Funny. I was just thinkin' bout you. I'll be in touch after I open it up and inspect.Quote:
Originally Posted by Jim Breazeale
Bob
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Funny. I was just thinkin' bout you. I'll be in touch after I open it up and inspect.Quote:
Originally Posted by Jim Breazeale
Bob
After checking numbers on transaxle I come up with 901/13-7197777. This is listed as a 911 trans with AFMSZ. I have never had any gear ratio issues (unhappiness) but my question is with the Z 5th. The 69 912 boxes are listed as AFMSX. I run 55 series tires so is the Z better for me with respect to hwy driving? I am 75mph @ 4k rpm now. I'm thinking I got lucky since a 912 X 5th gear on 55 series tires would be geared way too low for the hwy. I never need that gear to AX anyways. Best to have it for the hwy.
Bob H.
I ran my car over to Michigan last summer with my other gear box installed. It has lower than Airport gears for 1 thru 4 gears and a "Z" for fifth. (Let's call it a autocross box with a traveling gear :) ) 165x15 tires at 25" diam. Got a whopper of a ticket in Michigan for driving my "audible" with the tach pegged at four-grand.... the "Z" put me a tad over 85mph (the standard box's "Y" runs at about 75 at the same rpm).... Go have fun.
You have a late '69 911 transmission with magnesium alloy housing.Quote:
Originally Posted by Bob Harriman
901/07......7190001-7192529......'69 5-speed with aluminum die-cast housing
901/13......7193001-7198787......'69 5-speed with magnesium pressure-cast housing
Gaskets, seals, differential bearings and several other parts differ between the two versions.
If you wish to gear 5th taller than 29:23 "Z", you have the option of 29:22 "ZA" or 31:22 "ZD".
Both can be found in good used condition.
Jon B.
Vista, CA
I think I'm good with the Z. The Vacabulary AEIOU gears with 55 series tires would have been too low. I also plan on a 911 transplant someday.:D
Is there anything different about the 911 901/13 compared to the 912 902/6 or 902/16?
I guess the R&P is the difference. Why is the 912 a 6:29?Quote:
Originally Posted by Bob Harriman
Not sure why a 6:29 ring & pinion was used in later 912 transmissions, maybe to lower 1st gear. It did, whether intended or not. Otherwise there was no lower 1st than the standard "A" ratio.
The AEIOU transmission was a racing option, not meant for street or highway use.
The '69 911 was the first model to use 4-bolt 108mm CV axles; the 912 probably did too but I'm not certain. The 912 front mount was different, and possibly the speedo drive gearing.
Jon B.
The 69 912s did use the 108mm Cvs, as well. Spedo drive gearing was the same, too.
Regards
Jim
Is the ZA that big of a difference from the Z gear?
Bob, the difference between 29:22 "ZA" and 29:23 "Z" is 23/22 (1.0455) greater output speed, or 22/23 ( 0.9565) less input speed required to achieve the same output speed. So 3000 rpm with a "Z" would be the same road speed as 2870 rpm with a "ZA" gear, a 130 rpm difference.Quote:
Originally Posted by Bob Harriman
Jon B.
Vista, CA