B
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post #22 of 63 (permalink) Old 07-11-2011, 02:54 AM
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So are there any of these sets out there that have been in service for a while longer than a year or two? I'd like to know the overall consensus before shelling out the dollars. I see the Rimicci brothers are Agents if OS Giken - any chance of some test case owners? Any known failed sets?
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post #23 of 63 (permalink) Old 07-11-2011, 06:15 AM Thread Starter
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Quote:
Originally Posted by pancho View Post
So are there any of these sets out there that have been in service for a while longer than a year or two? I'd like to know the overall consensus before shelling out the dollars. I see the Rimicci brothers are Agents if OS Giken - any chance of some test case owners? Any known failed sets?
Paul Spruell has built 20 or so GB and sold them to racers, said no problems to date. Check with him. Also check with the Rimicci's. As I said mine is perfect. If you want to buy a GB assembly procedure that guarentees no leaks and a perfect job, get back to me. Check OSG's web site they sell a lot of stuff for rice rockets, the domestic Japanese markets and are a high end mfg using the latest materials and mfg processes. The roller bearings they use for 1st / 2nd / 3rd are the same as the stock 5th gear in the Alfa GB and I have yet to hear of any 5th gear roller bearing related failures. OSG has been selling these gear sets in Japan for a long time so they have history with the product. Do your research and convince yourself.


happy motoring
b
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post #24 of 63 (permalink) Old 07-19-2011, 08:34 PM
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Os giken quality

Group 2 Motorsports is a dealer for OS Giken. To date I believe we have built twelve to fifteen differentials for local BMW racers and would attest to the quality of their products.

We have experienced NO quality issues with the product.
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post #25 of 63 (permalink) Old 07-29-2011, 10:21 AM
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OSG gearsets

Interesting conversation. Thought I would wait a while and see what came along before offering my comments. No worries! We have sold over 30 of these gearsets without a known failure. So, let me address some of the concerns submitted.

The syncro teeth on the gear mesh with the sliding syncro sleeve. This unit is pressed onto a splined hub in the standard Alfa gears. Conversely, the OSG syncro tooth unit is welded onto the gears and as Richard points out, can be removed and a new one welded in place if necessary.

The stock 5th needle bearing is much smaller and is a comfortable fit in the 5th gear with room to spare. The 1st-3rd journals are much larger and require a much larger bearing. The stock copper bushing is very thin and allows room for splined mounting of the syncro unit.

Why do the OSG syncros need to be welded instead of splined? This is a neat piece of engineering. I have always made my own gears, hated the copper bushings that go bad and tried my best to fit 1st-3rd with needle roller bearings. The limiting factor was that the copper bushing is very thin and the needle bearing is much thicker. There was simply not enough meat to bore out the hole to fit the needle bearings. One has to machine off most of the metal base supporting the mounting splines to accomplish this. I even selected the same needle roller assembly that OSG ultimately used, but could not make it work. Mr. OS ingeniously attached his syncro unit by welding which leaves sufficient meat to bore out the cylinder to fit the needle bearing.

Bill has done a very thorough job documenting the metallurgy. So, I see no stones left unturned with regard to the quality or functionality of the OSG gear sets we have been selling for several years.

The only thing that has not been mentioned is that performance can be enhanced by REM finishing the gear sets before assembly. This is a process that tumbles the gears in a matrix of special stones and a chemical bath of polymer solution. This micro polishes the tooth surface and works the polymers into the pores of the metal. For friction reduction and longevity, this process is superior to any coating. This makes the gears so pretty that it is a shame to hide them inside a gearbox.

We have REM finished several sets for customers since Bill made his purchase and have now decided to offer it as an option on our website. This also works wonders for ring/pinion sets. Every little bit of friction reduction from engine to differential adds up to significant reduction of parasitic power loss.

Unfortunately the current prices will increase with the next run of OSG gearsets delivered. We currently have (probably) the last of both the close and super close gearsets on the planet until the next batch is done, so grab one now if you have been inhibited by the misinformation. ( Please note that some pricing on our ABB ads need correction, but they do not perform that service that anymore. So it will have to wait for us to generate new ads. )
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post #26 of 63 (permalink) Old 07-29-2011, 10:40 AM
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Thanks for these comments Paul. I too have been lurking here!


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post #27 of 63 (permalink) Old 07-29-2011, 12:33 PM Thread Starter
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Thanks Paul. It would seem there are no stones left unturned regarding OSG gearsets??? I have one thing to add: Before installing the OSG gearbox I filled it with 75-140 Mobil 1 synthetic gear lub and it shifted pretty well. OK so the GB has about 1K miles on it, the car was up on stands for something else, so I decided to change it. I wanted to see how much metal was on the drain plug magnet after doing Paul's synchro ring pre-wear-in procedure when I built the GB. BTW: there was zilch metal on the magnet (as in almost none), thanks Paul great idea. So I went back to my old standby Lucas 85-140 heavy duty gear oil on the change. The difference in shifting was night and day. The Lucas oil has some additives that make it stick to the parts such that the GB shifts so much easier it's almost laughable. Am guessing the stickier Lucas oil is adhering to the synchro rings and sliders so they lock up faster during shifting. There's less bearing noise as well. Based on what I have seen here, there maybe merit in using the OSG gear oil which is heavier still???

Happy Motoring,

b

Last edited by awesomeBLT; 07-29-2011 at 12:57 PM.
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post #28 of 63 (permalink) Old 07-29-2011, 04:42 PM
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I'll take that set Paul thanks for your info.

I have a condition unknown GB and I'm going down this path anyway. I'll put my trust in OSG and what others have said and see what transpires.
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post #29 of 63 (permalink) Old 12-10-2011, 02:47 PM Thread Starter
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OSG gear material

Found out the gears are made from a JIS version of 9310 steel. Which is an updated version of 4000 series steel with lots of chrome and nickel... Very tough stuff. If you want to know more go to the ANSI standards and look it up.

Happy Motoring

b

Last edited by awesomeBLT; 12-10-2011 at 02:49 PM.
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post #30 of 63 (permalink) Old 12-11-2011, 07:54 PM
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Has anyone really re-welded a carrier on personally, and it stayed together? I have been down that road with a Colotti gear set, same story syncro carriers are welded on, Have tried welding, pins and welding etc. etc. and they kept breaking after a few races, Other problem is welding distorts needle bearing bore and that has to be refinished. OS has the luxury of welding pre hardening.

ZF has had welded on carrier failures in stock trans, 94-95 LS especially 1st gear with the multiplied torque load they shear off and no luck fixing one of those either. Pretty bad spending 8 hours putting an LS trans axle back in and two days later it's broken again. Customer not happy.

That is my personal experience with welded carriers, I take splines any day.

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