RR tire temp way hot

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10-09-2018, 11:35 AM
jasjenh

RR tire temp way hot

Hi guys, Been away from the racing scene for a couple of years but got a chance to help a buddy with his car this last week. We went to a test session and i noticed after a couple of sessions his rr tire was extremely hot and the air pressure had risen by about 15 lbs. It explains why the car would go away after 10 laps. He says the car is real neutral in and through the center but loses drive as the race goes on. We are running 80lbs of bite without driver right now. Now i have heard two different opinions on this issue. raise the bite to load lr more. And to add more weight to the hottest tire to make it slip less. What are your opinions on this issue, or what adjustments would you try to correct the problem. Thanks for any input.
10-09-2018, 09:18 PM
ZERO25

Are both tires hot and are they spinning? If not , I would reduce stagger and/or increase bite. That may loosen entry off the gas though.
10-10-2018, 03:33 PM
jasjenh

The lr was warm to the touch and the rr would almost burn your hand. The biggest complaint is forward drive. My thought was the same as what you just said but trying to refresh my memory. Do you think to much rollsteer will cause the rr tire to scrub to much?
10-10-2018, 03:56 PM
cjsracing

I've had the same problem. After a 20 lap feature the LR is 130 degrees and the RR is 175 degrees.
10-10-2018, 04:19 PM
Matt49

Drivers are stupid...don't trust them :-)
Check to see where he had the brake bias set and if on 3-wheel. This will tell you everything you need to know about how corner entry handling really was. Especially on a slick track, drivers will always say the car was "good" on entry even if it is super tight because that feels pretty good.
Then take a closer look at your RR tire wear. Which edges are taking the biggest beating, side or front? If side, he's sliding the car too much. If front, he is likely spinning the tires due to the car being too tight in the center. Even a good driver will do this almost unconsciously and describe what you are describing. But it is a classing tight in loose off condition.
10-10-2018, 04:43 PM
jasjenh

LOL I tell him that all the time. The driver is the problem. I did check and he had all 4 brakes on. The balance bar is pretty close to center. It was a really dry black slick track. The outer edges seem to have a bit more wear. I actually believe him its not to tight but it does seem to slide the rr up the track a bit before it starts going forward and thats where he complains not enough drive. He is staying on the bars the whole time because the car doesnt change hike all the way around the track. Is that a bad thing?
10-10-2018, 05:09 PM
Matt49

Quote:

Originally Posted by jasjenh

LOL I tell him that all the time. The driver is the problem. I did check and he had all 4 brakes on. The balance bar is pretty close to center. It was a really dry black slick track. The outer edges seem to have a bit more wear. I actually believe him its not to tight but it does seem to slide the rr up the track a bit before it starts going forward and thats where he complains not enough drive. He is staying on the bars the whole time because the car doesnt change hike all the way around the track. Is that a bad thing?

Let me guess...about 4 inches of rear stagger???
10-10-2018, 05:19 PM
jasjenh

At one point he had 5 inches but i talked him down to 2 3/4 right now. But it has a lot of rollsteer i am guessing. It seems to have alot more hike then the rest of the local cars.
10-10-2018, 06:37 PM
ZERO25

Quote:

Originally Posted by jasjenh

At one point he had 5 inches but i talked him down to 2 3/4 right now. But it has a lot of rollsteer i am guessing. It seems to have alot more hike then the rest of the local cars.

If the car is better at 2 3/4 then that's your answer!

As a crew chief, I always took big swings at adjustments, to make sure I was going the right way. And sometimes what I thought was too big, wasn't big enough! Plain and simple, give the car what it wants!
10-10-2018, 06:47 PM
jasjenh

The car got a little better. Its about a mid pack car now. Just trying to figure out the next miracle adjustment. lol The rr was still way hot with the lower stagger but i forgot to check it hot. Probably was back at 5" after it gained the air pressure. I think i will add some bite and maybe take away some rollsteer and see what happens. thanks
10-10-2018, 06:50 PM
jasjenh

The problem its a local built car that went out of business years ago. So no support. But he is trying to update it and just have some fun running an older car.
10-11-2018, 08:08 PM
keeks

Wouldn't hurt to get some bleeders on the rear wheels.
10-12-2018, 08:54 AM
cjsracing

Quote:

Originally Posted by Matt49

Drivers are stupid...don't trust them :-)
Check to see where he had the brake bias set and if on 3-wheel. This will tell you everything you need to know about how corner entry handling really was. Especially on a slick track, drivers will always say the car was "good" on entry even if it is super tight because that feels pretty good.
Then take a closer look at your RR tire wear. Which edges are taking the biggest beating, side or front? If side, he's sliding the car too much. If front, he is likely spinning the tires due to the car being too tight in the center. Even a good driver will do this almost unconsciously and describe what you are describing. But it is a classing tight in loose off condition.

I've made a very conscious effort this year to get my car freer on entry. I honestly don't know what else to do to it if it is indeed to tight on entry still.
10-12-2018, 11:30 AM
jasjenh

Not sure if bleeders are allowed where he runs. I will check into it. Kind of forgot about those, been helping mod guys for so long they were never legal in those classes. He has made a lot of changes to free the car up too, thats why i questioned the rr tire heat. I guess he isnt spinning out yet on entry yet so loosen it up some more.