shifter tie rod replacement issue

chuck hurlbert · Posted: Sun Aug 19, 2012 2:04 pm Post subject: shifter tie rod replacement issue

i broke my shifter tie rod linkage today and need to replace it... i cannot find a replacement for mine, is this 'custom' or am i just not looking in the right places.

and it looks like fatigue is the main issue. has some wear on the bottom though.

_________________
Shifter newb

Curtis Ruth · Joined: 24 Jul 2001 Posts: 656

toot tight of a bend on that bad boy. 45 degrees or less. The hex rod have more strenth as well.
_________________
Innovative Karting/ Intrepid karts
Glendale, Arizona
WWW.INNOVATIVEKARTING.COM

chuck hurlbert · Posted: Sun Aug 19, 2012 2:13 pm Post subject:

Roger Miller · Posted: Sun Aug 19, 2012 2:55 pm Post subject:

Shifter tie rods come straight, and then you give a bend as needed.
The one you have, as mentioned was way over bent. Nice radius and all but it puts all the force on the bottom of the curve so it fatiqued and broke. Probably was not the tightest shift either, and felt a bit soft as it flexed every time it was shifted.

Like as said, you want it as straight as possible.

So, it usually goes down beside the seat, and then a bit of an upward bit to attached to the J-Arm. Also J-Arm should be as close to vertical as comfortable to fit with the seat.

And check after install to make sure it isn't hanging or getting a tight spot in either direction of shifting. You can see if it rubs the seat and such.

Bill Schmidt · Posted: Sun Aug 19, 2012 4:03 pm Post subject:

I would like to see what your shifter handle looks like to demand that much of a bend in the rod. Something is amiss here.
_________________
Bill Schmidt

'95 Trackmagic 125 shifter (Kawi)
'88 Red Devil F500 4-link rear (Rotax)

Benn Herr · Joined: 18 Jul 2001 Posts: 1580

The problem is that aluminum doesn't like to be bent, and it really doesn't like to be bent back!

While they were making that piece they probably made a bunch of little bends getting it just right. If they went a little too far they would have bent it back a little. That weakens it a bunch. Then every shift you make flexes it tighter on the up shift and straightens it out on the down shift. It was only a matter of time until it broke.

We had that happen on ours (it was made out of the standard Italian hex material) It's since then been replaces with a piece of 1/2" 4130 tube with right and left hand bungs welded on. Something else will break first!
_________________
Benn Herr
Come see our Superkart Build Off @
http://www.lostenduros.com/?page_id=1534
beherr3@cox.net
http://www.southwestkarters.com/
http://www.lostenduros.com/
Kart Design
Chandler, Az.

Ken Schilling · Joined: 01 Dec 2005 Posts: 1345

The shift rod started out way too long to begin with. Cut off the right hand tapped end to length, drill & tap for the rod end, keep as straight as possible, use hex rod for more strength. You should also always keep a spare one too.

You may need two different length rods depending on gearing from track to track to try and keep the engine near the optimal spot fore to aft. I use two different length chains and shift rods to accomplish this. On my gearing chart I have a spreadsheet that tells me what length chain and shift rod to use with what gearing.
_________________
Ken Schilling
#21x / S4 / ProKart Challenge (PKC)
SKUSA Data Administrator

Good luck is where preparation and opportunity meet!!!

The opinions I express are mine alone and do not reflect those of any organization of which I am a member.

Mike Goebel · Posted: Sun Aug 19, 2012 7:23 pm Post subject:

If you want an indestructible one make it from 4130 tubing from Aircraft Spruce.

7/16 OD
.095 Wall

Part # 03-02100 $7.25/ft

Click Here ---> Aircraft Spruce

Mike G.
_________________
Closet KZ Lover!!!
mfg Technology Centre
So Cal’s #1 Non Profit Engine Builder

chuck hurlbert · Posted: Sun Aug 19, 2012 9:22 pm Post subject:

Alan Sheidler · Joined: 09 Aug 2001 Posts: 471

That looks pretty much like the rod that broke on my kart too. Close inspection revealed that a small nick had allowed for corrosion to start. That then expanded into a developing stress fracture, until the remaining "good" metal was no longer strong enough to handle the load.

Good advice from Ken about cutting to length and re-tapping the RH thread end. FWIW, I have never understood why they come with both R and L threaded ends to begin with. Since they have a bent shape, they can't be adjusted like a tire rod anyway.

I suggest that you get a pipe bender from your local hardware store, with a 4' pipe handle. The hex rods are really stiff, and you will need a lot of leverage and control to get a smooth bend. Clamping it in a vice and yanking on it is not the way to go.

Bill Cox · Posted: Wed Aug 22, 2012 12:09 pm Post subject:

+1 on the Pipe Bender.

Tip: buy some lengths of cheap conduit tubing to practice your bending skills. It's a lot cheaper than the shifter tubing you'll be using. Proper, accurate bending is a skill that can be learned...but you have to practice on cheap materials!
_________________
Bill Cox
NCK Super Stock CR125 #36

Greg Wright · Posted: Wed Aug 22, 2012 12:54 pm Post subject:

Alan Sheidler · Joined: 09 Aug 2001 Posts: 471

Mike Goebel · Posted: Wed Aug 22, 2012 5:33 pm Post subject:

chuck hurlbert · Posted: Wed Aug 22, 2012 8:07 pm Post subject:

so this is what i have to deal with..

as you can see, i have a ways to go... i can see why they bent it so much to start with.

should i make two bends to do this? that way i wouldnt have to go past 45 degrees.

thanks for the replys everyone.
_________________
Shifter newb