Portal axles are the most invasive bolt-on you'll do to an SCX24. It's not just “unscrew the old axle, screw on the new one.” The new axles change wheelbase, track width, driveshaft length, sometimes the servo mount, and often the link length. Plan the whole job before you start.
If you haven't picked portals yet, see the best portal axles buying guide. For background on what portals actually do, see the all about SCX24 axles.
Before you start
- Confirm fitment to your specific model. Most kits target the standard 133mm wheelbase (Jeep, Deadbolt, Bronco, C10, Base Camp). Body posts on the C10 in particular may need spacers after the install because the truck sits taller.
- Plan for new driveshafts. The taller housing moves the pinion location. Stock driveshafts are often the wrong length and angle after install. Best case: the kit includes adjusted shafts. Worst case: order them separately and wait a week.
- Plan for a new servo mount. Stock mount references the stock axle. The portal axle is taller and wider. Steering geometry changes. Many kits don't include a mount.
- Plan for new link lengths. Wider stance and taller housing change link geometry. Some kits include links; many don't.
Tools and parts
- Hex drivers: 1.3mm, 1.5mm, 2.0mm.
- JIS #00 and #0 Phillips. The SCX24 uses JIS on some axle screws. A regular Phillips will cam them out and you'll have to drill them.
- Needle-nose pliers for ball-cup removal.
- Blue threadlocker (Loctite 243). Every M2 and M2.5 fastener.
- Hobby knife for trimming any flash on chassis mounts.
- Bench-top magnifier or strong desk light. You will drop M2 screws.
- Replacement link kit if your portals don't include one.
- Replacement driveshafts if your portals don't include them.
- Servo mount that fits the new axle if your portals don't include one.
Time and difficulty
Plan 2 to 4 hours for your first install, 1 to 1.5 hours once you've done it. Intermediate to advanced difficulty. If you've never had the axles off, do a stock teardown and rebuild first as a dry run.
1. Strip the chassis
Body off. Battery disconnected. Take photos as you go. Remove the wheels, the shocks, the driveshafts, the servo (or at least the drag link), and finally the upper and lower chassis links from the axle housings. The axles should be loose and ready to lift out.
2. Pre-build the new axles on the bench
Most portal kits ship partially assembled but always benefit from a once-over before installing. Things to check on the bench, where you can see what you're doing:
- Threadlock every screw. Blue Loctite on every M2 and M2.5. The portal boxes vibrate at speed and screws back out if they're not threadlocked.
- Check the gear mesh in each portal box. Spin the input by hand. Should be smooth, no grinding. If it binds, loosen the cover screws slightly and re-torque evenly.
- Confirm the diff is properly greased. Most kits ship with grease applied, but check for missed spots.
- Verify the bearings are seated and not crushed. Crushed bearings (over-tightened housings) feel notchy when you spin the shaft.
- Pre-fit the CVD shafts or U-joints. They should slide and rotate freely.
3. Install the rear axle first
Rear is easier because there's no steering geometry to worry about. Mount the new rear axle to the chassis using the upper and lower links. Set link length so the axle sits roughly in the same fore-aft position as stock (you can fine-tune later with shock collars or different-length links).
Connect the rear driveshaft from the transmission to the axle pinion. If the shaft is too short or too long, this is the moment to figure that out, not after you've buttoned up the front.
4. Install the front axle
Same drill as the rear: bolt up links, connect the driveshaft. Then deal with the steering setup.
Mount the new servo bracket (or re-drill the stock one) to the new axle housing. Drop the servo in. Connect the drag link to the steering knuckle and the servo horn. With portals, the knuckle arm is in a different position and the stock drag link is usually the wrong length. Most kits include the right link. If yours doesn't, measure from horn ball to knuckle ball at neutral and order accordingly.
5. Set steering travel
With the chassis on the bench and the battery plugged in, sweep the steering full left and full right. Check:
- No mechanical bind at either endpoint. The servo should not stall against the knuckle stop. Reduce endpoints in the servo program card if it does.
- No body interference at full lock. Especially on the C10 and Wrangler. The wider stance plus the taller housing can push tires into the fender.
- Smooth, symmetric steering. Equal travel each way. If asymmetric, the servo isn't centered (re-do the centering step from the servo install).
6. Re-mount the shocks
Portal axles change ride height. Some kits include longer shocks; some don't. Check that the shocks aren't topped out or fully extended at static ride height. Adjust spring pre-load to set the ride height you want. The truck should sit slightly above the natural shock midpoint with all weight on the wheels.
7. Reinstall wheels and test under power
Wheels back on. Truck on the bench with wheels free. Plug the battery in. Drive forward and back at low throttle. Listen for:
- Smooth transmission, no grinding from any portal box.
- No driveshaft clicking (sign of bad angle or wrong length).
- No knocking from the diff (sign of mesh problems).
Anything that sounds wrong, stop, investigate. Portal boxes don't self-heal.
8. Body back on, drive carefully
Reinstall the body. Check that body posts still align and that the wider stance isn't pushing the body upward. Spacers on the body posts can recover proper ride height if needed.
First drive: flat ground. Get a feel for the new steering radius and the slower wheel speed from the portal reduction. Then take it to your usual terrain and watch for clearance gains.
Things that commonly go wrong
- Wrong driveshaft length. Clicks at speed or won't fully seat in the cup. Order the right length and don't force the stock shafts.
- Servo stalling at endpoints. Set servo travel in the program card or trim it from the radio. Stalling kills servos.
- Body rub at full lock. Wider stance plus taller housing. Trim the fender or run hex extenders.
- Portal gear noise after a few runs. Bearings not properly seated. Take the portal box apart and check for crushed bearings or missing shims.
- Loose screws on the trail. If you skipped threadlock, you'll find out the hard way.
Once portals are in, the truck is a different vehicle. Higher, wider, slower at the wheels, more capable on technical lines. Where this sits in the overall plan: see the staged upgrade path.