Springer front forks

[grandpanystrom61]

Good day to everyone, well I have this set of forks off the trike.

They are heavy for the size and should be if solid bars of metal were used in making them.

The neck stem is 3/4" dia. and much longer than the neck tube, which is only 7" long.

The main fork is 1 1/4" dia. and the spring fork is 3/4" dia., and the lower tree and spring fork are welded to the main fork.

Lower bearing is worn and thrashed, the lower inner race is also worn with a lip/groove on the back edge, guess if I could look at the front edge it would have offsetting wear, or should have it.

Here are some pics.





when the forks are laying in the above positon there is a rock from left to right, and the forks rest on the tips of the rockers and the tree holding the spring/forks. I understand that might not be a true level machined edge.

The tip pic above is with weight pushed down on the tree and it lifts up this tip, other side stays on the ground.

Next pic is with now weight on the tree and both tips set on the ground, look at the shadowing.



oops, the first tip pic is of both tips on the ground, than when weight is on the tree the left tip lifts up a little, 2nd pic.



tried to get a pic of lower bearing race wear, not so good.





As you can see the left tube sticks above the tree while the right tube is flush in the top tree. This is the position the tree slide onto the forks when I put the right tube into the tree first. If I try the left tube in the tree first I can not get the right tube to slide in, a bit of work with the hands and it fits on. I do not think a heavy tweak is in any tube, I do think there is a tweak going on from wheelie's and bouncing back down onto the ground, but solid tubes helped this not be so noticeable, but is the lower tree bent and the neck stem ?



Not sure, but I was told one could carefully grind off the welding so all could come apart and parts replaced, if you know what is bent out of whack.



In this resting position there are 3 points of contact, the center of the bottom tree and the end of the rocker arms and main tube connect. They do rest solid on the floor in this position, but kind a hard to get a rock out of the 3 point resting position. I am not a biker, getting to the triker, so have not seen springer forks this up front and personal ever, but there is a first time for everything, cross this off the bucket list, LOL

[LarryA]

I would remove spring rods and springs, also the rockers, then check fork tubes for being like the letter H but racked, in other words the lower tree not square with the tubes........then check forks for twist or the letter H laying flat ,but with both top legs on a flat surface, then checking the rocker ends of the tubes for being parallel with the top tubes.

a local machine shop may have precision levels, surface tables etc, they will be able check this out. Or a good eyeball and some ingenuity witha good square and level go ahead and have at it. a machine shop with a press should be able to straighten minor bends.......good luck!

[grandpanystrom61]

I wish I knew if these were original old time springer forks, guess some of them are worth more than most think, but they are newer in design and probably mid to late 70's as best as I can tell.

Larry thanks again for your input. I think yesterday I spent wondering what I am going to do, but now I have a plan of attack and things to do or get done.

[grandpanystrom61]

Okay I am bad, thought I had gotten all the fork pics up, did that, but the neck tube alignment got forgotten.

I took a piece of 1 1/4" fence pipe, never used as it was cut off waste, and slide it down inside the neck tube and tried to rest it centered in the tube.



I could not get back far enough to get top and bottom of pipe in the picture, I just have to much crap in the garage, problem is it is not all mine. I know the camera can make things look off when we take a picture, so I have tried to keep these things in mind when I take the pic, try to stay square and horizontal if possible.

[vwbug72501]

From the sounds of things your trike has been rode hard and put away wet a few times. From the wear you are finding the trike has obviously had a lot of miles put on it. Testament to a good riding trike. I'll bet when all is freshened up it will ride really nice.

IMHO the forks are probably going to be the weak "sacrificial" link here. The main neck tubing is probably heavy enough to take a fork destroying lick with little or no damage to itself. The bearings and races definitely need to be replaced!

The fork pictures do look tweaked. Can't tell just where with out measurements. Here's an "Old School" CAD drawing of a fixture idea that I had that might help facilitate the measurements.



This fixture should give you a sufficiently straight and accurate measuring point to determine if the tubes are bent. By accurately building the 2 wood end brackets you will be able to support the disassembled rear fork tube assembly by 2 points on each tube and remove any errors added by the brackets touching any surface. The tubes should seat in the v notches on both ends and you should be able to take measurements at intervals along the tubes from end to end. I thought that an L square run along the top edge of the tube would allow you to make measurements easier. If you set the spacing for the slots in the wood fixture so the L square is vertical from the edge of the tube you will be able to measure easier. Just make sure that the horizontal leg only rests on one fork tube at a time.

