front coil overs for a 700 lb front end with leading link. help question

[butchvoss]

Im not smart enough to figure out what coil over springs i need to support 700 lbs on front wheel with leading link fork set up. Anyone on the forum able to help me pick a set of coil over springs would be greatly appreciated. Funds are low so please keep that in mind.. thanks all, butch

[irmagoo]

Im not smart enough to figure out what coil over springs i need to support 700 lbs on front wheel with leading link fork set up. Anyone on the forum able to help me pick a set of coil over springs would be greatly appreciated. Funds are low so please keep that in mind.. thanks all, butch

hi butch
to get the right spring rate that you need you first need to know what angle you will be setting them up at... so ok a 100 lb spring is 100 lbs per inch of travel when installed straight up and down the more you angle it the lower the rate the spring rate so if you can tell me what degrees off vertical we can get spring rate you need - spring at 25 degrees off is 100 x .82 = 82 lbs so spring at 45 degrees is 45 degrees off is 100 x .50 = 50lbs per inch of travel .. these rates can be looked up where they sell springs...
mike aka magoo

[butchvoss]

hi butch
to get the right spring rate that you need you first need to know what angel you will be setting them up at... so ok a 100 lb spring is 100 lbs per inch of travel when installed straight up and down the more you angle it the lower the rate the spring rate so if you can tell me what degrees off vertical we can get spring rate you need - spring at 25 degrees off is 100 x .82 = 82 lbs so spring at 45 degrees is 45 degrees off is 100 x .50 = 50lbs per inch of travel .. these rates can be looked up where they sell springs...
mike aka magoo

thanks so much for the help and info.. since i was sick i cant seem to get this stuff all in my mind then on paper. What would you call a set up like this for the shock spring . I am basically coping this setup , This guy was triker don. he passed away a couple years back but lots of info on his page that i copied http://bettertrikes.yolasite.com/resources/Pict0596.jpg .. along with your trees that i just had water jetted . http://i1172.photobucket.com/albums/...psq8zvsudp.jpg

[irmagoo]

thanks so much for the help and info.. since i was sick i cant seem to get this stuff all in my mind then on paper. What would you call a set up like this for the shock spring . I am basically coping this setup , This guy was triker don. he passed away a couple years back but lots of info on his page that i copied http://bettertrikes.yolasite.com/resources/Pict0596.jpg .. along with your trees that i just had water jetted . http://i1172.photobucket.com/albums/...psq8zvsudp.jpg

hi butch
well since the rockers are not tied together (like a springer or leading link)your pivot bolt area will need to be very strongly built as the rockers will try to move independently of one another and could try to twick wheel/tire out of plum sideways on hard bumps,,, I could not get any help from anyone selling coil over shocks they don't get the trike stuff they all said I should talk to bike shock people .
one thing to keep in mind is that car shocks coil springs are 3-3.5 inch or so in diameter.. since I went to 7 inch wide tire- my trees are a little close for 3-3.5 springs. I was going to use QA1 shocks 6" travel was told I could not get shock spring with lower rate than 100 lbs. per inch... so I am trying out some hd shocks - I have since found springs in 10 inch @80 lbs per inch - if I can find them in 10-12 inch I will go to QA1 shocks they are adjustable and 400-600 per set. I
I was going to set them up so that 4" travel shock - with them compressed 1.5" with trike loaded and that would give me 2.5" for compression,,,,
already set my front end up for 12 inch center shocks so I don't want to redo it.. I will have to use 6" travel shocks - 10inch springs
re-welding chrome-moly is not to cool for me!!,,,
best of luck with your project I'm excited for ya!!!
magoo

[butchvoss]

wow good info.. I think im going to tie the rockers to each other as u suggested. Thanks again for your help and info

[Loner]

First, don't read into this until after lunch when you are alert and sharp or, alternately, slightly drunk and dull. Second, I apologize for throwing out a ton of numbers and calculations like this, but simplifying the complex and complicating the simple is what engineering is about.

