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Login to post Forums » Grassroots Motorsports » Motorcycle Shock discussion (from EMOD V12 MGB thread)

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May 19, 2011 12:01 p.m. nocones HalfDork

nocones wrote:

I'm running motorcycle shocks on the MG project (I say running but more acurately should say parking). I've not had the pleasure to drive it, however It will weigh in the 1500lb range with driver so I'm on the bubble for 4x MC rear wheel load area. that said they may work ok for you Civic Dave as you probably will be installing them with a MR that is low enough that their spring rate remains high. Mine are installed at ~2.5hz (E/Dmod car) so I'm using a wheel rate of ~400lbs out of a shock that has a spring rate of 800lbs. I get ~3" total travel out of the suspension. Things to remember when using MC shocks. Unmodified they are short stroke (~2" for most), High spring rate (600-800lbs), and have lots of pre-load (My R1 shocks have ~150lbs minimum pre-load which works for me as I need to maximize shock travel for my desired spring rate). If you can install them at a MR that works for your application then they are pretty well damped shocks that a VERY cheap and quite adjustable. My front shocks are CBR600F4i shocks and even have remote resivoirs. Dave whats your wheel rate target (in HZ) and what are your front and rear corner weights? That information can tell you if they will be suitable.

alfadriver wrote:

In reply to nocones:

Sorry about the tangent, and perhaps a separate thread is needed. BUT- that's some great info there, nocones. Are there any web pages that outline MC shocks, stroke, and stock dampening rate?

edit- there is a webpage that does calculate geometry rates, BTW. Not sure what specific infomation is needed, and if the calculations will produce that or not....

I've been toying with the idea of a 2000lb car with inexpensive shocks, 500-700lb spring rates in the front, 300-500 lb in the back. Heavier than a Locost, lighter than the Pink Panther.

I'd love to make said car a GRM challenge car that's capable of winning at a national Solo event....

tuna55 wrote:

Let's just say "me too" except replace this: "I'd love to make said car a GRM challenge car that's capable of winning at a national Solo event...." with this: "I'd love to make said car a GRM challenge car that's capable of driving to work every once in a while and running tens pretty much at will...."

New Thread to discuss the wonderful cheap decent shocks.

In reply to Alfa, I've seen websites mostly dedicated to Motorcycle use of these shocks that do sumarize the spring rates and travel. I'll look for one tonight, I've seen them linked on locostusa.com forums before. I've not seen alot of information about pre-load on these other than the adjustment method.

Calculations are the same as other springs WR=SR/MR^2 where SR=spring rate, WR=wheel rate, and MR is the Wheel travel/shock travel (oh noes I hope this doesn't cause one of those damn 288 problems).

As I said the SR's are high on these for the most part so the short stroke isn't terrible however they are really only suitable (IMHO) at corner weights of 500-600lbs max to get a decent natural frequency at the wheel (say 1.5-2.5 hz). Some of them have Very high spring rates and longer strokes (here's looking at you Hyabusa shock) so they may extend that range of allowable corner weight.

I'll look tonight when I get home for some of the information I compiled when I was determining if I could use them. My MG will have a suspension frequency of 2.4-3.6hz adjustable at the front(slightly lower in the back 2.0-3.0hz) That is assuing I get the car's corner weights to my estimated 1600lb gross weight. I know some members of this forum have played with these in the past so I'm up for having some discussions and sharing my knowledge and I'm 100% sure I will learn from others as well.

