Greenspeed Magnum steering shake

ianlaidlaw
Posts: 6
Joined: Sat Dec 19, 2015 10:17 am

Greenspeed Magnum steering shake

Postby ianlaidlaw » Thu Dec 29, 2016 10:17 am

I am encountering issues with bad steering shake or wobble when I let go of the steering grips. If I let go of the steering handles, the wheels start to wobble and this wobble gets worse and worse, almost shaking the frame apart. After advice from GS I tried addressing the toe in - was around 21mm and got it back to under 8mm. It should be under 2mm but could not get it any lower even with expert help. While improved, the issue is still there if speed exceeds 20 kph. I have been told that this is a long standing issue with Greenspeed steering although GS do not acknowledge this.

So, my question is - dose anyone else have knowledge or experience of this problem?
Thanks Ian

zebee
Posts: 324
Joined: Sun Nov 10, 2013 8:37 am

Re: Greenspeed Magnum steering shake

Postby zebee » Thu Dec 29, 2016 7:14 pm

Place to ask is probably the trike forum at bentrider online.

http://www.bentrideronline.com/messageb ... y.php?f=13

I have ridden a GT3 that seemed to wobble a bit, someone suggested loose kingpins

Zebee

User avatar
chuckchunder
Posts: 372
Joined: Sun Mar 09, 2008 12:18 pm

Re: Greenspeed Magnum steering shake

Postby chuckchunder » Thu Dec 29, 2016 9:13 pm

I've had two GS trikes, older style with the brass bushings in the king pins as opposed to the Magnum with the ball bearing. Never heard of that problem with GS trikes, and not experienced it myself.

I'm surprised you cant get the toe-in closer, did the expert help suggest a reason? 8mm is significant, if it were my trike I would be pressing the matter with Ian.

But I agree with Zebee, head over and ask the question on BROL - its winter and they could use something more to argue about.....
"We have thousands of miles of cycling infrastructure, we just need to get the cars off them....." US advocate

OldBloke
Posts: 249
Joined: Sun Mar 02, 2014 10:27 pm

Re: Greenspeed Magnum steering shake

Postby OldBloke » Thu Dec 29, 2016 10:57 pm

I ride regularly with a bloke with a Magnum and he has no problems with steering shake.

If you can't get the alignment any closer and can't find any looseness in the front end, I'd suggest you have a Warranty issue.

OB

John Lewis
Posts: 1297
Joined: Tue Oct 02, 2007 7:12 pm
Location: Albany. 400km South of Perth

Re: Greenspeed Magnum steering shake

Postby John Lewis » Sun Jan 01, 2017 12:39 am

What is preventing you from adjusting the toe in closer?
I'm not familiar with the GS but our Logo trikes have left and a right hand thread ball joints and that makes it pretty easy.

On a trike I built with the plain bearings I had no problems but the next one with ball bearing kingpins was prone to shimmy.
The quick cure was some O rings between the ball joint and its mount point.
This introduced a bit of "stiction" /friction and cured the problem.
The problem I felt was in the ball bearing kingpin setup being too free but we couldn't find a way to tighten it.
As has been mentioned, go ask on BROL. A lot of experience over there.

John

ianlaidlaw
Posts: 6
Joined: Sat Dec 19, 2015 10:17 am

Re: Greenspeed Magnum steering shake

Postby ianlaidlaw » Sun Jan 01, 2017 11:26 am

John
Thanks for your input. Your first question is a good one. I don't know the answer other than to say that once we reached the 8mm point, adjusting at any one of the 4 possible points either had no effect or in fact made the toe in gap worse. I suspect that we also had some issues with accurate measurements at times as we did not have a trammel (see following from GS manual))

[Steering alignment should be done once a year or when excessive tyre wear is noticed. The front wheels should ‘toe in’ between zero and 1/16" (0-2mm). That is, the measurement across the front of the wheels should be between 0 and 1/16’ less than the measurement across the back of the wheels, at axle height.

