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Re: Porpoising
[Re: Dodgem]
#1264927
07/10/12 07:34 PM
07/10/12 07:34 PM
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Joined: Apr 2005
Posts: 399
metro detroit
turner
OP
enthusiast
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OP
enthusiast
Joined: Apr 2005
Posts: 399
metro detroit
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After measuring the front ends travel I have found the following.......at static height the shock has a grease mark showing it has compressed 1 1/4" on both sides......I tied a zip tie to to the rod just above the shock body and jacked the car up until the wheels hung in the air and the shocks traveled or extended 2 1/8" each side, and an extended length of 15 1/4" long from the underside of the fenderwwell to the lower bolt hole.......... thats 3 3/8 of shock travel total! That sure doesnt seem right to me, when I launch the it car only extends the shocks 2 1/8" from its ride heigth!  http://youtu.be/CheDA5ffmbclooking at this video, the car shows very little front end rise at the launch, verifing the 2 1/8" shock extension before bottoming out
Last edited by turner; 07/10/12 07:46 PM.
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Re: Porpoising
[Re: turner]
#1264928
07/10/12 09:50 PM
07/10/12 09:50 PM
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Joined: Jul 2004
Posts: 4,384
Worst Weather USA
493_DART
master
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master
Joined: Jul 2004
Posts: 4,384
Worst Weather USA
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Some things to try -- jack up the car on the rear frame rails so the rear end extends fully---pull off the bottom end of the shock. It should extend at least 1" past the stud. If you want a decent and affordable race shock --call Calvert. They have the Rancho 9-way design rear shocks--many lengths available. They will have you take a few measurements and get you the RIGHT model. dont just guess---they are good at this ! Their front drag shocks have a super loose extention--I like mine ! On your SS springs = fab some clamps up and clamp anywhere you can on the springs in front of the axle . They are super easy to make with a cutter/grinder / drill . 
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Re: Porpoising
[Re: turner]
#1264929
07/10/12 10:00 PM
07/10/12 10:00 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
After measuring the front ends travel I have found the following.......at static height the shock has a grease mark showing it has compressed 1 1/4" on both sides......I tied a zip tie to to the rod just above the shock body and jacked the car up until the wheels hung in the air and the shocks traveled or extended 2 1/8" each side, and an extended length of 15 1/4" long from the underside of the fenderwwell to the lower bolt hole.......... thats 3 3/8 of shock travel total! That sure doesnt seem right to me, when I launch the it car only extends the shocks 2 1/8" from its ride heigth!
http://youtu.be/CheDA5ffmbc
looking at this video, the car shows very little front end rise at the launch, verifing the 2 1/8" shock extension before bottoming out
Not enough travel... a lot of guys have the front
lifted up so they like the ride height... but you
cut the travel down at the same time... soft front
bars are a big plus... you gain stored energy to
help push the front up but you have to have long
enough shocks to let it... it should also move freely
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Re: Porpoising
[Re: sixpackgut]
#1264931
07/11/12 06:18 AM
07/11/12 06:18 AM
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Joined: Apr 2005
Posts: 399
metro detroit
turner
OP
enthusiast
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OP
enthusiast
Joined: Apr 2005
Posts: 399
metro detroit
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I will do as you say with the rear shocks, take them off the stud and letting them hang, to see their length. I have the front segments of the springs already clamped, and my front moves freely......I had the car chassis dynoed at 440 to the rear wheel and with a 125-150 shot of NOS I thouhgt I was fairly close to 700hp at the flywheel. The car ran a 10.59 at 128 in the 1/4 with a 1.630 60' time and spinning the first 100', how many horses do you think it has, the car also has a 4.10 gear and 28" tires if it matters. I will be calling caltrac today and see if I cant get some shock answers.
The cars weighed 3200 before the moly 12pt cage was installed
none of the videos I posted are with nitrous, I only spray it for funsies, I bracket race it without NOS and have at least 400-500 passes on this car(and still cant get it to 60')
Last edited by turner; 07/11/12 06:34 AM.
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Re: Porpoising
[Re: turner]
#1264932
07/11/12 09:32 AM
07/11/12 09:32 AM
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Joined: Jun 2003
Posts: 9,225
Charleston
sixpackgut
Drag Week Mod Champion
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Drag Week Mod Champion
Joined: Jun 2003
Posts: 9,225
Charleston
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my challenger ran 10.50s on motor at 3700 lbs and i dont think it could have been more than 600hp.
the calvert shocks work pretty damn good for the money. i think your rears are way to loose. some nice aluminum body single adjustables from strange or QA1 are not that expensive either. good luck
Gen 3 power 6.22@110, 9.85@135
Follow @g3hemiswap on instagram
performance only racing, CRT, ultimate converter, superior design concepts, ThumperCarbs
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Re: Porpoising
[Re: turner]
#1264934
08/14/12 09:54 AM
08/14/12 09:54 AM
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Joined: Apr 2005
Posts: 399
metro detroit
turner
OP
enthusiast
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OP
enthusiast
Joined: Apr 2005
Posts: 399
metro detroit
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At the next race you can see in the pic that I now have the chassis hooking up awesome, and the porpoising is gone. I made several of the changes that were advised here on the board, the rear shocks are calvert adjustables set at 8, fronts are calvert non-adj, switched from 870 bars to /6 bars, new 29x13.5 QTP,s, and adjusted the pinion snubber wich is still in question. The car was leaving at 1800rpms and got a best 60' of 1.54 w/125 shot of nitrous via a WOT switch, and a 1.61 60' on motor, anyway the porpoising is gone and the car seems to be deadly consistent running its dial. I was talking to my race partners and they said that I finally got that suspension transferring weight and I did it with some Hoosier QTP's wich are just about as good as slicks, for my slow car.
