[stewhatch]

I heard back from the guys at JH Motorsports today. Looks like this might just work. But I need one more thing - <b>does anyone know what the final drive is on the '93 6-speed gearbox?</b> I need to get him that information before I can order the right ratio. Seems my 6th gear options are a .68 / .60 / .56 I need the final drive ratio to ensure I order the right one - I am leaning towards the .68 because it's (a) karma ([img]style_emoticons/<#EMO_DIR#>/cool.gif[/img] approx. 500 rpm drop (to be confirmed) I am worried that too low RPM on hwy may cause some exhaust "drone". 2,500 - 2,600rpm at 75 mph should be fine. Does anyone know the answer to my final drive question? Thanks - Stew

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[stewhatch]

I did some research and found these guys in Lake Havasu City AZ. All the info you'd need can be found on the following site - http://www.californiamotorsports.net/968.htm. I am working on a couple of options but may settle on a 0.68 ratio for 6th .... I am guessing my speed at 2500 RPM would be somewhere around 75 - 80 mph with OEM rear wheels / tires (225/50-16). I'll keep you posted.

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[stewhatch]

More info - this is available for the 968 : 0.66 6th gear has been produced in the past. Taller gears are available. However, as was the case with the 0.66, the case had to be machined for additional clearance & they don't recall how much more material could be machined & therefore don't know how much larger the drive cog can be. The 0.66 gear will allow the car to run a hair over 88 mph at 3100 rpm. The stock 6th gear runs 74.5 mph at the same rpm. I don't think I need anything taller than 0.66 or 0.68 at this point. So the bottom line is that there will have to be some modification to the transaxle case to allow the larger 6th cog to fit.

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[jpr]

Another thing to consider is while leghthening the 6th gear is also my goal, you should look into extending the 5th as well since you will then bridge the gap between 4th and the new 6th. these 5th gears are also available from jh motorsports from the stock audi gearbox.

Jpr

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[stewhatch]

Well, I opted to leave 5th gear as-is and ordered the 0.68 6th gear cog. That ought to allow me to lope along the hwy at 75mph - 2650 rpm +/-

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[flash]

i'll be very interested to see how that works out - i'm not opposed to yanking my box again and changing that out - i'd love to see what the top speed would be with the new power AND better gearing

the improved fuel economy wouldn't bug me either

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[stewhatch]

Gearbox is apart and I rec'd some interesting news. My original reason for doing this rebuild was to repair what I believed to be a pinion bearing issue. I've read numerous posts about this and heard about the "jet plane" sound coming from the rear of the car on the hwy. The noise I was hearing wasn't what I personally considered to be like that of a jet, but more of a low "moaning" sound, but I chalked that up to differing levels of perception. It started at around 40-45 mph and became louder as I sped up, to the level that I had to turn the stereo up to drown out the noise. Turns out my pinion bearing is fine, but the differential bearings are completely shot: metal particles of what was once my diff bearings are now floating around inside the gearbox. So, I will be replacing that as well as renewing the pinion bearing while things are opened up. My new 6th gear is on a UPS truck and should be ready to install sometime in the next 3-4 weeks. Is there any rigid restriction on what Transmission fluid to use? I have heard so many great things about Royal Purple products, including transmission fluid, and wondered if anyone has any experience with that product. Any suggestions would be appreciated.

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[bob blackwell]

I have been using SWEPCO in my transmission and differential since it had the ring & pinion gear fixed and 2nd gear synchro replaced. Shifts very smooth and operates very quiet. No experience with Royal Purple products. Good luck, Bob Blackwell.

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[flash]

a LOT of guys use swepco, and swear by it

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[stewhatch]

That's all I needed to hear. Swepco it is. Thanks guys.

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[flash]

i've never used swepco, but i hear it's great

i've heard good things about royal purple too

redline has also been touted

i am currently running an industrial castrol product with a LOT of moly

bobby at california motorsports would probably be a good source for a recommendation

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[PorscheDude]

I've been using swepco in all my gearboxes for the last 6 years.
Really made a big difference in my 180k mile 944.

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