Leaf springs & CalTracs separation

Brad Hawk · 12-18-2020, 01:48 PM

I'm interested in people's feedback on how they've set up their leaf spring suspension when using CalTracs, Assassin Bars, etc. w/ respect to promoting vs restricting chassis separation.

My original understanding was using these "devices" allowed for more control of the rear suspension on launch w/o having to rely on a large amount of chassis separation as was expected (required?) w/ Super Stock springs, Try-City Launchers, "slapper" bars.

However, I'm seeing plenty of Stockers w/ CalTracs & Assasins where there still appears to be significant amount of separation happening. I'm wondering if it's an "it depends..." thing, whether certain chassis combinations (like my Mopar E-body) respond better to this approach, or what other factors may need to be taken into account (leaf spring lengths before & after axle? weight distribution? ...?).

For reference, here is the data from a series of passes made before I pulled apart the car (quite a ways back, unfortunately). The CalTracs & split mono-leaf springs were strapped down a good bit w/ the old Ranchos on setting 4 of 5, so there was minimal separation. The front suspension was very loose (possibly too loose) w/ 5-1/4" extension from static ride height. Unfortunately, no good pics or videos to go w/ the data.

Also, in case the 60-fts look "slow", it's cuz this is a street/strip car w/ only a 4500-flash converter, 4.10s, and 9" DOT drag radials. Welcome to my build of compromises...

- 60 - / 660 / MPH / 1320 / MPH / Weather conditions
1.459 / 6.682 / 101.66 / 10.566 / 126.01 / < No weather #s >
1.468 / 6.677 / 101.87 / 10.561 / 126.00 / 74*, 48%, 30.57"
1.463 / 6.698 / 101.45 / 10.582 / 126.18 / 65*, 42%, 30.38"
1.464 / 6.682 / 101.71 / 10.563 / 126.12 / 72*, 33%, 30.35"
1.459 / 6.681 / 101.47 / 10.570 / 125.97 / 73*, 33*, 30.33"

Not asking for "trade secrets", but some feedback would be appreciated. Thx!

GTX JOHN · 12-18-2020, 03:47 PM

I run Ranchos with Caltracs on same settings
Not a bunch of separation but 1.3s in 60fts. on our 340
Stockers.

Very Consistent and well pleased with John Calvert's stuff!!!

Stan Weiss · 12-18-2020, 04:35 PM

I have not raced in a while. But it used to be that as I improved my 60 foot time my 1/4 et improved. It seems as your 60 foot times get worse you et gets better.

Stan

- 60 - / 660 /// MPH /// 1320 //// MPH /// Weather conditions
1.459 / 6.682 / 101.66 / 10.566 / 126.01 / < No weather #s >
1.459 / 6.681 / 101.47 / 10.570 / 125.97 / 73*, 33*, 30.33"
1.463 / 6.698 / 101.45 / 10.582 / 126.18 / 65*, 42%, 30.38"
1.464 / 6.682 / 101.71 / 10.563 / 126.12 / 72*, 33%, 30.35"
1.468 / 6.677 / 101.87 / 10.561 / 126.00 / 74*, 48%, 30.57"

NHRA1926 · 12-18-2020, 05:00 PM

You will need a good pair of rear shocks too control the separation. I use Afco double adjustable shocks on the rear of my 67 Camaro which has Caltrac's bars and split mono leaf springs. I tried Competition Engineering 3 way adjustable shocks and QA1 double adjustable shocks. Neither one of these shocks are strong enough to slow down the body separation when using the Caltrac bars. My car 60ft 1.35-1.37 When I brought my car to Mark Markow for some suspension work, he is the one that recommended the Afco shocks. I had just bought a brand new pair of QA1's right before I brought the car to him. Even though they were brand new, he told me they wouldn't be strong enough to handle the pressure from the Caltrac bars. Car hooks hard now.

Lenny5160 · 12-18-2020, 05:29 PM

I always assumed separation was somewhat the point of the CalTracs. They convert the rotational force of the rear housing trying to "wrap" into a downward force on the front of the spring, causing it to arch and lift the body.

