Coilovers
- Thread starter Rob1400T
- Start date
MikeHynes
True Classic
On the later cars, '79 up, you can raise the upper mount a bit without modification of the engine cover. On the early cars you have to remove or cut the plastic filler strips on either side of the engine cover.
For the front struts there is no room to raise the top mount, but you can raise the bottom mount just a bit.
Either way, you probably won't get enough extra room to prevent bottoming out your struts if you lower your car very much. If you use stiff springs you can mitigate the problem, but shorter struts are what is really needed (not cheap).
rx1900
1981 X1/9
Hey Rob. Those struts with those spring rates should - in theory - provide a nice ride and good handling.
I highly suspect something is very wrong with your installation. And that you have run out of shock travel somehow. Or are just running on the bump stops or something.....
Can you honestly tell me that you checked your set-up for proper travel by first trying the struts on the car with the springs removed ? To check for sufficient bump travel of the shock ? And then carefully set your bump stop length ?
Looking at the one pic you posted of the strut on the car..well assuming that pic is with wheel off and the suspension at full droop ??....you should be seeing about 5" at least of the chrome shock shaft. Pic may be deceiving but does not look like anything near that.....
What tires and wheel offset do you have ? Looks kinda large with lots of offset . With that....and stock suspension bump travel....your tire would hit the fender long before the shock bottomed out. I suspect that - perhaps - your upper mounts and camber plates are limiting the bump travel to less than what it should be. If....for example....those fancy new struts were designed for the camber plates to be mounted on TOP of the strut tower...rather then below it as you have it.....that would explain your troubles. As surely the upper mount should not be crashing into the strut body as your are !!
Doug
I highly suspect something is very wrong with your installation. And that you have run out of shock travel somehow. Or are just running on the bump stops or something.....
Can you honestly tell me that you checked your set-up for proper travel by first trying the struts on the car with the springs removed ? To check for sufficient bump travel of the shock ? And then carefully set your bump stop length ?
Looking at the one pic you posted of the strut on the car..well assuming that pic is with wheel off and the suspension at full droop ??....you should be seeing about 5" at least of the chrome shock shaft. Pic may be deceiving but does not look like anything near that.....
What tires and wheel offset do you have ? Looks kinda large with lots of offset . With that....and stock suspension bump travel....your tire would hit the fender long before the shock bottomed out. I suspect that - perhaps - your upper mounts and camber plates are limiting the bump travel to less than what it should be. If....for example....those fancy new struts were designed for the camber plates to be mounted on TOP of the strut tower...rather then below it as you have it.....that would explain your troubles. As surely the upper mount should not be crashing into the strut body as your are !!
Doug
Dr.Jeff
True Classic
Regarding the front hood clearance to raise the strut mount. I've not measured it, or even looked to see what's there, but I know it has to be very tight on the X. On another make of vehicle with close hood clearance they gain about 20mm extra room by notching the corner of the hood's support brace, like this:
Like I said, I haven't looked to see it this would help on the X. But the idea is this notch allows the extended strut mount to stick up further without the hood hitting it.
This is one example of how the upper strut mount can be raised (again, on a different make of car):
Like I said, I haven't looked to see it this would help on the X. But the idea is this notch allows the extended strut mount to stick up further without the hood hitting it.
This is one example of how the upper strut mount can be raised (again, on a different make of car):
Rupunzell
Bernice Loui
What size wheels & tires are on your exxe? They appear kinda big.
150 lb/in front, 200 lb/in rear are nearly stock spring rates and should not produce a horrid ride. What might be the source of the ride problem is damper ratio. If the AVO dampers have a high force for compression with low force on rebound ride will be stiff and hard. This damper ratio is typical for a track car where the road is mostly smooth and the high force required to compress the damper aids in suspension response by resisting rate of change in suspension movement. Low rebound force allows the suspension to recover faster after being compressed.
Typically, dampers set for ride quality have low compression force allowing the suspension to compress with ease and a high rebound rate to slow the suspension recovery to reduce sudden chassis movements. There are no damper ratio settings that work best for both smooth road performance and good ride quality. It is always a trade off between suspension-chassis performance-road surface performance-ride quality.
As the suspension- chassis is lowered, suspension travel will be given up. Essentially lowering the suspension on the exxe nearly mandates higher spring rates to limit suspension travel. If you go beyond the designed in suspension travel, the geometry will be all outa whack. Know there is an optimum range for any suspension design. This is the concept behind using really stiff springs limiting suspension travel.. to keep the suspension limited to it's ideal operating range trading off bump capability and ride quality. Which brings up the idea-belief that lowering the chassis-suspension is better.. Not really correct at all due to the reality of what has been designed into the suspension which is essentially fixed... unless one completely re-designs the entire suspension as a system.
