Spring Rate Q's

[ScotcH]

Hey all,

So, anyone who saw my car at the track last weekend could probably tell that I need a new suspension setup :)

The current setup is koni reds with H&R sport springs (all show, no go!). The tires are rubbing the inside of the fender wall in tight corners (not the fender edge, so offset is not the problem).

So, here's my choices: OEM springs are about 300/200 (front/rear). The H&Rs are about 400/260. Ground controls are 450/315, but they can put in custom rates (about $400US). These are just the sleves and coils ... I'd still use the konis. Finally, JIC SF-1's are 674/450 (about $1300US), and again they can put in custom rates. These are a full coil-over setup, with the shocks matched to the springs. Keeping in mind that the car is 3600lbs, and there are no anti-roll bars available, what would you do as a starting point?

Another option I have read about is binding a few coils (welded strapping) on the OEM springs to increase the rate ... would this work as an interim solution? Would I still take the 4 PIP hit if I modify the OEM springs? Maybe the best option is to just put back the stock springs, and drop down a class ....

Anyway, I'm done ... let me know your thoughts (asks the student of the masters :))

[GregR]

Were you the white Acura on Sunday?

For what it's worth, my Prelude's setup is H&R Race on KYB AGX. I do get some rubbing on the inside of the wheel-well liner, but that's with 205/55-16 tires (stock was 205/50-16). To be honest, I haven't even compared the spring rates between the stock SH springs and the H&R's I'm using. I should do that!

Sounds like the GC's would be a good bet since you get the adjustable sleeves. Then - since you're in Ottawa - you hook up with Nigel Mortimer (check the MCO forum) and get your car corner-weighed and balanced.

[Dave]

Arek, binding the coil or cutting stock springs is never a good idea for race use, plus you'd still be required to take the 4 PIPs since you've modified the part.

If you can sell your Koni reds, I would strongly suggest getting a set of adjustable shocks like Koni yellows or go to a full coilover suspension like Tein or JIC. Having adjustable valve stiffness, even single adjustables that change rebound and compression at the same time, will really help you tune the handling characteristics of your car at the track. As it is, I'm sure your car understeers a lot, but with adjustable shocks you can stiffen the rear valving and reduce understeer considerably.

Since you don't have sway bar options without going to an expensive custom set, your best bet is to simply tune with spring rates. With a front heavy car like yours (and most FWD cars for that matter) using stiffer springs on the rear of the car will really help its on-track performance by reducing understeer and potentially even inducing a bit of rotation or oversteer (back end coming around before the front tires start to plough). For example, I'm running about 800 lbs or 14k springs on the back of my Civic and 550 lbs or 10k springs on the front, with no sway bars front or rear. This set-up is pretty harsh on the street, it's not particularly comfortable for street driving that's for sure, but it's fantastic for the track. You'll find that most of the fast Honda guys are running a similar stagger of spring rates with stiffer springs out back to help eliminate the brutal understeer that our cars suffer from due to the front wheel drive and front engine configuration. A more tolerable streetable set-up that would still yield excellent results at the track for your car might be something like 400 lbs (or 7-8k front) and 550 lbs (or 10k rear). Springs are fairly inexpensive at about $80-100 each, so many of us have done some experimenting with different spring rates before settling on a set-up that suits our needs and driving style the best.

For the best overall balance, having shocks and springs that are specifically designed to work well with each other is the way to go. Tein, for example, valves their shocks aggressively enough that you can run a fairly wide range of spring rates without over- or under-matching them to the point that performance becomes unpredictable. Off-the-shelf Konis or KYBs, on the other hand, are valved fairly mildly so you can't go much above 400 lb. springs before you've over-matched them.

It's really all about your budget, what sort of compromises you're willing to make between streetability and track performance, and then choosing the right set-up based on these parameters. If you give us a bit more info on what you're looking for, I'm sure we can get you pointed in the right direction.

Cheers,
Dave

[andrew1984]

800 lbs per inch?!?!