Frank Castros · 12-18-2020, 07:05 PM

Ask Pete Lanciers.

SSGN · 12-19-2020, 09:04 AM

I remember seeing lots of very fast stockers that used the Caltracs and the Rancho adj rear shocks. Way back when Top Stock was around this was the recipe.

SSDiv6 · 12-19-2020, 12:22 PM

Prior to CalTracs, many were using Greg Luneack's Super Launcher Springs. They had lots of separation during launch.

340Cuda · 12-19-2020, 12:57 PM

It was a long time ago but when I first got my CalTracs I sent them a photo of my car and asked them if there was too much separation. They said there was and sent me another set of springs at no charge.

ken robinson · 12-20-2020, 10:45 AM

I run cal trac springs & his 9 way shocks on the back ( set on like 7 } , some of same combos in stock separate more & some less than my car . Looking at some pics of the races from this year alone . I might try to tighten up my rear shocks . And after 10 years of racing & trailing they may be done .

12-18-2020, 01:48 PM	#1
Brad Hawk Junior Member Join Date: Nov 2009 Posts: 20 Likes: 1 Liked 2 Times in 1 Post	Leaf springs & CalTracs separation I'm interested in people's feedback on how they've set up their leaf spring suspension when using CalTracs, Assassin Bars, etc. w/ respect to promoting vs restricting chassis separation. My original understanding was using these "devices" allowed for more control of the rear suspension on launch w/o having to rely on a large amount of chassis separation as was expected (required?) w/ Super Stock springs, Try-City Launchers, "slapper" bars. However, I'm seeing plenty of Stockers w/ CalTracs & Assasins where there still appears to be significant amount of separation happening. I'm wondering if it's an "it depends..." thing, whether certain chassis combinations (like my Mopar E-body) respond better to this approach, or what other factors may need to be taken into account (leaf spring lengths before & after axle? weight distribution? ...?). For reference, here is the data from a series of passes made before I pulled apart the car (quite a ways back, unfortunately). The CalTracs & split mono-leaf springs were strapped down a good bit w/ the old Ranchos on setting 4 of 5, so there was minimal separation. The front suspension was very loose (possibly too loose) w/ 5-1/4" extension from static ride height. Unfortunately, no good pics or videos to go w/ the data. Also, in case the 60-fts look "slow", it's cuz this is a street/strip car w/ only a 4500-flash converter, 4.10s, and 9" DOT drag radials. Welcome to my build of compromises... - 60 - / 660 / MPH / 1320 / MPH / Weather conditions 1.459 / 6.682 / 101.66 / 10.566 / 126.01 / < No weather #s > 1.468 / 6.677 / 101.87 / 10.561 / 126.00 / 74, 48%, 30.57" 1.463 / 6.698 / 101.45 / 10.582 / 126.18 / 65, 42%, 30.38" 1.464 / 6.682 / 101.71 / 10.563 / 126.12 / 72, 33%, 30.35" 1.459 / 6.681 / 101.47 / 10.570 / 125.97 / 73, 33, 30.33" Not asking for "trade secrets", but some feedback would be appreciated. Thx! Last edited by Brad Hawk; 12-18-2020 at 01:49 PM. Reason: typos*

12-18-2020, 03:47 PM	#2
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,537 Likes: 2,238 Liked 1,875 Times in 577 Posts	Re: Leaf springs & CalTracs separation I run Ranchos with Caltracs on same settings Not a bunch of separation but 1.3s in 60fts. on our 340 Stockers. Very Consistent and well pleased with John Calvert's stuff!!! __________________ John Irving 741 Stock 741 Super Stock

