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Discussion Starter · #1 ·
What are the specs on the 122 coil springs? Inner diameter, outer diameter, length with no compression (when not installed, I guess), and spring rate. Front and rear too.

Maybe there's a write-up on this somewhere I haven't been able to find?
 

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The spring rate is determined by the wire diameter, coil diameter (which you can estimate from the total OD by subtracting the wire diameter) and number of coils. The spring length will determine the ride height. I have an old worn out ipd spring there somewhere, but I do not have a stock spring. You can measure the wire diameter on your spring, and may be raise the car off the suspension and measure the OD (most of the load is removed, so the OD should should be close). But the unloaded height you will not be able to measure that way. Still, the above will determine the spring rate.
 

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Volvo's racing recommendations were to cut the front springs by 2 coils and the rear by 3 (along with sway bar mods). That will increase the stiffness inversely proportional to the reduction of coils (i.e., if the stock spring had 10 coils, removal of 2 coils will increase the the stiffness by a factor of 10/8). IPD followed the same recommendation.
 

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Discussion Starter · #4 ·
So what's the outer diameter of the recommended spring?
 

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Volvo's racing recommendations were to cut the front springs by 2 coils and the rear by 3 (along with sway bar mods). That will increase the stiffness inversely proportional to the reduction of coils (i.e., if the stock spring had 10 coils, removal of 2 coils will increase the the stiffness by a factor of 10/8). IPD followed the same recommendation.
Have you ever driven a car done like that? The handling is crap! A well sorted set up uprated springs and dampers will give some very good results and transform the handling.
 

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Have you ever driven a car done like that? The handling is crap! A well sorted set up uprated springs and dampers will give some very good results and transform the handling.
These were the recommendations from Volvo. I have an ipd Amazon (with also thicker sway bar on the front and a sway bar on the back), and the results are very good, at the expense of deterioration in ride. But if you are looking for improvement in cornering, you will definitely get it. Now, without the rear sway bar, you will likely get a bit too much understeer, which can be reduced by change in camber. But the rear sway bar sounds like a better solution to me.
 

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Dimitri is not speaking from experience with the Volvo Racing recommendations, he is only recycling information he picked up somewhere, so he is not familar with the fact the car will drive like crap that way.. LOL He uses no discretion in dishing out recycled information, he just puts it out there, without having any practical knowledge if it works or not.
 

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These were the recommendations from Volvo. I have an ipd Amazon (with also thicker sway bar on the front and a sway bar on the back), and the results are very good, at the expense of deterioration in ride. But if you are looking for improvement in cornering, you will definitely get it. Now, without the rear sway bar, you will likely get a bit too much understeer, which can be reduced by change in camber. But the rear sway bar sounds like a better solution to me.
I would not have thought that Volvo would recomend something like that. To me sound more like a dealers suggestion than something to come direct from volvo.

You do not realy need to mess with sway bars as well made stiffer springs and good quality dampers will give some very good results. I have driven a couple of cars with only a front IPD sway bar fitted and I would go as far as saying a setup like that is lethal. You some into a corner and the front is nice and positive and the rear ends rocks around all over the place. The imbalance between front and rear is huge and causes a scary experiance when cornering.
There are some rally cars over here that have done away with the sway bars all together and have just used increased spring rate to acheive what they want.

Bottom line is I would not recomend cutting springs to anyone regardless of who has said it is ok. After all if someone had a crash as a result would you want to take responability?
 

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Allow me to say that I have quite a lot of experience with this. I have never cut springs. I have used both the IPD "Street Coils" and the VPD progressive springs on many cars, with just the front IPD bar. The trick is to run a fair amount of negative camber, at least 1/2 degree depending on tires. This produces a little bit of understeer on turn-in, but not once the car "takes a set." You can still easily induce oversteer with the throttle, and use much more power driving out of turns than you can with a rear bar fitted. I built a winning Carrera Panamericana Amazon using this setup, so I can say this works on real roads as well as on a race track.

Now, a gravel rally is a completely different situation. It could well be that sway bars would not be appropriate in that context, and doing all the stiffening with spring rates would be the way to go. I do not have first hand experience with this.
 

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This recommendation for cutting the springs was from a Volvo publication which is posted somewhere in the internet. I think though that they were not talking about "cutting coils" but by inches of uncompressed spring. That was long before IPD, apparently.

I have driven my Volvo without the rear sway bar (but also without the negative Camber that Phill was talking about) and I did not like it. Too much understeer, and the conrering limits were reduced. It would probably be better in the wet (which I did not try), but not on the dry. I was also driving the car on relatively wide curves (limit about 45-55 mph, chasing an M3). On tighter curves may be w/out the sway bar it would have been better, but did not try.