A check can be made with a tape measure, and adjustment made by undoing one of the steering connections (eg steering arm on kingpin) and screwing one of the rod ends (ball joints) in or out half a turn at a time. Note you will notice that the rod ends have a jam nut (lock nut) to prevent them unscrewing and to eliminate movement on the thread. This will have to be loosened first before the rod end will turn and locked up again before each measurement is made.

A more accurate way is to use a trammel (see fig. 15). A trammel has two pointers on a bar, which sits at the back of the tyres at axle height. A mark is made on the tyre with a pen, the trike rolled forward half a wheel revolution, and the marks compared against the trammel pointers. This method eliminates any inaccuracies due to wheel run out etc. All measurement should be done with rider on seat if possible as this helps flex and preload everything into position]

Regards Ian

User avatar
chuckchunder
Posts: 372
Joined: Sun Mar 09, 2008 12:18 pm

Re: Greenspeed Magnum steering shake

Postby chuckchunder » Sun Jan 01, 2017 9:28 pm

Hi Ian

This has been going around in my head the last couple of days. A couple of thoughts that may help.

Instead of a trammel I have used an old telescopic radio aerial. You can measure between the rims at the front and the back quite accurately that way.

I've had trikes since 2002 and I still get caught out when adjusting toe-in thinking I've turned the connection one way but turned it the other. Screwing them out will bring the front of the wheels closer together, and screwing them in will spread the front wheels further apart.

If you are over here in WA PM me and bring it over to my place, I'd be happy to take a look at it.

cheers
"We have thousands of miles of cycling infrastructure, we just need to get the cars off them....." US advocate

User avatar
exadios
Posts: 514
Joined: Fri Dec 21, 2007 2:07 am
Location: Melville, WA
Contact:

Re: Greenspeed Magnum steering shake

Postby exadios » Sun Jan 15, 2017 4:51 pm

ianlaidlaw wrote:John
Thanks for your input. Your first question is a good one. I don't know the answer other than to say that once we reached the 8mm point, adjusting at any one of the 4 possible points either had no effect or in fact made the toe in gap worse. I suspect that we also had some issues with accurate measurements at times as we did not have a trammel (see following from GS manual))

[Steering alignment should be done once a year or when excessive tyre wear is noticed. The front wheels should ‘toe in’ between zero and 1/16" (0-2mm). That is, the measurement across the front of the wheels should be between 0 and 1/16’ less than the measurement across the back of the wheels, at axle height.

A check can be made with a tape measure, and adjustment made by undoing one of the steering connections (eg steering arm on kingpin) and screwing one of the rod ends (ball joints) in or out half a turn at a time. Note you will notice that the rod ends have a jam nut (lock nut) to prevent them unscrewing and to eliminate movement on the thread. This will have to be loosened first before the rod end will turn and locked up again before each measurement is made.

A more accurate way is to use a trammel (see fig. 15). A trammel has two pointers on a bar, which sits at the back of the tyres at axle height. A mark is made on the tyre with a pen, the trike rolled forward half a wheel revolution, and the marks compared against the trammel pointers. This method eliminates any inaccuracies due to wheel run out etc. All measurement should be done with rider on seat if possible as this helps flex and preload everything into position]

Regards Ian


I have adjusted my alignment a number of times - mainly after changing the Heim links. I use two lengths, each about 2 meters, of extruded box section or channel (aluminum). To make the measurements / adjustments I remove the tires and clamp one end of these lengths to the wheels at ground level with the excess to the front. That is, the trike is sitting on its front rims on the hard stand with the clamped extrusions running forward. I then make a measurement of the distance between the extrusions at a point near the wheel and compare it with the distance at the ends. Since I adjust for parallel alignment I adjust until these two measurements are identical. If you want some other alignment then elementary Trig. is your friend.

Obviously, it is important to firmly clamp the extrusions to the wheels. I use at least three cable ties - 4.8mm or heavier - as tight as possible.

Who is online

Users browsing this forum: No registered users