Educate me on drag shocks.

Educate me on drag shocks. - 02/12/13 08:24 PM

Have a friend with a 68 B-body looking for advice on drag shocks.

His car can hook well on a perfect track, but most times it will hook and then let go.

His car is a 1968 Road Runner, 3400lbs, 500cid, CalTracs, Split Mono-leaf, Rancho 9 way adjustable rear shocks, Calvert 90/10 front shocks, 29x10 Hoosier slicks, 4:10 gears, .880 Dia(slant six)torsion bars, tubular upper control arms w/rod ends, and greasable lower control arm pins w/urethane bushings.

He just ordered a pair of the Firm Feel .820 Dia (drag race) torsion bars.

He is wanting to here some opinions about changing over to the AFCO racing shocks.

Thanks.

Posted By: MR_P_BODY

Re: Educate me on drag shocks. - 02/12/13 08:31 PM

Afco are a better shock but he needs to make sure he
has good front end travel... if he takes a video of
the launch he can get a better idea of what is really
happening... I'm thinking he is running out of front
end travel and as soon as it tops out it falls back
down to cause the spin... also when its on a lesser
hooking track he needs to loosen up the rear shocks
for more lift

Posted By: Mr.Yuck

Re: Educate me on drag shocks. - 02/12/13 08:34 PM

Boy he's already into it for a bunch of money. I take it he's adjusted the Cal-Tracs a few different ways? What are his 60 foots? Hook and let go? like at the 1-2 shift? Only cars I've seen start blowing the tires apart at the 100 foot are turbo cars when the boost comes on hard.

Posted By: chromedome426

Re: Educate me on drag shocks. - 02/12/13 09:31 PM

He has 5.25 inches of travel on the front suspension. The 60' times are in the 1.43 - 1.50 area. He did have a 1.41 once.

When the track is perfect he can get 12 inches of air under the front tires and it will stay hooked even when the front comes back down. When the track is marginal he can only get 2 inches of air under the front tires. He does loosen the shocks for those conditions but feels that the rear shocks may need to be double adjustable. He is also wondering if the double adjustable front shocks would help?

Here is a picture of the car in storage. Sorry for the poor quality pic, it's the best I have of it on this computer.

Attached picture 7585862-05-04-11_1749.jpg

Attached picture 7585862-05-04-11_1749.jpg

Posted By: MR_P_BODY

Re: Educate me on drag shocks. - 02/12/13 09:47 PM

At 5.25 travel he has plenty... myself I only use a
single adjustable shock...I've always felt the compression
(on a double adjustable) was for down track... the extension
was for the starting line

Posted By: StealthWedge67

Re: Educate me on drag shocks. - 02/13/13 01:54 AM

Seems to me that he's got all the right stuff there. I'm sure there's guys out there going fast and hooking hard with LOTS less than he has. Something else has to be at issue here. I'd be hesitant to just throw more money at it. What sort of performance levels are we talking about, here?

As said, Video will be needed before anyone here can really offer any good help.

Posted By: 10.90 Racer

Re: Educate me on drag shocks. - 02/13/13 02:17 AM

Quote:

Afco are a better shock but he needs to make sure he
has good front end travel... if he takes a video of
the launch he can get a better idea of what is really
happening... I'm thinking he is running out of front
end travel and as soon as it tops out it falls back
down to cause the spin... also when its on a lesser
hooking track he needs to loosen up the rear shocks
for more lift

What setting are the rear shocks on???

Posted By: MR_P_BODY

Re: Educate me on drag shocks. - 02/13/13 03:28 AM

Quote:

Quote:

Afco are a better shock but he needs to make sure he
has good front end travel... if he takes a video of
the launch he can get a better idea of what is really
happening... I'm thinking he is running out of front
end travel and as soon as it tops out it falls back
down to cause the spin... also when its on a lesser
hooking track he needs to loosen up the rear shocks
for more lift

What setting are the rear shocks on???

I dont now why your asking me... its not my car

Posted By: Irun5snd8th

Re: Educate me on drag shocks. - 02/13/13 04:17 AM

Mopars have a super short leaf spring compared to the Chevys. The hit and unload, often called porpoising, is common to the Mopars for this reason. Lil bro's car was awesome till we put the stroker in it and then it started the same deal as your friend. The answer was a good pair of double adjustable shocks along with a pinion angle change. Check the angle first cause thats cheaper than a set of shocks. You should have at least 5 degrees on a leaf spring car and it is absolutely critical on a leaf car.

