Interest on Scion TC Springs Upgrade?

[E21fun]

Would anyone be interested if i did a write up on how to modify the TC springs to fit the E21? Its very easy but since Im in the process i figure some people might be interested on the details other than cut the top off and boom your done. If theres no write up on how to install aftermarket springs in general I could do that aswell.

[dictator]

sure, i am always interested in strange aftermarket refits

[MrGumby]

I approve of this thread!

[E21fun]

I approve of this thread!

You got em right???

I put Tein springs on my friends TC and told him to give me the stock ones

[je320]

Interested

[MrGumby]

You got em right???

I put Tein springs on my friends TC and told him to give me the stock ones

You bet, and for the same price!! I'm quite happy with them and would have a thread for installing them if I would have taken pictures along the way, but I did it at work on a Saturday after I ran out of work. I might be inclined to throw in my $.02 if you don't mind.

[bassboy3313]

yes please do this!!!

[vtbimmer]

Interested in knowing how it's a upgrade. Higher spring rate? Lower ride hieght I presume? In for more info and pics.

[MrGumby]

Interested in knowing how it's a upgrade. Higher spring rate? Lower ride hieght I presume? In for more info and pics.

It's definately a higher spring rate, you end up cutting a coil & a half off (I think) which makes the coils dimensionally shorter than OE springs, but sits at stock ride height. I ended up cutting a total of 2 coils from the rear and 1 1/2 from the front. Without slotting the rear subframe for camber, you'll want to only take off 1 1/2 from the rear. You'll have to excuse the "festiveness", it's the only picture I have of it with the tC coils.

[dictator]

how much lower does it sit now?

[MrGumby]

how much lower does it sit now?

That is how it sits now. Well, technically at the moment it's about an inch and a half higher in the front, but that's because the engine is on a stand and the hood is up against the garage wall.

[m20powered]

I was keeping an eye out for these and managed to score a cheap set recently. Here`s what I got:

rear:
height ~11.75"
rate ~210lbs/inch

front:
height ~12.625"
rate ~140lbs/inch

Do those sound like the right ones? The coil diameters are a bit different on one end compared to the other, did that present any problems installing in the e21?

[bflan2001]

i don't understand the point of scion springs if you just cut them anyway, why not just cut your stock springs?

[E21fun]

the spring rates are higher

[Isdera]

Hmm interesting choice in spring. Interested!

[bflan2001]

the spring rates are higher

maybe stock for stock, but if you're cutting them that completely changes things

[milotrain]

1. equating increased spring rate with "upgrade" is patently false. It might be better, but it depends on many factors and if makes something better then it will make something else worse that's a law in suspension work.

2. spring rate is a useless metric in general. Primarily because a spring installed in a suspension system does not exhibit 100% of it's rate; secondarily because a coil spring is not the only contributing factor to a corner's wheel rate.

First tell me what wheel rate you are trying to get to, then tell me how the spring rate of the Scion springs gets you close, then tell me what real world application testing you have done and how it shows which of your calculated numbers to be less than ideal, and then I'll begin to believe that this might be an upgrade.

Regarding the change in spring rate of the spring:
If the spring is progressive then it will be impossible to calculate what rate the new spring is after cutting without testing it. It's easy to test, throw some weight on the spring until it compresses 1", write down how much weight it took to do this. Double the weight, should move the spring 2", Double it again, should move it 4". If it's progressive then it will take a non linear amount of weight to create a linear travel.

<del> If the spring is not progressive then take the spring rate, divide it by the number of active coils, then take that number and multiply it by the number of coils you have left and you'll have an approximation of your spring rate. You should still test it as above. </del>
EDIT: My bad, Beemer Tech below is of course correct.

[Beemer Tech]

if you shorten the spring you make it stiffer.

[Layne]

1. equating increased spring rate with "upgrade" is patently false. It might be better, but it depends on many factors and if makes something better then it will make something else worse that's a law in suspension work.

2. spring rate is a useless metric in general. Primarily because a spring installed in a suspension system does not exhibit 100% of it's rate; secondarily because a coil spring is not the only contributing factor to a corner's wheel rate.

First tell me what wheel rate you are trying to get to, then tell me how the spring rate of the Scion springs gets you close, then tell me what real world application testing you have done and how it shows which of your calculated numbers to be less than ideal, and then I'll begin to believe that this might be an upgrade.

