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-   -   redblockpowered converts from 240 to 940 (https://forums.turbobricks.com/showthread.php?t=345277)

redblockpowered 03-03-2020 07:48 PM

Braces are in. Handling dynamics feel the same but steering seems a lot more precise. No more small mid-corner corrections. 940s can't use the middle bolt hole without modification but I think this is known. Car is starting to feel pretty good. Certainly can't complain about a palpable handling upgrade for some $40 from the dealer.

Careful not to dump the big pile of engine dirt from the crossmember jacking point on your face when you put them in.

soclosenotnear 03-04-2020 08:39 AM

95+ 940's use all three holes. But you will have to drill a hole to use the third mounting point earlier than that

redblockpowered 03-13-2020 03:46 PM

Just got back from the dyno. T cam, 13C, stock exhaust, boost controller set to 14 lbs, car made 184 whp and 253 wtq on tuned LH 2.4.

https://i.imgur.com/dHBDCCZl.jpg

or https://imgur.com/gallery/IDfh4Bh if you want to look closer

klr142 03-13-2020 04:20 PM

Nice! You could cross post this in Kenny's BPU thread for fun(Linuxman). I thought you already had the V15T cam in? But, didn't you want to measure it first?

How do you make the picture bigger on imgur? It's still small on the computer for me.

What RPM were the peaks at and what rpm did you start the pull at? Someone posted a comment on Imgur.

redblockpowered 03-13-2020 05:00 PM

Clicking on the gallery version of the image should enlarge it, at least it does on my computer. Pulls started around 2500. Peak torque is at 2800 and peak power at 4800.

redblockpowered 03-27-2020 08:10 PM

Chassis dynamics update: It wasn't rolling onto the bump stops at autocross.

Why? There aren't any.

redblockpowered 03-27-2020 08:11 PM

On a less silly note I'm using the fact that I'm always at home to replace all my bushings with new rubber.

redblockpowered 04-02-2020 04:25 PM

Alright, since I was curious about the stock front spring options on this car and confused about where my new springs come from, I did some research.

On the 1329826 front spring I (still) have yet to fit, the catalog on GCP.se says as follows:
14.8mm wire, for chassis code 161, 278, 279

This number only appears in the 85-87 740/760 catalog. Perhaps it was superseded but the following information tells me it likely wasn't and is a three year only part.

If you look up p/n 1329826 on the Volvo Parts US Web Store no results are returned. What gives? A quick look at GCP's 85-87 catalog reveals that it is specifically *NOT* for US/Canada market cars. So, it's a RoW only front spring, for 760 with any of the available engines (D24/B280/B230FT). At least, originally. It seems like the Kilen/Lesjofors equivalent was probably available everywhere seeing as I was able to pick up a set with basically no issue. Maybe I'm just lucky.

Looking at my build plate, the car has front spring code AC which cross references to 1329824, the fabled "diesel" front spring. If you take the Kilen applications list as law my car should have the 14 mm x 385 mm 1329823 front spring, instead of the 14 mm x 435 mm spring the Volvo catalog claims the car has. So who's right? I guess we'll find out when I take the front suspension apart. It seems to ride high in the front and is definitely soft. Does anyone around here have an 85-87 760 with one of these chassis codes?

https://i.imgur.com/s4gCJ4S.png

https://i.imgur.com/bKY3n0E.png

At least the rear springs are simple. Sedan or wagon? It sure looks like 240 rears will fit if you really wanted to get weird.

Next up, some fun with stock spring rates.

I figured I'd start with something RWD of comparable weight to figure out a wheel rate target, and found this forum thread on the similarly-weighted BMW E36 M3.
https://www.bimmerforums.com/forum/s...de-Frequencies

So to compare, I need to know the ride frequency front and rear, and to know that I need to find my corner weights and motion ratios front and rear. First, the corner weights as measured by TB user Magnum TE in a thread started by... Me, age 13!

http://forums.turbobricks.com/showthread.php?t=252873

1992 940T Sedan
Total: 3220

Front : 1780
Rear : 1460
FL: 900 - FR: 860
RL: 740 - RR: 740

One model year off but it'll do.

