October 19, 2015 at 5:41 am #55548
Hi. I need to replace the bearings on my spindles – they appear to have broken on both sides, and are allowing movement in the kingpin.
I need 10x26x8.
The kart vendors have bearings for sale with no specs.
What bearings are recommended? Any specific brands that can handle the loads? Does it make sense to get ceramic – do they last longer?
October 19, 2015 at 9:37 am #55567
Another related question: rubber seals, or metal?
October 19, 2015 at 12:17 pm #55568Dan BrownParticipant
When I replaced the spindle bearings on our Margays I went to the local Kaman Industrial bearing store and purchased metal seal Timken bearings. Although the spindle doesnt rotate all the way around a good quality bearing that is precise and smooth helps the feeling in the front end. I am very happy with them, some of the no name imported bearings are questionable quality and good bearings aren’t very much more money.
How is the Ikart chassis working for you? We race against Stephano at Cherry Valley sometimes, he’s a great guy.
October 20, 2015 at 6:37 am #55611
Hi Dan. Thanks. And thanks for asking.
We finally (and I mean just this past weekend) have the ikart working well- my son had some very fast times at Englishtown this past weekend. He had the fastest lap in the pre-final till he had a racing incident on his way to the front, and had this front bumper fly off – it broke and separated from its support when it hooked into another kart’s rear bumper in a turn .
We’ve been having conversations with John Martin to get it working, and also took it to Indy/New Castle a few weeks ago. John Martin has been pointing out some basic settings that we had totally wrong, which I have since corrected – switching to long wheel base, lowering the seat, moving the seat back, removing rear shims, moving weights to top of back of seat, moving battery behind radiator, etc.
I’m discovering that it’s a very tunable chassis – both my 13yr old and I are learning a lot as we experiment with settings and he develops the language and understanding to give meaningful feedback so I can make adjustments.
Also, we recently discovered that with the chassis being low, chassis protectors create understeer, as does the front bumper which wears out on the bottom rear. We removed the chassis protectors, and figured out a way this past Sunday to raise the KG EVO front bumper (rubber hose on the bottom tube), and that seems to have made the kart work brilliantly all of a sudden, allowing my son to push with confidence as he now has front grip. (iKart has switched to a different bumper and fairing on their new karts, I suspect to fix this problem).
We’ve also always sucked at OVRP with this chassis and Rotax, with massive understeer problems, and I’ll bet it was due to the front bumper and chassis protectors. I need to take it back to try again now.
All summer, I’ve been pushing my son to find and explore the limits of the chassis – ie skid under braking in practice, go a little sideways, trail brake etc, which he was scared to do, given that it’s his first year with a 27hp engine, and the chassis understeered.
Once the chassis was balanced by eliminating the front bottoming out issues, he suddenly found speed! (A gear change helped too.) To understand how much of a difference the bumper height made, Raif did a 41.575 sec in quali (5th) with the rubbing front bumper vs 40.885 pole; Raif: 40.719 secs in first race (pre-final) with raised bumper after our kludge rubber hose fix – which was the fastest lap of the event in all classes for both days till that point, till he got knocked out!
And all this with a sloppy front end as both spindles rock due to broken kingpin bearings.
I’ve still not gotten him to lock up or go sideways under braking, so I think there is still more speed to be found. And he still needs to learn to pass more aggressively, instead of getting stuck following the driver in front.
So, we’re finally liking the chassis, and I’m learning how think about kart physics and how to adjust it. The last 2 races this Sunday were very exciting and gratifying for me, even though I screwed up by giving him the wrong gear for the final.
Stefano needs to try this chassis now!
October 20, 2015 at 7:06 am #55613
I decided to get EMQ bearings – Electrical Motor Quality, made with 52100 chrome steel bearings. Slightly less Rockwell hardness than ceramic, but should be more than good enough. Also tight specs for play.
October 20, 2015 at 11:39 am #55636Dan BrownParticipant
Glad to hear you have the Ikart working well. We bought a 2014 Ikart off Jarett Belge that he raced only 3 or 4 times the end of last season. So far my 13 year old has had decent succes with it, but we too are finding that tuning it is different than tuning the Margays, so I havent quite given Jake the feel he is looking for. We did race a night race in the pouring rain with it, and we both feeel there is no better chassis than the Ikart for rain racing. I widend the front out, raised it all the way up, dropped and norrowed up the rear and it drove amazing, almost as much grip as dry conditions. We will be racing it again this Sunday and it looks like rain is again in the forecast. I will let you know what how we do amd I am sure we will run into each other at the track soon as we plan on running every northeast track we can next season.
October 21, 2015 at 11:45 am #55683
Watch out for the nose scraping. Fixing that was key to finding the speed. Also move the seat as far back as possible.
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