[David Goldman]

Does anybody know the true difference between a 40mm and 50mm axle? I used to drive a 40mm axle on my old kart, but now i have a tony kart with a 50mm axle, but most people in my class use 40mm axles. How do you know which one is better? Is one better than the other for certain applications? Please help!

Thanks,
David

[Sonja]

Hello David,

a 40mm axle is harder .Why?the axle thickness,here is 3mm.for the 50mm is there 2mm,the axle is weaker and she can better work.

what i know,weaker axles in 40mm is not allowed->is the safety.weaker is softer.

go to the BIREL, www.birel.com ,then go to Freeline ,then go to Axles Freeline,then download AXLE BROCHURE TO BE DOWNLOADED,theres the moduls .

sorry for my english ,is long time ago,when i go to school

Sonja

[David Goldman]

Thanks Sonja,

So when would using a 40mm axle be better than using a 50mm axle? Are there any times that using a 50mm axle would be a very poor choice?

[Sonja]

Hey David,

i send you go to BIREL,look there and see,

at Birel/Freeline you have six differents for the 50mm and from SKM you have three for the 40mm

SKM->A is soft,B ist medium and C is hard

i used the 40mm in my HAASE and i used 50mm in FIRST,i found three differents of choices is ok.

i need a soft for lot of rubber and a medium.

in a raceweekend my 40mm is broken,never had a 40mm and on the track is no kartshop,this is the problem here,spare parts of 40mm a rare.

and a 50mm in soft is softer ,when you used a 40mm,why?the thickness and the hardness,look at the moduls from BIREL,you have the answer .50mm are flexible then 40mm,why?the thickness here 2mm(50mm)and 3mm(40mm).

you understand me,

Sonja

[TJ Koyen]

Merlin's 50mm and 40mm are the same thickness.

I switched to 50mm this year too and as far as I can tell, it just made the kart feel more stable. I know at some tracks, people were switching from 50 to 40 or vice versa and dropping their lap times. Both will go fast at all tracks though. Julia Landauer used a 40mm all year in the 100cc stuff I think and I used 50mm all year and we both were fast and won races.

50mm is cheaper because that's what the karts come with stock so that's what I would continue to use.

I think if you look at most of the national competitors David, you'll see that the majority used the 50mm axle for HPV/Yamaha.

[Sonja]

Hello TJ,

you say 40mm and 50mm are the same?How thick?

in Germany,is 3mm for 40(axle)required->safety.For long time ago many people used 2mm(40mm) and many axles broken and burst.the racecommissioners are there hard ,no 3mm in 40 axle no start.

here in Germany race people with 50th and hoppypilots race with the 30th and 40th.

when you used the 40mm the peopleto laugh at so.

sonja

[TJ Koyen]

I think they are 2.5mm, I'm not sure though.

[RocK]

people still use 40mm??

[Mikko Nassi]

people still use 40mm??

I know right .

Remembering the talk when they were becoming popular the main reasons given were that they saved a bit of weight (do they?). The larger axle is able to use a thinner wall to obtain the same properties.

[TJ Koyen]

Well for the lower horsepower classes (Yamaha Supercan, HPV100), 50mm hasn't even been legal before this year in the States. They wanted to keep costs down by making people use the 40mm and not having to buy two sets of axles, bearings, etc. for each axle size.

[Sonja]

Hello,

@TJ, thanks for the answer.

we have a world formula class and there used the 40s ,the 50 are not allowed.They used the Briggsmotor.

I used in my Haase a 40s and i think a 50s is bad for my kart,why?the kart is from 1999. the kart is designed for the 40th.in this years you can used 40s an 50s.

the costs are high in kartracing.thats true.Go fishing or lot of another,thats costs .is in almost the same manner.

but,i love karting an race with peoples and it´s my hobby.

sonja