Any way to improve shift into 2nd on 915?

[jwakil]

Originally Posted by calling911

If you are pausing in neutral with the clutch in you are wearing it out.. if the clutch is out then you are not.

I would suspect pausing wears things out a lot less than double clutching. Talk about lots of stuff working twice as much per shift.

[lindy 911]

To the original poster, I have a 915 with over 100,000 miles on it. I had some notchy shifting when the motor went back in but I traced it to the shift coupler. I would make sure the coupler got reinstalled correctly. Slight changes in the adjustment of the coupler makes a LOT of difference.

Mine has no trouble shifting from 1st to 2nd. You can't bang on it like American Iron but it doesn't weigh 10 tons either.

Lindy

[Wil Ferch]

It simply seems that with the baulk-ring transmissions, the higher revs makes the synchromesh action work a lot better....therefore...one can argue that shifting at low revs doesn't allow the synchros to work as well, and therefore the *synchros* are taxed more and may wear out sooner...makes sense, maybe?.

[T77911S]

Originally Posted by calling911

It is what it is boys. Be one with it

One thing that has helped me immensely is blipping the throttle on UPSHIFT.. as well as down.. my 2.7 must enough compression to wind down too quick for the 915... maybe yours does too? This trans CAN be shifted well but not fast.. buy the gates too from our host.. gave me way more confidence.. but upshift blips has been the key for me especially with a bad 3rd gear syncro.. I rarely grind now.

And by all means.. be nice to it.. do not force it and try to shift like a BMW.. it ain't gonna friggen happen.

would this be a good reason to keep the decel valve or why it was put on?

a friend at work just dumped his swepco and put in royall purple, i told him to use kendall, but i also told him to use swepco. he noticed a difference withthe RP. ill keep on him til he goes with the kendall.

[Jdub]

You might remove the plate (four bolts) at the bottom of the trans at your next trans fluid change and see if the shifting fork is at all loose on the plate, inside your trans. Common to loosen up over the years and easy to overlook. Have a fresh gasket on hand.

Suggest blue Loctite on each nut, clean surgically so it adheres. Will improve your shifting immediately IF the fork was loose to begin with.

Again, all peripherals - bushes x4 from shift to coupler; adjust at trans, solid pedal rack.

[tcar]

Originally Posted by jwakil

I would suspect pausing wears things out a lot less than double clutching. Talk about lots of stuff working twice as much per shift.

Double clutching, done properly, causes a lot LESS wear.

It's the incorrect blipping on an upshift that increases wear; that's just the opposite of rev matching.

Only blip the throttle on Downshift to match revs.



Also, with the 915 tranny, don't shift into first while the car is moving; stop first.

[davidbir]

Originally Posted by tcar

Also, with the 915 tranny, don't shift into first while the car is moving; stop first.

Why is that? I have noticed that with my SC but with all the old English cars that I drive (no synchro on first) it helps to shift into first just as you come to a stop.

[Mahler9th]

Assessing the shifting "qualities" of a 915 one way or another depends on what you use as a basis for comparison. Lots of great suggestions in this thread... hopefully the original poster has some local resources as well.

By the way, in my experience and in the experience of many of my local friends, synthetics like Redline can work fine in a 915. The definition of depends on your specific requirements. I mention that a lot in posts... because it is true. For a pure street car, I like Swepco. I have used Swepco on my Porsche street cars since 1987. But for my race car with 915, I have used Redline for the past 9 seasons. Meets my requirements for that application.

This is apparently a street car application and there are numerous helpful suggestions in this link. Running Swepco is perhaps one of them.

[T77911S]

Originally Posted by davidbir

Why is that? I have noticed that with my SC but with all the old English cars that I drive (no synchro on first) it helps to shift into first just as you come to a stop.

do what works for your tranny. these are tried and true practices but it is not the gospel. i can do either with mine.

for some reason a post from a guy that complained he could not down shift into first at 30mph always gives me a chuckle.

[don hopkins]

Thanks for all the advice and ideas but I have found someone who can modify my 915
so it will shift faster.

Don
________________________
1965 912
1981 911SC
2006 Cayman S

[LUFTMAN]

next time you rebuild transmisson before installing dog teeth on gears grind every other tooth off of dog teeth. this is a old drag racer trick that we did to many a muncie 4 speed gearbox in the 1960,s

[midnight911]

I find it easier to shift up when i depress the clutch quicker. don't know why but that's how it is on my 915.

[turbochad]

Anybody try this on a 915?

next time you rebuild transmisson before installing dog teeth on gears grind every other tooth off of dog teeth. this is a old drag racer trick that we did to many a muncie 4 speed gearbox in the 1960,s

[Bob Kontak]

Originally Posted by James Brown

However, you say the transmission was rebuilt, it should slide right in.

My 81 915 was rebuilt by Mayo Performance last year. Sent it to them UPS. First to second is like butter at all speeds with or without double clutching. They did say to double clutch as a rule to lengthen synchro life.

With my limited driving 3rd is progressively getting less balky - just like they said.

Also bought Swepco 210 (red) in the late 1990's and they said "NO" and replaced with 201 (green). Said 210 is great for gear life but not so for synchros (friction).

[turbochad]

The term "rebuilt" is often used improperly. Very few boxes out there that have been opened are proper rebuilds. If it cost less than $3k from a shop and doesn't shift smoothly it wasn't done correctly. This is true more than not, ask the pros in our midst.

[Bob Kontak]

$2,600 for mine without the engine R&R. The disassemble and reassemble is "cheap" - $750-ish. Only takes a handful of $180-$250 parts over the basics to run it right up there.

Mayo sent pictures of "screw-ups" that had been done on a prior rebuild. One of the main shafts was supposed to have about a million and a half foot pounds of torque on the nut and it had 15. There was also a huge lock nut that is supposed to be a one-time use and you use a punch to lock it into place. The original had been beaten off with a chisel and reused.

[esotoracing]

Instead of the annoying double clutch. . . . .learn to take it out of first gear without clutch. Its easily done if you shift out of first rights as you take your foot off the gas, theres a moment in the engine tranny where there are no forces in effect and it will slide out of first, then as your momentarily in neutral slide in the clutch and go into 2nd and see if that works.

I have done this all of my life in all standard cars i have had to save on release bearing use.
In some race cars i dont even use the clutch at all (even on syncro boxes)

[don hopkins]

Which transmission do you think is better, 901 or 915? I have a 1965 with a 901 and 1981 with a 915. There's no doubt in my mind that the 901 is better. My mechanic says that when Porsche designed the 915 they took the 901 and made it larger and one part that didn't work well in a larger size was the slider for 2nd gear.

Don
_____________________________
1965 912
1981 911SC
2006 Cayman S

[esotoracing]

i have never driven a 901 box porsche at the same have never had any issues with the 915, when i had mine i didnt spend much time in first or second