I've so far designed 3 supespensions from the ground up so have a good knowledge of the basics, although not the most practicle experience so would love to learn more from people that have the experience.
May 19, 2011 12:24 p.m. loosecannon Reader

Ok, I'll add my 2 cents. I am using 2007 Yamaha R1 shocks on all 4 corners of my EMod car. It weighs 2300 lbs with me in it and the shocks are hooked to rocker arms that allow adjustment of motion ratios. I have only had the car at one autocross event and the handling was amazing. The shocks are set at full soft for high/low speed compression, rebound and spring preload. The current motion ratio front and rear is 1.42:1 and the suspension frequency is around 2.4 Hz front and back. From what I have found, the spring rate on the springs is 525 lb/in.
May 19, 2011 12:46 p.m. alfadriver SuperDork

Not sure how much this helps- but here's a spreadsheet of the car I speak of:

http://www.fatcatmotorsports.com/FRC_TUTORIAL/FCM_MSDS_TUTORIAL.htm

Yea, it's the Answer.

Basically, the wheel size article in the recent GRM started a cost/value argument about all of the CSP mods, and that the guys who are at the front are very adamant about having to spend thousdands on each of the major go fast parts- particularly the shocks, diff, and ECU. I was on the article size arguing about cost vs improvement value, when it kind of got out of hand...

But the end was me considering how to make a Challenge able Miata be the best that it can possibly be, perhaps even being able to be competetive on a national basis.

So how that relates to this thread- the shocks. I can find springs- particularly, long coil overs that can be cut- stock car places have an awesome selection that it takes just some math to cut and make 14" springs into 7" coil overs (plus some minor fab). But shocks to match that is still proving to be an issue. Which is why it's making me ask the questions I'm asking here.

I've seen suggestions from 500/300 up to 700/4(something), and springs are a non issue to try a bunch. Since they are $65 apice, and one can be cut for 2 corners, well.... Just need to find shocks to match. On a major budget.

using the above range, figure 2- 2.4Hz front, 1.85-2.1 Hz rear. Roughly 500-540lb/corner front, ~500lb/corner rear.

does that help?
May 19, 2011 7:59 p.m. ditchdigger HalfDork

I apologize for the terrible sharing service but here is a spreadsheet with MC shock stroke lengths. I have no other way of hosting non picture files.

http://www.4shared.com/file/zzpJKSNa/shock_length_chart1.html

I am planning my suspension around bike pieces as well.
May 19, 2011 8:08 p.m. Toyman01 SuperDork

The Abomination is running R1 shocks on all four corners. I'm not sure about the spring rates, but I sure Curmudgeon will be by shortly. He built it, he knows. I have been real happy with how it handles. Happy enough that I haven't messed with the adjustments on them and probably won't until something fails.
May 19, 2011 8:26 p.m. alfadriver SuperDork

ditchdigger wrote:

I apologize for the terrible sharing service but here is a spreadsheet with MC shock stroke lengths. I have no other way of hosting non picture files.

http://www.4shared.com/file/zzpJKSNa/shock_length_chart1.html

I am planning my suspension around bike pieces as well.

Good info, but it appears that the shocks will be too short for a Miata....

And I wish I could figure what spring rates those work with..... Getting close, I think. (in theory)
May 19, 2011 9:00 p.m. Curmudgeon SuperDork

Toyman01 wrote:

The Abomination is running R1 shocks on all four corners. I'm not sure about the spring rates, but I sure Curmudgeon will be by shortly. He built it, he knows. I have been real happy with how it handles. Happy enough that I haven't messed with the adjustments on them and probably won't until something fails.

I'd tell you but then I'd have to kill you. Or, you could just look at the Eibach springs on them and read da numbers. I crunched the freq numbers etc and that's how I wound up with the springs that are on that car. Damn if I know where my notes are, though. I used 2.25" ID springs.

That car has the earlier (2001-2003) R1 shocks. They have the reservoir in line with the shock body which made them much easier to install and like loosecannon said they have lots of damping adjustments, both compression and rebound. The R6 shock is almost exactly the same length, but the reservoirs are at 90 degrees to the shock body making them difficult to use in a direct mount application like the Abomination. If you are using a pushrod setup, that won't be a problem.