When I ran my 10.59 my 60' was 1.63 and my 1/8th time was 6.89 I was racing 1/8th mile only so I dont have any new 1/4 ile times but I know its gunna beat a 10.59. I only made one nitrous run and the car went 1.54 60' with a 6.75 1/8th time, im driving to the track soon to get that new best slip soon, after I refill my bottle!
What is the recommended distance the pinion snubber should be set from the floor?
Last edited by turner; 08/14/12 10:04 AM.
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Re: Porpoising
[Re: MR_P_BODY]
#1264937
08/14/12 12:41 PM
08/14/12 12:41 PM
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Joined: Jan 2006
Posts: 39
indiana
65mike
member
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member
Joined: Jan 2006
Posts: 39
indiana
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Quote:
If your rear springs are working correctly you wont
need the snubber
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Re: Porpoising
[Re: 65mike]
#1264938
08/14/12 01:18 PM
08/14/12 01:18 PM
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Joined: Apr 2005
Posts: 399
metro detroit
turner
OP
enthusiast
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OP
enthusiast
Joined: Apr 2005
Posts: 399
metro detroit
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I had it on before all the changes trying to get this thing to 60', probably will unpin and lower it out of the way at the next T&T session and see what occurs. My springs probably have close to 1000 passes on them, I bought them used from a yellow wheelstanding duster that races at Milan, and ive put 500 passes on them in the last 5 years......so I think they could be wore alittle or arent what they used to be at least.
car does have a 4:10 gear, not sure how much faster 60' I can expct to get.........Im looking for a 4000-4500 convertor, then it should really launch
Last edited by turner; 08/14/12 01:21 PM.
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Re: Porpoising
[Re: turner]
#1264939
08/14/12 02:57 PM
08/14/12 02:57 PM
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Joined: Dec 2006
Posts: 1,178
Indy
FlyFish
super stock
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super stock
Joined: Dec 2006
Posts: 1,178
Indy
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What is you tire pressure, the pic of the launch looks like you have those pumped WAY up (are they radials)? I still think your 60' times are slow for a 10.5 et...you should be deep in the 1.40's.
For what its worth, my 67 ran 1.49 60' times with 10.8 second et's @ 123 (6.86 @ 99mph in the 1/8).
67 Barracuda street car, 408, e85, 1.38 60', 6.44 @105.9 in the 1/8 mile, 10.19 @130.5 in the 1/4...so far....
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Re: Porpoising
[Re: FlyFish]
#1264940
08/14/12 03:07 PM
08/14/12 03:07 PM
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Joined: Apr 2008
Posts: 1,141
Phoenix,Az.
hemicop
super stock
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super stock
Joined: Apr 2008
Posts: 1,141
Phoenix,Az.
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I had a 3800# non-Mopar running 1.30 60'times running the rear tires in the 9psi range. My Guess is you're real close to your ideal times. I'd start playing with the rear shocks now, and would even consider turning down (yeah, it's a TON of work & hard on your lathe) the t-bars. Don't laugh---I was talking to a well-known formwer P/S racer from back in the day & he did just that! Caught s@#t from the Mopar engineers who said it wouldn't work but it cured his problem & that car's still around.
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Re: Porpoising
[Re: hemicop]
#1264941
08/14/12 03:27 PM
08/14/12 03:27 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
I had a 3800# non-Mopar running 1.30 60'times running the rear tires in the 9psi range. My Guess is you're real close to your ideal times. I'd start playing with the rear shocks now, and would even consider turning down (yeah, it's a TON of work & hard on your lathe) the t-bars. Don't laugh---I was talking to a well-known formwer P/S racer from back in the day & he did just that! Caught [Email]s@#t[/Email] from the Mopar engineers who said it wouldn't work but it cured his problem & that car's still around.
I wouldnt waste my time trying to turn down the bars...
there are other diameters if you needed them but I
doubt it... I have plenty of experience with T bars...
I did the transverse torsion bar set up on the F & M
body development... now its a matter of tweaking it
all in and most of it will be shocks and tire pressure
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Re: Porpoising
[Re: turner]
#1264943
08/14/12 04:09 PM
08/14/12 04:09 PM
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Joined: Dec 2006
Posts: 1,178
Indy
FlyFish
super stock
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super stock
Joined: Dec 2006
Posts: 1,178
Indy
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Quote:
I started with 17lbs and then went all the way down to 12lbs, the tires are Hoosier QTP's
I run the same tire, my car likes 12.5-13psi, no tubes.
67 Barracuda street car, 408, e85, 1.38 60', 6.44 @105.9 in the 1/8 mile, 10.19 @130.5 in the 1/4...so far....
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Listen to the noise, loose the snubber 
I listened, complied and went faster 