Front suspension converting from 4CS To 48AER

[Neal 408]

I have a 2017 & a 2018 MX with the junk 4cs front forks . I just picked up two sets of 48AER FORKS. Does anyone know if the only difference is the front axles or are the bearings and races different as well? If it’s only the axles are they the same as the KTM axles?

 

[snydes]

I believe the axles are slightly longer, it may be close enough that a KTM axle would work, but I’d check with Liquid Performance first and see if they have the Alta axles. You would then also need the Alta front wheel spacers, I think Liquid has those as well.

 

[Neal 408]

Awesome thanks,
Ordered 2 axles this morning and 2 sets of spacers. Not sure if the spacers are for the 4CS or the 48AER. Part# 6800579-00 outer axle spacers?

 

[snydes]

Awesome thanks,
Ordered 2 axles this morning and 2 sets of spacers. Not sure if the spacers are for the 4CS or the 48AER. Part# 6800579-00 outer axle spacers?

@Rashid510 is the part number guru, hopefully he can answer that.

 

[Neal 408]

Thank you

 

[F451]

You could also use KTM triples and the matching KTM axle, bolts right onto the Alta.

 

[Trauma154]

I have a 2017 & a 2018 MX with the junk 4cs front forks . I just picked up two sets of 48AER FORKS. Does anyone know if the only difference is the front axles or are the bearings and races different as well? If it’s only the axles are they the same as the KTM axles?

My 2017 is apart right now with the air forks on it. The 2017 Alta forks have a roughly 10mm larger gap between them. I will need upper and lower triple clamps for the air forks along with an axle, spacers, and a nut (called a screw by KTM.) The wheel bearings can remain the same because the spacers fit inside them. I'm going to buy a 2020 KTM triple clamps head set. I will reply here to report how it goes.

 

[Jayfox911]

My 2017 is apart right now with the air forks on it. The 2017 Alta forks have a roughly 10mm larger gap between them. I will need upper and lower triple clamps for the air forks along with an axle, spacers, and a nut (called a screw by KTM.) The wheel bearings can remain the same because the spacers fit inside them. I'm going to buy a 2020 KTM triple clamps head set. I will reply here to report how it goes.

The newer triple clamps will not work due to the Alta have a larger frame where the triple clamp stem goes through. You will need 2014 or older triple clamps if look for stock. The part that hits on newer upper clamps is the handle bar clamp but on the underside of the top clamp. The older Ktm top clamps do not use the nut because they screw into the upper clamp.

see my post about the conversion I did. However when I switched to a newer Alta (less hour) I didn’t put the Ktm clamps back on and stayed with stock.

Cone valve wp forks on an Alta

 

[snydes]

My 2017 is apart right now with the air forks on it. The 2017 Alta forks have a roughly 10mm larger gap between them. I will need upper and lower triple clamps for the air forks along with an axle, spacers, and a nut (called a screw by KTM.) The wheel bearings can remain the same because the spacers fit inside them. I'm going to buy a 2020 KTM triple clamps head set. I will reply here to report how it goes.

I’m not understanding the need for changing the clamps? The AER’s should go right into those Alta clamps and then all you need is the smaller axle and wheel spacers for the Alta wheel. Am I missing something?

 

[Neal 408]

Thanks, I have had spacers made for the conversion, and they have been alodined a gold color. They work with the stock triples, I tried a set of KTM triples and they wouldn't clear the upper frame tube. If you are interested in the spacers I listed them in a post earlier. I have 6 or 7 sets left. If you are interested they cost me $55 per side $110 per bike, since it was a small run of 15 sets. The only other thing you will need is an axle and nut, and a set of fork guards for the AER forks. I have them on my 2018 and 2017 models and its working great.
Cheers

 

[F451]

Just for clarification, the '14 KTM 500 EXC triples bolt on with no modifications, no interference with the fork stops.

Those KTM triples have 20 mm offset, stock '18 MXR offset 22 mm (can also be set to 18 mm) btw, something to keep in mind. I love them, haven't noticed any difference in handling for the trail riding that I do.