12-18-2020, 04:35 PM	#3
Stan Weiss Senior Member Join Date: Apr 2020 Location: Phila, PA Posts: 609 Likes: 0 Liked 545 Times in 291 Posts	Re: Leaf springs & CalTracs separation I have not raced in a while. But it used to be that as I improved my 60 foot time my 1/4 et improved. It seems as your 60 foot times get worse you et gets better. Stan - 60 - / 660 /// MPH /// 1320 //// MPH /// Weather conditions 1.459 / 6.682 / 101.66 / 10.566 / 126.01 / < No weather #s > 1.459 / 6.681 / 101.47 / 10.570 / 125.97 / 73, 33, 30.33" 1.463 / 6.698 / 101.45 / 10.582 / 126.18 / 65, 42%, 30.38" 1.464 / 6.682 / 101.71 / 10.563 / 126.12 / 72, 33%, 30.35" 1.468 / 6.677 / 101.87 / 10.561 / 126.00 / 74*, 48%, 30.57"

12-18-2020, 05:00 PM	#4
NHRA1926 Member Join Date: Dec 2015 Location: Bowling green, Ky Posts: 208 Likes: 11 Liked 161 Times in 51 Posts	Re: Leaf springs & CalTracs separation You will need a good pair of rear shocks too control the separation. I use Afco double adjustable shocks on the rear of my 67 Camaro which has Caltrac's bars and split mono leaf springs. I tried Competition Engineering 3 way adjustable shocks and QA1 double adjustable shocks. Neither one of these shocks are strong enough to slow down the body separation when using the Caltrac bars. My car 60ft 1.35-1.37 When I brought my car to Mark Markow for some suspension work, he is the one that recommended the Afco shocks. I had just bought a brand new pair of QA1's right before I brought the car to him. Even though they were brand new, he told me they wouldn't be strong enough to handle the pressure from the Caltrac bars. Car hooks hard now.

12-18-2020, 05:29 PM	#5
Lenny5160 Senior Member Join Date: Nov 2015 Location: Inver Grove Heights, MN Posts: 898 Likes: 604 Liked 432 Times in 225 Posts	Re: Leaf springs & CalTracs separation I always assumed separation was somewhat the point of the CalTracs. They convert the rotational force of the rear housing trying to "wrap" into a downward force on the front of the spring, causing it to arch and lift the body. __________________ S/ST 51 S/C 53

12-18-2020, 07:05 PM	#6
Frank Castros VIP Member Join Date: Nov 2001 Location: The Lowcountry. Posts: 2,647 Likes: 2,161 Liked 2,100 Times in 774 Posts	Re: Leaf springs & CalTracs separation Ask Pete Lanciers.

12-19-2020, 09:04 AM	#7
SSGN Senior Member Join Date: Feb 2006 Posts: 625 Likes: 111 Liked 130 Times in 46 Posts	Re: Leaf springs & CalTracs separation I remember seeing lots of very fast stockers that used the Caltracs and the Rancho adj rear shocks. Way back when Top Stock was around this was the recipe. __________________ The more people I meet the more I like my dog Kevin

12-19-2020, 12:22 PM	#8
SSDiv6 VIP Member Join Date: Feb 2003 Location: Glendale, Arizona Posts: 2,991 Likes: 693 Liked 1,457 Times in 543 Posts	Re: Leaf springs & CalTracs separation Prior to CalTracs, many were using Greg Luneack's Super Launcher Springs. They had lots of separation during launch.

12-19-2020, 12:57 PM	#9
340Cuda VIP Member Join Date: Apr 2003 Location: Tulsa, Oklahoma Posts: 1,573 Likes: 3,225 Liked 681 Times in 292 Posts	Re: Leaf springs & CalTracs separation It was a long time ago but when I first got my CalTracs I sent them a photo of my car and asked them if there was too much separation. They said there was and sent me another set of springs at no charge.

12-20-2020, 10:45 AM	#10
ken robinson Member Join Date: Dec 2001 Location: tomsriver nj Posts: 441 Likes: 37 Liked 164 Times in 69 Posts	Re: Leaf springs & CalTracs separation I run cal trac springs & his 9 way shocks on the back ( set on like 7 } , some of same combos in stock separate more & some less than my car . Looking at some pics of the races from this year alone . I might try to tighten up my rear shocks . And after 10 years of racing & trailing they may be done .