Recommended Ride Height?
09-05-12, 10:23 PM
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Recommended Ride Height?
I gots the Respeed race coilovers, rear coilovers, sway bar, camber plates, 1.5" roll center spacers, and Illumina's installed. What's a good baseline to start with as far as measured ride height? And where do you measure; control arm to frame rail, top of rear housing to frame rail, etc.?
I found a local-old-school-active-dirt-racer guy who has scales for corner weighing and finally talked to him on the phone today...I was thinking: you buy this stuff, determine a "visual", "aesthetical" ride height, then balance on corner scales with the four coilovers...Guy with the scales says NO WAY! you need to have a ride height to set it to first...One that maintains the proper suspension geometry, height of front vs rear, etc.
I just want a kick *** handlling street car, and fill some of the gap in the wheel wells after putting 15" wheels with lower profile tires on with an overall smaller diameter compared to the stock 14" wheels and tires...
Anybody have any "hard" measurements or a rough baseline to start with? I unfortunatlely took no measurements whilst still on stock components to compare to, either...
On a side note; I initially had the coilovers all set to max height, and the illumina's on 1, and the stock wheels on. It drove...ok. I'm sure alignment is all screwed up. THEN I dropped it with only five more threads on the rear collars, and 12 more threads remaining on the front colllars, and put my 15" wheels on, and set the shocks to 5. As soon as you let the clutch out, you feel the rear "hop" or gently bounce like you have a bent wheel or axle, and the steering is HEAVY and bad. I'm guessing this is TOO low, or badly misbalanced...
I found a local-old-school-active-dirt-racer guy who has scales for corner weighing and finally talked to him on the phone today...I was thinking: you buy this stuff, determine a "visual", "aesthetical" ride height, then balance on corner scales with the four coilovers...Guy with the scales says NO WAY! you need to have a ride height to set it to first...One that maintains the proper suspension geometry, height of front vs rear, etc.
I just want a kick *** handlling street car, and fill some of the gap in the wheel wells after putting 15" wheels with lower profile tires on with an overall smaller diameter compared to the stock 14" wheels and tires...
Anybody have any "hard" measurements or a rough baseline to start with? I unfortunatlely took no measurements whilst still on stock components to compare to, either...
On a side note; I initially had the coilovers all set to max height, and the illumina's on 1, and the stock wheels on. It drove...ok. I'm sure alignment is all screwed up. THEN I dropped it with only five more threads on the rear collars, and 12 more threads remaining on the front colllars, and put my 15" wheels on, and set the shocks to 5. As soon as you let the clutch out, you feel the rear "hop" or gently bounce like you have a bent wheel or axle, and the steering is HEAVY and bad. I'm guessing this is TOO low, or badly misbalanced...
09-05-12, 11:17 PM
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somewhere in the FSM is a ride height spec (i always have a hard time finding it) and i notice my car is actually right at the low end of the stock spec (it just happened?).
or you can pick a right height that looks good + some room for bumps and make it even side to side. front to back can be even, or have a little rake depending on looks.
the factory tends to measure from the top of the wheel arch thru the center of the wheel to the ground, and the SCCA likes to use the pinch weld. it doesn't matter as long as you can get a repeat measurement.
with the corner scales you set the height you want, and then tweak a corner or two to get the weight even side to side.
most US (non chinese?) coil over sleeves are a 1.0 thread pitch, so 4 turns is an inch
or you can pick a right height that looks good + some room for bumps and make it even side to side. front to back can be even, or have a little rake depending on looks.
the factory tends to measure from the top of the wheel arch thru the center of the wheel to the ground, and the SCCA likes to use the pinch weld. it doesn't matter as long as you can get a repeat measurement.
with the corner scales you set the height you want, and then tweak a corner or two to get the weight even side to side.
most US (non chinese?) coil over sleeves are a 1.0 thread pitch, so 4 turns is an inch
09-06-12, 10:01 AM
#3
With my RB springs, I was originally 1" down from stock, and between my slightly lower-than-stock sidewall height & the springs being around 12 years old, I'm probably down about another quarter inch from that.
Cornering at decent speed:
I like my height (clears speedbumps without dragging, handles nicely & doesn't bottom) but compared to modern cars, it looks rather high.
Cornering at decent speed:
I like my height (clears speedbumps without dragging, handles nicely & doesn't bottom) but compared to modern cars, it looks rather high.
09-06-12, 11:27 AM
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Divin', That's a really nice picture of your car.
