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PostPosted: Mon May 02, 2011 8:34 am 
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Location: Iowa
I wanted to start this thread to see who out there is using leafs and in the end find out how they are working for everyone.

Another thing I want to get going is a pool of information to maybe help out some of us gain some understanding as to what makes a leaf spring suspension work well, spring rates, shock settings, tire pressures, ladder bars, cal-tracs, weight % front-rear. Whatever it may be. if its relavent to getting a leaf car to hook I want to hear about it.

Im not asking anyone to give up their chassis tune secrets if they dont want to, most of the time one cars perfect setup wont do a differant car any good anyways.

It seems there are alot of leaf sprung cars on here, so maybe some of us can learn from this, me included.

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'63 Plymouth, Straight axle, Leaf springs, Drum brakes, 31x10.5wx15 Rears 3215lbs
Best time to date 7.99 @ 170 mph
572" Wedge 8-71 @ 28% OD, ALKY, Glide, Dana

http://www.youtube.com/watch?v=vq-xzFWHtFk
http://www.youtube.com/watch?v=JfyZSw59R_o


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PostPosted: Mon May 02, 2011 9:13 am 
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Location: Iowa
I've been drag racing for around 10 years or so, I built my car when I was still in High School and since my main advisor (my dad) was an old school kinda guy we kept the leaf spring rear.
Anyways, I caught ALOT of crap at the drag strip about how my suspension would never work right, blah blah, from all the 4 link guys right up until they lined up against me. It always seemed that I could always walk right past the 4 link cars in the first 330' of the guys that were comparable to me in times. (we were a 10.4-10.6 second car back then)

We run the same springs, shocks, bars, and almost the same tire size now, sure the tune has changed a bunch but most of my parts are the same now and I find it amazing that the suspension from a maybe 650hp car, is holding a 1500hp blower motor to the track.

We are definently overpowering it, I dont have any illusions about that. Our 60' times are not up to par with the other guys we run with anymore, but its still holding it and its pretty consistant if I dont mess something up.

One thing I've noticed has changed alot is that the car is really picky about track condition, on a average-good track it will hook, lift the front a bit and get, if its a really sticky track it becomes a beast to drive, wheel stands, tire shake, borderline spooky, feels like I'm sitting in a fuel altered sometimes, if everything goes right and I dont mess up it flat flies though. Slick tracks are almost out of the question, its fun to drive and puts on a show but its not fast and very inconsistant.

I know I need to change shocks and maybe some other stuff, but right now we are running Mopar Performance Super Stock springs and cheap adjustable shocks with homemade bars on 10.5W x 31.25 tires with between 9.0 and 9.75 psi.

Sorry for the long post.
.

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'63 Plymouth, Straight axle, Leaf springs, Drum brakes, 31x10.5wx15 Rears 3215lbs
Best time to date 7.99 @ 170 mph
572" Wedge 8-71 @ 28% OD, ALKY, Glide, Dana

http://www.youtube.com/watch?v=vq-xzFWHtFk
http://www.youtube.com/watch?v=JfyZSw59R_o


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PostPosted: Mon May 02, 2011 8:52 pm 
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For the ET's you're running, I think you'd find some benefits to lowering the car. I know that's not the "Look" you're after, but it would probably help make the car work better. What's it 60' at now, weight and tire size?

Just my opinion, but it probably doesn't need that high of a center of gravity.

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PostPosted: Tue May 03, 2011 6:23 am 
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Location: Iowa
It weighs 3250lbs at the end of a run, tires are 10.5wx31x15 tread width of 12", most of our 60's are in the 1.30-1.33 range and the best was a 1.28.

There should be a picture showing ride hight and yea I know its too tall, expecially because the motor is setback 9.5" and up 1 or 2"


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'63 Plymouth, Straight axle, Leaf springs, Drum brakes, 31x10.5wx15 Rears 3215lbs
Best time to date 7.99 @ 170 mph
572" Wedge 8-71 @ 28% OD, ALKY, Glide, Dana

http://www.youtube.com/watch?v=vq-xzFWHtFk
http://www.youtube.com/watch?v=JfyZSw59R_o
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PostPosted: Tue May 03, 2011 6:43 am 
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Location: Resume Speed, Kansas
At that weight and power, you're probably leaving just a tad on the table. I'd guesstimate if it was working as good as possible it would be in the mid to upper 1.20's consistently.

Do you guys attempt to get to a certain wheel speed with that setup?

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PostPosted: Tue May 03, 2011 11:06 am 
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Location: Sahuartia Az
I dont have anything to add about your question but I saw a very nice pic of your car in the Goodguys magazine :thumb: thought you would like to know.


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PostPosted: Tue May 03, 2011 12:06 pm 
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John_Heard wrote:

Do you guys attempt to get to a certain wheel speed with that setup?


The way I understand it, get the most wheel speed you can without smoking the tires, too little wheel speed makes the tires wad up, shake and takes to long to get them round again.

Thats what I try for, but with no data recorder or video we just look at time slips and guess.

To be honest I havent tried to hard to get the 60' times down yet, it hasnt been my main concern but this year I want to work on it.

Thanks SC, it sure attracts the camera guys, last year I think it was on a flyer to a race I have never been to, I thought that was funny.

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'63 Plymouth, Straight axle, Leaf springs, Drum brakes, 31x10.5wx15 Rears 3215lbs
Best time to date 7.99 @ 170 mph
572" Wedge 8-71 @ 28% OD, ALKY, Glide, Dana

http://www.youtube.com/watch?v=vq-xzFWHtFk
http://www.youtube.com/watch?v=JfyZSw59R_o


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PostPosted: Tue May 03, 2011 1:30 pm 
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I'd highly recommend at the minimum an entry level datalogger such as the one from RPM Performance. Get driveshaft RPM, Engine RPM and a Accelerometer. This will give you a real good insight into what the car is doing. Add a rear shock sensor if it's in the budget too.

