Categories
Chassis

Progress Group CSII/CSIII Spring Rate Guide

Progress Group coilovers are configurable with a variety of spring options for all different sorts of use profiles. Here is a blog to help understand what the different spring rate selections will do for you!

ALWAYS CONSIDER the following:
* Primary vehicle use
* Secondary vehicle use
* Weather and road conditions
* Driver skill & experience

CONSIDER…
For the sake of comparison, typical OEM spring rates for these applications are approximately 220#/in front, and 110#/in rear. With the numerous Civic & Integra applications, there is a range of spring rates, and these C.S. (Competition Series) systems are significant-to-dramatic upgrades from your OEM damper and spring calibrations.

SHOP: Once you’ve decided on a spring rate choice for your car, shop Progress Group CSII & CSIII Coilovers on Heeltoeauto.com

CSII Non-Adjustable Damping

D-SERIES/Single cam applications

350/250: Best ride for a daily driver. Great for commuting. The front may bottom out if set up too low.

350/350: A good compromise, less understeer & more fun. A modest concession to ride quality. This may be choppy for some drivers with short wheelbase models; Civic Hatch and CRX.

350/450 or 350/550: Offers minimal understeer, quick turn-in, less roll, fast & fun, with the 55 rears being even better for a good for drag launch. Rides rough on bumpy or poor roads.

B&K-SERIES/Twin cam applications

450/350: Best ride for a daily driver. Fun and well-mannered. Modest understeer. Recommended for street/performance & daily drivers.

450/450: Good compromise, less understeer, less roll & more grip.

450/550: Minimal understeer, awesome handling, quick steering response, good for drag launch. Rides rough on bumpy or poor roads.

550/550: Good for track cars equipped with a front end spoiler or splitter. Also for street cars running super-wide wheels & tires and low ride heights. At this point, you should know you are signing up for a huge compromise in ride quality. Very stiff!

Here is MORE DETAILS about these combinations:

** STREET-PERFORMANCE
FRONT HEAVY setups (350/250, 450/350 etc.)
Good for Daily Drivers (DD), poor weather and road conditions because these setups do not upset the ride on the highway and during cornering. The softer rear suspension tracks nicely and rides better because it is more compliant. These calibrations ride well on uneven road conditions if set up at a reasonable ride height around 1.0 in.to 1.5 in. less than OEM (12.5 in.). Expect a dramatic improvement in handling capability and steering response. These setups will still have some mild understeer, less than OEM but still easy and forgiving to drive every day and in all weather conditions. This is the choice for sport-tuned Daily Drivers.

** STREET-SPORT
SQUARE setups (350/350, 450/450 etc.)
These setups are a compromise between ride quality and all-out handling. Some impact on ride quality makes for less understeer and faster vehicle response. The stiffer front springs also help prevent bottoming out. This combination is plenty stiff, and NOT recommended for true daily drivers (TDD) on poor roads, or drivers rolling a lot of commuter miles. Good for ‘fun cars’ driven by more experienced drivers.

** AUTOCROSS-TRACK & DRAG SPECIFIC
REAR HEAVY setups (350/450, 450/550 etc.)
Much more aggressive. This calibration has more grip, and is intended for use with ‘performance/track’ alignment settings and sticky tires. If ride quality is a major concern, don’t go here because the stiffer rear springs make for an uncomfortable (and choppy) highway ride. This is a more balanced and LESS FORGIVING setup intended for enthusiast TRACK days and AUTOCROSS events. These combinations will also launch well for mild drag applications on DOT tires. Expect a HUGE improvement in handling capability. This would also be a great low-budget setup for new (road racing) drivers going to a (track) DRIVING SCHOOL or TRACK events.
Faster chassis response, less forgiving, and MAX GRIP in most cornering situations. The chassis balance will be very close to ideal, having minimal understeer with ‘track-oriented’ alignment settings and good UHP tires. This is a BIG compromise in ride quality and will require more DRIVING SKILL to drive at the limit (on the track please!) NOT RECOMMENDED for wet/snow/poor weather and road conditions.

ALWAYS CONSIDER the following:
* Primary vehicle use
* Secondary vehicle use
* Weather and road conditions
* Driver skill & experience

CONSIDER…
For the sake of comparison, typical OEM spring rates for these applications are approximately 220#/in front, and 110#/in rear. With the numerous Civic & Integra applications, there is a range of spring rates, and these CS-II systems are significant upgrades from your OEM damper and spring calibrations.

