Wheel hop help

[PONTIACMAN3]

Hey guys just got my car out for the first time of the season. I mini tubbed the car and put hoosier et 29x11.5. I also put in an anti roll bar and coilovers w double adjustable strange shocks. I eliminated the old lakewood lift bars I had and put double adj upper and lowers. I set the car slammed with the lower control arm parallel to the ground. When doing my burnout I have some small wheel hop that I never had with the old setup, car also seems to be spinning off the line and 60ft has slowed up........any ideas...... stiffen shocks? raise the rear ride height to change the lower control arm geometery ???? any input or thoughts would help. also running pinion angle at -2 thanks

 

[UMI Sales]

Hey Pontiacman3. Do you have LCA lowering brackets at all? If not, you may have to raise the rear ride height a tiny bit to keep your LCA's from going past parallel. Can you stiffen RR shock?

ramey

 

[PONTIACMAN3]

I do not have relocation brackets, I ditched the lift bars last year and use the double adj control arms since the car makes alot of power, just sucks cause the car looks great lowered, any thought on intervals of raising it to get the hop to go away, there is not a ton just a little on burnout and does not seem to be any on launch. I do have strange 12 setting double adjustable shocks set at 3 rebound 6 compression on both sides, car weighs 2900 with me in it 4:56 with a glide 5500 converter

 

[tiedyemike8]

I agree with ramey, try small adjustments to the ride height, and also small shock adjustments, but I would only do 1 change at a time. No simple "cure all" for things like this. If raising the ride height helps, you can make new mounting holes for the lower arms to keep the new angle and allow you to lower the car back down. Make sense I hope?

 

[UMI Sales]

My ride height recommendation would be to put zip ties on your rear shock shafts and check after each run. You can use the zip tie location to determine if one or both LCA's are going positive angle (up toward rear). Since your car is leaving pretty awesome already it may be a matter of a half inch. If it's consistent in how it launches you could nail it on the first try. Keep in mind wheel hop can give you "untrue" shock travels. If it's too bad you may need to launch easier to get a true (minus a few thousandths of what would be true shock travel).

Do you have adjustable shocks on all four corners or just the rears?

Oh, and tiedyemike8, I noticed your sig says 434... Stock block or aftermarket? How big can a stock SBC 400 block go? Building an autocross car

ramey

 

[tiedyemike8]

That's a great idea with the zip ties, I'm going to remember that one!

It's a Dart Little M block, Scat superlight crank, Scat 6" rods, JE pistons.

You can build a 434 out of a stock block, but most don't recommend it. Grinding rod clearance along the pan rails gets you really close to the water jackets. Plus, stock 400 blocks are very prone to cracking, they're not particularly strong, even with block fill. If it's going to be a big dollar motor, spend a few more bucks on a solid block.

 

[UMI Sales]

Thanks for the 434 info. I've pretty much resigned to the need for an aftermarket block. Will the 420 kits work or does the grinding need to be about the same? My problem is I have a pristine stock bore 400 that would clean up perfect at +0.010".

The zip tie thing is from my circle track days. Now that I'm working at UMI I get to teach some and more importantly learn some. The drag knowledge around here is awesome.

 

[PONTIACMAN3]

thanks great info guys, remember my wheel hob is only occuring during the burnout, it seems to have none when I launch?????? any more thoughts looks like its either going to be stiffening shocks or setting more of an angle on the lower control arms, any thoughts on pinion angle in this equation?

 

[UMI Sales]

Hey PMAN3. Do you daily drive this monster at all? Pinion angle can get sketchy if there's too much on a street car. Your 2 degrees is pretty common. You could try 1/2 more degree.

If you could improve anything about your launch, what would it be? You mention hopping on burnout only.

Does your car leave straight?

ramey

 

[grizwald]

what about going back to LCA relocation brackets instead of raising the car? wouldn't it have the same effect, but with more adjustability? not sure that would stop your wheel hop during the burnout, but would help with spinning off the line, i would think.