Giant655

iTrader: (5)

I ran in the MWS in Dayton just last weekend. The track was like a skating rink, but I cooked a brand new shoe (8th scale open). Obviously the shoe was slipping but like the thread title, what causes that and how do I stop it?

azeroth

iTrader: (21)

i have only seen pictures of the track if it was like last years small and tight I
1 geared down (so motor spools up faster making the clutch engage like on a big track)
2 Closed up the clutch gap

some of the guys add weight as well (set screw in flyweights)

Roelof

Slip... is mostly caused by a to high engage of the clutch. Gap and spring pre-tension are mostly the factors. When setting up a clutch with a fresh shoe it is wise to set a smaller gap than you normally use, the first moment of use will deform and wear the first layer of the shoe, this can take 0.1 up to 0.2mm.
And check/correct the gap from time to time!

A cold clutch can have more slip than when it is warmed up. The heat will make the spring weaker and the gap smaller due expansion of the clutchbell. The first moment of warming up you have to pulse the engine so you will prevent large moments of slip.

Gearing: an early shift to a 2nd gear or a to high gearing on the 1st gear can give more slip on the clutch. Try different gears, for sure on smaller tracks use a smaller pinion or a larger spur.

gesser26

You can also polish the clutch bell.
Assuming the spring and end play is correct, take some 1200 sand paper. Spin the bell in a drill with a little oil on the paper.
This will help also.
Greg Esser

Giant655

iTrader: (5)

Im going to assume it was my gearing. I raced the weekend prior at my hime track, which is a bit larger, all season actually, and have had no issues. Popped up instantly the minute I hit that tight track

nitrodude

iTrader: (8)

I've had the same problem, a lot! While other drivers with the same car at my track do not. I believe part of it had to do with driving styles. About doing it at one track and not the other, you have to take into account that different tracks will have different levels of traction and different types of surfaces.

The way I've solved it is by using weights on the clutch weights

Giant655

iTrader: (5)

Yeah the surface had no traction!! Zero tire wear all weekend! Literally! I put a brand new shoe on the night after qualifying (bad weekend, only ran 1 lap that counted towards quali..) And shredded it pretty bad within...15 minutes. The shoe I replaced I ran on all season, zero issues, it dusted a tiny bit, but never had a run last long enough to kill it like the new unseated shoe

Racermac73

iTrader: (3)

Were you running the correct shoe for the bell... Black with aluminum, yellow or red with steel, ect

djiewie

new shoe`s are soft and will get a harder surface with the heat from the slip it has. its called running in the shoe. When run in the shoe will last longer.

What i do to all my clutch shoe`s is, i do the running in in the oven.
Bake them in a hot air oven for 20min on 200degrees Celsius.

Never had a problem with clutch shoe dusting. Shoe lasts a whole year.
Use 0.7 to 0.9 gap with hard clutch spring.

Maybe helpful to try one.

Have fun.

dan_vector

iTrader: (27)

If your gap is right 0.6-0.7 and spring tension 1.5 turns out from fully tight (serpent) then I'd be checking my clutch bell if I was burning shoes out that quickly! A worn clutch bell can cause burning out of the shoe.

Rick Davis

Another issue that can occur is if you slip a shoe bad enough to cause dusting quite often the teflon from the shoe will adhere or coat the bell , just take some 320 or 400 paper and clean till you see bare steel before reassembly or you'll ruin shoe after shoe.

GPXJOE

iTrader: (1)

I think before this thread becomes dysfunctional, I think its better to first ask instead is is there a benefit when the clutch is dusting, if it reduces laptimes or not. Because I saw.Robert pietch's car after a race he won and the.clutch was pretty much dusted. So why did he win with it? It's in his fb photos.

P2gee

I guess the first thing I check for when this type of thing occurs is to remove the shims for the inner bearing and the bearing itself from the clutch bell and make sure the bell sits completely down on the clutch shoe with no mechanical interference from the spring adjusting nut or flywheel mounting nut. It should be able to do this with a new shoe or even one that is worn

JamesHealey

iTrader: (1)

Make sure you run any new yellow material clutch shoes in first though, with minimal pre-load for a tank or two to brown them off so they won't burn up.

0.5 to 0.8 gap is normal on 1/8 clutches.

I run 0.5 on the Shepherd clutch, this seems to be the most consistent and works well over a long final.

As for end play, just set it to the minimum you can with the clutch bell still able to spin free.

The pre-load of the clutch spring just wind it all the way in and keep winding it back out a few turns until the clutch engages hard without any slip, you can do it the other way also wind in until it stops bogging down, either way your goal is the same, you want positive clutch engagement with minimal slip.

You can always do a lap to see if any dust is coming off the clutch shoe.

lagcisco

iTrader: (40)

Good tips here.

Been killing clutch shoes on my 977 lately, looks like my bell is warped.

I have a new bell now and will try the the whole sand/polish thing along with oiling the new shoe before use and running loose spring for breakin/glazing. Didn't do any of that before.