155mph with 26" tires is 6600rpm. did you shift at 7200rpm??? 
5 Speed conversion progress
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From: Bird lover in Sharpsburg
yes, you explained it well. you do gain efficiency, but the problem is, you spend most of your time on a track in 3rd gear, so it really doesnt matter that much. Now, at a fast track, thats not the case, you could gain that few hp that being in the direct drive gear would provide. you certainly woldnt want to do it, and sacrafice optimization at a track like laguna if you have under 300 or over 550hp. far more gains are to be made by optimizing the HP of the engine, rather than the efficiency of the gear box. 
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From: Up Nort
yes, you explained it well. you do gain efficiency, but the problem is, you spend most of your time on a track in 3rd gear, so it really doesnt matter that much. Now, at a fast track, thats not the case, you could gain that few hp that being in the direct drive gear would provide. you certainly woldnt want to do it, and sacrafice optimization at a track like laguna if you have under 300 or over 550hp. far more gains are to be made by optimizing the HP of the engine, rather than the efficiency of the gear box.
Yes we all know with you behind the wheel nothing ever breaks. Most other 928 owners / drivers are not so lucky.
Not to mention 95% of the time Jim is at Road America with three very long straights, the longest is about 5,000 ft.
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From: saratoga, ca
thats where you would need the 2.75. with more than 375rwhp that is. after 155, if you dont have a 2.75, you are dead in the water, but if you are not getting this fast, then 2.2 is the way to go. remember andersons video of him banging off the high end rev limiter when he was there in the late 90s or early 2000s? 2.2. now with 500rwhp, he needs another gear with "Bite"!!
went what route with the tranmission? going to a 2.75 or going to the 2.2?
what does it have to do with longevity anyway. just curious. havent heard that before.
yep, nothing breaks. (knock, knock, knock! ) thats why you guys built me that motor, so I wouldnt break it!!
went what route with the tranmission? going to a 2.75 or going to the 2.2?
what does it have to do with longevity anyway. just curious. havent heard that before.
yep, nothing breaks. (knock, knock, knock! ) thats why you guys built me that motor, so I wouldnt break it!!
That's all fine and dandy, you skipped the primary reason they went this route and that's longevity of the transmission, not efficiency (which is an added side benefit).
Yes we all know with you behind the wheel nothing ever breaks. Most other 928 owners / drivers are not so lucky.
Not to mention 95% of the time Jim is at Road America with three very long straights, the longest is about 5,000 ft.
Yes we all know with you behind the wheel nothing ever breaks. Most other 928 owners / drivers are not so lucky.
Not to mention 95% of the time Jim is at Road America with three very long straights, the longest is about 5,000 ft.
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Joined: Aug 2006
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From: Atlanta
Hacker' makes another good point, 5th gear is 'direct' and more efficient'
Isn't it nice of Greg to start this gearing thread for us?
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From: Bird lover in Sharpsburg
There really is no room to get pics of the pedals and firewall part, and swapping the trans out is pretty straight forward.
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From: Bird lover in Sharpsburg
tis a thought.
I was going to send you a PM, would you happen to have pics of a stock trans tunnel opening for a 5 speed?
I want to do mine as close to stock as I can and I am not real sure what the difference is between the two.
I am talking about the part that the shifter handle goes into the interior of the car.
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Joined: Apr 2003
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From: Abbotsford B.C.
I dont have a picture, but if you remove the boot assembly off the auto so you can see the chassis it becomes pretty obvious.
On the auto there is an extra amount of material which is added by riviting and gluing into the normally rectangular hole.
I removed 90% of this material on my install.
On the auto there is an extra amount of material which is added by riviting and gluing into the normally rectangular hole.
I removed 90% of this material on my install.
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Joined: Feb 2004
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Hi Greg,
This is from my 1986.5 track car auto to 5 speed conversion.
Come to think of it, this was another PITA part of the conversion. Not that difficult, just time consuming and messy.
As you can see I trimmed off the raised lip around the opening. I then used double sided tape to stick the rubber 5 speed cover over the opening.
You might want to leave the raised metal lip alone so the rubber part can be fit over it as the stock 5 speeds do.
HTH,
This is from my 1986.5 track car auto to 5 speed conversion.
Come to think of it, this was another PITA part of the conversion. Not that difficult, just time consuming and messy.
As you can see I trimmed off the raised lip around the opening. I then used double sided tape to stick the rubber 5 speed cover over the opening.
You might want to leave the raised metal lip alone so the rubber part can be fit over it as the stock 5 speeds do.
HTH,
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From: Bird lover in Sharpsburg
Hi Greg,
This is from my 1986.5 track car auto to 5 speed conversion.
Come to think of it, this was another PITA part of the conversion. Not that difficult, just time consuming and messy.
As you can see I trimmed off the raised lip around the opening. I then used double sided tape to stick the rubber 5 speed cover over the opening.
You might want to leave the raised metal lip alone so the rubber part can be fit over it as the stock 5 speeds do.
HTH,
This is from my 1986.5 track car auto to 5 speed conversion.
Come to think of it, this was another PITA part of the conversion. Not that difficult, just time consuming and messy.
As you can see I trimmed off the raised lip around the opening. I then used double sided tape to stick the rubber 5 speed cover over the opening.
You might want to leave the raised metal lip alone so the rubber part can be fit over it as the stock 5 speeds do.
HTH,
, that added a bit of added difficulty to it.Got every thing swapped over to the new cross member and the 5 speed wining harness set up on the trans, so at this point it is pretty much just putting every thing back in the car, I still have to install the starter bridge in place of the relay.
I hope I can get in back in tomorrow, only about 2 more days than I thought it was going to take.
BTW
Collin, my hats off to ya brother to do the while conversion in a day, or 2.5 taking the engine out.
Three Wheelin'
Joined: Aug 2006
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From: Atlanta
Greg, the lip around the shifter opening orients the rubber shifter boot. Any way of orienting and holding down that boot would be a good thing, it might even be better than original to screw in strips along the edges.
In my racer I have nothing but that rubber boot. There are 2 fire extinguisher lines that run on either side of it. I mounted the clamps for the lines close to the boot and the lines act to hold the boot down. it really works nicely and it's a treat to not have that boot come off the lip
In my racer I have nothing but that rubber boot. There are 2 fire extinguisher lines that run on either side of it. I mounted the clamps for the lines close to the boot and the lines act to hold the boot down. it really works nicely and it's a treat to not have that boot come off the lip