Installation instructions Rev 1.0 / 10-2026

APPLIES TO: AWD 996 / 997 C4, C4S and Turbo, 991.1/991.2 and 992.1/992.2 Carrera 4, 4S, 4 GTS and Turbo/Turbo S with our 15 mm Front Axle Spacer Kit (403-10035).

*IMPORTANT – DO NOT INSTALL UNLESS MEASURED*
The spacers are included with our AWD and Turbo/Turbo S suspension packages in case your car needs them. Many cars do not. Installing them when they aren't needed can push the axle into the front differential and damage the driveshafts or differential. Leaving them out when they are needed can over-extend the axle and cause vibration.

WHY WE MEASURE:
Adjustable front LCAs, shims, camber changes and lowering all change the length the front axle sits at. Instead of guessing from the shim stack, you measure the axle before and after the alignment and let the change decide.

TOOLS NEEDED:
▪ Alignment rack or flat 4 post lift
▪ Calipers or a steel scale
▪ Socket/bit to suit the axle flange bolts
▪ Torque wrench

 

STEP 1 – BASELINE (BEFORE INSTALLING ANY PARTS)

1. Put the car on the alignment rack at stock ride height with the stock alignment, wheels loaded and suspension settled.

2. Remove the front under-panel as needed for access.

3. Unbolt one front axle from the front differential output flange (6 bolts).

4. Push the axle all the way toward the knuckle and hold it there.

5. Measure the gap between the differential output flange face and the axle flange face at three points around the flange (12, 4 and 8 o'clock). Record the smallest reading.

6. Reinstall the axle and torque the flange bolts to 40 Nm.

7. Repeat on the other side. Record Baseline Left and Baseline Right.

* PRO TIP *:
One side is usually enough, but measuring both takes little extra time and catches side-to-side differences.

 

STEP 2 – INSTALL THE SUSPENSION AND FINISH THE ALIGNMENT

Install your Dundon Motorsports suspension parts and set ride height and alignment to the final setup. DO NOT install the axle spacers yet.

 

STEP 3 – FINAL MEASUREMENT (AFTER THE ALIGNMENT)

8. Repeat steps 3–7 at the final ride height and alignment. Record Final Left and Final Right.

 

STEP 4 – DECIDE (EACH SIDE)

Change = Final − Baseline. A positive number means the axle now sits longer than stock.

▪ −8 mm to +8 mm: Do not install the spacer.
▪ +8 mm to +23 mm: Install the 15 mm spacer on that side.
▪ More than +23 mm: STOP and call us. The axle is still too long even with the spacer, and the setup needs changing.
▪ Less than −8 mm (shorter than stock): NEVER install the spacer. Call us.
▪ Left and right differ by more than 5 mm: Recheck both sides, then call us.

*NOTE ON SHIM STACKS*
With less than 16 mm (5/8") of LCA shim per side, measure the axles or call us before deciding. With more than 16 mm of shim per side, or if the car is lowered significantly, the spacers are typically needed, but still measure and call us to confirm.

 

STEP 5 – INSTALLING THE SPACERS (IF NEEDED)

9. Unbolt the axle from the differential output flange.

10. Fit the 15 mm spacer between the output flange and the axle flange.

11. Install using the 12x M8x60 Grade 12.9 bolts supplied in the kit and torque to 40 Nm. The kit bolts fit 996, 997, 991 and 992 (the 996 factory bolts are 5 mm longer, but the kit bolts still fit).

12. Turn the steering lock to lock and check the axles turn freely with no binding.

 

STEP 6 – SEND US YOUR NUMBERS

Email sales@dundonmotorsports.com (or reply to your order email) with: order #, VIN, car, LCA shim stack per side, ride height, Baseline L/R, Final L/R and whether the spacers were fitted. Every measured install helps us refine these numbers.

 

You have successfully measured and set up your front axles.