For the sake of simplifying things I averaged out the front axle as 880 lbs on both sides. I won't be staggering spring rates so this will do. I estimated my unsprung weights as follows:
Wheel and tire 40 lbs
Rear axle 131 lbs
Half lower control arm 3 lbs
Half the shock 3 lbs
Half tie rod negligible
Front brake 20 lbs
Spindle/hub 6 lbs
Rear brake 16 lbs

And that gives me sprung corner weights of:
Front: 808 lbs
Rear: 612.5 lbs

Now we move on to the motion ratios. With a McPherson strut setup the motion ratio is simple, equal to the cosine of the strut angle. I put an angle finder on both struts compressed to ride height and averaged it out since I didn't trust that the car was on level ground. This returned a measurement of 12.45 degrees. Cosine of 12.45 degrees is (almost, I hope I'm not getting graded on this) 0.976.

In the rear, I measured from the center of the trailing arm bolt to the center of the wheel, and to the center of the rear spring.

Trailing arm to wheel 665 mm
Trailing arm to spring 810 mm

810/665 = 1.218 motion ratio in the rear.

Wheel rate = spring rate * motion ratio^2

I calculated the following wheel rates based on the various wire diameters I found in the parts catalog, assuming (oops) they would all work out to have the same number of active coils as I measured on my car, that being 7.5 rear and 4.25 front.

Front springs:
1329822 13.6 mm wire, 126 lb/in spring, 120 lb/in wheel rate
1329823 13.7 mm wire, 130 lb/in spring, 124 lb/in wheel rate
1329824 13.8 mm wire, 134 lb/in spring, 128 lb/in wheel rate
1329825 14.4 mm wire, 161 lb/in spring, 153 lb/in wheel rate
1329826 14.8 mm wire, 181 lb/in spring, 173 lb/in wheel rate
IPD front spring measured by mikep 145 lb/in, 138 lb/in wheel rate

A company called Rallyboutique sells a 16.1mm front spring for rally use, that works out to a 261 lb/in rate at the spring and 249 lb/in at the wheel.

Rear springs:
1273759 9.8 mm wire, 51 lb/in spring, 76 lb/in wheel rate
(???) 10.2 mm wire, 60 lb/in spring, 89 lb/in wheel rate
1273977 11.3 mm wire, 93 lb/in spring, 138 lb/in wheel rate
1359710 11.9 mm wire, 117 lb/in spring, 174 lb/in wheel rate
1273978 12.1 mm wire, 125 lb/in spring, 185 lb/in wheel rate
IPD rear spring measured by mikep, 95-140 lb/in spring, 141-208 lb/in wheel rate

If you have more spring information please let me know!

The formula for ride frequency in Hertz is (1/2pi)*(sqrt(K/M) where K is the spring rate in N/m and M is the sprung mass in kg. Plugging in previously mentioned values provides the following results:

1329822 13.6 mm wire, 1.206 Hz
1329823 13.7 mm wire, 1.235 Hz
1329824 13.8 mm wire, 1.254 Hz
1329825 14.4 mm wire, 1.374 Hz
1329826 14.8 mm wire, 1.457 Hz
Rallyboutique 16.1 mm wire, 1.747 Hz
IPD ??? wire, 1.306 Hz

1273759 9.8 mm wire, 1.095 Hz
(???) 10.2 mm wire, 1.192 Hz
1273977 11.3 mm wire, 1.485 Hz
1359710 11.9 mm wire, 1.661 Hz
1273978 12.1 mm wire, 1.722 Hz
IPD ??? wire, 1.499-1.848 Hz

For comparison's sake, the BMW stock regular springs measure in at 1.02/1.12 F/R and their factory "Sport" springs measure in at 1.47/1.41 F/R. Conventional wisdom says you want a 10% higher rear ride frequency. My car stock comes in at 1.25/1.48 and with the RoW 760 front/wagon rear setup results in ride frequencies of 1.46/1.66.

Neat.

shoestring 04-03-2020 12:21 PM

I smell nerd.

esmth 04-03-2020 01:14 PM

make like the kool kids our age and just cut the damn sprangs

JK, but seriously I wonder how my 300 and 150 lb/in springs do in regard to ride frequency. Probably not remotely close to 10% higher in the rear, ahah

DET17 04-05-2020 01:28 PM

If memory serves, the Herb Adams (who?) suspension book recommended never to exceed 2.0 hz ...... I don't recall if that was for street usage or ANY usage.

Herb, the first GM Engineer to get 1.0g lateral on the skid pad. Claimed it "was an accident".....that his WS6 T/A out cornered the current year Vette. The GM suits fired him shortly thereafter.......

