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Author
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Topic: Rear Suspension Setup
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Scott (69Mach)
Gearhead Posts: 787
From: Walnut Creek, CA USA
Registered: Jun 99
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posted 02-07-2005 10:03 AM
   
OK Alex, it's tune up time for my rear suspension. I'll put the QA1's on the rear and take the car out this weekend. I was hoping for help on a baseline for the shocks and the CalTracs.The car weighs 3,300 with half a tank (which is what I typically run) and the battery is in the trunk. I run MT ET Streets at 15 psi. The car 60s at 1.79. The CalTracs are currently 1 turn gapped away from spring contact. The car has not been hooking consistently lately and commonly spins a little off the line. The body launches fairly flat with only a slight rise. Reaction times for the last 20 launches or so average 0.081 with only 1 red light. I'm guessing we could set the suspension up to react quicker and improve the RTs as well as to hook better. Thanks, Scott
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Ryan Wilke
Gearhead Posts: 2289
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 02-07-2005 12:06 PM
Scott,
1) What rearend gear ratio is in the car?2) What type of differential; traction-loc, locker, etc.? 3) What size are the M/T ET Streets? 4) What trans and/or converter are you using? 5) What front shocks are you using, 90/10s? If you would provide answers to the above questions, I'd say more chassis tune-up advice could be obtained..... Ryan 
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Scott (69Mach)
Gearhead Posts: 787
From: Walnut Creek, CA USA
Registered: Jun 99
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posted 02-07-2005 04:03 PM
4.11 locker in the rear
26x10.5x15s
3,800 stall behind a manual reverse pattern C6.
Cheap Summitt drag shocks up front.Let me know if I need to add anything else. Thanks, Scott
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Moneymaker
Administrator Posts: 26813
From: Lyons, IL, USA
Registered: May 99
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posted 02-07-2005 05:19 PM
Tighten up the Cal-Tracs to 1/2 turn preload.
1/2 turn after contact.
Set rear shocks to 3 clicks from zero on the right.
2 clicks from zero on the left.
Disconnect or remove the front sway bar.
You can just unbolt the links at the track.
Try the tires at 16 or 17 lbs.
Should work with this set up from jump street.
------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,'04 &'05
First SS/MA in the TENS!
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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Ryan Wilke
Gearhead Posts: 2289
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 02-07-2005 05:52 PM
Oky-doky. That all sounds like you're going in the right direction! This is a strip-only car that is street legal, right?  How about frame connectors (at the least) or a 8-point cage (at the most)? Does it have front discs? At rest, do they spin freely or do they still drag some? If the tire doesn't spin freely when elevated, then they may benefit from a caliper rebuild...which may allow the piston to retract more and demonstrate less drag at rest. (Anything more you can do to free up the front suspension would also help) What's up with the rear leafs? New 4 or 5-leaf OEM-style units are too stiff. Mono-leaf set best.
What's the rating of the front coils? 6-cylinder front coils would help.... With an auto trans, you should have your Cal-Trac "force transfer link" mounted in the upper or top "front pivot" mounting hole.......Your front pivot does pivot freely, right? Sometimes they are 'pinched' and aren't allowed to work as they should. As Alex stated, bump the air pressure up on the ET STREETS.... I'd even try them at 18-20 psi with that heavy of a car. GOOD LUCK!
Ryan
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Ryan Wilke
Gearhead Posts: 2289
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 02-07-2005 05:56 PM
Oky-doky. That all sounds like you're going in the right direction! This is a strip-only car that is street legal, right? How about frame connectors (at the least) or a 8 or 10-point cage (at the most)? Does it have front discs? At rest, do they spin freely or do they still drag some? If the tire doesn't spin freely when elevated, then they may benefit from a caliper rebuild...which may allow the piston to retract more and demonstrate less drag at rest. (Anything more you can do to free up the front suspension would also help) What's up with the rear leafs? New 4 or 5-leaf OEM-style units are too stiff. A mono-leaf set (like those Calverts sell or fiberglass like Alex runs) would be better....
What's the rating of the front coils? 8-cyl coils are too stiff. install some 6-cylinder front coils.... With an auto trans, do you have your Cal-Trac "force transfer link" mounted in the upper or top "front pivot" mounting hole.......Your front pivot does pivot freely at the spring mount, right? Sometimes the pivot plates are 'pinched' in & aren't allowed to work as they should. As Alex stated, bump the air pressure up a few on the ET STREETS.... I'd even try them at 18-20 psi with that heavy of a car. Sounds like you're getting there... Keep us posted with your success!  GOOD LUCK!
Ryan
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Scott (69Mach)
Gearhead Posts: 787
From: Walnut Creek, CA USA
Registered: Jun 99
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posted 02-08-2005 10:48 AM
Excellent, thanks guys.
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Scott (69Mach)
Gearhead Posts: 787
From: Walnut Creek, CA USA
Registered: Jun 99
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posted 02-11-2005 12:20 AM
Ryan/Alex,I have the bar in the lower pivot mounting bolt. Do I need to move it to the upper???
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Ryan Wilke
Gearhead Posts: 2289
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 02-11-2005 08:03 AM
The location of the bar determines how hard the torque is applied to the tires. It goes without saying that the type of shocks (both front & back), size & type of rear tires, launch rpm, chassis rigidity, etc. all play a factor in how your particular car will react off the line. Generally speaking, it has been my observation that most auto cars run the bar in the upper hole and stick cars run it in the lower hole. So - since you're running an automatic trans, I recommended that you start out with it in the upper hole; and then try to establish some consistant 60'ers. However, once you've obtained a fairly consistant 60' performance, there's nothing saying you can't switch it to the lower hole just for experimentation's sake. Ryan
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