Phil has a point, on using the throttle more to kill understeer, and therefore possibly go a bit faster. But you will have to enter the curves a bit slower, which will take away at least some of the benefit. It may also depend on how much power the car has. If you have a well built B20 with a nice tight rear gear (4.56), may be entering into the curves a bit slow is not too bad.

One thing I do not like with the negative camber for a street car is that it will wear your tires unevenly.

At the end of the day, it may be matter of preference, and what you are used to.
 

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Actually, I forgot. A friend of mine had actually tried the spring cutting advice while building a budget race car, and he was pleased with the results. He also did not use rear sway bar, and he probably used the stock front sway bar. He had also removed a lot weight from the car.

Phil, may be you can have better results w/out rear sway bar when you remove a bunch of the weight of the car, but when the car is for street use, the rear sway bar may give better results. Yes? This is speculation of course. I am happy with the rear sway bar on my ipd volvo ...
 

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There are a number of ppl out there who run on cut springs and think they are great (not just amazons). Put them in a properly set up car with well made springs and good dampers and they quickly change their mind!

As to the sway bar v spring rates it is down to the use of the car and the driver. There is no hard and fast rule on how to setup the car as each driver will have his own prefernce on steering response etc.

Phil, you mention the VP progressive springs. I've ended up replacing a lot of sets over here with my own springs as the VP ones have sagged and quite often one more than the rest. Is this a problem you have come accross?
 

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I know many people have had problems with the VPD progressive springs collapsing. I had what I think was the second set made on my 1800S, and they stayed good for the eight or nine years I owned the car. I also used them without problems on several of my customers' cars. I don't know if the problems were limited to a particular production lot, or if the quality is variable from set to set.

I agree that different drivers prefer different handling characteristics. Vintage racers seem about equally split on whether to run a rear bar or not. I had both IPD bars on my 1800, but removed the rear after doing a track day in the rain -- I spun completely off the track once and barely caught several more spins due to snap oversteer, which I didn't feel coming on at all. I had no problems with understeer with it off, and could still very easily rotate the car with the throttle. I later took the rear bar off our Amazon, and it's no different. For my particular driving style, the fastest way around is to get on the throttle as early and as hard as possible coming out of turns, and if I'm giving up a little speed going into them, I'm not really aware of it.

Our cars are not lightened at all, they are in full street trim. I stripped everything I could off the Carrera Panamerica car, but it still ended up heavier than stock, with an extensive roll cage and reinforcements in other places. The rules require a full-sized spare tire on board, and in this case both the driver and navigator were big guys weighing well over 200 pounds. So, I don't think it's a matter of weight as long as the distribution stays roughly the same.
 

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Phil and wede, here is another thought on this. Essentially stating the same thing we all said, but in a bit more "depth".

A car set up with inherent understeer means that it is set up such as it demands too much cornering force from the front tires. A car set up in a more neutral arrangement (but still slightly leaning on the understeer side) has more even demands in cornering forces both from front and rear. Therefore, if everything else is equal, the cornering limit will be superior with the more neutral car, because both front and rear wheels are contributing. Also, in the under-steer set up car, the demands on power mean that you give up potential cornering traction force for accelerating traction, therefore even greater loss in cornering force. This will show more in entrance of curves, and also in continuous curves, especially where if you rely to much on the throttle you may end up exceeding the speed limit of the curves.

However, clearly the more neutral car (in this case the ipd) is more tricky to drive. This is the typical trade off between "stability and agility". Given the above, I think it is absolutely critical that you do not have very low profile tires on an IPD car (low profile tires give you less progressive transition), and it is also critical to have a small aftermarket steering wheel to catch the scary moments (Phil, did you have a small steering wheel?). Also, when driving the ipd car, you tend to be a bit more conservative the first time you enter an unknown winding road, whereas with the stock car, you may be less so. Also, the Amazon, having a bit more wheel base, may be better suited for the ipd w/ rear sway bar than the P1800.

I too am super careful with the ipd car in the rain. Part of the reason is the super cheap tires that I have on it, which unfortunately still have lot of life in them! Also, going down hill curves I am careful with the throttle (which you need less of) and I often use a higher gear (I may be doing 55-65 and I will have 4th instead of 3rd on down hill) as an extra precaution against too much torque reaching the back wheels.

I would certainly not recommend the ipd set up to a person that has not fully mastered the stock system. Also, the stock suspension can be more entertaining when in normal street driving, because you can get it going sideways without going too much faster than traffic (I suspect the same may apply to Phil's set up). Whereas the ipd car has such high cornering limits that you end up going way much faster than traffic and still not feel you are approaching the limit (despite cheap tires!).
 
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