I'll bet you will find that the tubes are bowed around the bottom triple tree bracket. You might be able to straighten the legs with a press and some suitable leg supports. Do the pressing cold and slowly (measure, press, measure, press, etc. High point center will move some.) will probably preserve the chrome too. If you have a local machine shop, check with them about shaft straightening. I have cold press straightened shafts to within .001" with just a hand arbor press and some v-blocks.

Check the front legs this way also. Also measure the flatness of the brackets by laying a straight edge across them. They should be flat.

Once you know the forks are straight, install new neck bearings and races and see what your tire alignment measures look like.

Hope this helps. Good Luck!

[grandpanystrom61]

As I was reading the Chopper's Handbook today I came across Ed Roth's name. I guess he ran around in the late 60's early 70's in Southern Cal pushing pamphlets about making your own Springer Front ends. He had some designs that he was pushing around. Allen and Finch I believe are the two gentlemen that took it much further.

I do wonder if Ed Roth designed this set of Springer Forks, they are to the size of this trikes rake and Ed's desired ride height. I just do wonder about it.

Hope everyone had a enjoyable day with the Mom's and Wife's today, we all can enjoy Mother's Day.

[grandpanystrom61]

VWbug, that was a lot of help to see how bad things are.

Once I got all apart and checked things the spring rods are bent and the spring tube legs are bent, plus the springs were not sized up correctly, or have just worn differently over the years, or the bent up front end was long ago and usage did the off wear on the springs......... just trash to me now....

Okay have been working on the new front end. I did get the neck tube welded into place on the insert tube. The bearing races pressed in and bearing pressed on lower tree, so I was playing with the mock up of rear fork tubes and the 5" rocker's.

I do not think there is the room in the fork width and size front tire for the shocks to be mounted to rockers and rear fork tubes. I really kind a liked that design, so I am looking at the springer design with maybe the mono shock, again room is an issue it seems.

The more I read and looked and building the springer type suspension, well the more I felt it was not what I wanted or I got lost in it all.

New soft springs will compress over usage and over all length change, hard springs can cause issue with a pogo effect in the suspension......

So do I even up the old springs, recheck the compression distance on them, if okay USE them with the mono shock.......... this is suppose to help smooth out the springer action of the fork set ?

Is the shock what is set for pre load ?

Preload of the springs, not much said on it, not sure how it is set.

If the front end weight is 200lbs and you built the front end unloaded, than when all is lowered of the blocks the suspension feels this 200lbs and absorbs it........so pre load is 200lbs of spring tension so when all is lowered off the blocks nothing moves...... is the preload set in the lower springs by pre compressing them some so they are 200lbs stiff so that when the weight of the trike is on them ..........lost break time.

[grandpanystrom61]

This is were I am at. Triple trees all mounted and leveled. It took some playing of back and fourth, but after some time I got it all to line up and give me the same distance reading on the tape measure's. Top shorter yellow level allowed me to make sure the top tree was set the same as the lower tree.



I think this was the best pic of the levels and their bubbles, I still did not get directly head on with the camera, but close.

[vwbug72501]

Looking good so far!

My first bike was a 65 Honda Dream (CA77) and it had an Earles or springer fork assembly. The springs weren't that big as shown below. They had a small diameter shock/spring and held up a 350 lb motorcycle and 250 lbs of rider/passenger weight.



I'd suggest that you fab up a portable jig to measure spring rates, determine the old spring rates, and then hit up the local MC salvage yard(s) to find a suitable shock assembly. The rear shock/springs of of some of these Chinese scooters or a small ATV/Dirt bikes might just fit your application. Your front end isn't that heavy due to the rearward weight bias of the design and the rear fork tubes are handling the major stresses. The shocks (especially when short) aren't affected by these major stress loads. It's when you add an extended lever arm to the springs/shocks as in a springer (or monoshock) fork that you have bending issues.

[LarryA]

nice looking side profile and angles.....you are making headway, good to see trike building activity!

[grandpanystrom61]

I did not find out how to delete a post, so this is just a error in posting.

[grandpanystrom61]

I had measured the compression of the old springs, was even thinking of using them again until my read yesterday.The old springer set was off, one of the lower springs were shorter than the other, and now you have the upper springs with different compression distance for same weight. Trash from what I read, good in a pinch, but not ideal for a new set of forks..The lower spring are 200 lbs per inch and the upper, and one is shorter by 3/16" from the other and up top the springs are equal length, but compression rate is a little stronger on one over the other.......orginaly they were 50lbs per inch.Lower spring is where the preload is set ??? The top springs are under tension also, but it is not much and it is there for the pre load rebound?