The Honda shocks with the remote reservoir, such as the CBR600 shock, has less travel than either of the Yamaha shocks meaning for the same amount of travel it has to be mounted closer to the inner control arm pivot point, meaning really stiff springs, plus it has a cone shaped spring making it difficult to go anywhere other than a bike shop for replacement springs. From personal experience, bike springs are MUCH more expensive than Eibachs etc.
May 19, 2011 9:13 p.m. MrJoshua SuperDork

alfadriver wrote:

ditchdigger wrote:

I apologize for the terrible sharing service but here is a spreadsheet with MC shock stroke lengths. I have no other way of hosting non picture files.

http://www.4shared.com/file/zzpJKSNa/shock_length_chart1.html

I am planning my suspension around bike pieces as well.

Good info, but it appears that the shocks will be too short for a Miata....

And I wish I could figure what spring rates those work with..... Getting close, I think. (in theory)

Using the r1 shock bolt mount, drilling out the Miata top mount to a slightly larger diameter, and making a new bushing for the bottom mount lets them bolt right into the Miata rear shock position and pretty much retains stock ride height. I made a pedestal to mount them in the front of my Miata in '08 but the clearance through the a-arm was so minimal that I think the arm was pretty much riding on the coil. It still was a great finishing autocrosser with crap tires and massive tuning issues.
May 19, 2011 9:26 p.m. nderwater Dork

alfadriver wrote:

The wheel size article in the recent GRM started a cost/value argument about all of the CSP mods, and that the guys who are at the front are very adamant about having to spend thousdands on each of the major go fast parts- particularly the shocks, diff, and ECU. I was arguing about cost vs improvement value, when it kind of got out of hand...

You kicked up quite the E36M3 storm in that thread. When you told those autocross champions "That's a lot of money to spend... Hope those jackets you are winning are honestly worth it" I about choked.
May 20, 2011 5:14 p.m. alfadriver SuperDork

nderwater wrote:

alfadriver wrote:

The wheel size article in the recent GRM started a cost/value argument about all of the CSP mods, and that the guys who are at the front are very adamant about having to spend thousdands on each of the major go fast parts- particularly the shocks, diff, and ECU. I was arguing about cost vs improvement value, when it kind of got out of hand...

You kicked up quite the E36M3 storm in that thread. When you told those autocross champions "That's a lot of money to spend... Hope those jackets you are winning are honestly worth it" I about choked.

Wow- just a bunch of typing, and boom- have to do it all over again... oh, well.

Anway, as I typed a few min ago... Almost couldn't be helped. Based on the article pointing out that "gotta be faster" parts are not always faster parts, I posted that nobody had come up with a good budget set up that would be competetive, but not win, at nationals. The reply was- of course we haven't. And then I asked what cost vs time were each part- and that reply was basically - worth it- see my jacket(s). And I got snarky after that.

I get the idea that few have any idea how much time they are gaining by installing all of those parts. Which made me think of the key components that are the big $$$- the diff, engine and shocks. And is it possible to come up with a car that will be cometetive at nationals (which I'll honestly never find out) AND be challenge legal?

So....

All that from an article that showed the heavier tire + narrower tires were faster than the opposite, more expensive set up.
May 20, 2011 5:16 p.m. alfadriver SuperDork

MrJoshua wrote:

alfadriver wrote:

ditchdigger wrote:

I apologize for the terrible sharing service but here is a spreadsheet with MC shock stroke lengths. I have no other way of hosting non picture files.

http://www.4shared.com/file/zzpJKSNa/shock_length_chart1.html

I am planning my suspension around bike pieces as well.

Good info, but it appears that the shocks will be too short for a Miata....

And I wish I could figure what spring rates those work with..... Getting close, I think. (in theory)

Using the r1 shock bolt mount, drilling out the Miata top mount to a slightly larger diameter, and making a new bushing for the bottom mount lets them bolt right into the Miata rear shock position and pretty much retains stock ride height. I made a pedestal to mount them in the front of my Miata in '08 but the clearance through the a-arm was so minimal that I think the arm was pretty much riding on the coil. It still was a great finishing autocrosser with crap tires and massive tuning issues.