Often the engineering calculations needed for dynamic applications are somewhat more involved than just a couple of factors. For example, I once went into an in-depth exploration on a mission to have a calculation path to determine the 'most effective' rake and trail for a trike. Starting with a basic set of influencing factors I kept finding layers of secondary and third level factors that would be needed to determine that 'perfect' solution. After listing 18 different factors and extending the formula to a quite complex level, I stopped, although I could foresee another 5 or more factors in the stream to be added. All just to find two base factors: rake degrees and trail distance.

The same is true for determining the 'best' spring load (not addressing 'best' spring rate) for a coil-over spring on your front end design. However, with only a few numbers you can calculate what you are wanting for your springs. So, your planned design photo displays one needed factor - you will be using two springs parallel to each other. If you can provide the dimensions between the three holes in rocker plates (axle, spring mount, downtube/hinge) and the spring angle degrees from vertical, you can yield a good spring load to look for in your setup. Also make sure your anticipated load (the 700 pounds number) on the front end is calculated at the axle point (not at the frame neck). So, gather these numbers:

- Anticipated total load at the front axle
- Number of parallel springs in the design (2 per Triker Don's representative photo)
- Spacing of 3 mount holes in rocker plate
- Angle from perfect vertical of coilover spring

To calculate:

1. Work rocker plate numbers first. With the rear downtube hole be considered the hinge point, the ratio of hinge point to axle hole vs. hinge point to shock hole is your first multiplier factor against final spring load (divide axle hole distance by shock hole distance).
2. Work spring angle next. Subtract spring angle degrees from 90 degrees. Now divide 90 degrees by that first number. That will yield a second multiplier factor against final spring load.
3. Now multiply your 700 pound vertical load times your first multiplier and then that product times your second multiplier.
4. Divide your end answer in number 3 above by the number of springs you will use (likely 2). That will be a close estimate of your spring load needed.

Now comes the 'engineering' part of your design. The final answer may be somewhat high for available candidate springs. You can adjust that final answer quite a bit by varying the hole distances in your rocker plates. By moving the shock mount hole forward you will be reducing the final spring load. Just adjust that measurement in this formula and recalculate to see the effect. You can actually move the spring mount hole forward of the axle hole to lower the spring load requirement to a reasonable range. You can alternately adjust the spring angle to change the final load rate - the nearer to vertical, the lower the spring rate required. This last part of moving and changing the design to get what you think is ideal is what makes engineering such a fun activity.

Gotta go take my meds now, and once I do they will let me out of my straight jacket for 1-hour rec time. It's rough to type on my computer with one hand that I wiggled out the top of my jacket. My life is like NASCAR - go fast, turn left, go fast, turn left - it's just that left turn I have problems with.

[irmagoo]

First, don't read into this until after lunch when you are alert and sharp or, alternately, slightly drunk and dull. Second, I apologize for throwing out a ton of numbers and calculations like this, but simplifying the complex and complicating the simple is what engineering is about.

Often the engineering calculations needed for dynamic applications are somewhat more involved than just a couple of factors. For example, I once went into an in-depth exploration on a mission to have a calculation path to determine the 'most effective' rake and trail for a trike. Starting with a basic set of influencing factors I kept finding layers of secondary and third level factors that would be needed to determine that 'perfect' solution. After listing 18 different factors and extending the formula to a quite complex level, I stopped, although I could foresee another 5 or more factors in the stream to be added. All just to find two base factors: rake degrees and trail distance.

