Wheel Hop

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blewbyoutobad said:
slapper bars should not be used on Mopars.
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Do you know this from experience?
With Mopars, you put the bumper UNDER the eye. I fail to see how that would have the potential to bend the spring.
I have no experience with slappers and SuperStock springs tho, just with street springs.
I agree with @MOPAROFFICIAL and others, on everything. and once you get the pinion under control, things will get brighter.
But one thing I am confused about; those 17s are not designed for drag-strip starts in the first place; why are you trying to re-invent the wheel. Since they don't work at 3500, don't go there.
Another thing that confuses me is why you are trying to run a 3500 to 7000 cam with 3.23s.
So clue us in, what cam specs are you running?

I once ran the 292/292/108 Mopar cam with a 4-speed and 3.55s, on the street. It didn't care how low or how high I launched at; it never wheel-hopped, never bogged, never complained, just motored. But; to be fair, she was running 11.3Scr and 170psi cylinder pressure.
Are you running a vacuum-secondary carb perhaps? If yes; my guess is your tune is also causing problems.
 
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AJ/FormS said:
Do you know this from experience?
With Mopars, you put the bumper UNDER the eye. I fail to see how that would have the potential to bend the spring.
I have no experience with slappers and SuperStock springs tho, just with street springs.
I agree with @MOPAROFFICIAL and others, on everything. and once you get the pinion under control, things will get brighter.
But one thing I am confused about; those 17s are not designed for drag-strip starts in the first place; why are you trying to re-invent the wheel. Since they don't work at 3500, don't go there.
Another thing that confuses me is why you are trying to run a 3500 to 7000 cam with 3.23s.
So clue us in, what cam specs are you running?

I once ran the 292/292/108 Mopar cam with a 4-speed and 3.55s, on the street. It didn't care how low or how high I launched at; it never wheel-hopped, never bogged, never complained, just motored. But; to be fair, she was running 11.3Scr and 170psi cylinder pressure.
Are you running a vacuum-secondary carb perhaps? If yes; my guess is your tune is also causing problems.
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I used that cam to get the car on the road. I had a set of 3:91s and they were bad once I drove the car, so I installed the factory 3:23s. So now waiting to get the funds to rebuild the pumpkin. Its interesting why so many people say no slappers on Mopars. I have always been told that and I think once mis-information gets out there its like a run away train. Mopar Officials video was very good and made sense. Never seen that before. This is a street car, not for the strip. Yes on the 750 vacuum. Thats the next thing after the gears. The cam is a solid Lunati I bought back in the 80s. 249 @ .050 and 508 lift. 108 LSA 31 degrees overlap. Pulls hard above 3500. Motor has ported X heads and RPM airgap.
 
blewbyoutobad said:
I used that cam to get the car on the road. I had a set of 3:91s and they were bad once I drove the car, so I installed the factory 3:23s. So now waiting to get the funds to rebuild the pumpkin. Its interesting why so many people say no slappers on Mopars. I have always been told that and I think once mis-information gets out there its like a run away train. Mopar Officials video was very good and made sense. Never seen that before. This is a street car, not for the strip. Yes on the 750 vacuum. Thats the next thing after the gears. The cam is a solid Lunati I bought back in the 80s. 249 @ .050 and 508 lift. 108 LSA 31 degrees overlap. Pulls hard above 3500. Motor has ported X heads and RPM airgap.
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Think I read that in a MPchassis book, in 1990....
 
I think the "don't use slappers on a Mopar" came about only because mopars generally don't need them. Unlike Ford and gm, Mopar springs have a short stiff front segment for axle control, and a long rear segment for a soft ride. Super Stock springs have a stiffer yet than stock front segment. The purpose of a traction (slapper ) bar is to stiffen the front segment, so that it doesn't wrap up/unwrap when power is applied. The wrap/unwrap is wheel hop.
The usual fix is stiffer shocks, or slappers.
 