Posted By: JAKE68

Re: Educate me on drag shocks. - 02/13/13 04:33 AM

CalTracs want 1-3 neg degrees of pinion angle relative to the trans. Its hard to answer any questions you may have without knowing the cars set up. Like how much preload,what rear shocks are set at,what size tire and air pressure,top or bottom hole, how much converter,. Most of the average 10.30-10.60 et car would usually 60 in the 1.40-1.49. Some well sorted out will go much better. He has allot of good parts there so it is got to be just the set up or combo and not to throw more parts at it. We have stock front end with dbl adjustable afco's and we 60 1.28-1.32. So he allready has more then us. So there is some work to be done.Jake

Posted By: sshemi

Re: Educate me on drag shocks. - 02/13/13 09:06 AM

Instructions for caltracs says 4* piniong angle

Posted By: 74yellowduster

Re: Educate me on drag shocks. - 02/13/13 01:51 PM

Quote:

When the track is perfect he can get 12 inches of air under the front tires and it will stay hooked even when the front comes back down. When the track is marginal he can only get 2 inches of air under the front tires. He does loosen the shocks for those conditions but feels that the rear shocks may need to be double adjustable. He is also wondering if the double adjustable front shocks would help?

this sounds like "when the track isn't perfect" his slicks don't hook.

it sounds like when they hook it works perfectly.

how much air is he running in them, how old are they, is he heating them up enough, can he go wider, etc.

it sounds like he has the suspension right, but he's spinning for some reason

Posted By: an8sec70cuda

Re: Educate me on drag shocks. - 02/13/13 02:15 PM

Try different front shocks, you might be surprised.

Posted By: chromedome426

Re: Educate me on drag shocks. - 02/13/13 06:44 PM

Unfortunately we don't have any video of the car. However, he will definately get some, once the 3 feet of snow melts off the track.

He sent me a few pictures that may or may not help for now.

He has tried every setting on the shocks multiple times. He has set the bars in both the upper and lower holes. He has also played with preload to no preload on the bars. Slicks are 29x10 on 10" wheels and has 14 psi hot.

The comment about pinion angle turned on a light bulb for him. That is something that he hasn't changed. I believe it's only at 2 or 3 degrees down.

The car has run 10.25 at 132 mph in good air but mostly in the heat of summer it's 10.40's at 129 mph.

Attached picture 7586880-BH12g(2).jpg

Posted By: chromedome426

Re: Educate me on drag shocks. - 02/13/13 06:46 PM

Picture from front view:

Attached picture 7586885-BH12s(4).jpg

Posted By: chromedome426

Re: Educate me on drag shocks. - 02/13/13 06:50 PM

Stance at 1/2 track:

Attached picture 7586891-325F.jpg

Posted By: chromedome426

Re: Educate me on drag shocks. - 02/13/13 07:03 PM

He said it's like the car is hitting the tires too hard and then unloading them when the body starts to come back down.

He wonders if the double adjustable rear shocks would slow the body from coming down too fast and help keep the tire planted longer?

He is also wondering what to use for front shocks?

Posted By: an8sec70cuda

Re: Educate me on drag shocks. - 02/13/13 07:13 PM

Preferably an adjustable front shock, but anything tighter than the Calvert's will be better. I use some old Lakewood 90/10s that are a lot stiffer than the Calverts which are REALLY loose. Sounds exactly like what my car did after I put on the Calvert 90/10 front shocks. I got it to hook once on a very well prepped track and "treated" tires...it almost went on the back bumper. The very next pass it started to unload again. Put my old front shocks back on and it went right back to hooking like always. The front rises too fast, bottoms out, and unloads the rear.
I put on new rear shocks, new tires, and every possible bar adjustment trying to fix it...didn't respond to anything. I never thought those Calvert shocks would be the problem b/c everyone says they're great, but I found out the hard way.

Posted By: 74yellowduster

Re: Educate me on drag shocks. - 02/13/13 07:23 PM

i cant tell too well from the pictures, but it doesnt look like he can go wider. is he 50/50 front to rear on weight?

he might be able to go with a softer compound?

HOOSIER CHART

MICKEY THOMPSON COMPOUND SELECTION CHART

Medium----------------------------------------------------------Soft
M7 X5 M5 M8 R1 L8 X7 L4

Posted By: JAKE68

Re: Educate me on drag shocks. - 02/13/13 08:32 PM

Quote:

Unfortunately we don't have any video of the car. However, he will definately get some, once the 3 feet of snow melts off the track.

He sent me a few pictures that may or may not help for now.

He has tried every setting on the shocks multiple times. He has set the bars in both the upper and lower holes. He has also played with preload to no preload on the bars. Slicks are 29x10 on 10" wheels and has 14 psi hot.