The same is true for determining the 'best' spring load (not addressing 'best' spring rate) for a coil-over spring on your front end design. However, with only a few numbers you can calculate what you are wanting for your springs. So, your planned design photo displays one needed factor - you will be using two springs parallel to each other. If you can provide the dimensions between the three holes in rocker plates (axle, spring mount, downtube/hinge) and the spring angle degrees from vertical, you can yield a good spring load to look for in your setup. Also make sure your anticipated load (the 700 pounds number) on the front end is calculated at the axle point (not at the frame neck). So, gather these numbers:

- Anticipated total load at the front axle
- Number of parallel springs in the design (2 per Triker Don's representative photo)
- Spacing of 3 mount holes in rocker plate
- Angle from perfect vertical of coilover spring

To calculate:

1. Work rocker plate numbers first. With the rear downtube hole be considered the hinge point, the ratio of hinge point to axle hole vs. hinge point to shock hole is your first multiplier factor against final spring load (divide axle hole distance by shock hole distance).
2. Work spring angle next. Subtract spring angle degrees from 90 degrees. Now divide 90 degrees by that first number. That will yield a second multiplier factor against final spring load.
3. Now multiply your 700 pound vertical load times your first multiplier and then that product times your second multiplier.
4. Divide your end answer in number 3 above by the number of springs you will use (likely 2). That will be a close estimate of your spring load needed.

Now comes the 'engineering' part of your design. The final answer may be somewhat high for available candidate springs. You can adjust that final answer quite a bit by varying the hole distances in your rocker plates. By moving the shock mount hole forward you will be reducing the final spring load. Just adjust that measurement in this formula and recalculate to see the effect. You can actually move the spring mount hole forward of the axle hole to lower the spring load requirement to a reasonable range. You can alternately adjust the spring angle to change the final load rate - the nearer to vertical, the lower the spring rate required. This last part of moving and changing the design to get what you think is ideal is what makes engineering such a fun activity.

Gotta go take my meds now, and once I do they will let me out of my straight jacket for 1-hour rec time. It's rough to type on my computer with one hand that I wiggled out the top of my jacket. My life is like NASCAR - go fast, turn left, go fast, turn left - it's just that left turn I have problems with.

my calculator smoked by step #3 !!magoo

[Loner]

I woke up with a headache this morning myself!!

[V-driver]

Im not smart enough to figure out what coil over springs i need to support 700 lbs on front wheel with leading link fork set up. Anyone on the forum able to help me pick a set of coil over springs would be greatly appreciated. Funds are low so please keep that in mind.. thanks all, butch

Here is a link to a shock calculator used for hot rod builders.
http://www.hypercoils.com/spring-calculator


I plugged in the following and got this result:

Corner weight: 750Lbs
Unsprung weight: 25 Lb
Dim. A (distance of pivot point to lower shock mount): 4.5"
Dim. B (distance of pivot point to "lower ball joint", axle in this case: 6")
Spring angle (I estimated 50 degrees from line thru pivot to line thru shock)
Shock ride height (I used 3.5" as 50% of a 7" stroke shock)

Result is 360 Lb/in compression coil spring load rate. Since this is for a 4-wheel vehicle, I'd use 80% of this value on a trike for 288 Lb/in spring rate.

[butchvoss]

Here is a link to a shock calculator used for hot rod builders.
http://www.hypercoils.com/spring-calculator


I plugged in the following and got this result:

Corner weight: 750Lbs
Unsprung weight: 25 Lb
Dim. A (distance of pivot point to lower shock mount): 4.5"
Dim. B (distance of pivot point to "lower ball joint", axle in this case: 6")
Spring angle (I estimated 50 degrees from line thru pivot to line thru shock)
Shock ride height (I used 3.5" as 50% of a 7" stroke shock)

Result is 360 Lb/in compression coil spring load rate. Since this is for a 4-wheel vehicle, I'd use 80% of this value on a trike for 288 Lb/in spring rate.