Bitter End Old school Choppers has spring sets for sale and also sells the mono shock with spring, but nothing listed about compression ratings....... It will get figured out, I hope I do soon.

http://www.bitterendchoppers.com/SpringerParts.html

[DeathBySnuSnu]

Yep.

It does sound like the old springs are dead.

So much for that.

I have never been real keen on an old school springer. It has no real dampening. The smaller top spring (rebound spring) with its preload and lbs/inch is what dampens in. Not a real great way of doing it. They ride a bit bouncy and unpredictable on rough stuff. That springer that has the hydraulic shock on it also is a way to make one a good bit better. I would guess it has no spring in it, just the hyd damper.

This is the primary reason I went with a rear motorcycle shock.

So like what was said before.....look into small motorcycle shocks.

I have seen Honda 250 rebel shocks used.

[grandpanystrom61]

I checked in at the shop the other day, looks like things should be ready for pick up after the Holiday weekend.

Not going with original style springer design, just not a huge springer design fan, so I found the shocks that meet the requirements for the trike, or should I say that they meet what is needed by my calculations.

I just hope they are the same and all works for me.

[DeathBySnuSnu]

Good news.

Shocks......as in hyd dampened motorcycle shocks?

Sounds good, I much prefer a hyd dampened spring.

If your numbers are good it will work fine.

[grandpanystrom61]

Yes they are the Hyd. coil spring motorcylce shocks. I have been looking at Progressive shocks, pricey, but I do like their design and warranty plan. The key is that it just has to be a shock that meets the needs and I do not care what brand, just that it is what is needed.

Fuel and me as the rider, the front end should feel 186.85 lbs of weight. Naked frame there is 60.2 lbs under the front tire, added 50lbs to frame by shifter location and we had 92.4 lbs under the tire. So 32.2 lbs of the 50lb weight is felt under the front tire. Using this difference I added rider/fuel and body weight and I feel all 50lbs of front fork weight will be felt on under the front tire. This all added up to 186.85 lbs.

I have this desire to find shocks with a 6" travel distance, and the first set I picked did not have adequate damper design, spring rate was great, but over all not recomended by manufacturer.

So I am at it again, but I understand it more now than before and it should help me find what I need.

Happy Thanksgiving to everyone.

[grandpanystrom61]

Okay, I have made some error's and I do think some would have been avoided if I had educated myself more about it all. Live and learn, at least that is what we are suppose to do, LOL.

The shock travel length is determined from upper mount to lower shock mount area as the suspension goes thru it's full travel range. NOT at the axle hole (which should have a 65 degree travel range, near 6" travel).

Once I figured out another error of mine, well finding a shock will not be so hard, actually have found a few, but need to get much closer total weight on front end before I make purchase.

One thing is "does anyone know how much spring compression is lost due to mounting angle of shock " ?????

I do believe anything over a 40 degree angle starts to diminish in spring compression rate compared to the vertical spring compression test.. I set at a 48 degree rake and the shock will mirror this angle......or does one bring out the top shock mount off the fork tube further so that the shock mounts on a different angle, like for me take it from a 48 degree angle to a 40 degree angle ???

Help me if you can, or is it truly nothing to worry about....shock mounting angle that is...…..

[DeathBySnuSnu]

Assuming you are going drop pivot with axle and pivot line being 90 degrees to the fork leg.

If your shocks are parallel to the fork legs then they would be considered "straight up".

So what angle the shock is in relation to the pivot to axle line is the angle I am assuming you mean to be asking.

For simplicity reason I would be figuring parallel.

You have to move the top a long ways before it makes a big difference.

The bottom point a little means a lot.

So as an example it the front axle weight is 300 lbs.

And the line from pivot to axle is 6 inches and the shock attachment point is in the middle.

You would have a 2 to 1 lever. Axle moves six to shock move 3.

Also the spring will be on the ratio also.

300 lb axle times 2 is 600 lbs of total weight the springs must hold up.

[grandpanystrom61]

And no one selling shocks has bothered to explain this, rather just ready to sell you what ever you want, not what you need.

Thank you Rex, you explanation was correct for what I am doing. I am not exactly 2 to 1, but it is very close. I can figure it out so that I do get the spring tension I need.

This is great, so glad I asked to make sure I get this correct, at least as close as possible.

[DeathBySnuSnu]

I think aftermarket shocks will be rated straight eye to eye.

So many different applications and bike differences that there is very little way to catalog them any other way.

Mine is a harley sportster shock. I had to put a friends back tire on a scale and sit on it to get a number to work with. Then measure the ratios of the harley swing arm. So I had to reverse engineer the bike and then apply it to mine. Then I tweaked the ratio of the rocker points to get it in range of the shock.

Shock came off ebay.