987 6 speed vs 986 6 speed

[rastta]

So more info on the 987 transmission from Bill Rader Motorsports who specializes in Porsche transmissions. He indicated that the 987 box isn't any stronger if at all, parts are very hard to find and are considerably more expensive than the 986 box. He doesn't seem to think there is any limitation on the number of rebuilds on the box. Waiting on more info from him on the issue.

[Crono0001]

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?

[rastta]

Originally Posted by Crono0001

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.

[Crono0001]

You've been incredibly helpful.
Thank you for the info.

[itsnotanova]

The audi transmission Brad referring to is the O1E transmission. It's a beast of a transmission but not easily installed into a 986 that I know of. The O1E came in many cars but the Audi diesel sold in Europe is the one most kit car guys go after. It is the only 2wd version that will work in a mid-engine car. I've heard some people have been able to modify the 4wd version to make it 2wd. Same goes for the audi OA3 six speed.
As for the 987 vs 986 6 speed. The 987 is geared slightly lower, slightly lighter, $1000 more expensive and you'll have to modify the axles. I think you have to run 986 axles with 987 inner CV joints, but don't quote me on that. I'll ask a friend who has a 987 6 speed in his 986. From what I've seen on the track. I don't think it's worth the hassle as I don't see a difference between the two at the track.
I recommend installing a trans cooler if you haven't already. I was at Hallet a few weeks ago helping a friend with his 986 S. With the trans cooler the trans temp was around 225. A cooler line broke and the driver went around the track once before they realized what had happen. The trans had dumped all its fluid on the track! He brought it back and we had to disable the cooler. We put some new fluid in it and he continued for the last hour of the race for that day. With nothing to lose he raced for 7 hours the next day. The trans temp got as high as 305 but never missed a beat even without the cooler. My friend finished second behind a 3.4 cayman and ahead of a 986 with a 987 6 speed in it.

[rastta]

Originally Posted by itsnotanova

The audi transmission Brad referring to is the O1E transmission. It's a beast of a transmission but not easily installed into a 986 that I know of. The O1E came in many cars but the Audi diesel sold in Europe is the one most kit car guys go after. It is the only 2wd version that will work in a mid-engine car. I've heard some people have been able to modify the 4wd version to make it 2wd. Same goes for the audi OA3 six speed.
As for the 987 vs 986 6 speed. The 987 is geared slightly lower, slightly lighter, $1000 more expensive and you'll have to modify the axles. I think you have to run 986 axles with 987 inner CV joints, but don't quote me on that. I'll ask a friend who has a 987 6 speed in his 986. From what I've seen on the track. I don't think it's worth the hassle as I don't see a difference between the two at the track.
I recommend installing a trans cooler if you haven't already. I was at Hallet a few weeks ago helping a friend with his 986 S. With the trans cooler the trans temp was around 225. A cooler line broke and the driver went around the track once before they realized what had happen. The trans had dumped all its fluid on the track! He brought it back and we had to disable the cooler. We put some new fluid in it and he continued for the last hour of the race for that day. With nothing to lose he raced for 7 hours the next day. The trans temp got as high as 305 but never missed a beat even without the cooler. My friend finished second behind a 3.4 cayman and ahead of a 986 with a 987 6 speed in it.

I had the 01E in my old S4 - while I'm sure it's stronger - it's got it's quirks too. I had that one rebuilt as well.......it grenaded while I was logging to find boost issues. LOL

They recommend the trans cooler on the 987 trans due to issues with overheating at the ring and pinion I remember reading. I'm wondering if that is a similar issue for the 986. I'll ask Bill Rader.

I've asked Bill if there are any upgrades I can do to the trans that will help with strength and or longevity and am awaiting an answer.