Steering rack/ratio question
12-29-2015, 07:49 PM
#31
Here's a summary of the steering racks and the factory published ratios, lower is quicker w/ higher effort/
Note that the 993RS uses a 964 rack, the resulting ratios are not quite the same, probably because of the wheel carrier difference.
Note that the 993RS uses a 964 rack, the resulting ratios are not quite the same, probably because of the wheel carrier difference.
12-15-2016, 12:03 AM
#32
Three Wheelin'
Bringing this back from the dead, finally with some answers:
Despite the Porsche TSB, the 993 rack will fit in the 964 C4 with zero problems. I can only guess that Porsche said that it wouldn't fit, because you need to remove the subframe longitudinals first in order to angle the 993 steering rack in to position around the C4 diff.
The two racks that I measured:
993 steering rack tag: 7832.955.169, K054690, 08.07, 2832.501.203, ZF rebuilt
964 steering rack tag: 7840.955.119, 964.347.009.02, 260046, 02.91
lock-to-lock turns, shaft travel, travel per 1 rotation
964 with 6mm steering stops (16" wheels): 2.81, 123.7mm, 44.0mm/turn
964 with 10mm steering stops (17" wheels): 2.64, 116.0mm, 44.0mm/turn
993 with stock stops: 2.47, 120.0mm, 48.6mm/turn
Just as the tech specs say, the 993 rack is faster.
Tie rods measurements:
M14 thread for all inner/outer along steering shaft axis
M14 into steering rack
M12 outer tie rod top nut, 964 and 993
964 inner tie rod -to- adjusting turnbuckle uses a reverse thread
Outer tie rod shaft height (above steering axis)
964 excluding threads=~39.2mm, length of threads=~18mm, to start of cone =~25.8mm
Outer tie rod cone diameters
964 min=14.53mm, max=15.93mm, m12 thread
993 min=15.16mm, max=17.11mm, m12 thread
Outer tie rod length (measured from cone bolt/mount)
964 =114mm, m14 thread end
Inner tie rod length (including steering stop)
993 =150mm steering stop to end
964 = ~100mm steering stop to start of threads, ~50mm length of threaded portion
Anyone know of a spherical inner tie rod replacement for the stock 964 inner? Seems that Porsche is a bit unique having rubber damping/isolation on the inner tie rods.
Despite the Porsche TSB, the 993 rack will fit in the 964 C4 with zero problems. I can only guess that Porsche said that it wouldn't fit, because you need to remove the subframe longitudinals first in order to angle the 993 steering rack in to position around the C4 diff.
The two racks that I measured:
993 steering rack tag: 7832.955.169, K054690, 08.07, 2832.501.203, ZF rebuilt
964 steering rack tag: 7840.955.119, 964.347.009.02, 260046, 02.91
lock-to-lock turns, shaft travel, travel per 1 rotation
964 with 6mm steering stops (16" wheels): 2.81, 123.7mm, 44.0mm/turn
964 with 10mm steering stops (17" wheels): 2.64, 116.0mm, 44.0mm/turn
993 with stock stops: 2.47, 120.0mm, 48.6mm/turn
Just as the tech specs say, the 993 rack is faster.
Tie rods measurements:
M14 thread for all inner/outer along steering shaft axis
M14 into steering rack
M12 outer tie rod top nut, 964 and 993
964 inner tie rod -to- adjusting turnbuckle uses a reverse thread
Outer tie rod shaft height (above steering axis)
964 excluding threads=~39.2mm, length of threads=~18mm, to start of cone =~25.8mm
Outer tie rod cone diameters
964 min=14.53mm, max=15.93mm, m12 thread
993 min=15.16mm, max=17.11mm, m12 thread
Outer tie rod length (measured from cone bolt/mount)
964 =114mm, m14 thread end
Inner tie rod length (including steering stop)
993 =150mm steering stop to end
964 = ~100mm steering stop to start of threads, ~50mm length of threaded portion
Anyone know of a spherical inner tie rod replacement for the stock 964 inner? Seems that Porsche is a bit unique having rubber damping/isolation on the inner tie rods.