CSIII Adjustable Damping

The above infor for the CSII mostly applies to the CSIII, although there is some additional capability with the CSIII that allows for higher rates than the CSII. Here are some notes for the CSIII’s expanded range.

550/450 – 550/550: Very stiff front and softer rear for poor roads and bumpy race tracks. Good for track cars equipped with a front end spoiler or aero-splitter. Also for street cars running super-wide wheels & tires and low ride heights. At this point, you should know you are signing up for a huge compromise in ride quality. Very stiff!

550/650 – 550/800 – 650/650 – 650/800: These setups are aggressive for track-only applications on smoother tracks with race tires or UHP shaved tires. At this point you should have some track experience and have some idea about what you are getting into. Call in and we can discuss these track-only setups and select one that best suits your application and specifics.

* FRONT HEAVY setups (350/250, 450/350 etc.)
Good for Daily Drivers (DD), poor weather and road conditions because these setups do not upset the ride on the highway and during cornering. The softer rear suspension tracks nicely and rides better because it is more softer & more compliant. These calibrations ride well on uneven road conditions if set up at a reasonable ride height around 1.0 in. to 1.5 in. less than OEM (12.5 in.). Expect a DRAMATIC improvement in handling capability and steering response. These setups will still have some mild understeer, less than OEM but still easy and forgiving to drive every day and in all weather conditions. This is the choice for sport-tuned Daily Drivers.

* STREET-SPORT ‘SQUARE’ SETUPS (350/350, 450/450 etc.)
These setups are a compromise between ride quality and all-out handling. With some impact on ride quality, you will have less understeer (more neutral balance) and faster vehicle response. The stiffer front springs also help prevent bottoming out. This combination is plenty stiff, and NOT recommended for true daily drivers (TDD?) on poor roads, or drivers rolling a lot of commuter miles. Good for ‘fun cars’ driven by more experienced drivers.

* AUTOCROSS-TRACK & DRAG SPECIFIC
REAR HEAVY setups (550/650, 550/800 etc.)
Much more aggressive. This calibration has more grip, and is intended for use with ‘performance/track’ alignment settings and sticky tires. If ride quality is a major concern, DO NOT go here because the stiffer rear springs make for an uncomfortable (and choppy) highway ride. This is a more balanced and LESS FORGIVING setup intended for enthusiast TRACK days and AUTOCROSS events. These combinations will also launch well for mild drag applications on DOT tires. Expect a HUGE improvement in handling capability. This would also be a great low-budget setup for new (road racing) drivers going to a (track) DRIVING SCHOOL or TRACK events. Faster chassis response, less forgiving, and MAX GRIP in most cornering situations. The chassis balance will be very close to ideal, having minimal understeer with ‘track-oriented’ alignment settings and good UHP tires. This is a BIG compromise in ride quality and will require more DRIVING SKILL to drive at the limit (on the track please!) NOT RECOMMENDED for wet/snow/poor weather and road conditions.

Check out this cool CSIII Unboxing Video on our YouTube Channel!

Categories
Chassis

Product Announcement: Medieval-Pro Torsion Bars Now Available

The torsion bar front end of a Honda Civic/CRX from 84-87 or Acura Integra from 86-89 is one of the more widely misunderstood components on these unique Honda models. But what generally isn’t misunderstood is that you want larger ones if your car has any sporting pretense.

The torsion bars are these cars’ front springs, supporting each corner of the car. They function as front springs but work a lot like sway bars. In these Hondas, splined bars connect a free-floating front control arm to the subframe via an adjustable “torsion tube.” Stock bars are around 17-19mm in diameter. The size relates directly to how “stiff” the suspension is.

For many years, a company in Los Angeles called Upgrade Motoring produced torsion bars, which Heeltoe had sold under our in-house label “Medieval-Pro.” However, in 2016, the supply of these bars began to fade. The pricing continued to rise and customers were unable to afford them any longer. In January 2017, Upgrade Motoring announced they could no longer produce torsion bars.

This sad day came just around the time that Heeltoe has decided to combat the rising prices by producing bars through another manufacturer. One was found and the second generation of Medieval-Pro Torsion bars are here!

