Oversteer help

[UMI Sales]

The foot high box thing is a great tip. Build some boxes like that with a step so the scale pad can be at one end and a flat spot to the other. So you can move the car back and forth onto the scale pad. Make sure you get wheel chocks for when you're under it. Never let anyone roll under without the chocks in place.

Weight outside the wheelbase is bad. Weight on the axle is ultra bad.

Unfortunately your left side weight is helping you a little bit right now. You need to get that down since you'll be up front and be in tech. 😀

I'd shoot for 52% cross weight. Cross below 50% really helps the car turn well but on these big cars is an invitation for a loose condition 15 laps into a run.

We had good luck before melting lead into a cookie sheet. It was really thin (obviously) and could be formed and placed under the floorboards and lining the driveshaft tunnel. We always had to paint our lead white and put our number on it.

Did you measure your ride heights? How is the car sitting? Do you have ride height adjustment via weight jacks or shims?

ramey

 

[ReQ]

We form our lead with small bread pans, makes nice little 30lbs bricks, we also have different size valve covers, have not thought of the cookie pan idea, seems like it could work really well for getting lead on the floorpan, we also have to paint our lead white with our number on it as well

most of the lead we have came from wheel weights, we have been cleaning all the local tire stores out 😳, we need around 380lbs of lead on the car to get the weight up, when we scaled the car I was in the car with full gear in my lap, steering wheel on the shaft etc., just like race night right down to the half tank of gas, though we will probably have more than that after each race, so the fuel ill change things too

tire pressures were pretty standard since we do not yet have ours nailed down, RF 50 RR 45 both left side at 25, which is within range of what we have been running, we have 2 different tires that we are going to swap around to get our stagger right, so we can run higher air pressures in the left side, hopefully keeping the tires from rolling so hard

we did bounce all 4 corners of the car to settle it and forgot to measure our ride heights, it was kind of a rush job as the shop we were at was closing, wanted to make 100% sure the floor was level so we took it somewhere, our main goal was to get the total and see how much under the legal weight we were, and to get a general idea of where to put some lead for now, working on getting a new slab poured that is completely level, just for scaling cars

now that we have some weights and know that the car will need 400 more pounds of lead, does this mean I need stiffer rear springs? not allowed to run spring rubbers or any thing on the springs, no adjusters of any kind, not even allowed to run a spring perch on the rear axle, spring pig tail springs only

 

[ReQ]

Took the car out last night and discovered a big problem with the rear end

First night we took the car out last season, unpainted with an automatic, just to see if the engine would preform(different engine then) the right rear wheel bearing was leaking and you could shake the right rear tire back and forth, went back to the drawing board as our engine just wasn't cutting it

last night the first few laps just warming up felt great, the new shocks made a noticeable difference, but as soon as I opened it up and dropped down into the first turn, rear swings around violently and MAJOR wheel hop, much worse than last week, after a few laps of trying to wrestle this into shape every turn, I came out of a corner and it quite pulling, RPMs shot through the roof and I backed off, pulled off the track and the right rear wheel bearing was pouring grease

you can grab the right rear tire and shake it around, and hear metal grinding inside, beginning to think my rear end has been big problem the whole time, I have no experience with these things, what could cause the wheel bearing to go bad so quickly? and could this be the wheel hop cause, I have a spare 8.5 10 bolt from another g-body

anything I should do before swapping it in? gotta change the ring/pinion, I have a spare set of 2.73s with an LSD

 

[UMI Sales]

Oh my. Absolutely that could cause your wheel hop.

Did you fix the source of the leak after last season? It could have been going bad then.

In the RR of these cars, normally they're the last to fail as they're lubricated all the time with oil going up the axle tube. That's also why the leak so much...

Seals-it makes an inner seal to keep oil from climbing up that tube and starving the R&P.

Once you get a good diff in it with solid bearings, your wheel hop might disappear...

ramey

 

[pontiacgp]

I agree with Ramey, a wheel that is flopping around will cause the car to do stange things...take about Strange they put out axles for a metric and some tracks make you run the right axle upgraded since that axle takes alot of punishment on a track. If the bearing grenaded you can bet the axles is junk as well. If your going to use the 8.5 you should be ok with those axles. I think you said the 2/73 gears work well at your track. If you are allowed to run the LSD, which really surprises me the track would allow that, you don't run stagger with a posi. You still need the stagger up front tho...

do you have a link to your track?