[Dave]

yup, lbs-in. An easy way to convert from kg-mm to lbs-in is to simply multiply the kg-mm rating by 56. For example, my 10kg-mm front springs and 14kg-mm rear springs are approximately 560 lbs-in front and 785 lbs-in rear. I have a set of 20k springs in the closet, which I plan to put on the rear of my car and move the 14k springs up front, but only once I have a trailer and tow vehicle :)

[ice/solo racer]

If I remember right Patrick Yorke is up to 1000 lbs/inch on the rear of his civic!A couple of years ago I was talking with the HART race team driver from the motorola cup civic SIR at mosport and they were up over 1000lb springs as well.And thats on a track car not a low speed autoX car.

[andrew1984]

dear god.

and i thought 300lb-inch was alot!

[Dave]

heh, 300 lbs-in is just the beginning Andrew! Invest in a kidney belt and start bumping up those spring rates! :p

[andrew1984]

no really..... its ok!


i love the way my car carves the road now :D

[ScotcH]

Originally posted by Dave
Arek, binding the coil or cutting stock springs is never a good idea for race use, plus you'd still be required to take the 4 PIPs since you've modified the part.

Ok .. forget that ... I was only going to do it if i didn't take the 4 PIP hit


If you can sell your Koni reds, I would strongly suggest getting a set of adjustable shocks like Koni yellows or go to a full coilover suspension like Tein or JIC. Having adjustable valve stiffness, even single adjustables that change rebound and compression at the same time, will really help you tune the handling characteristics of your car at the track. As it is, I'm sure your car understeers a lot, but with adjustable shocks you can stiffen the rear valving and reduce understeer considerably.

Sure I could sell them, but I couldn't buy anthing else ... reds are all they make for the Legend. However, they are adjustable (rebound only) I already have them on full stiff. Also, the only JIC for the Legend is the SF-1, which has anon adjustable damper :( Basically, the Legend is hosed as far as aftermarket, but, damit, I'm going to make it work! :)


Since you don't have sway bar options without going to an expensive custom set, your best bet is to simply tune with spring rates. With a front heavy car like yours (and most FWD cars for that matter) using stiffer springs on the rear of the car will really help its on-track performance by reducing understeer and potentially even inducing a bit of rotation or oversteer (back end coming around before the front tires start to plough). For example, I'm running about 800 lbs or 14k springs on the back of my Civic and 550 lbs or 10k springs on the front, with no sway bars front or rear. This set-up is pretty harsh on the street, it's not particularly comfortable for street driving that's for sure, but it's fantastic for the track. You'll find that most of the fast Honda guys are running a similar stagger of spring rates with stiffer springs out back to help eliminate the brutal understeer that our cars suffer from due to the front wheel drive and front engine configuration. A more tolerable streetable set-up that would still yield excellent results at the track for your car might be something like 400 lbs (or 7-8k front) and 550 lbs (or 10k rear). Springs are fairly inexpensive at about $80-100 each, so many of us have done some experimenting with different spring rates before settling on a set-up that suits our needs and driving style the best.

Well, if I'm going to experiment, I might be best off with the Ground Control coil-over, which fits over the koni shocks ... they're cheap, leaving some cash for other springs to try. I find it odd that all the sets most manufacturers sell, even the race setups, have higher rates in the front ... also, when I asked the guy if he could do 1000lbs/in springs, he thought I was crazy! Oh well, I'll probably get the GC's with 12/8 rates and see how they do. Basically, I plan to swap the suspension before track events, so streetability is not really an issue (I can do it in about 2 hrs now since I've done it a bunch of times). I will also look into some custom work (or a modded Tein or something) ... it might end up being cheaper than a JIC set

Thanks for the help, and of course keep the info coming!

[Dave]

Arek, the reason all the manufacturers sell coilover set-ups with higher front spring rates is simply a matter of liability. A car that understeers like a pig is a safe car (but unfortunately a slow car), so they all make kits that result in understeer, though generally less so than the stock set-up so the car's handling will improve enough to keep most customers happy. But for a true track set-up, you definitely want the 12k springs out back and the 8k springs up front. I'd say give the GC's a try with these spring rates and if you're unconvinced try it with the 12k up front and you'll see for yourself just what a difference it makes to have the rear spring rates higher than the front.