O.P., The way I setup my old FB was to put the front ride height to where the lower control arms were slightly higher on the body than the tire at the front. If you have them lower at the body than the tire it's too low for good geometry. Then I put the rear of the car slightly higher than the front , like a half inch or so. That is so you have some rake in the car to stop any aero lift at speed. It worked great for me and I left it that way for many years with no complaints. I have my current FC setup that way with good results as well.
O.P., The way I setup my old FB was to put the front ride height to where the lower control arms were slightly higher on the body than the tire at the front. If you have them lower at the body than the tire it's too low for good geometry. Then I put the rear of the car slightly higher than the front , like a half inch or so. That is so you have some rake in the car to stop any aero lift at speed. It worked great for me and I left it that way for many years with no complaints. I have my current FC setup that way with good results as well.
09-06-12, 02:09 PM
#6
i have 15" wheels on mine, and i measured from the top of the wheel (not the tire) to where the fender starts and i have about 4.5 inches. i found that doing it this way kinda evens out weight transfers also since the drivers side will want to be a bit lower than passanger. This is for the front only, the rear, i have coil over springs but no coil over so it sits fairly low on the back. as far as tires go i have 195/60 up front and 195/65 rears.
i could go lower, but decided that this was a good ride feel and its fairly low. it doesn't look like it, but it is. enough for my brother in law that owns a 2011 acura TL says my car is waaaay too low, altho his looks lower. i may could go another inch lower if i get lower profile tires also(which i prefer to have a bit of sidewall), these ones may end up rubbing if i do..don't know haven't tried it yet.
here's what it looks like:
i could go lower, but decided that this was a good ride feel and its fairly low. it doesn't look like it, but it is. enough for my brother in law that owns a 2011 acura TL says my car is waaaay too low, altho his looks lower. i may could go another inch lower if i get lower profile tires also(which i prefer to have a bit of sidewall), these ones may end up rubbing if i do..don't know haven't tried it yet.
here's what it looks like:
09-06-12, 09:50 PM
#7
I'm on the stock 13s and what I usually do is space it so that when I put my hand into the wheel well the fender is on the back of my hand and the wheel is on my finger tips my hand will sit flat parallel to the ground. So I would say maybe 1/2" from tire to fender. I did this all around for mine, love the way it feels.
Edit: I should also probably say that I have the geostar tires in the rear and whatever the really cheap ones were, I can't remember the name but I think they were a low end brand from goodyear, in the front.
Edit: I should also probably say that I have the geostar tires in the rear and whatever the really cheap ones were, I can't remember the name but I think they were a low end brand from goodyear, in the front.
Last edited by Jingkun; 09-06-12 at 09:56 PM.
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09-06-12, 10:04 PM
#8
For the front end with the spacers you want the inner control arm bolt height to be 5/8" higher than the center of your balljoint.
Changing the ride height in the rear will effect your handling a lot. Once the front is set take a look at the car and get the rake you like. Depending on what you have back there, you can't go too low. Too low and you'll bind up your drive shaft and screw up the phase of the u-joints.
Changing the ride height in the rear will effect your handling a lot. Once the front is set take a look at the car and get the rake you like. Depending on what you have back there, you can't go too low. Too low and you'll bind up your drive shaft and screw up the phase of the u-joints.
09-06-12, 10:24 PM
#10
Thanks; it was shot by Victory Jon along the Snake in Malibu. Liked it so much I bought the original file off him (he sells online), and I now have a 24x36 print of it. Awesome detail.
Actuals on my car, top of wheel well arch to the ground on level pavement:
Front 609mm
Rear 605mm
Spec for the 80 from the FSM is taken from wheel center to the fender line, and is given as 364+/-20mm front, 358+/-20mm rear. Measured that way, mine comes in at ~340 front, ~335 rear.
Actuals on my car, top of wheel well arch to the ground on level pavement:
Front 609mm
Rear 605mm
Spec for the 80 from the FSM is taken from wheel center to the fender line, and is given as 364+/-20mm front, 358+/-20mm rear. Measured that way, mine comes in at ~340 front, ~335 rear.
09-07-12, 01:17 PM
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my rear is significantly higher than the front. I'll take measurements when I get home. I'll measure from bottom of bumpers. I am running 16" wheels so my car looks like a RC car especially with the radio antanae up all the way.
09-07-12, 01:42 PM
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For the front end with the spacers you want the inner control arm bolt height to be 5/8" higher than the center of your balljoint.
Changing the ride height in the rear will effect your handling a lot. Once the front is set take a look at the car and get the rake you like. Depending on what you have back there, you can't go too low. Too low and you'll bind up your drive shaft and screw up the phase of the u-joints.