Keep up the good work, kid.

redblockpowered 04-17-2020 04:22 PM

Quote:

Originally Posted by DET17 (Post 6066001)
If memory serves, the Herb Adams (who?) suspension book recommended never to exceed 2.0 hz ...... I don't recall if that was for street usage or ANY usage.

Herb, the first GM Engineer to get 1.0g lateral on the skid pad. Claimed it "was an accident".....that his WS6 T/A out cornered the current year Vette. The GM suits fired him shortly thereafter.......

Keep up the good work, kid.

Thank you very much!

Further research has revealed a whopping thirteen P/Ns for OE front springs and eight P/Ns for OE live axle rear springs. Yikes. If you have these part numbers and can measure the wire diameter/number of active coils, please let me know:

1387677/6819661 (seems to be superseded p/n I think)
1293449
1387679
9140532 (factory sports kit front lowering spring for "light" car)
9140533 (factory sports kit front lowering spring for "heavy" car)
9173796
9173797
1273706 (weirdly, the only OE rear spring without a spec'd wire diameter)

I wouldn't be surprised if the B&G/Lesjofors lowering springs were copies of the dealer-installed lowering kit, seeing as they were the original spring supplier.

My dad and I finally got to the first front spring yesterday and confirmed that my car is equipped with the P/N 1329824 "diesel" front springs, which measure in at 13.9 wire diameter x 428 mm length as measured by me. With the new front springs the car should be approximately 15 mm lower in the front. We also found some pretty trashed strut mounts and bearings. Not sure why I didn't expect this. They're on order and have an outside chance of arriving tomorrow.

Check your build plate before you buy springs, maybe you already have the "diesel" springs you crave. I can't imagine my car was the only US 944 Turbo delivered with them.

DET17 04-19-2020 08:25 AM

Quote:

Originally Posted by redblockpowered (Post 6064885)

1992 940T Sedan
Total: 3220

Front : 1780
Rear : 1460
FL: 900 - FR: 860
RL: 740 - RR: 740

One model year off but it'll do.

For the sake of simplifying things I averaged out the front axle as 880 lbs on both sides. I won't be staggering spring rates so this will do. I estimated my unsprung weights as follows:
Wheel and tire 40 lbs
Rear axle 131 lbs
Half lower control arm 3 lbs
Half the shock 3 lbs
Half tie rod negligible
Front brake 20 lbs
Spindle/hub 6 lbs
Rear brake 16 lbs

And that gives me sprung corner weights of:
Front: 808 lbs
Rear: 612.5 lbs

Now we move on to the motion ratios. With a McPherson strut setup the motion ratio is simple, equal to the cosine of the strut angle. I put an angle finder on both struts compressed to ride height and averaged it out since I didn't trust that the car was on level ground. This returned a measurement of 12.45 degrees. Cosine of 12.45 degrees is (almost, I hope I'm not getting graded on this) 0.976.

In the rear, I measured from the center of the trailing arm bolt to the center of the wheel, and to the center of the rear spring.

Trailing arm to wheel 665 mm
Trailing arm to spring 810 mm

810/665 = 1.218 motion ratio in the rear.

Wheel rate = spring rate * motion ratio^2

I calculated the following wheel rates based on the various wire diameters I found in the parts catalog, assuming (oops) they would all work out to have the same number of active coils as I measured on my car, that being 7.5 rear and 4.25 front.

Front springs:
1329822 13.6 mm wire, 126 lb/in spring, 120 lb/in wheel rate
1329823 13.7 mm wire, 130 lb/in spring, 124 lb/in wheel rate
1329824 13.8 mm wire, 134 lb/in spring, 128 lb/in wheel rate
1329825 14.4 mm wire, 161 lb/in spring, 153 lb/in wheel rate
1329826 14.8 mm wire, 181 lb/in spring, 173 lb/in wheel rate
IPD front spring measured by mikep 145 lb/in, 138 lb/in wheel rate

A company called Rallyboutique sells a 16.1mm front spring for rally use, that works out to a 261 lb/in rate at the spring and 249 lb/in at the wheel.