Also, some of the JDM manufacturers use higher spring rates up front because in Japan the tuner philosophy tends to favour MASSIVE rear sway bars to eliminate understeer and create controllable oversteer in the corners. The North American the philosophy tends to favour high rear spring rates to achieve the same result. The Realtime Integra Type R's, for example, run 1200 lbs-in rear springs along with 600-800 lbs-in front springs depending on the track. It's important to recognize, however, that a race suspension set-up like this also includes aggressive wheel alignment settings with negative camber in the 3-4 degrees range in order to make full use of the tire section width as well as lots of other suspension tuning tricks.

If you're considering modified or custom Teins or JICs, give Ray at KHF a call at 416-752-4950. KHF/Kensai Racing is a HADA club sponsor and they are also the official Tein and JIC distributors for Canada, so they'll be able to get you custom stuff that nobody else in Canada can. Tell Ray that Dave from HADA referred you and he should treat you right. And hey, if you join HADA we do have sizeable discounts on Tein, JIC, and all of Kensai's product line. Check out their website at www.kensairacing.com for more info.

[ctenche]

ScotcH...what guy thought you were crazy asking about the the 1000 lb/in springs?

Also, if I'm reading things right you are have Koni Reds right? If so, when you say you're going to go with the GC 12/8 keep in mind that the 12K springs might be too much for the stock Koni Reds to handle. Koni Yellows are generally valved to handle a maximum of 500-600 lb/in depending on application. With 12K (approx 670 lb/in) springs you will definitely pushing the limits of the shock. It will not be able to dampen the spring properly and as a result the handling will suffer and the car will feel rather unstable.

[ScotcH]

Ok ... so I've been contacting a few people regarding this. The JIC's can be made with whatever rates I want, with the struts to match. However, they are not adjustable, so I can't experiment with different damper settings. Do you see this as a problem?

I also talked to koni, and they can rebuild my koni reds with adjustable guts for both rebound and compression, and revalve them to handle the higher spring rates. Then I could just get the GC coli-over sleves, and use whatever rates I want. This is looking like a more flexible solution, but cost might be high ...

Dave: I could not get a hold of Ray at KHF ... the number you posted has been busy for the last day. Too much business, I guess :)

Thanks for the input guys, and I will keep you posted

[ctenche]

Adjustability in a shock is good. It is the simplest and definitely the quickest way to tune the handling charactersitcs of your car. It's amazing just how effective changing the rebound damping can be on combating over/understeer. At the very least, it's super handy to have for those days when it's raining and you want to soften your ride.

To be honest with you, based on the feedback from other competitors who have run both the Koni/GC and Tein setup, I'd go with the Teins. They seem to have damping characterstics out of the box whereas the Koni's require to be revalved for higher spring rates.

It just avoids a lot of work and cost.

[ScotcH]

Originally posted by ctenche
ScotcH...what guy thought you were crazy asking about the the 1000 lb/in springs?


Some guy at Ground Control when I called them. Must have just been a lowly salesman or something.

[ScotcH]

Originally posted by ctenche
To be honest with you, based on the feedback from other competitors who have run both the Koni/GC and Tein setup, I'd go with the Teins. They seem to have damping characterstics out of the box whereas the Koni's require to be revalved for higher spring rates.

It just avoids a lot of work and cost.

Except that Tein does not make an application for the Legend. JIC does, but the damper is not adjustable. Damn luxury car ;)

[GR8 Ride]

Originally posted by ScotcH
Some guy at Ground Control when I called them. Must have just been a lowly salesman or something.

No, it was probably Jay Morris. There are two schools of thought when it comes to suspension design on hybrid track / street cars.

One, to go with as much spring as possible, and maybe eliminate the swaybars. This is the more common setup among pure race cars, and can be the faster of the two, on smooth tracks (which Mosport is, and Cayuga isn't too bad).

Two, to go with soft springs which are more suitable for the street, and then use ultra-stiff sway bars to control body roll and to transfer weight back to the inside wheels. This method works a little better on race tracks where the surface isn't smooth, and a lot better when you're talking about a hybrid street / track car.


Pat

[GR8 Ride]

Originally posted by ScotcH
Except that Tein does not make an application for the Legend. JIC does, but the damper is not adjustable. Damn luxury car ;)

I wouldn't worry about adjustability being a primary factor when looking at suspension for your car. What you'll often find happens is that a person will adjust their suspension for the ride / handling they want, and then just leave it that way.

