FJ1100 - Raising the rear end with shorter dog bones

[ZOA NOM]

I use a "go, no-go" version on the backside of the cam lobe rather than trying to get a 90 degree bent feeler under the elephant feet on my Porsche. It makes trackside valve adjustments much quicker and easier access. It allows me to just rotate the engine without worrying too much about TDC for each cylinder, as long as the rocker isn't anywhere on the lobe, the adjustment can be made.

[fj1289]

I will add to routinely examine the homemade links.  I saw noticeable ovaling on mine after a couple years on the street bike.  That's why I went with Soupy's .....

All modifications have their compromises - just be aware of them and deal with them appropriately! 

I'd like to fab a pair of "fat" links with serviceable bushing for the street bike.  Probably way overkill .... And unknown what their compromises might be!

[T Legg]

I didn't know what you were talking about Rick. The only Porsche I've ever worked on was a friend's 914. I had to Google valve adjustment for a 911. I didn't know they have dual overhead cams and no pushrods. The guy in the video used a special dial gauge that screwed on to the valve cover stud then he zeroed the gauge with the rocker pushed against the cam lobe then pushed it down until it touched the valve stem for his measurement.

[axiom-r]

Just not at all worth it to take any chances on a critical suspension component.  I was SOOOO lucky not to be hurt.  For me, the obvious test is; "was the part manufactured to be a suspension component?"  The Soupy's links were not.  They are assembled parts from a hardware supply.  NO - you would not expect one to break - I certainly was surprised. But looking back at the situation - Why did I take that chance?  Totally unnecessary.  AND....  look at the dogbones and links used as stock components; they are solid or billet material 100% of the time.

Heim joints, even used in pairs, allow rotational and torsion forces to arrive in the linkage - this = "ovaling" as mentioned above.  My spacers and fittings were heavily worn at the centers.

"Keep checking it for wear" is a foolish approach because you cannot tell from looking at it when it is about to give...  observe the clean break on my unit it looked fine minutes before the break.

Adjust your rear height on the shock - like a pro. 

OR - buy parts that are manufactured and engineered for the specific job.

JMHO...


tim

[Pat Conlon]

I recall Aviation Fred made a pair of bones out of titanium.

[ZOA NOM]

I didn't know what you were talking about Rick. The only Porsche I've ever worked on was a friend's 914. I had to Google valve adjustment for a 911. I didn't know they have dual overhead cams and no pushrods. The guy in the video used a special dial gauge that screwed on to the valve cover stud then he zeroed the gauge with the rocker pushed against the cam lobe then pushed it down until it touched the valve stem for his measurement.

I think you're referring to the Stomski tool video. That's a nice accurate way to do it with the engine on a stand, but it's too tight inside the engine compartment for that method. I like using the "backside" method, which sets the gap using a feeler gauge between the cam and the rocker when the valve is not under tension of the cam lobe. It makes access much easier, and you get to the point where you don't even need the feeler gauge, you can feel the right amount of movement with your fingers. Haven't broken a rocker yet, and I spin her up to 7k. The spec is pretty wide, between .002" - .006", and they should be set on the loose end, because they tighten as the valve seat wears.

Here's how a master Porsche Mechanic does it. Note the wiggle check at the beginning.

https://youtu.be/kbR2T6Ue-Ds

[ribbert]

....It makes trackside valve adjustments much quicker and easier access.....

Why are you adjusting valves at the track?

[ribbert]

..... and you get to the point where you don't even need the feeler gauge, you can feel the right amount of movement with your fingers....

Here's how a master Porsche Mechanic does it.
https://youtu.be/kbR2T6Ue-Ds

...and he calls himself a Porsche Master Tech?, tell him to come back when he can do it without feeler gauges.

[aviationfred]

I recall Aviation Fred made a pair of bones out of titanium.

The Titanium dogbones are installed on the Streetfighter project.



Fred

[ZOA NOM]

....It makes trackside valve adjustments much quicker and easier access.....

Why are you adjusting valves at the track?

Because you may have set them at home when the engine was relatively cooler, and they may be tight. It happens. The point is the access, which is also useful at home.

[ZOA NOM]

..... and you get to the point where you don't even need the feeler gauge, you can feel the right amount of movement with your fingers....

Here's how a master Porsche Mechanic does it.
https://youtu.be/kbR2T6Ue-Ds

...and he calls himself a Porsche Master Tech?, tell him to come back when he can do it without feeler gauges.

I'm sure he uses the gauges when he's being paid to adjust someone else's valves.

[aviationfred]

Here is a up close photo of the Titanium dogbones.


Fred

[Pat Conlon]

Thanks Fred....No worries about ovaling out those bad boys...
Fred, remind me, where did you find the stock, how much? Was it hard to cut and drill? Any special tools needed?
I've never worked with titanium before....

[ZOA NOM]

I've heard titanium can be brittle. I don't know enough about it in this application. My mild steel version would likely bend before breaking, which I would prefer.

[Waiex191]

You can get Ti here:
https://www.titaniumjoe.com/

We use a lot of Ti in helicopters.  It has a similar strength to steel but in some applications will show worse fatigue life.  It is hard to work with.  My airplane landing gear is a 1.125" 6A-4V rod and that is a bear to drill through.

Without loads or analysis hard to tell if it is good or not.  As long as Fred is leading the fleet it is probably not that scary of a part.  For the relatively small weight savings for those small pieces, steel seems like a good bet.