Initial ride height for the exxe should be set with the lower front control arm about level to the ground with the rear similar. Lower more than this will put the dynamic roll center below ground-road level causing the force applies to the tire's contact patch to be into the side wall area causing poor grip from the tire, essentially causing the tire to roll into itself. Once that initial ride heigh with the proper size wheels & tires (about 22.5" OD total) the rest of the ride height of the car is set by corner weight.. regardless of how one wants the visual appearance of the car to be. One can set it up to look good, perform poor, perform good, looks not as expected.
Alternatives to singe rate springs would be to combine springs or variable rate springs and apply a progressive bump stop as a spring rate increaser as the suspension approaches it's bump stop. This was done on the production NA-NB miata aka MX-5. This is how Mazda got market acceptable ride with sort of OK body roll in cornering. It is also why there are so many aftermarket bump stop offerings for NA-NB miata to improve cornering and such.
As for stability bars aka anti-roll bars, they are OK if they are a minor suspension tweak. As these bars go up in diameter-stiffness, the suspension behaves as if it has solid axles which causes a long list of ills. The stock exxe set up with no stability bars aka anti-roll bars is good and better than most would understand. If more roll stiffness is desired, going up in spring rates is one way or combine higher spring rates with a modest stability bar. This all must be tuned-setup with proper damper ratios and wheel-tire combo.
The whole thing works as a system with each item affecting the overall performance of the system.
Bernice
150 lb/in front, 200 lb/in rear are nearly stock spring rates and should not produce a horrid ride. What might be the source of the ride problem is damper ratio. If the AVO dampers have a high force for compression with low force on rebound ride will be stiff and hard. This damper ratio is typical for a track car where the road is mostly smooth and the high force required to compress the damper aids in suspension response by resisting rate of change in suspension movement. Low rebound force allows the suspension to recover faster after being compressed.
Typically, dampers set for ride quality have low compression force allowing the suspension to compress with ease and a high rebound rate to slow the suspension recovery to reduce sudden chassis movements. There are no damper ratio settings that work best for both smooth road performance and good ride quality. It is always a trade off between suspension-chassis performance-road surface performance-ride quality.
As the suspension- chassis is lowered, suspension travel will be given up. Essentially lowering the suspension on the exxe nearly mandates higher spring rates to limit suspension travel. If you go beyond the designed in suspension travel, the geometry will be all outa whack. Know there is an optimum range for any suspension design. This is the concept behind using really stiff springs limiting suspension travel.. to keep the suspension limited to it's ideal operating range trading off bump capability and ride quality. Which brings up the idea-belief that lowering the chassis-suspension is better.. Not really correct at all due to the reality of what has been designed into the suspension which is essentially fixed... unless one completely re-designs the entire suspension as a system.
Initial ride height for the exxe should be set with the lower front control arm about level to the ground with the rear similar. Lower more than this will put the dynamic roll center below ground-road level causing the force applies to the tire's contact patch to be into the side wall area causing poor grip from the tire, essentially causing the tire to roll into itself. Once that initial ride heigh with the proper size wheels & tires (about 22.5" OD total) the rest of the ride height of the car is set by corner weight.. regardless of how one wants the visual appearance of the car to be. One can set it up to look good, perform poor, perform good, looks not as expected.
Alternatives to singe rate springs would be to combine springs or variable rate springs and apply a progressive bump stop as a spring rate increaser as the suspension approaches it's bump stop. This was done on the production NA-NB miata aka MX-5. This is how Mazda got market acceptable ride with sort of OK body roll in cornering. It is also why there are so many aftermarket bump stop offerings for NA-NB miata to improve cornering and such.
As for stability bars aka anti-roll bars, they are OK if they are a minor suspension tweak. As these bars go up in diameter-stiffness, the suspension behaves as if it has solid axles which causes a long list of ills. The stock exxe set up with no stability bars aka anti-roll bars is good and better than most would understand. If more roll stiffness is desired, going up in spring rates is one way or combine higher spring rates with a modest stability bar. This all must be tuned-setup with proper damper ratios and wheel-tire combo.
The whole thing works as a system with each item affecting the overall performance of the system.
Bernice
Dr.Jeff
True Classic
Not necessarily. On a stock chassis and suspension yes, but with some modifications the spindle and/or strut's location can be moved (relocated) relative to the chassis to lower the vehicle around the strut without decreasing the strut's travel. I'm not saying this is the "perfect" design solution, but in a real world where the owner desires a much lower vehicle height (for whatever reason) then mods can allow for it and still not bottom out the suspension. Some circles may refer to this as a "spindle drop", "body drop", "channeled", "Z'ing the frame" or other terms depending on the approach taken or the genre of enthusiasts. Lots of alternatives, all requiring modification of the stock design, which is not everyone's cup of tea. And often mods do come with a tradeoff, in one form or another. But depending on the owner's goals those tradeoffs may be worth the outcome. Anything is possible.