Also, *tweaking* the suspension without a solid understanding of what effect each change will have on the handling of the car can lead to far poorer performance than you might expect. By changing the damping rate for either bounce or rebound on a single shock can have a huge effect on the remaining 3 wheels.



Pat

[ScotcH]

Originally posted by GR8 Ride
I wouldn't worry about adjustability being a primary factor when looking at suspension for your car. What you'll often find happens is that a person will adjust their suspension for the ride / handling they want, and then just leave it that way.

I'm not worried about playing with them all the time. It's that initial setup that I'd like to be able to dial in. If I get the JIC, I'm stuck with whatever they send me. This will likely be just fine for my inexperienced ass, but it would be nice to have the adjustability :)

[ScotcH]

Ok ... so, I have some final numbers. See what you guys think:

1. JIC full coil-over setup, any spring rate, matched struts, no adjustability: $1300 USD

2. Revalved koni, externally adjustable rebound, coil-over sleeves, any rate springs: $1140 USD

3. Revalved koni, externally adjustable rebound and compression, coil-over sleeves, any rate springs: $1740 USD

The last option is too pricey at this point, and I'm not sure option 2 is worth the extra cost just for the rebound adjustment. Also, with the koni rebuild, I'd have to send them mine for revalving, or have to buy a new set ($500USD), so down-time is an issue.

I'm leaning toward the JIC, with maybe a 700 front, 900 rear (up from the default 675/450). Try that out for the rest of the summer, and then I have all winter to do other things if needed.

[GR8 Ride]

700 front and 900 rear will be kidney belt time for a daily driver though.

I'm running 650 lbs/in on the front of my race car, and 900 lbs/in on the rear, with custom valved Bilsteins to match. It's too stiff to be a daily driver (car is no longer street legal anyway, so it doesn't matter).

But if you're planning on driving the car daily, it's tough to put up with that for long (though you will like it on the track).

How much does the Legend weigh?


Pat

[ScotcH]

The setup will be track use only, so no worries about my kidneys ;)

The car weighs 3650 stock

[GR8 Ride]

Ok, that makes more sense then.

What's the weight distribution of the car like? Being a FWD car, it may still be worth it to look at stiffer springs in the front.

A lot of this depends upon suspension geometry as well. Spring rate and wheel rate are often two different things, depending upon how the suspension (front and rear) is setup. On a McPherson strut (or any coilover), the spring rate and wheel rate are identical. On a modified McPherson strut (such as the Mustang SN95 platform), the spring rate is stiffer than the wheel rate, because the spring sits inboard on the lower control arm.

Same logic applies in the rear.

Ultimately, the best place to start would be to talk to some people who actually race / open-track an Acura Legend (or have done so in the past), and see what they recommend. Otherwise, it's just guessing as to what works and what doesn't.



Pat

[ScotcH]

Here's all the info I can find, without actually putting the car on scales:

weight: 3542 lb
ratio (f/r): 60%/40%
wheelbase: 111.4 in
track (f): 61.0 in
track (r): 60.6 in
Suspension (f): Independent double-wishbone with coil springs and stabilizer bar
Suspension (r): Independent double-wishbone with dual trailing arms, coil springs and stabilizer bar

The car is FWD, but engine is mounted north/south, so the L/R distribution is pretty good, and the drive shafts are equal length.

Basically, I'm looking for a starting point for a track setup to reduce the understeer, and help the car rotate in corners. As it is (with koni and H&R 400/300 rates, progressive) the front wheels go way too deep into the wheel well, and end up hitting the fender liner

[ScotcH]

Originally posted by GR8 Ride
Ultimately, the best place to start would be to talk to some people who actually race / open-track an Acura Legend (or have done so in the past), and see what they recommend. Otherwise, it's just guessing as to what works and what doesn't.

You know, I may actually be first (except maybe in Japan, but I can't speak Japanese) :cool:

[alexb]

Wow that is one pig of a car.
Most honda guys will run the heavy springs out back.But we are talking cars 1000# lighter.
The HADA group should be able to help you out.
I am afraid to give any recomendations on a car that heavy.

[ctenche]

ScotcH...I just realized something. You said that you are running on H&R Sport springs and that they are 400/300. Where did you get that info?

