533 replies to this topic

[JohnTurbo]

- What I meant is Im forced to run really low just so it doesn't run permanent topped out.

 

I would want the ride height 10-20mm higher.

[alexb]

Ah, you made one already!! Can be made a bit more tidy and made stronger with some welded side plates, but this does the job.

(not sure on clearances there, but can you not rotate the hose to the subframe side for better wheel clearance? And as the shock is on an angle, maybe the new bottom hole has to be slightly more out than the top one. But that's just minor tweaking.)

 

 

And hate to stir in this pot again, but longer dampers is probably only half of the solution, as this new found droop travel can only be used with sufficient spring load. (I do assume people want to keep their current ride height...)

So the spring perch will have to be set higher and without quite soft springs or helpers, the spring can become loose at full droop.

For me no problem, but it has to be considered of when you decide to lengthen your shocks... 

 

 

Keeping same ride height with longer dampers will mean you get less preload. At least with my 350 lbs/inch springs. To calculate max springrate at which you still can get 125 mm ride height (as I measured it on my car!): my 125 mm ride height corresponds with 373 mm at the damper. If the damper is 420 mm, so 25 mm longer than my current damper length, you need to compress the spring 47 mm, or 1.85". The sprung weight at a rear corner is about 260 kgs (Scuffers has some good data, but I can't find it anymore, so this from the top of my head), or 575 lbs. That means fitted rate of the spring to get to that level is 575/1.85 is about 310 lbs/inch. Multiply by leverage (1.35) to get spring rate: 420 lbs/inch. Theoretically and assuming I didn't make a mistake, with a 420 lbs/inch spring and a 420 mm damper you end up at a ride height of 125 mm (my car). Anything above that and you have to close a gap.

 

I wonder why you don't have big aluminium washers to close that gap. There is nothing really against that and in most cases the gap is small anyhow. Washer at the bottom so that it doesn't move I mean.  

[Scuffers]

I wonder why you don't have big aluminium washers to close that gap. There is nothing really against that and in most cases the gap is small anyhow. Washer at the bottom so that it doesn't move I mean.

 

 

err...

 

if you have negative spring pre-load, filling the spring gap with a solid 'washer' is just the same as closing the gap by adjusting the spring collar.... ie, you have just raised the ride height.

 

you are right about the point of zero pre-load, this goes back to the fundamentals of how you sped your suspension...

 

unless you built them to run at a very specific ride height, you will always be into this one way or another.

 

this is why using single rate plain springs on an adjustable platform is hard work, and hence why using either progressive springs or tenderd/helpers is the preferred route as you can then have a height adjustable setup over a reasonable range without compromising the total travel etc.

 

Traditionally, one of the issues with aftermarket shocks was they had limited stroke, and with plain springs had to be closely matched with the intended ride height, this meant that you had to be very specific about what right height you wanted with little option to change it.

[Exmantaa]

My head hurts, but that sounds about right.

260kg/575lbs rear sprung weight gives you 775lbs force on the spring, so divide by your needed 1.85" static compression is a 420Lb spring. anything aboove that needs helpers to keep the spring seated.

(Washers will not help to fill the gap, as solid discs have "infinite spring rate"  and so you will need to raise the spring collar upwards  to get your static ride height back...)

 

I just fitted mine with 600lb springs + 300lb helpers (on 427mm NTR's), but it will not go that low. will measure) Also found that the longer & higher spring combo rubbed my subframe at a certain point. (Think the 46 Nitrons have/had a similar problem?) I fixed that with some fine tooling. (= big hammer + wood block.  ) 

 

Your crude lowering brackets may not be so bad at all, as these will keep the springs in a lower position with less subframe problems and also you can mount the shock a little more outboard...

[Rosssco]

 

I wonder why you don't have big aluminium washers to close that gap. There is nothing really against that and in most cases the gap is small anyhow. Washer at the bottom so that it doesn't move I mean.

 

 

 

this is why using single rate plain springs on an adjustable platform is hard work, and hence why using either progressive springs or tenderd/helpers is the preferred route as you can then have a height adjustable setup over a reasonable range without compromising the total travel etc.

 

Traditionally, one of the issues with aftermarket shocks was they had limited stroke, and with plain springs had to be closely matched with the intended ride height, this meant that you had to be very specific about what right height you wanted with little option to change it.