Rear springs:
1273759 9.8 mm wire, 51 lb/in spring, 76 lb/in wheel rate
(???) 10.2 mm wire, 60 lb/in spring, 89 lb/in wheel rate
1273977 11.3 mm wire, 93 lb/in spring, 138 lb/in wheel rate
1359710 11.9 mm wire, 117 lb/in spring, 174 lb/in wheel rate
1273978 12.1 mm wire, 125 lb/in spring, 185 lb/in wheel rate
IPD rear spring measured by mikep, 95-140 lb/in spring, 141-208 lb/in wheel rate

If you have more spring information please let me know!

The formula for ride frequency in Hertz is (1/2pi)*(sqrt(K/M) where K is the spring rate in N/m and M is the sprung mass in kg. Plugging in previously mentioned values provides the following results:

1329822 13.6 mm wire, 1.206 Hz
1329823 13.7 mm wire, 1.235 Hz
1329824 13.8 mm wire, 1.254 Hz
1329825 14.4 mm wire, 1.374 Hz
1329826 14.8 mm wire, 1.457 Hz
Rallyboutique 16.1 mm wire, 1.747 Hz
IPD ??? wire, 1.306 Hz

1273759 9.8 mm wire, 1.095 Hz
(???) 10.2 mm wire, 1.192 Hz
1273977 11.3 mm wire, 1.485 Hz
1359710 11.9 mm wire, 1.661 Hz
1273978 12.1 mm wire, 1.722 Hz
IPD ??? wire, 1.499-1.848 Hz

For comparison's sake, the BMW stock regular springs measure in at 1.02/1.12 F/R and their factory "Sport" springs measure in at 1.47/1.41 F/R. Conventional wisdom says you want a 10% higher rear ride frequency. My car stock comes in at 1.25/1.48 and with the RoW 760 front/wagon rear setup results in ride frequencies of 1.46/1.66.

Neat.

Alright Kid, you've got me thinking (thanks for that!).

I've decided that my car is UNDER sprung..... this conclusion comes from years of hot rodding which now include ~11 years with these old Volvos.

Currently my 92 sedan runs the B&G progressives all around, mated with KONI sports. Based upon the online research I could locate, the KONI's need a front spring rate of ~ 250 #/in to 300 #/in (Towery says up to 325 #/in) and perhaps 175#/in to 225#/in the rear. While it corners well with QSRC's and a 25mm front bar, the behavior over road undulations is less than ideal (that is, not "once and done").

Last year I sold a 92 745T which had factory wagon springs and BILS HD dampers.... and it was the nearest to PERFECT of any RWD vehicle I've ridden within. This confirms the long held conviction that BILS HD are damping rate matched to factory springs. I drove that wagon for a year while I finished my sedan..... hated to sell it, but too many vehicles in the driveway.

THEREFORE, based upon the KONI Sport target spring rates (or rather than spring rates that the KONI Sports were designed for), I'm in the process of building coil overs using Ben's parts. With all this research along with conversations with Ben Kaplan and Michael Yount ( who run's Ben's parts on his 242) I purchased 250#/in front springs and 175#/in rear springs. Since I'm not driven by stance but rather performance for a DD, I won't shorten my struts.

Where did you get your information claiming that a 10% increased frequency in the rear is desired? I know what Uncle Herb says about the limits of Hz in suspension motion. Your listed RallyBoutique springs are nearly the same spring rate as I have up front. What rate rear springs were matched with those?

Lastly.... this old Engineer's brain is having problems with your stated different frequency F to R. In order to present the minimum input to the passengers, why wouldn't the design Hz of suspension be targeted for equal? Remember, we are trying to insulate the cabin & contents from the highways' inputs. Motion ratio's aside.... we desire the sprung mass & contents to be uninfluenced by unsprung suspension travels.

My deep thoughts this morning, on the first cup of coffee......;-)

redblockpowered 04-27-2020 03:50 PM

Quote:

Originally Posted by DET17 (Post 6071313)
Alright Kid, you've got me thinking (thanks for that!).

I've decided that my car is UNDER sprung..... this conclusion comes from years of hot rodding which now include ~11 years with these old Volvos.

Currently my 92 sedan runs the B&G progressives all around, mated with KONI sports. Based upon the online research I could locate, the KONI's need a front spring rate of ~ 250 #/in to 300 #/in (Towery says up to 325 #/in) and perhaps 175#/in to 225#/in the rear. While it corners well with QSRC's and a 25mm front bar, the behavior over road undulations is less than ideal (that is, not "once and done").