Regarding the change in spring rate of the spring:
If the spring is progressive then it will be impossible to calculate what rate the new spring is after cutting without testing it. It's easy to test, throw some weight on the spring until it compresses 1", write down how much weight it took to do this. Double the weight, should move the spring 2", Double it again, should move it 4". If it's progressive then it will take a non linear amount of weight to create a linear travel.

If the spring is not progressive then take the spring rate, divide it by the number of active coils, then take that number and multiply it by the number of coils you have left and you'll have an approximation of your spring rate. You should still test it as above.

[m20powered]

My current ride height is fine, except that it`s inconsistent. With stiffer springs weight differences shouldn`t have as much effect. Plus it will cut down a bit on body roll, squat, and dive. And my old springs are rusty and I want to replace strut mounts. I`ve never driven on a track in my life but I like the stiffer springs I have on my e28 so it could work out nicely on the e21 as well. If not, oh well... the springs were $22...

[milotrain]

I`ve never driven on a track in my life but I like the stiffer springs I have on my e28 so it could work out nicely on the e21 as well. If not, oh well... the springs were $22...

That's cool, and I'm all for cheap experimentation. It's a great thing to do just for fun and just to see what it would do.

With stiffer springs weight differences shouldn`t have as much effect.

That sentence means nothing. weight differences shouldn't have as much effect on what?

Plus it will cut down a bit on body roll, squat, and dive.

So would sticking a solid pipe in there instead of springs but see, that's not a good idea.

I'm not saying it's a bad thing to do, I'm saying that doing it because you think it's an upgrade or it will help something based on common sense assumptions is a really really bad way to go about trying to improve a car. There is nothing wrong with doing it just for the hell of it though, and your justification is totally valid.

If you want to be helpful to the community, instead of just doing a write up of how to do this, once you've cut the springs then test them for spring rate. Then when installed test the corners for wheel rate and corner weight. That information is actually very very useful to keep a log of and will help everyone make their cars handle better.

Not trying to be snarky here at all, just throwing some shit out there.

[m20powered]

That's cool, and I'm all for cheap experimentation. It's a great thing to do just for fun and just to see what it would do.

Yes I like experimentation (although I prefer the kind that doesn`t involve removing and installing all my struts, but what can you do)

weight differences shouldn't have as much effect on what?

I was referring to ride height. In other words, if my spring rates were 210 instead of 60-ish then loading a bunch of stuff into the trunk wouldn`t compress the rear suspension as much. I`m more concerned about the front though really, because it`s currently lower on the passenger`s side.

I'm saying that doing it because you think it's an upgrade or it will help something based on common sense assumptions is a really really bad way to go about trying to improve a car.

It isn`t the best way, but I would argue that the gearhead crowd has a proud tradition of making modifications based on gut feeling. Often there is no choice, because we have limited data, tools, and funds.

If you want to be helpful to the community, instead of just doing a write up of how to do this, once you've cut the springs then test them for spring rate.

That I can do, but how would I measure wheel rate?

[milotrain]

I'm certainly not trying to discourage gut feeling experimentation, it's just a lot of what I see with suspension, wheel, and brake "redesign" by owners is really bad news. Most of it never takes into account any suspension design considerations which are fairly easy to learn by reading a few books. Not to say that those books are the end all be all but it's much better to go forward semi-informed. Again, not saying that you aren't doing this, just that it is what I see in general.

Measuring wheel rate is very simple actually. You jack the car up (not under the wheels but under the subframes). Then you stick a floor jack under the wheel you want to measure (a block under the opposite wheel), and stick a heavy duty scale between the wheel and the jack. Then lower the car onto the wheel jack. This will give you corner weight and compress the spring to ride height. Then you pump the wheel jack until the wheel travels up 1", the new reading on the scale at 1" traveled minus the corner weight is the weight it takes to move the wheel 1" through it's suspension travel. That's it's wheel rate.

If you know the corner weight then it's easier as you can just float the whole car pump the jack until you see corner weight then pump through 1" of travel.

http://forums.bimmerforums.com/forum....php?t=1588653

[m20powered]

I ran into a problem here... after cutting 1.5 coils from the Scion front springs, they are too short to stay in place in the e21 strut. Is there a shock with a shorter rod to solve this issue?

[DHoang]

Bilstein sports dampers have shorter rod lengths vs. Bilstein HD & Boge