Changing the ride height in the rear will effect your handling a lot. Once the front is set take a look at the car and get the rake you like. Depending on what you have back there, you can't go too low. Too low and you'll bind up your drive shaft and screw up the phase of the u-joints.
09-07-12, 02:37 PM
#14
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In a race setup guide I read a long time ago, it said that the rear should actually be slightly lower than the front.
On my car, with 13" wheels, ground to wheel arch = 21.5 f/22.25 r
Seems to work very well.
However, due to the length of Illuminas, you might not be able to get that low without bottoming them out. I'm running short Bilsteins on the rear.
.
On my car, with 13" wheels, ground to wheel arch = 21.5 f/22.25 r
Seems to work very well.
However, due to the length of Illuminas, you might not be able to get that low without bottoming them out. I'm running short Bilsteins on the rear..
09-07-12, 04:09 PM
#15
Based of the design of these cars and their stock power to weight ratio (and relatively limited acceleration vs braking/turning G capacity) the vast majority of high-dynamics maneuvers is going to start with weight transferring forward, compressing the front suspension on one or both sides.
09-07-12, 04:59 PM
#16
The rear ride height issue is more about roll center height and the resulting roll axis angle when figured with the front roll center.
If you still have the stock Watts link, your roll center will go up in relation to the chassis when the car is lowered, it moves with the rear end(Watts center point)
If you have a panhard bar the roll center is usually set up lower than stock with the bar at the height of the bottom of the rear diff. The roll center is in the middle of the bar if it it set up level.
The roll axis is flatter with a panhard bar and front spacers even with the car lowered. Changing the rear ride height by a half inch up or down is a nice tuning feature to tweak the handling without changing spring rates. It effects how the roll resistance of the rear suspension works against the chassis.
Adjustable control arms are a good idea. You can unwind the rear end housing(raise the pinion) that rolls forward when the upper arms start pulling the top forward because they are so much shorter.
If you still have the stock Watts link, your roll center will go up in relation to the chassis when the car is lowered, it moves with the rear end(Watts center point)
If you have a panhard bar the roll center is usually set up lower than stock with the bar at the height of the bottom of the rear diff. The roll center is in the middle of the bar if it it set up level.
The roll axis is flatter with a panhard bar and front spacers even with the car lowered. Changing the rear ride height by a half inch up or down is a nice tuning feature to tweak the handling without changing spring rates. It effects how the roll resistance of the rear suspension works against the chassis.
Adjustable control arms are a good idea. You can unwind the rear end housing(raise the pinion) that rolls forward when the upper arms start pulling the top forward because they are so much shorter.
09-07-12, 05:58 PM
#17
Just done mine with 38mm r/c blocks, coilover sleeves and rear adj. spring perches, about an inch cut off all four bumpstops (only 15mm left on the front ones).
From top of wheel rim to guard lip - fr; 85mm, r; 100mm (approx)
From guard lip to floor; fr; 580mm, r; 590-600mm (approx) tyres are 205/50/15
front cntrl arms still have a bit of angle. no bottoming as yet, rides nice, handles great. Aesthetically could probly use more low, but might raise the front a bit more anyway and see how that feels.
[edit]
and guard to wheel center; 297mm front
305~315mm rear. either the garage floor or the car isnt straight, lol.
im yet to get it whheel aligned and cnr weighted, gotta sort cpl other issues first.
From top of wheel rim to guard lip - fr; 85mm, r; 100mm (approx)
From guard lip to floor; fr; 580mm, r; 590-600mm (approx) tyres are 205/50/15
front cntrl arms still have a bit of angle. no bottoming as yet, rides nice, handles great. Aesthetically could probly use more low, but might raise the front a bit more anyway and see how that feels.
[edit]
and guard to wheel center; 297mm front
305~315mm rear. either the garage floor or the car isnt straight, lol.
im yet to get it whheel aligned and cnr weighted, gotta sort cpl other issues first.
Last edited by WANKfactor; 09-07-12 at 06:17 PM.
09-07-12, 08:27 PM
#18
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Allright, thanks a lot, guys. I'm taking it all in...And I do have stock watts for now. (#1)As far as weighing the car, if you DO balance it front and back ~50/50, does the rear end up higher or lower than the front? (#2)Is the "rake" more important than the front/back balance?
I guess to avoid damaging my trans or rear diff I just rebuilt, I think I'll forgoe trying to go LOW for now. (#3)SO, with 1.5" R.C.S in the front, would I want a 1.5" lower ride height than stock in the front and then set the rear slightly lower in ride height than the front. (#4)And then corner weigh it just to set left and right, not front and back?