Last year I sold a 92 745T which had factory wagon springs and BILS HD dampers.... and it was the nearest to PERFECT of any RWD vehicle I've ridden within. This confirms the long held conviction that BILS HD are damping rate matched to factory springs. I drove that wagon for a year while I finished my sedan..... hated to sell it, but too many vehicles in the driveway.

THEREFORE, based upon the KONI Sport target spring rates (or rather than spring rates that the KONI Sports were designed for), I'm in the process of building coil overs using Ben's parts. With all this research along with conversations with Ben Kaplan and Michael Yount ( who run's Ben's parts on his 242) I purchased 250#/in front springs and 175#/in rear springs. Since I'm not driven by stance but rather performance for a DD, I won't shorten my struts.

Where did you get your information claiming that a 10% increased frequency in the rear is desired? I know what Uncle Herb says about the limits of Hz in suspension motion. Your listed RallyBoutique springs are nearly the same spring rate as I have up front. What rate rear springs were matched with those?

Lastly.... this old Engineer's brain is having problems with your stated different frequency F to R. In order to present the minimum input to the passengers, why wouldn't the design Hz of suspension be targeted for equal? Remember, we are trying to insulate the cabin & contents from the highways' inputs. Motion ratio's aside.... we desire the sprung mass & contents to be uninfluenced by unsprung suspension travels.

My deep thoughts this morning, on the first cup of coffee......;-)

Lots of good thoughts here. The need for different front to rear ride frequencies (for comfort, as far as I can tell), so I've read, are to counteract the fact that the rear of the car makes contact with a hypothetical bump such-and-such amount of time after the front does. Since the rear suspension responds to a bump at wheelbase times rate of travel after the front does (yes, this does mean you'll have to optimize for a certain speed or better yet shoot for "good enough" at a plausible range of speeds) the higher rear ride frequency allows the rear suspension to "catch up" to the front such that the peak forces from the impulse are in phase. 10% is a typical rule of thumb for passenger cars traveling at passenger car type speeds, though I suspect you can err on the higher side in a 940 given the longer wheelbase. Not that the difference is really more than a few percent at most for cars that seat 4/5 people.

Rallyboutique claims their front springs should be paired with a 11.5 or 12.0 mm rear spring here: https://www.rallyboutique.com/store/...er-fram-581508 and I'm curious as to how that works out in practice with such a significant rate difference front to rear.

Anyway, the suspension refresh has been completed (for now) and initial thoughts are positive. I wish the front had been lowered more for aesthetic reasons, but it feels good on the street. Only time will tell how performance has changed in an actual high load handling situation, and at this point who knows how long that will be. Coupled with the all new rubber bushings is new strut mounts with the front bolt "camber mod" moved in 20 mm, and a set of Hydras off of a parts car with 205/55/16 Firestone Firehawk Indy 500 summer tires. The same car also donated its hood and trunk lid lending my car a distinctly less shabby look.

https://i.imgur.com/23ivPYOl.jpg

shoestring 04-29-2020 02:50 PM

In 25mm.

I would add it's about 12mm lower than it was up front.

DET17 05-02-2020 07:43 AM

Quote:

Originally Posted by redblockpowered (Post 6073789)
Lots of good thoughts here. The need for different front to rear ride frequencies (for comfort, as far as I can tell), so I've read, are to counteract the fact that the rear of the car makes contact with a hypothetical bump such-and-such amount of time after the front does. Since the rear suspension responds to a bump at wheelbase times rate of travel after the front does (yes, this does mean you'll have to optimize for a certain speed or better yet shoot for "good enough" at a plausible range of speeds) the higher rear ride frequency allows the rear suspension to "catch up" to the front such that the peak forces from the impulse are in phase. 10% is a typical rule of thumb for passenger cars traveling at passenger car type speeds, though I suspect you can err on the higher side in a 940 given the longer wheelbase. Not that the difference is really more than a few percent at most for cars that seat 4/5 people.

Rallyboutique claims their front springs should be paired with a 11.5 or 12.0 mm rear spring here: https://www.rallyboutique.com/store/...er-fram-581508 and I'm curious as to how that works out in practice with such a significant rate difference front to rear.

Thinking further about the 10% increase in rear Hz by design, I can understand that designers would want to minimize the "impulse width" or duration, to reduce transmission to the cabin & occupants. We can be certain lots of empirical data was collected, ride testing with calibrated arses in the front and rear seating positions. Certainly that frequency is driven by the speeds at which the vehicle encounters the road disturbance. I suppose this falls within the H criteria of NVH.