But don't get me wrong, I'm not disagreeing with the overall intent of your message at all.
Rupunzell
Bernice Loui
PBS approach.. lower the chassis around the suspension to gain-retain suspension travel.
Absolutely can be done, question is why and what are the goals?
Before any things is altered-modified, it must be very clear what the goals are and why any alteration-modification needs to be done.
Bernice
Absolutely can be done, question is why and what are the goals?
Before any things is altered-modified, it must be very clear what the goals are and why any alteration-modification needs to be done.
Bernice
Rob1400T
Daily Driver
Thank you everyone.
I'm running 15" wheels all round with 7" on the front and 8" on the rear, ET 20 with hub-centric spacers to clear the larger brakes.
I'll investigate putting the camber plates on top of the body and replacing components in rod with shorter ones, I have a plan!
I'm running 15" wheels all round with 7" on the front and 8" on the rear, ET 20 with hub-centric spacers to clear the larger brakes.
I'll investigate putting the camber plates on top of the body and replacing components in rod with shorter ones, I have a plan!
Dr.Jeff
True Classic
Exactly, which is why I say this sort of approach may not be for everyone.
rx1900
1981 X1/9
No......I did NOT say that should be your next step........but I did say you should FIRST investigate whether or not you will have to do something like that...
First things first.....did you actually ever check the suspension travel with your current set-up ?? Are there bump stops in your set-up now ? From your chosen ride height, how much travel is there until the bump stop engages ? And from there, how much more travel is remaining in the shock ? you will have to determine ALL that before planning your next step.....
And by the way, what size tires are you running ?
Rupunzell
Bernice Loui
What size tires? Keep in mind, 7" front 8" rear is awful big for s stock body.
Wider tires do not increase grip, they alter the tire contact patch shape of the same area of a less wide tire. Wider rims also alter the dynamic roll center and not always for the better. Wheel spacers on the front will alter the scrub radius which can affect braking stability, steering feel and a list of other dynamic suspension behaviors.
~What are the original goals of chassis-suspension alterations?
Bernice
Wider tires do not increase grip, they alter the tire contact patch shape of the same area of a less wide tire. Wider rims also alter the dynamic roll center and not always for the better. Wheel spacers on the front will alter the scrub radius which can affect braking stability, steering feel and a list of other dynamic suspension behaviors.
~What are the original goals of chassis-suspension alterations?
Bernice
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Rob1400T
Daily Driver
Hi Bernice, I don't really have any goals or intentions really, it's not a track or hill climb car. I've owned it 20 years and modified it bit by bit to my taste. I used to run 195/45 tyres all round and the grip improved significantly over stock. I now use 215s on the rear and 185s on the front as I wanted the staggered set up. Brakes are 284mm vented discs all round with 4 pots, bias valve and bigger MC which stops the car on its nose. Engine is 3 times the hp of the original and the back end stays planted in the bends with those tyres.
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Dr.Jeff
True Classic
Wow, there is a LOT to be gained there.
It appears they were originally designed to be used with the stock rubber top mounts. That may be why they have the "aluminum" colored cone (yellow arrow):
You should be able to eliminate that completely. And the "red" color spring-hat can be replaced with the one in your hand to reduce the height more.
Is the "gold" color plate is a solid mount (spherical ball joint)? Or just a spacer? Because the "blue" plate is the camber adjuster and might have a spherical joint in it? Seems like way too many layers.
By mounting the blue camber plate on top of the strut towers, and replacing the rest with the one in your hand, you will get enough suspension travel to make a nice ride without bottoming out. Some mods will be needed to do all this, but it doesn't look too difficult.
[Sent you a message]
It appears they were originally designed to be used with the stock rubber top mounts. That may be why they have the "aluminum" colored cone (yellow arrow):
You should be able to eliminate that completely. And the "red" color spring-hat can be replaced with the one in your hand to reduce the height more.
Is the "gold" color plate is a solid mount (spherical ball joint)? Or just a spacer? Because the "blue" plate is the camber adjuster and might have a spherical joint in it? Seems like way too many layers.
By mounting the blue camber plate on top of the strut towers, and replacing the rest with the one in your hand, you will get enough suspension travel to make a nice ride without bottoming out. Some mods will be needed to do all this, but it doesn't look too difficult.
[Sent you a message]