Early vs. Late offset
01-25-2005, 01:54 AM
#1
Early vs. Late offset
As it pertains to the front axle...what is/are the difference/s between the early ('86) and late offset fronts. Are the lower control arms the same size?...late is just beefier? Is the main difference in the spindles?...late just brings them out 29mm more? Looking at putting turbo calipers on an '86 n/a...just wanted some insight before I dive in.
Thanks!
Thanks!
01-25-2005, 02:11 AM
#3
Race Car
As I understand it, the control arms are different, as well as the spindles. The spindles were modified to accept ABS wheel speed sensors. To accomidate this, they moved the ball joint outward, and I believe this involved lengthening the control arms, but I'm not positive on that.
If you wish to fit turbo brakes on your NA, then you would be best off locating some 86 turbo brakes. That would make the swap simpler, but I believe you would still need the complete spindle assembly? Perhaps somebody else knows this for certain.
Would you be upgrading the rear brakes as well?
If you wish to fit turbo brakes on your NA, then you would be best off locating some 86 turbo brakes. That would make the swap simpler, but I believe you would still need the complete spindle assembly? Perhaps somebody else knows this for certain.
Would you be upgrading the rear brakes as well?
01-25-2005, 11:02 AM
#4
Burning Brakes
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Zero is on the money. Your most cost effective brake upgrade would indeed be to score a set from an '86 (early offset) Turbo. As I understand it, the swap is a bolt up, but you will need to run 16" or larger wheels to clear the larger caliper. OE on 86 Turbo was 7/8 16" combo, either phone dials or option Fuchs. You can also run later Porsche spec wheels with spacers.
01-25-2005, 11:11 AM
#5
Rennlist Member
For the front, you will need the spindles, hubs, brake calipers, and rotors from an 86 turbo. Actually the brake calipers are basically the same for any 86-88 turbo and S2s and 968s, but the other components are for the early offset only (hubs, spindles, and rotors). If you change to the later offset, you will have to get late offset control arms, spindles, hubs, rotors, and tie rods.
01-25-2005, 07:51 PM
#7
From my understanding and the info in the factory service manual the difference in offset is primarily in the control arms, not the spindles. That said, the spindle is different. As per the FSM:
"wheel-bearing pin larger. Cars with ABS have a hole to locate wheel-speed sensor"
The hub "geometry" is modified as well, though I am not clear as to whether that is to facility the different disk mounting position and larger wheel bearing or to actually effect the offset of the wheel.
"wheel-bearing pin larger. Cars with ABS have a hole to locate wheel-speed sensor"
The hub "geometry" is modified as well, though I am not clear as to whether that is to facility the different disk mounting position and larger wheel bearing or to actually effect the offset of the wheel.
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01-25-2005, 08:29 PM
#8
Race Director
The offset of the wheel is probably the very last factor. It's determined after all the other stuff has been put into place. So you take an early offset car and do the following:
1. add longer control arms (better camber-curve, goes positive-gain later)
2. add bigger bearings and spindles for durability
3. add ABS brakes
4. select offset to put wheel with rim-edges in same location as before.
The change in scrub-radius actually makes the late-offset cars more stable than before, but turn-in response and zig-zags feels sluggish.
1. add longer control arms (better camber-curve, goes positive-gain later)
2. add bigger bearings and spindles for durability
3. add ABS brakes
4. select offset to put wheel with rim-edges in same location as before.
The change in scrub-radius actually makes the late-offset cars more stable than before, but turn-in response and zig-zags feels sluggish.
01-25-2005, 08:52 PM
#9
So basically, the offset is mainly dictated by the lower control arms, cool. Not looking to change the offset. I'll just pick up a set of '86 turbo spindles and hubs and be on my way.
Thanks!
Thanks!
01-26-2005, 12:07 PM
#11
Rennlist Member
I have an '86 951 with stock spindles and brakes on early offset Charley arms, Leda struts, and camber plates. The car is used only for DE events, no street, and zero plans for SCCA or Club Racing. I'm planning to install Turbo S spindles, and hubs, primarily for better strength, with bigger brakes part of the deal. I'm also considering installing manual steering.
Trying to draw some conclusions about early vs. late offset, this may help others deciding on which car to purchase or whether to modify:
The advantages of early offset are:
better turn in
can use manual steering rack - tie rods are different, and NLA for late offset
can use wider standard wheels on front -have used 9 inch D90's with room to spare, but they protrude out too much on a late offset.
Advantages of late offset:
More choices in aftemarket contol arms
Spindles/wheel bearings are stronger
Better stability
More negative camber available both statically and dynamically.
Would not need spacers for most available wheels.
Rotors much easier to change
Can use ABS brakes
I recognize I'm going for track only, and others want to maintain more of a street/track compromise, or street only. The manual steering and wider wheels may not be a good combination. Any offset is available with 3 piece wheels, but they are expensive.
I'm still working this out myself, and would like to hear the opinions of others on the above.
Trying to draw some conclusions about early vs. late offset, this may help others deciding on which car to purchase or whether to modify:
The advantages of early offset are:
better turn in
can use manual steering rack - tie rods are different, and NLA for late offset
can use wider standard wheels on front -have used 9 inch D90's with room to spare, but they protrude out too much on a late offset.
Advantages of late offset:
More choices in aftemarket contol arms
Spindles/wheel bearings are stronger
Better stability
More negative camber available both statically and dynamically.
Would not need spacers for most available wheels.
Rotors much easier to change
Can use ABS brakes
I recognize I'm going for track only, and others want to maintain more of a street/track compromise, or street only. The manual steering and wider wheels may not be a good combination. Any offset is available with 3 piece wheels, but they are expensive.
I'm still working this out myself, and would like to hear the opinions of others on the above.
