Automatic Transmission - 4 spd weak link
12-12-2004, 07:40 PM
#16
Burning Brakes
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Hi pappy92651,
you raise an interesting point regarding the ATF. All lubricants are not the same and ATF is the most complex of all used in a motor vehicle
A suitable synthetic ATF (I use Castrol's excellent Transmax Z) can reduce operating temperatures by up to 20C and will have MUCH better flow characteristics. Transmax Z works very well in all 928 Autos - I have used it for over a decade in a variety of applications. This is especially so in very high and very low temperatures
Regards
Doug
you raise an interesting point regarding the ATF. All lubricants are not the same and ATF is the most complex of all used in a motor vehicle
A suitable synthetic ATF (I use Castrol's excellent Transmax Z) can reduce operating temperatures by up to 20C and will have MUCH better flow characteristics. Transmax Z works very well in all 928 Autos - I have used it for over a decade in a variety of applications. This is especially so in very high and very low temperatures
Regards
Doug
12-13-2004, 03:23 AM
#17
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Pappy I would also like to know more about the fluid you run. Ive added a BIG tranny cooler on my SC install to deal with the heat, but i woudl like to run the best fluid possible. recomendations?
TIA
TIA
12-13-2004, 02:04 PM
#18
Racer
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Doug - Good choice. Almost any synthetic ATFs will out perform non synthetic ATF, but some formulations are special purpose. For instance synthetic racing ATF is formulated to allow brake bands to snap closed quickly. While this produces faster shifts it also translates to shock loads. So, I agree with your choice. Thermal stability is far better with synth.
Tony - I would use one of the major brands. Doug indicated one of them. Unless you are drag racing constantly I would stay away from synthetic racing ATF. The shifts are harsh. The Kinematic Viscosity should be about 35 cSt @ 40C and 7.5 cSt @ 100C. Here are the brands that I have tried and liked:
Mobil 1
Amsoil
Castrol
Redline
As Doug indicated operating temperatures will drop, the transmission will run quieter, and last much longer.
Tony - I would use one of the major brands. Doug indicated one of them. Unless you are drag racing constantly I would stay away from synthetic racing ATF. The shifts are harsh. The Kinematic Viscosity should be about 35 cSt @ 40C and 7.5 cSt @ 100C. Here are the brands that I have tried and liked:
Mobil 1
Amsoil
Castrol
Redline
As Doug indicated operating temperatures will drop, the transmission will run quieter, and last much longer.
12-13-2004, 04:04 PM
#20
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Hello Bill,
They hold the same general specifications. I could not tell a difference when driving. All seem to hold up well under extreme conditions. When compared to non synthetic you can feel and hear a difference, especially after a hard run. The exceptions might be Redline High-Temp or Racing ATF, both having viscosity index modifers (cSt @ 40C ~ 55 and @100C ~ 10). The higher vicosities might have better film strength but cause friction surfaces to slip more during shifts. My feeling is that the standard synthetic offerings are best suited for our 928 transmissions. The 4 brands have data to support similar superior performance.
They hold the same general specifications. I could not tell a difference when driving. All seem to hold up well under extreme conditions. When compared to non synthetic you can feel and hear a difference, especially after a hard run. The exceptions might be Redline High-Temp or Racing ATF, both having viscosity index modifers (cSt @ 40C ~ 55 and @100C ~ 10). The higher vicosities might have better film strength but cause friction surfaces to slip more during shifts. My feeling is that the standard synthetic offerings are best suited for our 928 transmissions. The 4 brands have data to support similar superior performance.