 

 

Do you know anyone who sells progressive springs (2.25") Simon, in a similar fashion to linear race coils with a variety of spring lengths and capacities? Or are they typically application-specific, where by you'd spec and order a batch to suit a specific damper? I realise the damping curves have to be matched, but wondered if there was scope to 'play' with these in a similar fashion to swapping linear springs to suit different uses, tracks etc.

[alexb]

 

I wonder why you don't have big aluminium washers to close that gap. There is nothing really against that and in most cases the gap is small anyhow. Washer at the bottom so that it doesn't move I mean.

 

 

err...

 

if you have negative spring pre-load, filling the spring gap with a solid 'washer' is just the same as closing the gap by adjusting the spring collar.... ie, you have just raised the ride height.

 

 

 

Jesuz wept, I feel stupid. I stand corrected ...  

[alexb]

 

Your crude lowering brackets may not be so bad at all, as these will keep the springs in a lower position with less subframe problems and also you can mount the shock a little more outboard...

 

You haven't seen the latest version. A work of art Hope to fit them this week, just so that I can set up the car correctly with about 40%/60% bump/droop, less preload and 125 mm ride height. And see if these brackets survive.

[Scuffers]

 

 

Do you know anyone who sells progressive springs (2.25") Simon, in a similar fashion to linear race coils with a variety of spring lengths and capacities? Or are they typically application-specific, where by you'd spec and order a batch to suit a specific damper? I realise the damping curves have to be matched, but wondered if there was scope to 'play' with these in a similar fashion to swapping linear springs to suit different uses, tracks etc.

 

That's not the issue, plenty of people will make them, the hard part is knowing what to ask them to make.

 

it's not just the start/finish rates, it;s where the transition starts, for how long, etc then consider what's physically possible to make.

 

 

 

 

Your crude lowering brackets may not be so bad at all, as these will keep the springs in a lower position with less subframe problems and also you can mount the shock a little more outboard...

 

You haven't seen the latest version. A work of art   Hope to fit them this week, just so that I can set up the car correctly with about 40%/60% bump/droop, less preload and 125 mm ride height. And see if these brackets survive.

 

PLEASE don't go this route, it's scary as hell watching from here...

 

please consider yours (and others) safety, the instantaneous loads on said bracket are in the 10,000+N range.....

[VXT Tim]

Aren't the OE front brackets held on by 2 very small bolts? I found it quite scary when I replaced them. Ignorance bliss in this case?

Edited by VXT Tim, 29 July 2013 - 01:08 PM.

[Scuffers]

Aren't the OE front brackets held on by 2 very small bolts? I found it quite scary when I replaced them. Ignorance bliss in this case?

Yes, but what's that got to do with it?

 

lookup the spec's for an M8 graded bolt, then consider how it's loaded in the design, and then consider the loads place upon them.

 

 

your also kind of ignoring the load paths here....

[VXT Tim]

 

Aren't the OE front brackets held on by 2 very small bolts? I found it quite scary when I replaced them. Ignorance bliss in this case?

Yes, but what's that got to do with it?

 

lookup the spec's for an M8 graded bolt, then consider how it's loaded in the design, and then consider the loads place upon them.

 

 

your also kind of ignoring the load paths here....

 

 

 

Nothing, this thread is so far off track, I felt like voicing a mildly related initial concern.

 

It's clearly fit for purpose and am aware of the direction of load, i was initially very surprised that's all.

 

 

I can see why you thought my post was in someway related having re read it, apologies.

Edited by VXT Tim, 29 July 2013 - 01:47 PM.

[alexb]

 

 

 

Do you know anyone who sells progressive springs (2.25") Simon, in a similar fashion to linear race coils with a variety of spring lengths and capacities? Or are they typically application-specific, where by you'd spec and order a batch to suit a specific damper? I realise the damping curves have to be matched, but wondered if there was scope to 'play' with these in a similar fashion to swapping linear springs to suit different uses, tracks etc.

 

That's not the issue, plenty of people will make them, the hard part is knowing what to ask them to make.

 

it's not just the start/finish rates, it;s where the transition starts, for how long, etc then consider what's physically possible to make.

 

 

 

 

Your crude lowering brackets may not be so bad at all, as these will keep the springs in a lower position with less subframe problems and also you can mount the shock a little more outboard...

 

You haven't seen the latest version. A work of art   Hope to fit them this week, just so that I can set up the car correctly with about 40%/60% bump/droop, less preload and 125 mm ride height. And see if these brackets survive.

