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Author Topic:   Braking Wheel Hop
outlawstock17
Member
posted February 21, 2004 08:48 PM
we had practice today. i had a rear wheel hop under severe braking after the track dried out. 3/8's semi banked with long straights and tight corners. stock '89 mustang swing arm type rear suspension with tubular upper links and 4-5 degrees pinion angle. 550-600 HP, 3000 lbs., asphalt takeoffs, 6.20 gear, detroit locker, 7400 rpms. 250 lb. LR spring and 225 lb. RR. both rear shocks are new afco gas 1096's mounted behind the rearend. LR spring might be bottoming out. could this be it? do i have too much rear brake bias or what? the car seemed a little on the loose side but not too bad for a dry slick track.


ctfarm
Member
posted February 21, 2004 09:16 PM
It sounds like you have too much rear brake.That causes wheel hop and looseness.A 90/10 shock will help to alleviate the problem or use less rear brake.If you can't use a 90/10, stagger mount your shocks with the left forward about 3" in front of the housing.


Ego Racing
Member
posted February 21, 2004 09:17 PM
550-600hp??

Check the shock travel and see if it is compressing all of the way or extending all of the way.
What shocks are on the front maybe it is nose diving and causing the rear to unload.


outlawstock17
Member
posted February 22, 2004 06:30 AM
030. over 351w, 6.200" rods, svo n351 heads, solid roller cam, victor jr., 830 double pumper, MSD, 1 3/4" headers, etc. HP number is a rough guess on my part. it's just as fast as everyone elses 600 HP dyno certified chevrolets, but my engine hasn't been dynoed.

stock macpherson struts on the front. according to the front rubber travel indicators, it's not nose diving. the rear shocks are getting almost fully comressed but they're not bottoming out.

it seemed like if i let out of it a little early the wheel hop was less severe or not noticeable. before the track dried out, the car was great. it was still fast with the wheel hop, but a little uncomfortable. the track was also very rough. it must be the brakes. i may try moving that shock. also, i wasn't the only one a wheel hop problem. several other were having it too.....even some of the sprint cars.

thanks guys. any other suggestions are welcome!

bobaluuu
Member
posted February 22, 2004 10:11 AM
If thats a #6 valving on the rear shocks I would think that was causing part of the problem. our car handled terribly with 6's
and 3/5 lr/5rr cured it.


Ego Racing
Member
posted February 22, 2004 05:57 PM
WOW......... Sprint car with wheel hop, bet that was fun to hold on to!
Try to soften the rear shocks. you many not need a shock that stiff, it will also let weight transfer to the back sooner to felp you get out of the corner.


Ego Racing
Member
posted February 22, 2004 06:08 PM
PS. We ran a DYNO proven 620 Hp CHEVY.
365ci, Honda journal Lunati 45# crank, 6.125 Rods, 14 to 1 pistons, 18 degree Bowtie heads 2.10/1.80 valves, Port matched Victor jr raised runner intake, and 700 lift roller cam, and a Bow Laws carb built for the engine it flowed over 1000cfm. To build it and pay a shop for the work it would have been about $8,000 to 10,000 dollars. We had an engine shop as a sponsor. He is now selling the limited late models engines for the Hooters LLM's at like $18,000. How is that for a 500hp motor. Castiron intake, Flat top piston, 500cfm 2bbl motor.


way2fast72
Member
posted February 22, 2004 06:09 PM
,outlaw, I would try a set of 94s on the rear,maybe be a little more balanced with the stock struts,also, the 90/10 shock is a great idea if allowed,dont get to much angle in it or you will add rear spring rate.

[This message has been edited by way2fast72 (edited February 22, 2004).]

outlawstock17
Member
posted February 22, 2004 08:27 PM
thanks for the input guys. this was my first time out on these particular rear shocks and i never had the wheel hop before. bad thing is i bought the shocks from jammin!

ego....18 grand for 500 HP....ouch!

i've NEVER seen a sprint car wheel hop before yesterdays practice. there's just not much suspension there to wheel hop......maybe the track condition was part of it....

way2fast72
Member
posted February 22, 2004 08:29 PM
the 96s should be fine on a heavy track.I always soften up on dry slick.


OppendikeRacing29
Member
posted February 23, 2004 11:29 AM
did u put more angle in the lower links? this could be causing it, i have had thsi happen where they are lifting the car so much (anit squat) that when u go to get on the brakes there is no wieght on rear tires. its hard to explain but if u think about it it makes since.


daddyrich
Member
posted February 23, 2004 05:19 PM
Hey jammin, I got a pair of 1097 afco's can you sell em for me, I haven't snared a bite on them yet. bob

------------------
Light it up, Baby!


outlawstock17
Member
posted February 23, 2004 07:24 PM
daddyrich, how much angle on the upper links is too much? they are pretty steep downhill and really short links. i have another set of holes on the frame that are a little higher.....i just hate to give up the forward bite. here's a link to a picture of the car during practice. notice how the RR tire is distorted. it has so much forward bite it's wadding the tire up in front of the rim and the tires are asphalt take offs. also notice the track conditions.
http://www.tulspeedway.com/Play7.jpg

[This message has been edited by outlawstock17 (edited February 23, 2004).]

pforsythe
Member
posted February 24, 2004 08:44 AM
Car looks great outlaw, hows that motor pull for ya? We are waiting to get our heads back so we can fire up the beast we bought from ya, I am very excited.


speedyd
Member
posted February 24, 2004 10:44 AM
pforsythe, engine ran like a swiss watch and pulled like a team of clydesdales, lol. good luck this season.

speedyd, thanks for the info.

rico 08
Member
posted February 24, 2004 04:48 PM
Looks like the track dried out before it got ironed in good,common on playday,i'd wait for a good track on a race night before i'd change anything if it were me.


outlawstock17
Member
posted February 24, 2004 06:28 PM
thanks ritchie, that's the plan...


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