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Old 11-07-2018, 12:40 PM   #15
rastta
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Join Date: Feb 2014
Location: Cowtown CA
Posts: 369
Quote:
Originally Posted by Crono0001 View Post
Been looking at this info as well.

I've been told (but not confirmed) that the 987 6spd will bolt up to 986S rear uprights. Is that correct?
Not quite sure what you are asking. Here's what I know:

The 987.1 trans will bolt to the engine. The 987.2 transmission will not.

You want the G87-20 not the 21 as that has the longer 1-2 for the Cayman.

I haven't determined whether or not you need to use 987 axles, but if you do, they splines and shaft diameter will work with the wheel hub and housing. The 987 axles are slightly beefier. It's a problem, I believe, going from a 5 speed to a 6 speed.

I've confirmed you need new shift cables and you need different mount flanges that attach to the 987 case - they are different. However, they use the same transmission mount that bolts to the subframe.

Here's the 986.



Here's the 987.



I've been exchanging information with Bill Rader Motorsports . They have indicated that they don't believe that the 987 6 speed is any stronger than the 986. They've also indicated that parts for that transmission are very difficult to get and are very expensive, the contrary with the 986.

They've also indicating that if you know what you are doing you can rebuild these 986 transmissions many times. They have done so on numerous race cars. Parts are also more plentiful and cheaper.

If I can work out everything, I'm most likely going to send my box to them for a rebuild. Depending on the problems and what needs to be replaced, I'm also looking at possibly shortening the 3 and 4 gears.
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