12-15-2016, 12:36 AM
#33
Rennlist Member
Bringing this back from the dead, finally with some answers:
Despite the Porsche TSB, the 993 rack will fit in the 964 C4 with zero problems. I can only guess that Porsche said that it wouldn't fit, because you need to remove the subframe longitudinals first in order to angle the 993 steering rack in to position around the C4 diff.
The two racks that I measured:
993 steering rack tag: 7832.955.169, K054690, 08.07, 2832.501.203, ZF rebuilt
964 steering rack tag: 7840.955.119, 964.347.009.02, 260046, 02.91
lock-to-lock turns, shaft travel, travel per 1 rotation
964 with 6mm steering stops (16" wheels): 2.81, 123.7mm, 44.0mm/turn
964 with 10mm steering stops (17" wheels): 2.64, 116.0mm, 44.0mm/turn
993 with stock stops: 2.47, 120.0mm, 48.6mm/turn
Just as the tech specs say, the 993 rack is faster.
Tie rods measurements:
M14 thread for all inner/outer along steering shaft axis
M14 into steering rack
M12 outer tie rod top nut, 964 and 993
964 inner tie rod -to- adjusting turnbuckle uses a reverse thread
Outer tie rod shaft height (above steering axis)
964 excluding threads=~39.2mm, length of threads=~18mm, to start of cone =~25.8mm
Outer tie rod cone diameters
964 min=14.53mm, max=15.93mm, m12 thread
993 min=15.16mm, max=17.11mm, m12 thread
Outer tie rod length (measured from cone bolt/mount)
964 =114mm, m14 thread end
Inner tie rod length (including steering stop)
993 =150mm steering stop to end
964 = ~100mm steering stop to start of threads, ~50mm length of threaded portion
Anyone know of a spherical inner tie rod replacement for the stock 964 inner? Seems that Porsche is a bit unique having rubber damping/isolation on the inner tie rods.
Despite the Porsche TSB, the 993 rack will fit in the 964 C4 with zero problems. I can only guess that Porsche said that it wouldn't fit, because you need to remove the subframe longitudinals first in order to angle the 993 steering rack in to position around the C4 diff.
The two racks that I measured:
993 steering rack tag: 7832.955.169, K054690, 08.07, 2832.501.203, ZF rebuilt
964 steering rack tag: 7840.955.119, 964.347.009.02, 260046, 02.91
lock-to-lock turns, shaft travel, travel per 1 rotation
964 with 6mm steering stops (16" wheels): 2.81, 123.7mm, 44.0mm/turn
964 with 10mm steering stops (17" wheels): 2.64, 116.0mm, 44.0mm/turn
993 with stock stops: 2.47, 120.0mm, 48.6mm/turn
Just as the tech specs say, the 993 rack is faster.
Tie rods measurements:
M14 thread for all inner/outer along steering shaft axis
M14 into steering rack
M12 outer tie rod top nut, 964 and 993
964 inner tie rod -to- adjusting turnbuckle uses a reverse thread
Outer tie rod shaft height (above steering axis)
964 excluding threads=~39.2mm, length of threads=~18mm, to start of cone =~25.8mm
Outer tie rod cone diameters
964 min=14.53mm, max=15.93mm, m12 thread
993 min=15.16mm, max=17.11mm, m12 thread
Outer tie rod length (measured from cone bolt/mount)
964 =114mm, m14 thread end
Inner tie rod length (including steering stop)
993 =150mm steering stop to end
964 = ~100mm steering stop to start of threads, ~50mm length of threaded portion
Anyone know of a spherical inner tie rod replacement for the stock 964 inner? Seems that Porsche is a bit unique having rubber damping/isolation on the inner tie rods.