Thanks for the help guys, I REALLY appreciate it. I'm dying to get my girl back on the road, I've allready missed the whole damn summer!!!
I guess to avoid damaging my trans or rear diff I just rebuilt, I think I'll forgoe trying to go LOW for now. (#3)SO, with 1.5" R.C.S in the front, would I want a 1.5" lower ride height than stock in the front and then set the rear slightly lower in ride height than the front. (#4)And then corner weigh it just to set left and right, not front and back?
Thanks for the help guys, I REALLY appreciate it. I'm dying to get my girl back on the road, I've allready missed the whole damn summer!!!
09-07-12, 08:28 PM
#19
Thanks; it was shot by Victory Jon along the Snake in Malibu. Liked it so much I bought the original file off him (he sells online), and I now have a 24x36 print of it. Awesome detail.
Actuals on my car, top of wheel well arch to the ground on level pavement:
Front 609mm
Rear 605mm
Spec for the 80 from the FSM is taken from wheel center to the fender line, and is given as 364+/-20mm front, 358+/-20mm rear. Measured that way, mine comes in at ~340 front, ~335 rear.
Actuals on my car, top of wheel well arch to the ground on level pavement:
Front 609mm
Rear 605mm
Spec for the 80 from the FSM is taken from wheel center to the fender line, and is given as 364+/-20mm front, 358+/-20mm rear. Measured that way, mine comes in at ~340 front, ~335 rear.
aparently my springs have not saged in 30 some years, but now I have an uncontrolable urge to get RB springs.
09-07-12, 08:49 PM
#20
Corner weighting by adjusting spring heights alone, without actually adding weights, wont change the inherent f/r, l/r weight bias, but will get the weight on all four wheels as even as possible.
For example, picture a table who's legs are uneven lengths, all the weight will be on two diagonally opposed legs and will rock diagonally. Make the legs the same length and the weight is distributed as evenly as you will ever get it even if one side is heavier than the other. Add weights and theoretically can get perfect 25% even distribution.
For example, picture a table who's legs are uneven lengths, all the weight will be on two diagonally opposed legs and will rock diagonally. Make the legs the same length and the weight is distributed as evenly as you will ever get it even if one side is heavier than the other. Add weights and theoretically can get perfect 25% even distribution.
Last edited by WANKfactor; 09-07-12 at 08:57 PM.
09-07-12, 09:38 PM
#21
I would start at the front of the car and work with the measurements I posted above, then go to the rear and set the look you want for rake. Changes in ride height in the rear are for very slight changes in handling, the kind of stuff that shows up when running 10/10ths. You have enough other adjustments to play with that will affect the car more.
When you're on the scales, try to have a half tank of fuel and you in the driver's seat, or at least enough weight to be 'you'.
The exact numbers at all four corners don't need to be the same for a good handling car. As for rear ride height it will only change corner weights a few pounds if raised and lowered evenly across the two springs. The magic numbers are cross weights. You want to get 50%. Most scales will do othe math for you automatically. It can be very tough to get without moving things in the car like the battery etc.
You put the car on the scales, set your ride heights as a baseline. You then chase your tail a few times around the car trying to get the numbers on the scales you like without changing the ride height very much. It will probably take an hour the first time.
When you're on the scales, try to have a half tank of fuel and you in the driver's seat, or at least enough weight to be 'you'.
The exact numbers at all four corners don't need to be the same for a good handling car. As for rear ride height it will only change corner weights a few pounds if raised and lowered evenly across the two springs. The magic numbers are cross weights. You want to get 50%. Most scales will do othe math for you automatically. It can be very tough to get without moving things in the car like the battery etc.
You put the car on the scales, set your ride heights as a baseline. You then chase your tail a few times around the car trying to get the numbers on the scales you like without changing the ride height very much. It will probably take an hour the first time.