How long are the front and rear's on the Miata?

And on your car, it wasn't hard to deal with the travel that is capable on the MC shocks?

I like the idea of the R1's, they are pretty cheap on e-bay.
May 20, 2011 5:21 p.m. 92CelicaHalfTrac SuperDork

nderwater wrote:

alfadriver wrote:

The wheel size article in the recent GRM started a cost/value argument about all of the CSP mods, and that the guys who are at the front are very adamant about having to spend thousdands on each of the major go fast parts- particularly the shocks, diff, and ECU. I was arguing about cost vs improvement value, when it kind of got out of hand...

You kicked up quite the E36M3 storm in that thread. When you told those autocross champions "That's a lot of money to spend... Hope those jackets you are winning are honestly worth it" I about choked.

Link? That sort of stuff interests me, and not just because of the E36 M3 storm.
May 20, 2011 5:43 p.m. MrJoshua SuperDork

In reply to alfadriver: I don't have the info on stock Miata shock length readily available, but I would bet it is easy to find. The front shock is the weirdo on the Miata. Because the shock goes through the upper a-arm the body is really long in relation to the shaft and travel and the spring mount is almost to the top of the body (above the a-arm). They also require higher spring rates than most cheapo shocks handle on a regular basis. I would think you could piece together a pretty good setup out of a circle track catalog. If nothing is readily available it seems like you could cut down the shaft length and cut new threads to keep the shock in the middle of its travel at competition ride heights. The talk of frequencies and all that is beyond my knowledge level so the above is all I can really offer.
May 20, 2011 5:43 p.m. Maroon92 SuperDork

92CelicaHalfTrac wrote:

nderwater wrote:

alfadriver wrote:

The wheel size article in the recent GRM started a cost/value argument about all of the CSP mods, and that the guys who are at the front are very adamant about having to spend thousdands on each of the major go fast parts- particularly the shocks, diff, and ECU. I was arguing about cost vs improvement value, when it kind of got out of hand...

You kicked up quite the E36M3 storm in that thread. When you told those autocross champions "That's a lot of money to spend... Hope those jackets you are winning are honestly worth it" I about choked.

Link? That sort of stuff interests me, and not just because of the E36 M3 storm.

I also want to read it...though admittedly mostly because of the E36 M3 storm.
May 20, 2011 7:16 p.m. alfadriver SuperDork

MrJoshua wrote:

In reply to alfadriver: I don't have the info on stock Miata shock length readily available, but I would bet it is easy to find. The front shock is the weirdo on the Miata. Because the shock goes through the upper a-arm the body is really long in relation to the shaft and travel and the spring mount is almost to the top of the body (above the a-arm). They also require higher spring rates than most cheapo shocks handle on a regular basis. I would think you could piece together a pretty good setup out of a circle track catalog. If nothing is readily available it seems like you could cut down the shaft length and cut new threads to keep the shock in the middle of its travel at competition ride heights. The talk of frequencies and all that is beyond my knowledge level so the above is all I can really offer.

It's been a while since I've looked under my car, but I think I know what you are talking about. The issue being finding a set up where the top has space taken up via a resivoir, so you need a short spring.

Springs are not an issue- stockcarproducts has a whole slew of 2.5" springs, and it's not hard to make one out of 2- since they have some at 14", just takes a little bit of some adapting for the "open" end.

And if I called them, and gave them a spring and wheel rate range, they'd be able to put something together- especially with the various lenght shocks they have. But before doing that, I wanted to look into the MC shocks based on the Pink Panther. Which is why I asked.
May 20, 2011 7:19 p.m. alfadriver SuperDork

Maroon92 wrote:

92CelicaHalfTrac wrote:

nderwater wrote:

alfadriver wrote:

The wheel size article in the recent GRM started a cost/value argument about all of the CSP mods, and that the guys who are at the front are very adamant about having to spend thousdands on each of the major go fast parts- particularly the shocks, diff, and ECU. I was arguing about cost vs improvement value, when it kind of got out of hand...

