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ride height adjustments...coilover questions
first350 - 21/5/11 at 03:14 PM

I'm trying to dial in my suspension, and all of the coilovers I've worked with have been on cars....and these are fairly different.

specs:
-Inboard front
-Miata donor
-195/50/15 tires (R888's)
-goal: front lower control arms level w/ ground and Rear about 10mm higher than front.

Questions:
1) The lower spring perches only have 1 collar...does the weight of the car keep that in place? (I've always had 2 collars, that can be tightened to each other to lock in the height)
2) To get my rear low enough, the spring collar is threaded so far down that when the car is on jack stands, the springs are loose. Is this ok? (I've seen other car coilovers that use "spring helpers"...basically a 2nd thin spring that doesn't add any force, but takes up the slack when the car is on jack stands)

coilover w/ spring helper:


here's a pic of the front coils...this is how my rear look to get the right height (the spring is loose)


Cheers!


bassett - 21/5/11 at 04:02 PM

I remember mine feeling a bit loose but the weight soon takes care of that and all of them only have one spring i guess due to the short length


tomgregory2000 - 21/5/11 at 04:18 PM

mine have a grub screw in them to keep them in place


Davey D - 21/5/11 at 05:00 PM

on the back of mine if i have it on axle stands the springs drop from the top cup. once it is dropped to ground though they always relocate with an un-nerving twang noise :-)


first350 - 23/5/11 at 01:43 PM

quote:
Originally posted by Davey D
on the back of mine if i have it on axle stands the springs drop from the top cup. once it is dropped to ground though they always relocate with an un-nerving twang noise :-)


mine did that too - freaked me out the first few times!!

Once I get the ride height right, I'll make some marks on the shocks bodies so that I can see if the spring collars/perches move over time. It'll be a good excuse to put as many miles on it as possible


BigLee - 23/5/11 at 08:31 PM

Thank god its not just me!! I had planned to get to the bottom of this problem tomorrow by removing most of the suspension and checking I hadn't got all the springs/shocks the wrong way around. Thats saved a job, but doesn't answer why this happens? Surely a shorter damper body should be used. Seems a little half arsed. Unless someone can explain the benefit of your wheels dropping in this manner when in the air?

Lee


Agriv8 - 24/5/11 at 06:40 AM

its normal - never known a colar move and as the do not rotate ( as the are bolterd into the mounting bracket) there is little roational force on them. They locate them selves very well when dropped to the ground though the first few times you get a big "Twang" as the seat will make you Jump

Ps the dampers are the length they are due to availability and cost a better I belive also sring strength and length is a factor. though the main reason is to save weight as the same basic chassis are used for the EC boys where shaving every Ounce is important.

hope that helps ATB

Agriv8

[Edited on 24/5/11 by Agriv8]


BigLee - 24/5/11 at 11:53 AM

Thanks for the info. Still sounds a bit iffy though. So when the car is "light" ie over a bump or hump back bridge ( in the extreme) then you have no suspension provided by the spring, it looks like the damper is too long or the spring too short.

Lee


Frosty - 24/5/11 at 02:18 PM

If the spring is slack then definitely get some helper springs in there, or a shorter spring.


procomp - 24/5/11 at 08:13 PM

Hi

The spring length on that first pic can't possibly be right. The spring is wound up towards the top end of its height adjustment. When the car is sat at static ride height the damper would only have 25 ish mm before siting on the bump stops. There is absolutely no room for movement in droop before the spring is unloaded.

It's quite common for the spring to become unloaded at full droop of the damper IE when the car is on a jack out of normal working range. But to have no load in the slightest of droop travel is ridiculous. Something is wrong with that setup.

Cheers Matt


BigLee - 24/5/11 at 09:06 PM

Rear shocks on mine. I presume the same as first350's as our chassis's were about 2 weeks apart. When the shock is fully extended by winding out the preload (no actual preload on the spring - just the slack taken up) the back end was sky high. Now wound down to get the ride height correct, but blows through half the damper travel. I can't believe this is how they are 'meant' to be considering they are supplied by MNR.
Description
Description


Shock
Shock


I know the brake line is in the way - it is getting shortened next week.