Here's why I ask. First of all, the "Sport" springs are progressive, not linear. Therefore, the rates will vary from pretty soft to full stiff on complete compression. Secondly, at least on the Integra application, the "Sport" springs are no where near 300/400. They're more in the mid 200's or there about. I don't have the #s in front of me but I'll check when I get home.

This might be your problem!

The combination of progressive springs plus a rate that might not be as stiff as you image might be causing all the wallowing you're experiencing.

[B18C5]

Yeah, but isn't it possible that since the car weighs 1000lbs more than the teg they'd sell springs that are much heavier weighted? Either way that's way too soft.

Having the rebound only adjustable isn't as bad as it sounds. When you adjust for compression you're basically adjusting for a certain spring rate. The spring should be doing most of the compression already. So when Koni rebuilds shocks they rebuild them with the compression damping already in the range for the spring rates you're planning on using. You don't really have to adjust it. Or something like that...

[Dave]

Geo, that was shockingly coherent! :p

Interesting that the coupe is FWD...for some reason I always thought they were RWD since they have the same engine block as a NSX. Man, every time I say (or type) the letters "NSX" I have the uncontrollable urge to mortgage my future and buy one!

[B18C5]

I found that if I slow down and actually think things through before I type I make a lot more sense. Only problem is it takes too long to reply. Hehe. Maybe I'll speed this up a bit.

My first thought was that it made perfect sense that the NSX is mid-engined, rear wheel drive and the Legend is front-engined, front wheel drive car. But then that comment about the engine being mounted north-south got me thinking. The NSX's engine is actually mounted transversely, so there's no possibility that the NSX and Legend share a transmission. I thought they might share at least the layout of the tranny case, if not the actual case it's self.

One interesting thing I found in my search is that you can pick up a rebuilt NSX engine for a little more than a GSR engine:

So cool! Honda engines here! (http://www.remanufactured.com/Acura_Engines.htm)

I assume the Legend's engine is mounted behind the front axle, since there isn't too much room in the front. I remember the Vigor having the same layout. I think it shared an engine with the Legend too.

Every time I hear the letters NSX I have an uncontrollable urge build a turbo block for it...

[ScotcH]

Yeah, I know ... the answer to all my problems is to sell the Legend and get an NSX ;) That would be cheating though! I want to work with what I got.

There has been a lot of discussion of Legend forums regarding NSX engine swaps, and basically, it's doable, but you'd need to cut holes in the hood to fit the massive vtec heads under there. Also, it's only 60 more horses ... for less cash, I could probably put in FI of some sort. Anyway, engine mods are really secondary on this car.... handling being definitly first!

I think I'm leaning toward getting the revalved konis with adjustable rebound. The JIC's will take 6 weeks to do (stupid slow ass Japan shipping).

What would you suggest as a good starting rate for the springs? Based on your feedback, I'm thinking 12k front 16k rear .... comments?

[tomfoolery]

If you want a custom swaybars for cheap contact

http://www.sanerperffab.com/

They will build you anything you want and are nice guys too :)

Before you go buying any suspension parts contact Lee Grimes at Koni as he is one of the head guys there and can advise you on what is the best route to take.

Hi email is lgrimes0@insightbb.com


If you get revalved konis he most likely would have had input in building them.

[ScotcH]

Thanks for the input ... I sent an e-mail to Lee, but have yet to receive a response. I assume he's a busy guy.

I had the car at Mosport last weekend (awsome track!), and I simply cannot wait any longer. I am going to get some Ground Control coil-overs with 10k/10k springs (they usually come with 8k/6k). I spoke to a tech at Koni and the stock konis should be able to handle the 10k rates. This will at least get me a better ride for the rest of this season, and give me time to find a proper solution. At least my tires won't rub the inner fender liner because of 258.3" of suspension travel :rolleyes:

[Dave]

sounds like a good starting point to me, Arek. You will probably want to go to higher rear spring rates or a big honkin' rear sway bar to help the car get through the corners with less understeer but the 10k/10k set-up will still be a huge improvement over what you've got now. Looking forward to seeing her go once you've got the GC's on it!

[Chris P]

Lee Grimes is currently on vacation. I believe he'll be back in a few days.

If you like i can give you his phone number at Koni.