You kicked up quite the E36M3 storm in that thread. When you told those autocross champions "That's a lot of money to spend... Hope those jackets you are winning are honestly worth it" I about choked.

Link? That sort of stuff interests me, and not just because of the E36 M3 storm.

I also want to read it...though admittedly mostly because of the E36 M3 storm.

You guys like train wrecks?

Miata.net, autocross section, the thread about wheel/tire weight. A guy got so offended by me that he even posted my name.

Others piled on, not knowing what I really meant. But a few knew what I was talking about.
May 20, 2011 8:00 p.m. 93EXCivic SuperDork

This thread should be very useful soon.
May 20, 2011 8:05 p.m. alfadriver SuperDork

Another question- what are the units for MC springs??

It's suggested to be kg/mm (which drives me nuts as an engineer, since kg is a mass and not a force, but that's for the off topic area...). And I'm seeing springs .9-1.2's, and if it's kg/mm, I'm calculating a 500lb spring to be about 9kg/mm. That sure seems like a big change.... Thus implying that I'm wrong somewhere...
May 20, 2011 9:41 p.m. Teh E36 M3 HalfDork

I'm pretty sure the R1 springs are about 500-525lb/in. I'm only "pretty" sure because that was the big pain in the ass of my ME degree. Springs are difficult to measure properly because the inactive coil isn't always perfect.

The good thing is that 7" 2.25 ID springs fit, and you can get a pretty good range from eibach or other sources. The Midget is running 350lb/in eibach's on R1 shocks.
May 20, 2011 9:54 p.m. Teh E36 M3 HalfDork

Hoosh. I tried to read that thread. Even got to the bottom of the third page. Then I realized that I didn't give a E36 M3.
May 21, 2011 11:29 a.m. alfadriver SuperDork

One other MC question- are there any decent non- resivior units? May be easier to fit something like that in a Miata, at least in the front.

To other challengers- anyone notice that we are working on a killer budget set up for you?

It's intentional.

Another interesting tangent- this work is sort of finding me some good alternatives for an Alfa. Funny how that works.
May 21, 2011 11:29 a.m. alfadriver SuperDork

Teh E36 M3 wrote:

I'm pretty sure the R1 springs are about 500-525lb/in. I'm only "pretty" sure because that was the big pain in the ass of my ME degree. Springs are difficult to measure properly because the inactive coil isn't always perfect.

The good thing is that 7" 2.25 ID springs fit, and you can get a pretty good range from eibach or other sources. The Midget is running 350lb/in eibach's on R1 shocks.

Any idea what units 1.1 would be, then? If I knew what that meant, there are other ones out there that would fit.
May 21, 2011 11:37 a.m. 93EXCivic SuperDork

alfadriver wrote:

One other MC question- are there any decent non- resivior units? May be easier to fit something like that in a Miata, at least in the front.

To other challengers- anyone notice that we are working on a killer budget set up for you?

It's intentional.

Another interesting tangent- this work is sort of finding me some good alternatives for an Alfa. Funny how that works.

I am noticing. Go go Spitfire. It should be prefect for this.
May 21, 2011 3:10 p.m. MrJoshua SuperDork

It will be very hard to use any of the motorcycle shocks up front because of having very little clearance to put the spring through the upper a-arm. I think you are most likely stuck with circle track on that one. Here is a pic of the front setup I used in '08:

You can't see it really well, but the clearance is less than 1/4" in several places. The vertical reservoir version doesn't work because it hits the top a-arm with minimal travel, and the horizontal reservoir one required a 1/4" wheel spacer to avoid contacting 4" backspace 13x8 diamonds with 225/45/13 hoosiers.

Here is a pic of the rear shock on my setup:
May 21, 2011 3:41 p.m. 93EXCivic SuperDork

The Spitfire uses the rear leaf spring. Could I remove the springs from motorcycle shocks for use on the rear?

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