Cheers

Lee


first350 - 25/5/11 at 04:50 PM

quote:
Originally posted by BigLee
Rear shocks on mine. I presume the same as first350's as our chassis's were about 2 weeks apart. When the shock is fully extended by winding out the preload (no actual preload on the spring - just the slack taken up) the back end was sky high. Now wound down to get the ride height correct, but blows through half the damper travel. I can't believe this is how they are 'meant' to be considering they are supplied by MNR.



Mine look very similar in the rear...while driving hard around corners (~0.9 G's), it doesn't seem to bottom out. However when I've hit descent bumps at speed, I'm pretty sure it's on the bump stops.

*My fronts are the opposite...when the car is on jack stands, the springs are not loose (the spring perch is all the way up so that the springs are firm, but no pre-load). When the car is on the ground, my front ride height is a bit too low (LCA is not parallel with the ground). I assume this is normal b/c my push-rods are at the minimum length...I planned to raise the front by extended the push-rods. Is it possible that the Front and Rear should be swapped??

-Peter


BigLee - 25/5/11 at 05:07 PM

Swapping the front and rear were my 1st thoughts but doesnt work. The rears are 2 inches longer and simply won't fit with the front rockers. I have extended the push rods by about an inch so far. Now the engine and fluids are in, it is almost there. Maybe another quarter inch.
I'll probably end up buying new shocks for the rear. Something that is correct for the job rather than driving on the bump stops!

Lee


lucy - 28/5/11 at 10:59 PM

Springs should not be loose on full droop for any situation and shouldn't be any need for helper springs with pushrod setup.

Adjust pushrods to achieve correct height.

One of the advantages of the pushrod setup is that you don't have to preload the spring to get the correct ride height unlike lesser manufactures.

Wind the single collar up until the spring is not loose and then adjust the pushrod.

Don't tell MNR but I've put softer springs front and rear for a more compliant ride on the road. Not all road surfaces are like race tracks. Much more compliant with 'normal' road conditions.

Lucy


spiderman - 29/5/11 at 12:22 AM

Shocks too long or springs too short, they should not drop away from the collar on full droop and twang when weight is reapplied, not a problem when jacked up, just surprising when reseating, however not good when on full droop when driving i.e. hump back bridge, and possibly dangerous!


bassett - 29/5/11 at 11:07 AM

Lucy what springs did you opt for and if you dont mind me asking how much and where from, thank.
Adam


BigLee - 29/5/11 at 11:26 AM

Lucy - thanks for the info. The front shocks on the push rods are fine. All adjusted and sitting firm. The problem lies with the rears. I wonder whether it is a recent thing or whether all MNR's have a dodgy rear setup.


Krismc - 30/5/11 at 08:08 AM

My Rears are set so Spring wound up around 15mm after spring contacts collar under droop to get desired ride height. it leaves me with 2-3inches of travel in rear suspension, doesnt hit bump stops, and never ride your bump stops even once or twice, it will cause damage!

My fronts can fit the larger shockers in, all apeared fine but after settling that left very little suspension travel (so dont do it!)

Ive got the shorter ones in now with heavier 250lb springs and im still concerned that under droop the rockers can hit chassis rails.



[Edited on 30/5/11 by Krismc]


marc n - 31/5/11 at 07:53 AM

quote:

The problem lies with the rears. I wonder whether it is a recent thing or whether all MNR's have a dodgy rear setup.



hi lee
when car has settled, you will need to wind the springs back up to acheive your correct ride height, so will not have spring collar loose, ride height / travel when car is fully settled will be 1/3 travel in bump, 2/3rds travel in droop
cheers
marc



[Edited on 31/5/11 by marc n]


stevegough - 31/5/11 at 08:07 AM

quote:
Originally posted by tomgregory2000
mine have a grub screw in them to keep them in place


