Hi guys,
I drive a KR2 chassis manufactured in 2024. I recently came up with a severe hopping problem when touching the kerbs, I then used an OTK steel round front torsion bar which worked kind of well to me. I was just wondering if I should used the KR factory nylon front torsion bar? Would it be better performed if I used that one? I always feel like the factory part would kind of cope better with the chassis. Hope to hear thoughts from all of you.
Thank you guys so much!!!
Generally the KRs do not run the front bar. I have tested it on the BestKart (KR2) and found it really flattens the kart and doesn’t improve turn-in that much. These karts are designed to not use the front bar much.
In that regard, yes it might help the hopping problem by flattening the whole kart, but it’s probably not the correct solution for ultimate performance, because it will hurt corner exit speed by reducing how well the kart unloads the inside rear wheel.
Instead, I would suggest removing caster, narrowing the front track width, widening the rear track, lowering rear ride height, or going to a different axle. Karts hop because of flexing too much or transferring weight too quickly, which overloads the tire.
Gafrarar’s KR2 had a plastic front bar installed when he won KA Senior at SKUSA last weekend. I’ve seen others use similar plastic bar’s in the KR chassis, but I can’t say I’ve ever seen anyone use a metal bar with any success.
Dropping the rear ride height from neutral to low fixed my hopping issue. The problem I faced as a result was heavy steering, which was helped by then dropping the front ride height.
A front nylon bar is the norm here in Aus, full 32mm, ribbed, or reduced to 15mm dia.
But also with Steering Arm extenders for increased Ackerman, which appears to be a bit unique to our market, and usually a short axle
Do you know for sure if it was a KR2? I only ask because I know CDR has been testing the 32.
Interesting.
I’d say new castle is a pretty unique track in that regard though. For some reason really stiff setups seem to do better there. From what I can tell it doesn’t look like he had a KR axle in there either - my guess is an OTK H or HH.
From watching the videos it was clear that thing was FREED UP though, I’ll say that.
Just to throw some numbers out there… a solid cross section 32 mm bar is about 4 times stiffer than a 32 mm tube with 1mm wall thickness for a given material.
Delrin (what the plastic bars are probably made of) is about 60 times less stiff than steel, so a solid delrin 32mm bar will be about 15 times less stiff (60/4) than a 1mm wall thickness steel bar.
Another way to think of it is that the delrin bar is about 7% as stiff as the thinnest OTK round bar. This jives with what I feel as well. The plastic bar almost feels like no bar, but with just a touch more front end that feels more stable. Any steel bar radically changes the character of the kart for me.
What’s the softest plastic front bar available on the market? I’ve got a nylon but would like to go softer again.
nylon is barely less stiff than delrin, but the point I am making is, any of the plastic bars are almost like no bar in comparison to the stiffness of the frame, so the variance between them is likely to be negligible.
Can’t say definitively. I’ve heard others using an updated version of the KR2 with less wall thickness, so I assumed that was the hot ticket.
DPE carry nylon blades now.
Yeah that’s what I’ve got. Was thinking there might be a hollow plastic one out there.
As noted, the difference in plastic/nylon/Delrin bars is going to be negligible. Once you start being able to flex them with your hands it probably isn’t doing anything for your kart.
The plastic bars can dampen some resonance in the frame making it feel slightly more stable
Going to a stiffer front bar may slow the kart off the slow to medium speed stuff.
My general approach is to go as soft as I can in the front-end. This is to help the kart release off the corner and tuning the rate of lift with camber and castor depending on the situation.
I’d put the softest bar back in and slowly dial negative camber into the front to slow the inside rear rate of lift and see how it goes!
I always used to think this too, but you guys and your seat stiffness changes (much softer than frame) prove me wrong all the time.
Please note the following information: The KR/FA karts typically do not use a front bar like other karts, such as Birel, OTK, etc. However, kart setup can sometimes be quite complex if changes are not tracked or you are not close to the standard setting. If the setup is wrong somewhere else, adding the bar can compensate for the error and feel like the kart’s balance has improved, but that doesn’t necessarily mean that it’s the correct way to have a competitive chassis. It also depends on other factors, such as whether the chassis is bent or swaying, etc. (I don’t think this is the case since it is a 2024 chassis), but you never know if it has been used before or crashed before it was bought… many factors.
It’s also true that using factory parts is the best bet, whenever possible since karts are designed to use their OEM parts, especially parts that affect the flexibility of the kart, like axles, torsion bars, spindles, etc.
Have a great weekend!
Is the BestKart the same as the KR stuff? I was under the impression that BestKart was AMV designed and made, at least according to the last homologation document that I saw which may not be current now.