What dampers do you have right now in this sedan? Essentially stock replacements, or are they Bils HD or Koni Sports? Front bar is a 25mm IPD or the factory 24mm early 960 bar? Remember, if you lower the front for asthetics, you WILL need to install the QSRC's from Ben. Made a world of difference on my 92, what with the front lowered ~ 40mm (estimated from factory claims, not before/after measured).

Shoot me a PM if you don't mind with your calculations for Hz with your current springs; I'm going to plug in my new Eibach spring rates and see how close my F/R Hz comes to those BMW rates you listed.

On a sidebar - is this car going to make any power? What have you done on that front?

bmos 05-02-2020 11:44 AM

Here's a great calculator for the stuff you're talking about.
http://fatcatmotorsports.com/FRC_TUT...S_TUTORIAL.htm

Calculate and plug in the various motion ratios, dimensions, etc and you'll get some very helpful figures.

redblockpowered 05-03-2020 05:51 PM

Current shocks are KYB Gas-A-Justs, advertised at 25% stiffer than OE so should pair well with my marginally stiffer than stock setup. Not a permanent solution, I'd like to move to a Bilstein HD or Koni Sport but should be close enough for now. I'm running both IPD sway bars but likely will swap back to the stock 19mm rear bar. When I put new strut mounts in along with all the bushings the car was aligned with as much negative camber as possible, as much positive caster as possible, and 1/16" total toe in. My dad (mostly) did this with strings on leveled ground with the suspension settled. This car only ended up with 0.4 degrees of negative camber, about a degree more than it had.

Although it would definitely look better with the nose down, I'm not planning on doing it beyond the couple of millimeters this spring swap caused for exactly that reason. No room for geometry correction in the budget for the time being. I could see lowering happening long-term along with some kind of LSD. The Truetrac seems like a particularly appealing option for this car.

As for power, it's currently running 13 psi (good enough for 184 whp after I dyno tuned the LH 2.4 with an Ostrich emulator) and I have an ENEM V15 that will go in in the next few weeks. I found it for sale locally at a silly price, and it came with a cylinder head that is basically useful as a core and not much else. Might need a re-tune after the cam goes in, we'll see what my accounting team (me) thinks about that. Phase 2 is a 16/18/19T and exhaust/intercooler, which should be more than enough for me to handle...

I bought a pair of 15Gs a while ago with the intention of rebuilding one to put on this car but looking at the compressor maps it seems like the later S70/V70 turbos are worth holding out for.

redblockpowered 05-03-2020 05:54 PM

Quote:

Originally Posted by DET17 (Post 6075262)
Thinking further about the 10% increase in rear Hz by design, I can understand that designers would want to minimize the "impulse width" or duration, to reduce transmission to the cabin & occupants. We can be certain lots of empirical data was collected, ride testing with calibrated arses in the front and rear seating positions. Certainly that frequency is driven by the speeds at which the vehicle encounters the road disturbance. I suppose this falls within the H criteria of NVH.

What dampers do you have right now in this sedan? Essentially stock replacements, or are they Bils HD or Koni Sports? Front bar is a 25mm IPD or the factory 24mm early 960 bar? Remember, if you lower the front for asthetics, you WILL need to install the QSRC's from Ben. Made a world of difference on my 92, what with the front lowered ~ 40mm (estimated from factory claims, not before/after measured).

Shoot me a PM if you don't mind with your calculations for Hz with your current springs; I'm going to plug in my new Eibach spring rates and see how close my F/R Hz comes to those BMW rates you listed.

On a sidebar - is this car going to make any power? What have you done on that front?