Aye! +1 (Gaz shocks) allen key grub screw is in the single adjusting collar.


also +1 for the twang! on the rears as they regain their seating as they come off the jack.


lucy - 31/5/11 at 07:44 PM

As marc n said; 1/3 travel in bump
2/3 travel in droop

Krismc - rockers hitting the chassis under droop! That can't be right. That isn't right. Would it help if the bolt on the top of the shocker was turned round? My bolt on the offside has been cut short to miss the tube.

stevegough - isn't right to have twang under any circumstances I would have thought.

bassett - for my bec setup I changed from 250lb x 8in and 150lb x 7in to 175lb x 9in and 125lb x 7in. £20 each approx

first350 - winding out the pushrods is the way to adjust for height. For my protech shocks the springs should be 5ins shorter than fully open length of the shock. ie 14in shock = 9in spring and 12in shock = 7in spring

Big Lee - as stated at the top, at the correct ride height the shocker pushrod should be 1/3 closed with 2/3 to go when hitting a bump ( without any spring slack at any point in the suspension travel). Sounds like shorter shocks would help. Are your springs loose at full droop when ride height is correct?

marc n - I'm struggling to see how the situation will be better when the suspension has settled. The shock length won't change and the spring may shorten making things worse not better (if there is slack in the spring at the moment, that will get worse, or am I missing something?)

ps I visited Protech for some work to be done on my shock. They wouldn't charge me!
I also bought my springs from them and they explained about the correct length spring for the particular shocks I had. Brilliant service.

pps I love my vortx.


daniel mason - 31/5/11 at 07:53 PM

^^^ have you bought my old car?


lucy - 31/5/11 at 10:04 PM

quote:
Originally posted by daniel mason
^^^ have you bought my old car?



Not yours Dan. But I did see yours for sale some time ago( the blue one that is) I think.

Mines orange and a Busa. Built by ANother who did a cracking job. Left to me it would still be in kit form, waiting for more time than I've got. Too many hobbies etc


Krismc - 1/6/11 at 05:29 AM

Nope it'd the bolt head that hits chassis ,so unavoidable, I've mention a few times but I keep getting told its my setup, but either way it catches. Unless I preload the spring a lot more so that its more difficult, but still happens when I lift car up!!


lucy - 1/6/11 at 09:51 AM

quote:
Originally posted by Krismc
Nope it'd the bolt head that hits chassis ,so unavoidable, I've mention a few times but I keep getting told its my setup, but either way it catches. Unless I preload the spring a lot more so that its more difficult, but still happens when I lift car up!!


Can MNR give you a clue as to what is wrong with your setup?
Which part of the rocker is hitting the chassis?
If it's hitting on full droop I presume the only thing you can adjust is the pushrod. The damper is the correct length I assume? Mine is 12in on the front for my bec. What length and poundage springs do you have?


Krismc - 3/6/11 at 07:13 PM

quote:
Originally posted by lucy
quote:
Originally posted by Krismc
Nope it'd the bolt head that hits chassis ,so unavoidable, I've mention a few times but I keep getting told its my setup, but either way it catches. Unless I preload the spring a lot more so that its more difficult, but still happens when I lift car up!!


Can MNR give you a clue as to what is wrong with your setup?
Which part of the rocker is hitting the chassis?
If it's hitting on full droop I presume the only thing you can adjust is the pushrod. The damper is the correct length I assume? Mine is 12in on the front for my bec. What length and poundage springs do you have?


The head of the top inner bolt is hitting the chassis under droop on the RHS, it was hitting on both sides before i had repair now its hitting on rhs only.

Im not keen on this so called adjustable suspension, that cant be adjusted, its set to what ever works and no way is it adjustable.


lucy - 4/6/11 at 10:45 PM

quote:
Originally posted by Krismc
quote:
Originally posted by lucy
quote:
Originally posted by Krismc
Nope it'd the bolt head that hits chassis ,so unavoidable, I've mention a few times but I keep getting told its my setup, but either way it catches. Unless I preload the spring a lot more so that its more difficult, but still happens when I lift car up!!