Slapper Bars worked well on the mono-leaf rear spring cars where the front half of the spring would "wrap" - literally twist into an "S" and snap back straight causing the wheel to hop, again, and again.
Slapper Bars created a solid link to the front spring eye to the shock plate, preventing spring distortion
Preload could be adjusted by rubber bumper .
Calv took that geometry and made it shiny and charges a fortune for it .

This wasn't nec with the mopar multi-leaf, short segmented springs, as explained in the Mopar Chassis manual.
Those that read the manual, learned that clamped front segments did what the slappers did, a solid link to the front spring eye, preventing "spring wrap" .
The adjustable pinion snubber controlled the torque, and weight transfer to the rear axle, - planting it .
So Mopar guys that know, point and giggle at slappers on a Mopar, cuz the owner and chebby guys don't know !
This doesn't mean slappers won't work on a Mopar, just unnecessary, - if you know .
That Chassis manual was our Bible back then, launching the Max's !
 
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blewbyoutobad said:
Look at this post on B Bodies. This why people have a bad impression of slapper bars.
Traction bar help
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I haven't read that whole thread you referenced, but....
I had those exact slappers on my 57 Chevy (370horse 350/ Muncie). They clearly aren't installed correctly on the b-body. Those need to be slid forward or backward till the snubber is directly under the front spring eye, and nowhere else!
Then, adjust the height of the snubber till they work the way you want. Simple as that.
 
blewbyoutobad said:
The cam is a solid Lunati I bought back in the 80s. 249 @ .050 and 508 lift. 108 LSA 31 degrees overlap.
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That looks an awful lot like the Mopar 292/292/108 cam I ran. In my combo it peaked at about 5400, and was all done by 6000...... but I revved it to 7000 anyway, because a 360 revving 7000 thru dual 3" exhaust is such a rush, lol .......
The thing is, She would idle down to 550 in starter gear of 9.44(manual trans) at just 5* of advance, and would start taking throttle right away. By mid to late teens she would take WOT with no drama, but to be fair, this was with a 750DP carb. She did not like the Vacuum Secondary type carb, in the turns.
Here is my timing for that combo; 14 Idle, 34 power at 3400 with the OOTB Edelbrock alloy heads, with a slope of ~.8* per 100 rpm,beginning at ~1000. With this, it would run on 87E10 full-time. As for vacuum advance, I cut the stops down, to get ~22 degrees, and brought it in as fast as possible. Additionally I installed a dash-mounted, dial-back timing delay box with a range of 15 degrees. I set it to get 6* advance/9* retard. This got me down to 14 less 9= 5* for idling around the A&W parking lot without bucking at ~4.5mph, and up to ~53* for cruising on. As previously stated this combo ran at 11.3Scr with a Quench of .028, with a CCP of 170. Peak torque was around 3800rpm.
But the VP was only 135 according to the Wallace Calculator, Read about VP here; V/P Index Calculation
and therein was my problem. With 3.55s and no torque convertor, the bottom-end was a lil soggy, and 6000 was over 50mph/ 60 was 7000 both in first gear. I had the wrong rear gear, and without an overdrive, I was unwilling to run any more. So I pulled that cam out and sold it.
The point is this; At 11.3Scr, I didn't think I wanted to run any higher than that, so I believed that I was maxed out for pressure (170), and the VP was only 135. I really wanted more torque, and was willing to give up useless rpm at the top. That was year 2000.
So I pulled the cam and in it's place I slid a 270/276/110 which was 223/230@.050 .. At the same time. I reduced the pressure with a thicker headgasket (.039), to 10.76Scr. This jumped the pressure up to 180psi with a new VP of 158.
Holy cow what a difference! The power peak came down to around 5000, but it still revved to 7000. But shifting at 5500 got me 47 in First and 65 in Second. With such a high VP, I could get rubber in Second gear any time I nailed it; so I was a happy guy. Now I needed bigger tires.

Now, if you want to get an idea of your power curve, all you need is one of those accelerometers. Mine is a G-Tec Pro SS, suction-cupped to the windshield; Pretty cool tool.
 