I'll clean up the spreadsheet I made for rates and ride frequencies and post it up here in a little bit.

redblockpowered 05-09-2020 01:06 PM

https://docs.google.com/spreadsheets...it?usp=sharing

Here's my spreadsheet. It's a little messy and doesn't include the IPD springs or 240 rear springs which some Swedish folks like to run. Hard to see why you'd want more rear spring than is already available. I included ride frequencies for all the available springs with one coil cut as well. I measured and calculated sway bar rates too but I don't think my results make much sense. I think I'm missing something there. I get 1.75/2.07 Hz ride frequencies for 250 lbs/in front and 175 lbs/in rear, provided your car has the same corner weights as mine.

mikep 05-20-2020 03:53 PM

Cool, nice work.
Regarding front to rear, you can vary it quite a bit. I usually tell people in a front engine world “start stiffer in front”. Lots of little reasons why, and i doubt they’ll listen to me if i explain.
I posted the link in the spring rate thread because i had to leave work. Now i’m on my phone, but exceptions to the rule:
As with many manufacturers, i tent to set a car up “tight” at first, especially considering most drivers suck.
The solid rear needs to be a little softer to keep it planted on rough surfaces. Ignoring their terrible motion ratio loss in roll and their high roll center compared to most IRS, it’s not good when the rear axle is too stiff. Think “older unloaded pickup on a dirt road”.
A car with fairly sporty rates on a segmented road can make you hurl if the rear is stiffer.
The worst case i encountered was the first stock car springs on a wagon attempt. We got the ride height close, it took turns, but with 350# front, 275# rear (412.5# vert at the wheels) on a 245 was not good on the ches bay bridge.
Those rear springs are going on my 245 With 425# fronts (taken from the rallycross 244 that had 300# rear).

mikep 05-20-2020 03:56 PM

The link if anyone wants it.
https://www.f1technical.net/forum/viewtopic.php?t=6371
The 245 near-disaster led to a long discussion with Drew (former student, now race engineer) on the front-rear split (designed for nice ride with soft springs) And all the stuff i mentioned above.
Also, include half of each spring, and only the strut cartridge outer, in unsprung calcs.

DET17 05-23-2020 09:27 PM

Quote:

Originally Posted by redblockpowered (Post 6077617)
I measured and calculated sway bar rates too but I don't think my results make much sense. I think I'm missing something there. I get 1.75/2.07 Hz ride frequencies for 250 lbs/in front and 175 lbs/in rear, provided your car has the same corner weights as mine.

The ratio shows about an 18% higher Hz rear over front. Higher than your 10% accepted target. It will be interesting to see how it behaves..... and if I need to, I can lighten those rear springs down to 150 lbs/inch.

redblockpowered 06-17-2020 01:19 PM

ENEM V15 Turbo is in for real this time, plus did some light tuning with the Ostrich for drivability/transient response. I mostly moved over the settings regarding closed loop operation from the Euro 984 ECU along with idle/cranking stuff. I'd be lying if I said it started faster but transitions from on to off load are MUCH smoother along with nicer off-throttle behavior. Idle vacuum is still pretty good with the cam, 17-18 inches instead of 19-20 although you can definitely hear the difference. Still gets mid 20s fuel economy somehow. I must drive like an old man.

Side note - I'm extremely satisfied with these tires. Grip and response are very good without sacrificing ride quality or road noise to a meaningful degree.

Lately I've been focusing on some quality of life improvements with this car. A few days ago the sunroof decided to get all askew, cleaning+lubricating+adjusting took some ten hours and was not fun in the least. Probably one of the least fun parts of the car to work on. I'd like to get cruise control (the stalk, likely) and A/C (leak at the condenser suspected) working but have to get myself back to working first before I have the budget to address this stuff...

redblockpowered 07-24-2020 11:40 AM

Recovered my front seats with new leather from lseat.com that I got for Christmas. This was a weekend project back in March(?) I think. Challenging, but rewarding. Dad and I ended having to put a lot of time in with a heat gun and a rag to shrink the covers down to an acceptable level on tension but it's a huge improvement over what was left of the factory leather.

https://i.imgur.com/yjV3lCLl.jpeg

https://i.imgur.com/pyMeGMcl.jpeg

https://i.imgur.com/WB32rJDl.jpeg

https://i.imgur.com/EABdXsml.jpeg

https://i.imgur.com/HOgzmt8l.jpg

The color/texture of the Lseat covers is certainly different from the factory ones, and they seem to fit a bit differently. The bottoms are dead on but it's almost like the backs are for a slightly different seat, like maybe 960 or something? Either way the top panel is too long and only one of the seams in the center of the seat back has a mounting area for hog rings, so when you put these covers on correctly you lose some of the definition in the shape of the original seat back foam. They look very matte in pictures, to the point where it almost looks like cloth but I assure you it is nice new leather.

After some attention with the heat gun the seats are now much more comfortable than before, and having seats that aren't all torn up is a huge improvement.


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