synchros question and problem

[hyperkinesis]

Hello, I need some help.. I buy synchros for my 915 trasm but for some error advice from pelican technical support or my wrong question I think I buy the wrong synchro.. My question Ways what synchro I need for st nd and th
answer for 1 and second 2 80mm synchros ans 1 70mm for the nd...I'm some Way the answer is correct but on the catalog there are 2 80mm different synchros

I buy 2 915-302-301-04-M157 915 80mm Synchro Ring (sold per each), st, nd 911 (1974-76), nd, 911 (1977-86)
and for nd gear 911-302-301-06-M157 915 70mm Synchro Ring (sold per each), 3rd, 4th, 5th 911 (1974-86)

Now when I change gears from st to nd fast it make a scrape noise

I verify and there is other 80mm synchro 915-302-301-06-M157 915 80mm Synchro Ring, st, 911 (1977-86)

this can be the problem??

[Peter Zimmermann]

Welcome to Red Line Porsche Wiki - Porsche Wiki

Scroll left side of page, click on "915" under "page tags" and the site will take you to my 915 Tutorial. Hope it helps!

[hyperkinesis]

thanks but my question is the part is an issue or not, both synchros are 80mm but the part number is diferrent, this can be the problem??
my car is 1984 911 carrera targa 915 trasm 5 gears
now the trasm have the 915-302-301-04-M157 915 80mm Synchro Ring ( on fisrt gear and second gear

Whats the Difference Between this 915-302-301-06-M157 and 915-302-301-04-M157

[Peter Zimmermann]

It problem be any number of things from driver technique (expecting the car to do something it can't), to incorrect assembly (you don't mention slider replacement), to the use of incorrect parts, to the fact that you used two 2nd gear synchro rings, instead of one "04" and one "06" ring.

[john walker's workshop]

later style 1st syncros have a groove round both sides. they are weaker than the 2nd syncros without the groove. two different numbers. did you mix them up?

[hyperkinesis]

the trasm have the 915-302-301-04-M157 915 80mm Synchro Ring on fisrt gear and second gear
Driver technique no way, this 2 synchros works fine when I change gears from 1rt to 2nd slow no matter what RPM but if I push the car over 3500 rpm and change gears fast make a scrape noise. thank the think.. I send the trans to change the synchro for a new 915-302-301-06-M157 915 80mm and I hope this eliminate the problem

thanks to all

[john walker's workshop]

06 is 1st only. 04 is 2nd. since you already have an 04 in 2nd and it grinds, maybe the shift sleeve is worn out or maybe you shift too fast. you cannot power shift these transmissions.