 

PLEASE don't go this route, it's scary as hell watching from here...

 

please consider yours (and others) safety, the instantaneous loads on said bracket are in the 10,000+N range.....

 

 

So what's the fun if not trying? OK, you convinced me not to. Next time please react a little faster, could have saved me a couple of hours with the angular grinder Kidding aside, thanks for the advice. Is there a way to bring the mounting points down (or up at the bottom) without risking life and limb? And not doing any irreversible things with the subframe or lower wishbone.  

[chris_uk]

Whats wrong with using his brackets scuffs? Surely they are only the same as the nitron ones or gaz ones which are a little wider to allow the body to fit in.. Or was it an issue with the materials? Or the lack of support in the bracket?

[CocoPops]

I think it's down to loadings and sheer forces by moving the pivot points etc?

[FLD]

IMO (and I'm no engineer) the new bracket buts sheet metal, albeit a short length, in compression.  Sheet meteal is best under tension as under compression it tends to buckle.  This could be solved by having the 'anti rotation bolt' into the subframe below the new damper mounting point but that would involve adding an anchor point to the subframe (which itself opens up a new debate).

[chris_uk]

It might just be as detrimental as cutting the fuel pump access hole bigger!

Edited by chris_uk, 29 July 2013 - 02:51 PM.

[Scuffers]

 

So what's the fun if not trying? OK, you convinced me not to. Next time please react a little faster, could have saved me a couple of hours with the angular grinder   Kidding aside, thanks for the advice. Is there a way to bring the mounting points down (or up at the bottom) without risking life and limb? And not doing any irreversible things with the subframe or lower wishbone.

 

Sorry, I only read stuff every so often.... don't assume that I have seen something and my non-comment means I approve..

 

 

Whats wrong with using his brackets scuffs? Surely they are only the same as the nitron ones or gaz ones which are a little wider to allow the body to fit in.. Or was it an issue with the materials? Or the lack of support in the bracket?

 

Not the same thing, changing the OEM brackets is fine (assuming they are designed and made right), the issue here is that your adding a fulcrum point to the load path, bit like putting a pivot joint into a walking stick.

 

I think it's down to loadings and sheer forces by moving the pivot points etc?

exactly...

 

 

the easy/simple/safe way to solve this issue is to have the dampers made longer!

 

cheapest way to change the dampers length is to make a new end eye, these just thread onto the end of the damper shaft so easy to change.

 

if I was making new dampers, I would make the body long enough to support ~100mm stroke, then make up the length with an extended end cap, as this also serves to keep the spring platform away from the top mount, as being as close in as they are, with 2.25" springs, they can foul the sub-frame if too high up the damper.

 

[Exmantaa]

 

Aren't the OE front brackets held on by 2 very small bolts? I found it quite scary when I replaced them. Ignorance bliss in this case?

Yes, but what's that got to do with it?

 

lookup the spec's for an M8 graded bolt, then consider how it's loaded in the design, and then consider the loads place upon them.

 

 

your also kind of ignoring the load paths here....

 

 

Std front bracket atachment is not the brightest of designs, as I found a few (if not all) buckled out out a bit at the bolt points. I normally fit them with 2 big steel washers either side to spread the loads. (after I straighthened them with a hammer first...  )

 

Indeed the loads are big on those attachment points, but if PROPER designed, such rear bracket can work OK. But a longer shock is better...

[Mike (Cliffie)]

Optimum ride heights on the standard car are a point of debate and I am amazed they haven't been discussed in more detail.

 

The wishbone angles suffered on the standard set up at anything below 110 front 120 rear are a major factor to consider.

[Exmantaa]

 ................................. 

 

the easy/simple/safe way to solve this issue is to have the dampers made longer!

 

cheapest way to change the dampers length is to make a new end eye, these just thread onto the end of the damper shaft so easy to change.

 

if I was making new dampers, I would make the body long enough to support ~100mm stroke, then make up the length with an extended end cap, as this also serves to keep the spring platform away from the top mount, as being as close in as they are, with 2.25" springs, they can foul the sub-frame if too high up the damper.

 

 

 

 

Nothing to add here and my longer dampers indeed fouled the subframe with their 2.25 helper springs...   

 

Only wished that Nitron or others had looked into this properly some years ago when they designed this...