09-09-12, 08:10 PM
#23
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Update
Got to my car today...Left it as low as it was, but moved the shock to the outmost position in the camber plate on each side, and reduced the shocks from 5 to 3. The front and rear height adjusters were equally adjusted side to side with even thread count remaining on each side. I measured each wheel from ground to fender lip through the center of the wheel. I got LF=22.5" - RF=23" - LR=22.75" - RR=22.69". Then I went to the guy with the scales, had between 1/4 and 1/2 tank, bars hooked up, and me NOT in it. Total was 2572lbs. LF=702lbs - RF= 662lbs - LR=607lbs - RR=604lbs. Cross weight? was RF<->LR=49.2%. Front=52.9% - Rear=47%. So this means with the rear lower than the front, there is allready more weight to the front, so I don't want to end up with my rear higher than the front, correct? Then guy had to go racin' and I spent the next 4 hours F'ing around with the tape measure and height adjustments... I started by trying to measure the control arm/frame bolt height vs the ~1/2 way upthe ball joint height from floor. I couldn't accurately make this measurement at all. It "looked" like it was more than or at least 5/8" as previously suggested. Then I adjusted only the front to a height of 23.69" on each side (with the swaybar disconnected). THEN moved on to the rear and tried to set it a little lower than the front, but could NEVER get equal on each side... I ended up with the LR adjuster maxed out(all the way up) for the lowest setting, and the RR was about 3/4"-1/2" away from being maxed out in the opposite direction to the highest setting. LR=23.25" and RR=23"...Gave up and reconnected bars and went for a ride. Rear made alot of noise (springs clanging) turning into driveway, pulling out, etc. Drove straight enough, but still felt heavy and slow in the steering and generally not happy. Where do I go from here? After setting the fronts, I imagine they ended up being different lengths, and that's what's making adjusting the rears to the same height so hard? You guys make it sound easy, I've found myself to be really lame at doing this stuff...Trying to learn, and here is the best/only option. Thanks guys
09-09-12, 08:55 PM
#24
Fun huh!?
I wouldn't set the rear lower than the front, no need to be that low on the street. The difference in weight front to rear is nill. You're effecting the location of the center of gravity to move weight front to rear. How much does your gear shift **** move back or forward when you raise and lower the car? That is about the location of your CG.
Without your weight in the car you are wasting your time. Unless your car goes out by itself for fun, lol.
The biggest thing to look at up front is that your ball joints are lower than the center of the suspension bolts. Small changes in that relation will change how effective the front bar is. Lower the car,roll center drops more than you lowered the car, bar becomes less effective, car falls over in a turn. It's all about roll center height. I'll throw you another issue. The roll center moves sideways too, especially with a strut car. As the car leans the roll center heads toward the inside of the turn, making the car want to lean MORE. Think about grabbing a sledgehammer by the end of the handle, hold it up vertical and wave it back and forth. Pretty tough. Now, grab it right under the hammer head, a lot easier to wave it back and forth, right? Your hand is like your roll center on your car.
Your sluggish steering feel may be alignment based. Castor, camber and toe. Make sure you have that stuff right too.
What spring rates do you have? The shocks just need to control the spring in rebound and the unsprung weight in bump. Loosen them up to 2 or 3 all the way around if you have street type springs. Drive the car see if it bouncey. You can tune how the car feels in the transitions(entering or exiting a turn) In the middle of the turn they are just along for the ride unless you hit a bump. Try going to 5 on the rear, you'll find the car will turn in a little better but may skitter on bumps on turn exit when you are putting the power down.
I wouldn't set the rear lower than the front, no need to be that low on the street. The difference in weight front to rear is nill. You're effecting the location of the center of gravity to move weight front to rear. How much does your gear shift **** move back or forward when you raise and lower the car? That is about the location of your CG.
Without your weight in the car you are wasting your time. Unless your car goes out by itself for fun, lol.
The biggest thing to look at up front is that your ball joints are lower than the center of the suspension bolts. Small changes in that relation will change how effective the front bar is. Lower the car,roll center drops more than you lowered the car, bar becomes less effective, car falls over in a turn. It's all about roll center height. I'll throw you another issue. The roll center moves sideways too, especially with a strut car. As the car leans the roll center heads toward the inside of the turn, making the car want to lean MORE. Think about grabbing a sledgehammer by the end of the handle, hold it up vertical and wave it back and forth. Pretty tough. Now, grab it right under the hammer head, a lot easier to wave it back and forth, right? Your hand is like your roll center on your car.
Your sluggish steering feel may be alignment based. Castor, camber and toe. Make sure you have that stuff right too.
What spring rates do you have? The shocks just need to control the spring in rebound and the unsprung weight in bump. Loosen them up to 2 or 3 all the way around if you have street type springs. Drive the car see if it bouncey. You can tune how the car feels in the transitions(entering or exiting a turn) In the middle of the turn they are just along for the ride unless you hit a bump. Try going to 5 on the rear, you'll find the car will turn in a little better but may skitter on bumps on turn exit when you are putting the power down.
09-09-12, 09:45 PM
#25
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