Setup Advice for a Rear Slide

What engine category?
Which model Hoosier tire are you running?
What tire pressure?
How old were the tires?
Are the track conditions you described similar to a “typical” race weekend (or practice weekend)?

KA100-Masters (380#)
Hoosier R60B
11 PSI Cold
8 Heat Cycles = Race Day + 4 practice sessions
Never been on this track with this kart but I suspect track had very little or no rubber.

TJ – What about moving the seat back? Since the front seems to work much better (turns in good) than the back.

Have you had the kart for long?

This caught my attention. Typically the rear of the chassis is set high and is rarely lowered. This gives me a suspicion that the chassis setup might be too far from standard to begin with… Might be worth going back to a “standard” base setting if you can get one and then tune from there.

Worth a shot. Should give more effective weight transfer on the rear wheels with a sacrifice in front-end pointiness. If it has good turn-in already, which it sounds like it does from the rear sliding issue, then moving the seat back would be worth a shot.

For me, seat moving is generally a fairly big change though. I would run through your smaller adjustments first to see if you can tune it out with track widths or tire pressures or front geometry first before actually moving the seat.

James makes a good point in terms of verifying the setup vs. manufacturer baseline. I would start here, and then proceed with making small adjustments. Tire pressure would be a quick and easy change. With the R60B being a harder tire and the track conditions being low grip, you may benefit from running higher tire pressures. I’ve found the R55’s to lose a noticeable amount of grip after 4-5 sessions, so you may be at that point with yours to where they’re starting to fall off a bit.

Other ideas would be to narrow the rear, or try longer rear hubs. If all else fails then you could try the ride height and/or move the seat.

James – Always good advise to go back to baseline, which is what I started with. Rear was at mid position, medium axle, etc. The kart works good with baseline at another track that gets more karts. This track is in the boonies, so less traffic and hence why we can still run there.

I think the low grip condition is really exaggerating the slightly too stiff chassis coupled to the lower grip Hoosiers. A TonyKart was also at track and he seemed hooked up, same class, same tires with equal condition.

What I learn will likely not be transferable to the my regular track but I can’t resist the challenge of getting the setup so that will work on a low grip track.

Thanks for the inputs. I’m going radical: Soft seat (VGR11), slightly back and raised with the chassis rear all the way up, to see if I can make it do something different.

As I was reading thru this from the top I was thinking – go back to the baseline. Seems like you guys thought of that but that is where Larry started. Alan Rudolph had a funny story today on the EKN’s Face2Face segment about going back to the baseline.

From the baseline, if I go to track with limited grip, here is what I do.

  • aluminum hubs
  • narrow the rear 5mm each side
  • softer axle
  • use wheels that give more grip center-off (you mention going from MXP to MXP so I am not sure what you did here). I don’t know OTK wheels that well but I think you want the MXJ here.
  • take some caster out

Instead of moving the seat up and back, can move lead to the back of seat and mount it up high? And can you sit on something that raises you up 4-5mm. I hate moving the seat. Such a hassle.

Just my 2 cent – you have some of the best minds working on this already.

Paul – Thanks for carefully reading my post. I had MXC on and need the MXP, the heavier thicker non-forged TonyKart wheels. Yes, I have aluminum hubs, I’ll try narrowing, it does work better narrow.

With regard to taking the caster out, that makes sense because the front work much better than the back. I thought of that while at the track but that seemed so counterintuitive to what is normal at this track, so I dismissed the idea. Usually, the front is the problem, so I always add caster at this track.

Get the outside rear to “dig” in, seems like the right idea. Seems like lowering the tire pressure might be the trick but that doesn’t fit my past experience but I’m going to try this. I have read that in big race car tires, lowering pressure increases tire temps.

Some great ideas.

Do you have the stock Croc wheels?

6 posts were split to a new topic: Tire Dynamics

I saw Evan’s post on the Croc wheels so I was hunting around the internet to find what wheels they use. Instead, I found this which you may already have. If not, maybe it is useful.

Lower tire pressure - sounds right to me if you are getting enough heat in the tire already.

Wheels - The stock Mad Croc looks like a 3 spoke magnesium. Interested to know how different it is from the MXP and MXJ. Btw, I believe the MXP has been superceded by the MXJ.

Now for a crazy idea: If it is not too hot, you might even want to try an aluminum wheel. This is something that I am working on with a driver that I work with who is struggling with center-off grip on his SSE 175cc for street circuits / temporarily layouts that don’t have much rubber / grip (cooler days). I will let you know how it goes.

Do you guys mind if I split the tire discussion off to a new topic? It’s a science all of its own.

Hey James – Whatever works for the forum, but it’s my guess that TJ and I have probably beat this one to death (with no conclusion…).

The stock Croc wheel for their tag chassis is the KKart model 2004, which as you noted is a three-spoke magnesium rim. The manufacturer’s website seems to have vanished, but it’s the same wheel that GFC uses on their tag chassis, for reference. Also the same as the gold wheels used by DR, though DR uses the 67mm (CRG) bolt pattern version.

It’s a fairly stiff wheel that produces a moderate amount of grip, and is suited to a wide variety of conditions, similar to the Douglas Low Volume in my opinion. This wheel should be better suited to the low grip conditions than the MXC. It’s been 10 years since I’ve used an MXP, so I can’t say for certain how that will compare, but it will definitely be better suited to the conditions than the MXC.

Paul- this may be better suited to a PM convo, but as an SSE owner I would never use an aluminum wheel outside of wet conditions. I would instead target ways to increase the load on the outside rear, similar to what we’re discussing in this thread, or work with the driver on throttle application (integral part of SSE driving style).

Sorry if this tip the scales for @KartingIsLife to split off into another thread, but I just have to know what the hell this means:

No. But the stock Croc wheels might be better. I always use Tony Kart wheels on all my karts regardless of brand. I think the MXC are the best in hot stick conditions. Why I ran them at this cold and no grip track, I was lazy and didn’t know how bad it would be. The MXP are good in colder and less grippy tracks but a big solid aluminum wheels might be the best.

To super simplify it, the amount of side grip available.

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Evan, thanks for the info. I searched the website for info on the Kkart wheels but could not find any. Do you have a link? I am putting together a wheel comparison sheet and would like to include the KKart wheels if possible.

Yes, I know about aluminum. Just something we were gonna try on a street race. While it was not recommended, the kart wheel manufacturer that I work with tested an aluminum wheel on OK/KF karts a few years back in cold weather conditions and they found it to be good. Interestingly, none of the race teams work with were interested in it though. This was an anecdotal story they told me so I don’t have any hard data.

Can’t find any sort of web presence for them anymore, so I’m not sure if the company exists any longer. I know that they did exist at one point, but it’s sometimes tough to tell who actually makes what across the pond.

It looks like Righetti Ridolfi makes the same wheel: https://www.righettiridolfi.com/en/product/search/wheels-1/magnesium-1/elz-type

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