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Old 07-15-2015, 02:19 AM   #1
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Can a G87-20 gearbox be used in a 986?

My G86-20 box is apart for some repairs. I have been told that these boxes can only be refreshed once due to interference fit of some parts. The newer G87 version is supposed to be more repair friendly.

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Old 07-15-2015, 09:11 AM   #2
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brad Roberts has done it, I've not. I have researched it pretty thoroughly, however. you'll need the 987 axles but can keep your old hubs and wheel bearings (987 tranny is shorter with better axle geometry). you'll need the 987 transmission brackets and shift cables. your clutch slave cylinder will work so don't have to change that. your clutch and pressure plate will work (don't use 99x clutches as their input shaft is larger so different pilot bearing, etc.). dunno what engine you are using, but the g86-20 is a stronger box, as well as a lot cheaper to buy used than a 987 unit (ie, might be cheaper to just get another g86-20 tranny when your current one fails). 987 unit is much lighter (hence weaker) than the 986 unit for the weight conscious. finally, there is also a g87-21 which is exactly the same unit but for the cayman with slightly different gearing in 1st and second.
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Old 07-15-2015, 09:49 AM   #3
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Thanks for the info. Current engine is an early 3.4 996 motor rebuilt by Porsche a couple years ago. I have already started looking for an 86-20 to keep on the shelf. Car is track only.
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Old 07-15-2015, 10:56 AM   #4
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yeah, guys who race with the 987 box seem to have a lot more issues. you never hear anything from the g86/96 guys. if you do go 987 get a cooler on it. of course, the cooler negates the weight savings and adds a level of complication. that's why I decided to stay with what I had and not change.
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Old 07-15-2015, 03:33 PM   #5
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With two drivers at DE events (the wifey drives) I get gearbox oil temps in the 240-250 range even with a cooler. Interesting the the G86 is tougher than the G87. Shop says it takes a 50 ton press to get the gears off the shafts.
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Old 07-16-2015, 12:27 PM   #6
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For tech info on these gearboxes ,I use Eric Johnson of RaceLine in Berthoudr Colorado.phone (970) 344-7761. He contributes here sometimes .You might send him a PM ?
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Old 07-17-2015, 09:51 AM   #7
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I was just looking through some old pms and found one from eric523 talking about how he prefers the 6-speed but with the albins 3 to 6 gearset. said it makes for a nice close-ratio box and bought him 2 secs on a 2.5 mile track. might want to think about that while you have your transmission apart.
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Old 07-17-2015, 03:16 PM   #8
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Not too much internal damage. All synchros will be replaced, 3rd gear and some bearings. R & P very good. This is a pretty stout box. Too bad they did not design it for repair/ refresh.

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