Thanks so much

[butchvoss]

I have to two ready. I welded in the bushings for the rockers and my buddy milled the slots yesterday. Now waiting for my 25 mm axle for the Harley wheel .. Should be ready to start testing the spring shock in a week or so.. That is the scary part .lol

[irmagoo]

Here is a link to a shock calculator used for hot rod builders.

http://www.hypercoils.com/spring-calculator

I plugged in the following and got this result:

Corner weight: 750Lbs

Unsprung weight: 25 Lb

Dim. A (distance of pivot point to lower shock mount): 4.5"

Dim. B (distance of pivot point to "lower ball joint", axle in this case: 6")

Spring angle (I estimated 50 degrees from line thru pivot to line thru shock)

Shock ride height (I used 3.5" as 50% of a 7" stroke shock)

Result is 360 Lb/in compression coil spring load rate. Since this is for a 4-wheel vehicle, I'd use 80% of this value on a trike for 288 Lb/in spring rate.

that's some cool calculation tool for sure!!

just wondering since there are two shocks on trike front end like mine use half the spring rate calculation?? also food for thought if 100 lb per inch spring mounted straight up is compressed 2 inch that should be 200 lbs preload on spring or 400 on 2 springs??? if that is true then I think that my static compression preload should come into this somehow? I want to have 1.5 inch spring compression minimum on mine and have minimum of 2.5 spring compression after that to suck up the road lumps and bumps and pot holes

on my trike front end weight is 550 lbs. loaded

so to compress 2 - 100 lbs. per inch springs mounted straight up 2.75" should take 550 lbs.

right ? so then would I need 6 inch travel shock to cover my requirements and get at least 2.5 inch compression before it hits the stop-bumpers? just wondering if this is flawed thinking on not

I know my shocks wont be straight up and down but this is just for checking my think'n or lack of it ???

magoo

[butchvoss]

they have some VW dune buggy coil overs on ebay for 90 bucks that are 200 lbs. Im thinking of trying them.

[butchvoss]

Ive got a question for you all. I have a 25 mm shaft and want to machine it to a fine thread nut to fit it . Any one know what size metric nut that i can buy to fit a 25 mm Od shaft. The old timer that is going to cut threads for me is not sure of the metric nut and i do not have a clue. thanks all

[vwbug72501]

I ran into this problem when I built my front end. I have metric forks with a Harley V-Rod front wheel. Harley (at least in 2003 for my wheel) is SAE. They use a 1" dia. axle that is really 25.4 mm. They also use (bless their hearts) Harley specific bearings (read non-standard, Harley Only). Can't just swap out the bearings. I ended up building a sleeve with a 1" OD and an ID to match the axle for the forks.

I would think going with an SAE thread that has appropriate thread depth in this application would work. Unless, of course, you want the build to be all metric.

[irmagoo]

butch

can your guy cut metric threads/ if so 25mm nut or you can reduce the shaft at ends to a size that you can get nuts for (example- 3/4 fine) what ever or if your buddy can cut threads on lath you can make your nuts also,,, I cut 24 thread per inch on my stem for trees and a nut for it I think a 1" nut in 24 per inch uses .987 shaft size in thread area would have to do the math -your 25mm is .984-a little loose for a 1" nut . for my axle I drilled and taped each end and will use studs and castle nuts - you have a few options

magoo

[butchvoss]

butch

. for my axle I drilled and taped each end and will use studs and castle nuts - you have a few options

magoo

I did that on the electric trikes i built in FL on the real axle hubs. Worked great , i will also do that on this application, I totally forgot i did that .lol. thanks .

[irmagoo]

I did that on the electric trikes i built in FL on the real axle hubs. Worked great , i will also do that on this application, I totally forgot i did that .lol. thanks .

I'm with ya butch

between with I've forgot and what I've screwed up can't remember getting anything right!!

magoo

[butchvoss]

I'm with ya butch

between with I've forgot and what I've screwed up can't remember getting anything right!!

magoo

Between getting sick a few years back and old age im lucky i can remember to wake up .

[irmagoo]

butch I like you have shock that I'm going to try for a while,,, but if I don't like the ride heres what I will be buying QA1 #US402 with 10" 115 lbs. springs $399.00 for it all at speedway, this will work for your front end also in my opinion- this combination will compress approx. 1&1/2 inch with my 500-550 lbs front weight,,,-your 700 lbs should compress 2" or a little more with that weight. will have 4 inch left for compression to soaking up the ruff roads!!! just something we can put in our memory bank to consider the possible future events...
magoo