The comment about pinion angle turned on a light bulb for him. That is something that he hasn't changed. I believe it's only at 2 or 3 degrees down.

The car has run 10.25 at 132 mph in good air but mostly in the heat of summer it's 10.40's at 129 mph.

Looking at this shot it looks like rear shocks are way to loose. 9 way rancho likes to be at #8 With bar in lower hole. Now on my brothers car we have a problem with it hooking and then nose diving becuase when it hooks it pulls the motor down below power band we are going to put more converter in it. It has a very high power band and a 5500 converter is not enough. based on dyno sheets we will be puting in a converter that will flash from 6800-7100. and go from there.

Posted By: MR_P_BODY

Re: Educate me on drag shocks. - 02/14/13 12:03 AM

Like Jake said.. the rear shocks look too loose plus
he can un-do a clamp on the rear springs... make the
shocks do the work of controlling the lift.. right
now the springs in the rear are trying to pull the
body back down(but really its lifting the axle)

Posted By: justinp61

Re: Educate me on drag shocks. - 02/14/13 01:54 AM

Quote:

Like Jake said.. the rear shocks look too loose plus
he can un-do a clamp on the rear springs... make the
shocks do the work of controlling the lift.. right
now the springs in the rear are trying to pull the
body back down(but really its lifting the axle)

The car has split monos on it according to the first post.

Posted By: prochargedhemi

Re: Educate me on drag shocks. - 02/14/13 02:10 AM

I agree with everyone else that the shocks are too loose. However, looking at the picture from the rear that left rear tire is "balling" up a little more than i like. along with tightening up the shocks i would also try another 1/2-1 lb of air in the tires

Posted By: CRIKEY

Re: Educate me on drag shocks. - 02/14/13 03:53 AM

put alot more air in those tires

Posted By: JAKE68

Re: Educate me on drag shocks. - 02/14/13 03:59 AM

Something to consider possable. With the amount of body seperation the car is showing it has very little pitch rotation. If it has a shackle that is laid back and the car is seperating that shackle goes threw an arch that untill it goes past center in the arch before it starts to pull the back of the car down to help make the car pitch. With a slider it is pulling down as soon the spring starts to arch hence pull the car back on the tires and holding as much as torque it has will allow. We have a slider and have a problem controling wheel stands, my brothers car has a shackle...hmm something to look at for us.jake

Posted By: sshemi

Re: Educate me on drag shocks. - 02/14/13 08:44 AM

Funny how you can see that the shocks are too loose from a picture.

Posted By: b1dartsport

Re: Educate me on drag shocks. - 02/14/13 11:01 AM

Here is a Cal-Trac chart that was posted on here some time ago. I hope the original poster does not mind me reposting it. Hope it helps.

Attached picture 7587762-#2.jpg

Posted By: chromedome426

Re: Educate me on drag shocks. - 02/14/13 01:23 PM

Quote:

Something to consider possable. With the amount of body seperation the car is showing it has very little pitch rotation. If it has a shackle that is laid back and the car is seperating that shackle goes threw an arch that untill it goes past center in the arch before it starts to pull the back of the car down to help make the car pitch. With a slider it is pulling down as soon the spring starts to arch hence pull the car back on the tires and holding as much as torque it has will allow. We have a slider and have a problem controling wheel stands, my brothers car has a shackle...hmm something to look at for us.jake

I forgot to mention, this car does have sliders too.

Posted By: JAKE68

Re: Educate me on drag shocks. - 02/14/13 02:42 PM

Quote:

Quote:

Something to consider possable. With the amount of body seperation the car is showing it has very little pitch rotation. If it has a shackle that is laid back and the car is seperating that shackle goes threw an arch that untill it goes past center in the arch before it starts to pull the back of the car down to help make the car pitch. With a slider it is pulling down as soon the spring starts to arch hence pull the car back on the tires and holding as much as torque it has will allow. We have a slider and have a problem controling wheel stands, my brothers car has a shackle...hmm something to look at for us.jake

I forgot to mention, this car does have sliders too.

Guess that blows that idea. Just trying to help.

Posted By: VernMotor

Re: Educate me on drag shocks. - 02/14/13 10:31 PM

I agree on too much body seperation. and the shocks are not doing thier job. how old are them shocks. I went though this with freds car. and found out the shocks was just wore out. same shocks. Got him tieing the car down in the trailer by the body now. he was tieing it down by the rear end and it was bouncing in the trailer wearing them out ! and border line on the air in the tires.