Sportster Chopper Trike Build

[sclarkfam]

With inpiration from Grimm and Joker, I am converting my wife's Sportster to a Frankenstein 34" trike and plan to install a Seeger Chopper wide glide kit.

The Frankenstein kit was well designed and easy to install however I was surprised at the low speed front end wobble from 10mph to 40 mph. Wobble went away at faster speeds. I increased the front fork bearing pre-load to take out the fall-away and that helped some. Frankenstein rep said they had heard of this issue, but had not seen it themselves. They also stated that the 5 deg EZ steer would increase the front end stability and make it easier to steer. Given I am going to try the Seeger Chopper kit, the EZ steer is not currently an option.

Wondering if anyone else has had this low speed wobble and could offer corrective action. The front tire is a new metzeler.

I believe the Seeger Chopper kit's increased rake will assist in reducing the wobble however, by design (reduced offset) the Chopper front end only slightly reduce's the stock trail and therefore the turning force to "steer" may still be too much for my bride. Any thoughts are greatly appreciated.

[sandrooney]

The ez steer cured it on my wife's trike. Mine already had it when I bought it so it never did wobble.

[Bob Witte]

With inpiration from Grimm and Joker, I am converting my wife's Sportster to a Frankenstein 34" trike and plan to install a Seeger Chopper wide glide kit.

The Frankenstein kit was well designed and easy to install however I was surprised at the low speed front end wobble from 10mph to 40 mph. Wobble went away at faster speeds. I increased the front fork bearing pre-load to take out the fall-away and that helped some. Frankenstein rep said they had heard of this issue, but had not seen it themselves. They also stated that the 5 deg EZ steer would increase the front end stability and make it easier to steer. Given I am going to try the Seeger Chopper kit, the EZ steer is not currently an option.

Wondering if anyone else has had this low speed wobble and could offer corrective action. The front tire is a new metzeler.

I believe the Seeger Chopper kit's increased rake will assist in reducing the wobble however, by design (reduced offset) the Chopper front end only slightly reduce's the stock trail and therefore the turning force to "steer" may still be too much for my bride. Any thoughts are greatly appreciated.

The "wobble of death" is often inherent in many of our 3 wheeled conversions. Since a rake kit is not an option, be sure that your front wheel is perfectly balanced and that your steering head assembly is in fact in good condition and nice and tight.

Another thing you can do is in stall a steering damper on the front fork. You can adapt lots of aftermarket units to work on your Sporty.

[yorskybugs]

Let me start by saying your trike looks awesome! Great job!

We just finished our install of a Cass County kit on my '99 FXSTS Springer this last weekend (let's just say we should have went with a Frankenstein kit...) and I have no front wheel wobble. We didn't change the tree or use a dampner, just left the front stock. So far my only complaint is figuring out how to turn left from a stop without reving the engine like a maniac, haha . Of course the bumps on the road will make my handlebars wobble some, but flat road, no troubles no matter the speed. We think the natural rake of the Springer may be why it's handling well enough. We used 14" rims with I think 205/70 tires left over from my hubby's '62 T-Bird and with those the trike sits just a bit lower in the rear, so that may account for the front end not wobbling. We are planning on putting shorter tires on some other rims which have a negative offset (more like deep dish), which will drop the rear more and make the back axle even wider, so I'm hoping I will get away with no mods to my front at all. I think once you stretch out the front end with that Chopper kit, the wobble may decrease or even go away since it changes the angle and where the pressure hits the front tire. Hope it all works out for you! Good luck

[sclarkfam]

Thanks for the excellent feedback. I considered the CASS trike conversion as I like their swing arm better, but went with the Frankenstein based on their excellent reputation. Given the front wheel requires a tube, I will relook the balance. Beyond that, I will wait to see the result from the Seeger front end before adding a dampener. Again, thanks.

[sclarkfam]

Finally completed the chopper trike project by adding the Seeger Cycle bolt on chopper front end. The desired look was achieved and it has turned into quite the conversation piece while out riding.

Kit quality and craftmanship were superb and easy to install as well. I attempted to attach the test report to document the handling qualities, but the .pdf file is too large.

Summary, The trike rear end and wide tires when coupled with the stock sportster front end produced an undesirable low speed wobble (even with the steering head stem tightened to remove the fall away). Additionally, the steering felt very heavy (as expected without raked triple trees) and quickly produced rider fatigue. With the Seeger front end installed, overall ride quality greatly improved. The longer wheel base absorbed road conditions much better, eliminated the wheel wobble and reduced steering forces approximately 30%.

Note: While the Seeger Bolt on kit adds 13 deg neck rake and 5 deg in the trees, it is designed to retain the bike's near original Trail dimension (great for motorcylces, but not necessarily preferred in Trike's). Simply adding 4-6 deg raked triple trees would reduce the Trail dimension and further reduce steering effort over what was accomplished with this project.

[Foodog2]

Any update on the ride? I emailed frankenstein and they were skeptical of the seegar front end being a good solution. They did not say it would not work but did not seem to like it. What size wheels and tires are those? I think something like that would be a cool alernative to my ultra sidecar rig around town.

[skuuter]

Sportsters in "Frankenstein Mode" are soooooo clean looking.....pepper

[KindaOldTriker]

Are those the 10" wheels/tires upgrade for Frankenstein/
I'm doing my wifes 1200 Sportster and thought about the 10" but decided not. I thought possibly just too big looking, heavier and possible stearing roughness?

She can't wait to get it finished.
Since hers has the 19" front cast wheel and 90 tire they sent the 4 degree rake trees.