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PostPosted: Tue May 03, 2011 5:11 pm 
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Location: Columbia, KY
My feelings on hooking a leaf spring car (most applies to about any car) is to get the car low, plenty of front end travel, soften the rear springs enough to let the shock do its job, get the car close to 50/50 front to rear and move it backwards and forwards to see what works, make sure the suspension isn't binding anywhere, good cage to control the chassis, get the converter right and a decent externally adjustable shock. Simple setups can work well on a small tires.

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Craig Watson
2QuickNovas Racing
5.30@133.25 on 26x8.5s
2008 Bounty Race Outlaw 8.5 Champion

Sponsors:
AEM Electronics
TRZ Motorsports
Carnivore Performance
Bradco Converters
Rapp Racing


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PostPosted: Wed May 04, 2011 7:29 am 
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Location: Rocklin, CA
John_Heard wrote:I'd highly recommend at the minimum an entry level datalogger such as the one from RPM Performance. Get driveshaft RPM, Engine RPM and a Accelerometer. This will give you a real good insight into what the car is doing. Add a rear shock sensor if it's in the budget too.


John - whats the ballpark cost for that minimum setup ?

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Blown 427 BBC, TH400 w/Brake, Back-Half Ladderbar
Narrowed 12-Bolt, 4.10 Gears, Spool, Moser 33 Spline

http://www.marsh-racing.com/harrys_camaro-1.htm


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PostPosted: Wed May 04, 2011 7:52 am 
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RPM Performance's Base system that has Engine and Driveshaft RPM is $588, add the accelerometer sensor for $178

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PostPosted: Wed May 04, 2011 8:50 am 
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$588, thats less than I expected, is that just 3 inputs or can you add more to it? If I put a data logger on I might as well get one that would do EGT's and fuel pressure, a fuel pressure/egt curve would make things so much easier on the engine side of things.

_________________
'63 Plymouth, Straight axle, Leaf springs, Drum brakes, 31x10.5wx15 Rears 3215lbs
Best time to date 7.99 @ 170 mph
572" Wedge 8-71 @ 28% OD, ALKY, Glide, Dana

http://www.youtube.com/watch?v=vq-xzFWHtFk
http://www.youtube.com/watch?v=JfyZSw59R_o


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PostPosted: Wed May 04, 2011 9:06 am 
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Moparious Maximus wrote:$588, thats less than I expected, is that just 3 inputs or can you add more to it? If I put a data logger on I might as well get one that would do EGT's and fuel pressure, a fuel pressure/egt curve would make things so much easier on the engine side of things.


It has 12 channels, and yeah, you can upgrade it up to 28 channels - more at http://www.racingconverters.com/dataloggers.html

I got mine as a basic unit and have been upgrading it slowly adding more and more sensors, etc. One nice thing is it uses standard 0-5 volt DC sensors, so you can use like GM 1bar vacuum sensors, etc. if you want.

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PostPosted: Sat Sep 08, 2012 2:14 pm 
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Craig W. wrote:My feelings on hooking a leaf spring car (most applies to about any car) is to get the car low, plenty of front end travel, soften the rear springs enough to let the shock do its job, get the car close to 50/50 front to rear and move it backwards and forwards to see what works, make sure the suspension isn't binding anywhere, good cage to control the chassis, get the converter right and a decent externally adjustable shock. Simple setups can work well on a small tires.




I know this is an old thread..... "soften the rear springs enough to let the shock do its job",

What spring rate does Craig use? How does one determine the best spring rate to let the shocks do there job....for there set up... I currently use 225# Calvert Split Monos and there shocks.... But after reading craigs comment , I question my self on my spring rate choice.. Ideas. thoughts?Thanks

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PostPosted: Sat Sep 08, 2012 3:12 pm 
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Location: Columbia, KY
I want to say my springs are 175 lbs/in but I'm not certain on that. They are 1" drop Calvert springs.

As for how to determine the proper spring rate for the weight of the car, that's a good question. People talk about this stuff all the time with coilovers but the same principles should apply to leaf springs too. I've been wondering if I need a softer spring now that the car is 100+ lbs lighter in the rear. I've struggled a little with the power of the new engine and the lighter weight of the car.

When I get the car rebuilt from the crash, I plan on going to better shocks in the rear. Probably AFCO big guns. I feel my car should 60' better than 1.26-1.28 that it normally does on a good run on 8.5s.


johnh wrote:
Craig W. wrote:My feelings on hooking a leaf spring car (most applies to about any car) is to get the car low, plenty of front end travel, soften the rear springs enough to let the shock do its job, get the car close to 50/50 front to rear and move it backwards and forwards to see what works, make sure the suspension isn't binding anywhere, good cage to control the chassis, get the converter right and a decent externally adjustable shock. Simple setups can work well on a small tires.




I know this is an old thread..... "soften the rear springs enough to let the shock do its job",

What spring rate does Craig use? How does one determine the best spring rate to let the shocks do there job....for there set up... I currently use 225# Calvert Split Monos and there shocks.... But after reading craigs comment , I question my self on my spring rate choice.. Ideas. thoughts?Thanks

_________________
Craig Watson
2QuickNovas Racing
5.30@133.25 on 26x8.5s
2008 Bounty Race Outlaw 8.5 Champion

Sponsors:
AEM Electronics
TRZ Motorsports
Carnivore Performance
Bradco Converters
Rapp Racing


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