Can MNR give you a clue as to what is wrong with your setup?
Which part of the rocker is hitting the chassis?
If it's hitting on full droop I presume the only thing you can adjust is the pushrod. The damper is the correct length I assume? Mine is 12in on the front for my bec. What length and poundage springs do you have?


The head of the top inner bolt is hitting the chassis under droop on the RHS, it was hitting on both sides before i had repair now its hitting on rhs only.

Im not keen on this so called adjustable suspension, that cant be adjusted, its set to what ever works and no way is it adjustable.


Does your front suspension look like the second photo at the start of the thread? Are we talking about the driver's side?

I would jack up the car and measure the overall length of the shocker from centre to centre of bolts either end. I also presume it's the bolt at the top of the shocker we are talking about hitting the chassis.

You're right that at full droop the rocker arm position will be determined by the open length of the shocker. Adjusting the preload won't effect it. Adjusting the pushrod will alter the height of the chassis from the floor but not the rocker position when at full droop.

Do you have a photo?


Krismc - 5/6/11 at 07:33 AM

quote:
Originally posted by lucy
quote:
Originally posted by Krismc
quote:
Originally posted by lucy
quote:
Originally posted by Krismc
Nope it'd the bolt head that hits chassis ,so unavoidable, I've mention a few times but I keep getting told its my setup, but either way it catches. Unless I preload the spring a lot more so that its more difficult, but still happens when I lift car up!!


Can MNR give you a clue as to what is wrong with your setup?
Which part of the rocker is hitting the chassis?
If it's hitting on full droop I presume the only thing you can adjust is the pushrod. The damper is the correct length I assume? Mine is 12in on the front for my bec. What length and poundage springs do you have?


The head of the top inner bolt is hitting the chassis under droop on the RHS, it was hitting on both sides before i had repair now its hitting on rhs only.

Im not keen on this so called adjustable suspension, that cant be adjusted, its set to what ever works and no way is it adjustable.


Does your front suspension look like the second photo at the start of the thread? Are we talking about the driver's side?

I would jack up the car and measure the overall length of the shocker from centre to centre of bolts either end. I also presume it's the bolt at the top of the shocker we are talking about hitting the chassis.

You're right that at full droop the rocker arm position will be determined by the open length of the shocker. Adjusting the preload won't effect it. Adjusting the pushrod will alter the height of the chassis from the floor but not the rocker position when at full droop.

Do you have a photo?


Definatly got the right shockers and springs, MNR just fitted them few weeks back. ill sort out a picture when im next in garage.


daniel mason - 5/6/11 at 09:23 AM

are your rockers on the right way round kris?


Krismc - 5/6/11 at 02:57 PM

Yip, Every thing is how it should be and all the correct bits and the right way round, MNR reassembled the front end the other week - ive just got it back so going to reassemble the car and noticed it catches- so was concerned!

here are the pics..............



LHS.....



RHS.........


daniel mason - 5/6/11 at 04:07 PM

looks like the pushrods need winding out a bit and suspension adjusting to suit. windind the rods out should give you a bit more clearence! unless the pushrods are actually too short. its hard to tell from the pics.


Johneturbo - 5/6/11 at 05:52 PM

Big Lee, what is the ride height of yours at the rear? i thought i'd set mine up right untill i had it corner weighted by matt at procomp, the rear springs arn't even loose when i jack the rear end up now.

i've also gone to 175lb rear and 125lb front for a bit more complience on the road, its a little bit understeery on roundAbouts, but my fillings are staying in

[Edited on 5/6/11 by Johneturbo]


Krismc - 5/6/11 at 06:38 PM

125lb on front, wow!! my CEC has 250 cant believe you running half!


Krismc - 5/6/11 at 06:42 PM

quote:
Originally posted by daniel mason
looks like the pushrods need winding out a bit and suspension adjusting to suit. windind the rods out should give you a bit more clearence! unless the pushrods are actually too short. its hard to tell from the pics.