Currently, Heeltoe offers bars in 24, 27, and 30 mm diameters, in CRX lengths. New circlips and snap rings are included.

Astute readers will know that some Civics actually come with a shorter torsion bar than the CRX does and that the Integra bars are nearly 1″ longer. Due to current production and demand limitations, Heeltoe is only producing CRX-length bars at this time. The good news is, any of these cars can use the CRX bars. If you have Civic tubes, the CRX bars will stick out the back slightly, which is not a functional problem. You will need CRX torsion tubes if you have an Integra, which can be found at junk yards and the like. For evidence, find this link: Integra Torsion Bar Installation

Keep in mind, the change in length from an Integra or Civic bar will also change the wheel rate. To make sure you are selecting the right bar for your application, find our Honda Torsion Bar Wheel Rate Guide here.

Shop For Medieval-Pro Torsion Bars Here: Medieval-Pro Torsion Bars

Categories
Chassis Heeltoe Explains

Tech: What’s the Spring Rate of my Torsion Bars? #torsionbarhondas Content Inside!

1984-87 Honda Civic/CRX and 1986-89 Acura Integra models came with a unique torsion-bar front suspension. Because of the non-conventional nature of a torsion bar as compared to a coil spring, people at times become lost on what various bars’ diameters equate to what would be conventional spring rates. This is an important figure for determining the balance of the car and for tuning the dampers.

Between the various diameters and lengths of bars available, we were a bit lost on it ourselves, but a little poking around led us to Sway-Away’s website. As some may know, Sway-Away is one of the foremost torsion-bar producers having even produced bars for said Hondas at one point in history. We knew this convenient calculator was something we could trust!

On the page there you will find the science behind the torsion bar wheel rate calculation. You’ll also see that the effective wheel rate is the same as the spring rate taken at the end of the control arm, or what is actually the lever on which the wheel’s movement acts.

You can play with it all you like, but we have taken the liberty of making a quick chart for fast approximate reference. Some of our dimensions are approximate but the spring rates should be accurate within about 5-10% and that’s really pretty good for our purposes.

Notes:

  • LCA stands for “lower control arm.” Since people tune both Integras and Civic/CRX models, and sometimes Civic/CRX people put the longer Integra lower arms in their car to increase camber, we include both here. We approximate a 13.5″ length on the Civic/CRX and 14.5″ on the Integra, from the center of the torsion bar to the end of the ball joint.
  • All rates are in pounds per inch of travel (lb/in), but we have a lb/in to kgf/mm charge just below.
  • Not all these torsion bar diameters are actually available, but we are listing them anyway since any of them technically could be made or exist.
  • The bar length will impact the wheel rate, too. The 24.3″ bar is the length of CRX and many Civic bars. Some Civics have a bar that is about 1/3″ shorter, but the rate change is fairly minor so we have omitted it to keep the chart simpler. The Mugen bars that were made long ago were shorter than the Civic/CRX ones, with an overall length of just under 22.5″. These would give the highest rate per diameter, and being the more compact bar would have the least weight (no surprise that the Mugen bar would be the ideal for performance yielding the most rate-per-weight!).
CRX LCA CRX LCA CRX LCA ‘TEG LCA ‘TEG LCA ‘TEG LCA
Diameter/
Lengths
22.5″24.3″25.7″22.5″24.3″25.7″
19mm978480847370
20mm1201091021039589
21mm145133125126114108
22mm175159150151139130
23mm209190179181165155
24mm247225212214195184
25mm291265250252230217
26mm340310293295269253
27mm396361340343313295
28mm458417393397362341
29mm527480452457416392
30mm603550518523477449
31mm687626591596543512

We work on Japanese cars at Heeltoe here, and oftentimes it becomes necessary to work in both lbs/in and kgf/mm (that’s kilogram of force per millimeter). They are different ways of saying the same thing about a spring’s rate, but we’ve offered this handy conversion chart for you to know the equivalents. This info is pulled from Tein.com’s Standardized Spring chart.

lb/inkgf/mm
1122.0
1402.5
1683.0
1963.5
2244.0
2524.5
2805.0
3366.0
3927.0
4488.0
5049.0
56010.0
67212.0
78414.0
89616.0
100818.0
112020.0

Please feel free to leave any commentary or calls for correction below! And never forget that Heeltoe is always in your corner, aiming to provide the best and most accurate info we can to help you tune your car!