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Old 05-10-2021, 07:39 PM   #1
HiSPL
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Default Paging Ben? Or anybody else regarding an upgrade path for fun street car...

So I want to make my daily into a more fun daily. Think M3 style. Stiffer, better, but still streetable. This won't go to the track but it will hit some backroads.

Is there an upgrade path laid out somewhere for something like this?

My plans so far are Gaz C/O's from Yoshifab front and rear.
QSRC
Ben's spherical rear trailing arm bearings, with stock rubber on the Chassis side.
Ben's torque rods that are spherical on the axle and rubber on the chassis side.
---That's all I know for sure.

Up front what would you do? Full poly in a lighter durometer? Full Volvo rubber? Mix of both?


This stuff will happen over a long period of time as I save up sheckels. Plus right now I'm rockin the stock steelies which have brand new tires so I'm probably going to get my money's worth out of these tires before I upgrade rimpz and tires. I'm probably going to do a 16" wheel. No larger than 17 for sure, I don't like huge rims on the 240.
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Old 05-10-2021, 09:29 PM   #2
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-full SuperPro poly in the front is good, could also consider STS delrin bushings, but probably unnecessary for a street car.
-Yoshifab lower chassis braces
-GT upper braces

What you have listed for the rear is good, keeping rubber bushings on the chassis-side mounting points. Poly or spherical there will be buzzy.
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Old 05-10-2021, 09:32 PM   #3
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That's a good start.
What ride height? A little lower, 2" or so?
And have you had much experience driving cars with stiff springs? I found that over 275# front was a bit much for most people in a 240, but I am ok with 350-400, and I like more spring, less bar.
I also think that huge bars are ok with stiff springs, but not with soft.
So there are my initial opinions based on cobbling lots of stuff and beating on it, but they certainly are not the only opinions.

Up front? Poly is good unless it's squeaking, and a lower chassis brace is a must. Top is not.
Damping properly matched to springs is more important than a lot of people think.
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Old 05-10-2021, 09:37 PM   #4
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Oh, and what's your driving style? smooth, hacksaw, trail brake, in love with oversteer? How much rear spring and bar compared to front wil vary depending on what you like the car to do.
Because of the 1.5 motion ratio squared in the rear, 200# rear is 350 in vert, but then you lose a lot in roll because of the solid axle with laterally inboard springs. Which is why a big rear bar on soft rear springs is so bad in a 240.
Getting a good posi? You will really appreciate one.
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Old 05-11-2021, 11:14 AM   #5
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Quote:
Originally Posted by oldschoolvolvo View Post
-full SuperPro poly in the front is good, could also consider STS delrin bushings, but probably unnecessary for a street car.
-Yoshifab lower chassis braces
-GT upper braces

What you have listed for the rear is good, keeping rubber bushings on the chassis-side mounting points. Poly or spherical there will be buzzy.
I absolutely hate my Yoshifab lower braces and can't wait to get them off the car. They are the low hanging fruit under a low car by a good margin, in the worst possible place. There's probably a gouge in the Lime Rock autocross course from mine still.

If your car is lowered I would not use a brace that puts 2" of tube sticking straight down at a right angle to your cross member just waiting to catch every dip, crack, pothole or bad angle it can find.
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Old 05-11-2021, 02:12 PM   #6
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Originally Posted by mikep View Post
That's a good start.
What ride height? A little lower, 2" or so?
A little lower. I like the look of slammed 240, but I am gonna daily this and I love not banging my air dam on everything right now. So call it an inch, inch and a half maybe.
Quote:


And have you had much experience driving cars with stiff springs? I found that over 275# front was a bit much for most people in a 240, but I am ok with 350-400, and I like more spring, less bar.
Some in cars, but lots on bikes. I was a full time motorcycle rider for about 4 years and part of that time I rode almost a full on dragbike. It was not pleasant. I prefer a cushy-er but well damped ride.
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I also think that huge bars are ok with stiff springs, but not with soft.
So there are my initial opinions based on cobbling lots of stuff and beating on it, but they certainly are not the only opinions.
I'm not a fan of giant swaybars. I'll get some roll control out of the springs and some out of an upgraded bar, but I don't mind a little lean when cornering hard.
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Up front? Poly is good unless it's squeaking, and a lower chassis brace is a must. Top is not.
Damping properly matched to springs is more important than a lot of people think.
Agreed.
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Old 05-11-2021, 02:14 PM   #7
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Originally Posted by mikep View Post
Oh, and what's your driving style? smooth, hacksaw, trail brake, in love with oversteer? How much rear spring and bar compared to front wil vary depending on what you like the car to do.
Because of the 1.5 motion ratio squared in the rear, 200# rear is 350 in vert, but then you lose a lot in roll because of the solid axle with laterally inboard springs. Which is why a big rear bar on soft rear springs is so bad in a 240.
Getting a good posi? You will really appreciate one.
I will be going posi sometime. It's not the priority now though.

I love driving smooth.




And donuts. I love doing donuts.
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Old 05-11-2021, 02:22 PM   #8
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Originally Posted by Stiggy Pop View Post
I absolutely hate my Yoshifab lower braces and can't wait to get them off the car. They are the low hanging fruit under a low car by a good margin, in the worst possible place. There's probably a gouge in the Lime Rock autocross course from mine still.

If your car is lowered I would not use a brace that puts 2" of tube sticking straight down at a right angle to your cross member just waiting to catch every dip, crack, pothole or bad angle it can find.

Yeah I was probably going to fab something on my own that doesn't stick down as far, I'm thinking 1/2"x1" rectangle tubing with a hole drilled in either end and a sleeve welded in. It may not be as strong as the YF, but it'll only hang down a half inch.
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Old 05-11-2021, 06:54 PM   #9
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Get as much caster as you can. Not sure how unpopular of an opinion this is around here but I like spring rate for ride control and ARBs for roll control. Figure ~2 Hz ride frequencies for a sporty setup, like 10% higher in the rear (call it like 300/175 lbs front and rear for a "sports" street setup on a moderately sticky tire, ie 200tw street tire or 250/150 if you want it softer). Big front bar, little to none rear bar depending on taste.

Good diff is a must. It'll always feel a little weak with an open one. Measure the QSRCs and set ride height to maybe an inch plus that dimension lower than stock.

I don't like poly bushings but I live in New England and drive my car all year. Don't put them anywhere where you wouldn't put a solid block of material unless you want to induce binding.

Figure that getting rates and damping right will take some trial and error if you want to really dial it in.

240grupp-a.se has a lot of interesting stuff on the factory race cars. Might be sensible to try and translate that in a milder form.
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Old 05-12-2021, 08:54 AM   #10
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I normally disagree on the old-school GM cushy-floaty ride school of 10% higher in rear, but with a solid axle it can't hurt to help counter roll.

For the OP's intended decent ride, 250# front, x.66 to get close to the number for the rear, =165, so go for 175# rears. Add bilshteeens and mix well with 23mm front 19mm rear and go drive it.

Quote:
Originally Posted by Stiggy Pop View Post
I absolutely hate my Yoshifab lower braces and can't wait to get them off the car. They are the low hanging fruit under a low car by a good margin, in the worst possible place. There's probably a gouge in the Lime Rock autocross course from mine still.

If your car is lowered I would not use a brace that puts 2" of tube sticking straight down at a right angle to your cross member just waiting to catch every dip, crack, pothole or bad angle it can find.
The overly complicated ones are not even necessary.
I only use a single pipe across the rear control arm mounts, mounted above the bottom of the brackets. Not sure I have pics anymore, but I can scab one together on my wagon and post a pic.
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