Yea, but the spring will always try to push the, damper to full extension and therefore the rocker arm against the chassis in full droop, no matter what the setting.

How much thread/tension do you have on you front springs with the push rods level?

My bloody manual doesnt have the section on setting up the front suspension, well it doesnt have anything for my car really, it might as well be for a differant make..... differant brackets, differant hubs, differant rear end, outboard, bike engined. hmm


Johneturbo - 5/6/11 at 06:47 PM

quote:
Originally posted by Krismc
125lb on front, wow!! my CEC has 250 cant believe you running half!


125lb for a 475kg car 250lb for a 950kg car


Johneturbo - 5/6/11 at 06:52 PM

quote:
Originally posted by Krismc
quote:
Originally posted by daniel mason
looks like the pushrods need winding out a bit and suspension adjusting to suit. windind the rods out should give you a bit more clearence! unless the pushrods are actually too short. its hard to tell from the pics.


Yea, but the spring will always try to push the, damper to full extension and therefore the rocker arm against the chassis in full droop, no matter what the setting.

How much thread/tension do you have on you front springs with the push rods level?

My bloody manual doesnt have the section on setting up the front suspension, well it doesnt have anything for my car really, it might as well be for a differant make..... differant brackets, differant hubs, differant rear end, outboard, bike engined. hmm


The front of mine with the car on the jack will almost hit the chassis, i turned the bolt around so the slimmer head was nearer the chassis, but it would never get that close driving on the road, unless i went 4x4 of roading!


Johneturbo - 5/6/11 at 06:56 PM

quote:
Originally posted by lucy
As marc n said; 1/3 travel in bump
2/3 travel in droop

marc n - I'm struggling to see how the situation will be better when the suspension has settled. The shock length won't change and the spring may shorten making things worse not better (if there is slack in the spring at the moment, that will get worse, or am I missing something?)






I think what marc means is about Big lee's ride height, he's saying its to high so has had to lower the platforms, but over time the springs will sag a little to allow him to raise the platforms

[Edited on 5/6/11 by Johneturbo]


procomp - 6/6/11 at 07:11 PM

Hi

If you are running the STD supplied protechs from MNR fitted to the inboard front end you will suffer all sorts of problems with picking a spring poundage to suit. This is due to the STD supplied protech being way way over valved for the application of inboard use due to the more direct acting nature of the ratio. You can change 50Lb on poundage and not see any real difference to the handling due to the damper being the over riding factor.

Hence we have developed a front end damper and spring package on one of the MNR'S that is running very successful now it's sorted in one the northern spring championships. This has now been fitted to a few road cars also and works very well.

Cheers Matt


daniel mason - 6/6/11 at 07:56 PM

do you have any more info on this matt? and would you be interested in doing a full suspension and geo setting on my mnr once iva'd later this year? thanks


ffrgtm - 8/6/11 at 04:15 PM

So you guys have better valving that taking into account the motion ratios of a pushrod setup.... I'm sitting here a little confused as to how mnr could accidentally valve the shocks for an outboard setup when one of the primary factors when doing valving is the motion ratio itself....

Have anything figured out for the rear? What's your take on that problem?


lucy - 11/6/11 at 10:06 PM

quote:
Originally posted by Johneturbo
quote:
Originally posted by lucy
As marc n said; 1/3 travel in bump
2/3 travel in droop

marc n - I'm struggling to see how the situation will be better when the suspension has settled. The shock length won't change and the spring may shorten making things worse not better (if there is slack in the spring at the moment, that will get worse, or am I missing something?)






I think what marc means is about Big lee's ride height, he's saying its to high so has had to lower the platforms, but over time the springs will sag a little to allow him to raise the platforms

[Edited on 5/6/11 by Johneturbo]



Perhaps I've missed the point here but if the ride height is too high now, it will still be too high if the springs settle and the platforms are raised to compensate.

Lets put it another way. Would shorter shocks and springs make the ride height lower and therefore not too high? Or is that too simplistic?