 

[ReQ]

took the rearend out of the car today, we didn't check much when we replaced the wheel bearing, just stuck the new one in, turns out the axle tube is pretty screwed up where the bearing goes, let the seal push into the bearing and eat the seal out pretty good, so we are swapping out our whole rearend

another problem was a slightly bent lower control arm, we really did not pay enough attention to the back of this car when we built it 😳 I am really surprised it actually made it around the track at all, I may not know how to drive it next week.. so use to having an animal underneath me by this point

I am slightly embarrassed to be honest, cannot believe I would let this much slip, such a beginner mistake to try and cure symptoms while ignoring the real problems

anyhow, yes we are allowed to run pretty much anything we want in our rearend, welded/spool/lsd but we may just weld our new rear, the LSD I have is in my 74 Nova and I don't really know if I want to start stealing parts from it for my racecar, I also have several control arms I am going to sort through, find the best ones and weld braces inside them, then stick my solid bushings in the rear, should feel like a whole new car next week

 

[pontiacgp]

no need to feel any embarrassment..at the beginning of the year with a new car you can expect anything and the first few runs are to find out what you found on the car. A friend of mine made it only about 10 laps in a nationwide race last year cause someone built the rear end wrong and it burnt up. Whoever built that rear needs to be embarrassed...

for the rear end if you can run a posi run it...it takes all the guess work for the stagger out of the picture so you won't be burning up any tires and you'll get out of the corner nicer and with more speed. On the other side the spool works better then than welding the gears. The spool spins thru the oil easier so there is less drag

 

[ReQ]

Alright, new rearend is in the car, we braced the control arms inside, then boxed them with thin gauge steel so they are extra beefy, new solid "spherical" bushings as well, did a little test down the street (we live on backroads) from a rolling start making the rear spin, don't like dumping the clutch, there is no more wheel hop, before even in a straight line it would bounce slightly, feels smooth as butter now

got more weight in the car and scaled it again, we did alright just guessing when we threw the lead in it, figured we would move it around but its just about as good as we can get it I think, suspension settled, correct tire pressure with half a tank of fuel+me with gear

total=3411
LF=874 / RF=805
LR=968 / RR=764

54% left side exactly (perfect)
51.9% cross
50.7% rear

our left side will be a little too high with a full tank, not sure what kind of tolerance they will have for left side weight, also wonder how the track scales will read, some things may be different, as far as we can tell our scales are correct, used a 100lbs dumbbell on each pad and they all read 100lbs, stuck the dumbbell on 2 sets of bathroom scales and they read 100 on the dot


the only problem I can see at this point are our springs and ride height, forgot to check after we put weight on the car but I am sure it dropped, bouncing on the left side causes the suspension to bottom out though it has a good 3-4 inches of travel down, would the left side drop enough to bottom out on the track? the right side feels alright though, should we be running stiffer springs now?


the whole car feels completely different just from bouncing on it, I am very excited to take it back out this Thursday

 

[UMI Sales]

You are definitely on the right track!

You can start low on the left side since it raises up during cornering (within reason).

Sounds like a track session then report in. I'm excited.

Take good notes. The info you posted about the weights was a good example of important data.

Ramey

 

[ReQ]

just got back from the track, did some hot laps with 4 other cars in my class, including the class champion 2 years running and the runner up, had some overheating problems but on a test and tune night, I have the fastest car in the class so far, I can't run it quite as deep in the turns as everyone else, so they gain on me a bit, but coming out of the turns I pull them 3 car lengths

if I run too deep in the turn it will push on the way out, not sure why, maybe the stagger since I only have about 1/2 an inch in the front, I got 1.5" in the rear which is what I need to run on this track for the rear, the front tires make a lot of noise even when I am just idling around the track, my toe should be correct as per factory specs, technically we are not allowed to change it, but in the interest of "testing" I think I may change it next Thursday, since its our last test an tune before the season starts

how should I set my toe adjustments on the front? 12 degree banking on the track, 225' diameter turn running the racing groove, if that matters.. I know it does for stagger and camber

either way, we are going to change the fan for next week, if it cools it off it should be ready to race, feels like a completely different car now, very happy with how ran tonight