Stalker steering arm problem

[homebrew]

I stumbled on this thread in the Locost USA forum http://www.locostusa.com/forums/viewtopic.php?t=4435&start=0 regarding the modified steering arm on the Stalker failing. Thought the Stalker owners in this group should be aware of this problem.

 

Jim

[slomove]

Quite lucky....

 

On the NorCal2008 tour the participating brand new S2K lost car control but not due to the steering arm but a failed rod end of the front suspension (IIRC). I believe it was also a fatigue failure.

 

Several Birkins of 2000/2001 vintage had weak lower front suspension ball joints and bad failures.

 

I know of one Caterham where the front lower A-arm bushing split up with complete suspension failure and serious damage.

 

For some reasons that appears to happen usually at low speed and with no serious consequences. I think I will go out now and have a look at my car.....

 

Gert

[case sensitive]

not good. i wonder if there is a similar steering arm that would be closer to the knuckle that will fit in the stalker. that would seem to me to be the best solution.

[locostv8]

Another solution is a steering quickner available in 1,5:1 and 2:1. This is a case for using joints that are way over the needed specs, this is not an area to save weight on.

[TxCoyote]

Before anyone has a cow or devalues the Stalkers look at Dennis' response. With hundreds of thousands of miles on the 100 plus cars on the road, there have been 3 failures. 2 were impact/race related and the one in question on the other forum is a possible hard road damage issue.

 

Dennis Brunton, the Stalker designer explains this much better on the Locost forum. My experience is that the downside to forums is that it allows people to jump to conclusions at the speed of cyberspace!

 

Russ Rosenberg

Denton, TX

TVR V8

Stalker #117 (still under construction)

[slngsht]

 

Dennis Brunton, the Stalker designer explains this much better on the Locost forum.

 

You could always post a link here

[GBOLT]

Guys,

 

 

Here is Dennis's full and complete response. Not much to add, other than as a Stalker owner they have been great at explaining the situation and offering an option to all of us.

 

 

Reply from Brunton

 

We would like to reply to the lengthy discussion of the quick

steering modification to the Chevy S-10 Spindles used in the

StalkerV6.

IMPORTANT.We do not know of ANY Stalkers that have had ANY

unexplained failures of ANY parts....If we EVER find any...ALL

STALKER OWNERS WILL BE NOTIFIED IMMEDIATELY.

All cars that are raced should have ALL balljoints and rod ends

replace EVERY season and carefully inspected after any ' off track '

 

First let's define the current situation:

My two cars alone have 130,000 miles between them. We have almost 100

cars on the road, with an additional few hundred thousand miles

combined. Most of these cars have the same design as the one that

failed in Mr. Bilinski's car. In all of that time, we know of two

failures similar to Mr. Bilinski's. Both were the direct result of

off track excursions, both cars also had significant suspension

damage, ( bent control arms), leaving Mr. Blinkski's. It appears

the Mr. Bilinkski's car hit two very severe (Scott wrote "…the side

that broke (left) has hit 2 what felt like VERY large bumps on a

section of road which was under construction, these bumps were bone

jarring and painful…") potholes. It seems likely to us this fits in

with our experience of this part failing after severe collision

loads, especially if the ride height was set too low. Those hits

could likely have damaged production vehicle with far higher safety

factors than are used in Seven style cars.

 

Given what we know about this isolated event, what should be done?

 

#1:

If you have an "off track" or hit anything that bends ANYTHING in the

suspension, replace all the rod ends and balljoints...ON ANY CAR !!!!

(two of the failures happened shortly after replacement of bent

suspension parts, and the rod ends were NOT replaced.)

If nothing appears bent, but you have had a "bone jarring

event"...inspect the suspension very carefully !

The only way one of these steering rod ends is likely to

break in normal driving, (normal driving in a Stalker includes

Autocross or Track racing, but not Off road Racing), is if the motion

range of the track arm balljoint is exceeded due to extreme loads in

the suspension causing the rod end to function as a "suspension

stop" . " Bone jarring bump, off track at speed, collision with wall

etc...

I would strongly recommend Mr Bilinski check the rest of the

suspension for stress damage.

The above situation is aggravated if the ride height is set too

low...The TA balljoint has a lower binding threshold, which leads

to.......

 

#2

Set the car up exactly as the manufacturer tells you.. It does not

matter if your neighbor or best friend is a master mechanic, or has

built a kit car, or designed his own. If you choose your own road,

then you are on your own.

 

We have a new steering arm design that we started using a few months

ago

. This change had NOTHING to do with Failures

The reason for the change was:-

We can no longer get the rod ends made without a sizable minimum

order and unacceptable price increase

Mine broke at the Run and Gun Autocross. I replaced the rod end and

completed the 2 day Road Course Event, finishing Second Fastest.

I knew exactly why mine broke, so happily continued to drive and race

the car for another six months.

I FIRST USED THE NEW ARMS ON APRIL 19 08...When we had only ONE

record of a damaged rod end MINE and we knew EXACTLY why it broke

 

We have made the new system available to all Stalker owners free of

charge, if they feel uneasy about their cars since this on line

analysis by " experts " .

IMPORTANT #1 and #2 still apply, and apply to ANY CAR

I have built and sold over 130 kits, I have Won the SCCA

SEDiv Championship four Times, Florida State Championship four times,

Gulfcoast twice, I was 3rd ( Podium) at the NASA

[powderbrake]

Glad to see Dennis's response in this forum. I started to read the locost forum thread, but stopped when I grew weary of the "experts" analyzing the design and failure by viewing pictures alone.

 

The whole idea of the Stalker designer hiding a problem is simply unbeliveable. If any of those guys who concluded the design was unsafe had ever watched Dennis or Justin on a road course driving his design, they would be astounded at his cojones and his car's abilities. Dennis is a straightforward guy who wil assist you in any way he can. Those of us who know him understand that.

 

If you have a problem with your kit car, the FIRST step is TALK TO THE KIT MANUFACTURER. He likely knows more about the car than you do, and has heard most of the comments relating to his car. Communicating with other similar car owners will also help, after you have talked to the manufacturer. Once you start knocking a product on a forum, you are directly attacking the manufacturer's product and his personal reputation. Would you do that face to face with him in public ?

 

Fortunately the discourse on this forum has been gentlemanly and will hopefully stay that way.

 

Also, don't forget that with the Chapman philosophy of "add lightness" a typical Seven is just barely strong enough to do the job. With heavy use, bumps and occasional abuse, they will break. After all, most of the forum threads have to do with working on or repairing these cars.