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Joey4speed said:
Rear wheel hop?
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No, the OP meant to state that he has a '98 Neon.....
















1 laugh 5.gif
 
Every time I had wheel hop issues it was cured by shocks and shock tuning. No slapper bars, snubber or clamps required. Anything beyond that and I move to a Caltrac/mono setup.
 
I like the caltrac/mono leaf springs and rear adjustable shocks, it works when properly set up. And also works on most of the fastest stock suspension Leaf spring cars in the world. I’ve used them on the last two street strip cars that I have owned with excellent success in controlling wheel hop and Improving traction.
 
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Problem appears to be solved.Lowered tire pressure from 35 (Discount Tire Installed ) to 28. Also advanced timing and launch at 2k instead of 3500. Leaves hard still spinning tires but not as bad as 3500. If it continues to run like this I'm not touching it. Thanks everyone for your input. If the wheel hop rears its ugly head I'll post again. It's fun to drive again.
 
blewbyoutobad said:
Problem appears to be solved.Lowered tire pressure from 35 (Discount Tire Installed ) to 28. Also advanced timing and launch at 2k instead of 3500. Leaves hard still spinning tires but not as bad as 3500. If it continues to run like this I'm not touching it. Thanks everyone for your input. If the wheel hop rears its ugly head I'll post again. It's fun to drive again.
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That's great, how we all missed tire pressure is beyond me, it is a major factor.
 
PG Duster said:
Is there a Mopar engine in that Ford Cortina?
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Nope sorry. Was originally gonna put a (iron head) 440 in it, but I decided it would be too nose heavy, and headers would be a fortune. It came with a set for a small block Chevy, so it ended up with a brodix headed 406.
I also test fit a 454, and found that a set of headers I had for a c10 would work, but then I still had the weight problem, so..... sbc it was.
 
blewbyoutobad said:
Problem appears to be solved.Lowered tire pressure from 35 (Discount Tire Installed ) to 28. Also advanced timing and launch at 2k instead of 3500. Leaves hard still spinning tires but not as bad as 3500. If it continues to run like this I'm not touching it. Thanks everyone for your input. If the wheel hop rears its ugly head I'll post again. It's fun to drive again.
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That's great! Sometimes we forget how greatly the tires can affect the suspension. Glad you figured it out. Now we want a tire smoke video.
 
The key to this whole problem with 3" sidewall tires is, you cant drop the clutch at 4K. By advancing the timing to where I can launch at 2k and not sidestepping the clutch but have the clutch engagement at the right spot when I nail it. It will still spin at 2k but not as much and it launches much better. So the fix was lower air pressure and perfect clutch engagment = no more wheel hop. I guess this is what happens with 17" wheels and trying to keep the overall tire diameter the same as stock at 25.7". This combination does not like 3:23s at all. Future now holds some 4:10s so I can run a taller tire like a 255x45x17. Those are 27.2" tall with more sidewall. Thanks FABO for all your advice.
 
blewbyoutobad said:
The key to this whole problem with 3" sidewall tires is, you cant drop the clutch at 4K. By advancing the timing to where I can launch at 2k and not sidestepping the clutch but have the clutch engagement at the right spot when I nail it. It will still spin at 2k but not as much and it launches much better. So the fix was lower air pressure and perfect clutch engagment = no more wheel hop. I guess this is what happens with 17" wheels and trying to keep the overall tire diameter the same as stock at 25.7". This combination does not like 3:23s at all. Future now holds some 4:10s so I can run a taller tire like a 255x45x17. Those are 27.2" tall with more sidewall. Thanks FABO for all your advice.
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According to tire size calculator, 255/45x17s are 25.7 tall. I've got Nitto 255/50x17s on the back of my 57, they are 26" tall on an 8" rim. Fit perfect. Just now measured slightly under 4"sidewall. Tire calculator says mine should be 27"tall, they ain't. Your 45 aspect will be shorter than my 50s.
 
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