Normal for DeDion to contact chassis rails?

[Pokey]

1 hour ago, KnifeySpoony said:

Yes i could shift the watts linkage, but that would just tilt the de Dion fore or aft (since it will rotate about the connection to the a frame). Tilting it forward would also bring it down which would worsen clearance. Tilting it back raises it but also pushes it back into the narrower "v" of the chassis rails. 

 

Got it.  In my mind's eye I was thinking you could shorten the forward arm without lengthening the rear arm and that would shift the axle forward and up.

[KnifeySpoony]

Message from caterham :

 

 I have discussed this with our production manager and it appears that it is not uncommon to see the central triangulated section come into contact with the inner diagonal tubes on full droop, even with the A-frame centralised correctly. However it is not a concern to us as it will not cause you any issues under real world conditions.

[Pokey]

I have a rough analog that occurred with my build.  The transmission kisses a frame member ever so slightly on one side of the tunnel.  I tried repositioning using different methods and even pulled the engine and started all over but in the end the transmission is a hair-width from touching at most.  I was concerned that movement would cause contact which would cause vibration, but in the end whatever vibration that might be transmitted is minor.  Sure seemed like an issue at the time, but in the real world it proved otherwise.

 

Interestingly enough, Bruce at Beachman Racing built a 420 a few months later and encountered the same situation, so when Caterham says "not uncommon" that is probably Caterham-speak for, "we made it that way."

 

[KnifeySpoony]

Yes my trans contacts the inside of the tunnel on the driver side, but i was expecting that based on numerous reports. However, I've never heard of this issue which seems quite different, as it's suspension to chassis contact. I guess I'll see if it causes an issue. I'd suspect if and when it hits it would be quite noticeable. 

Edited April 29, 2021 by KnifeySpoony

[Pokey]

If you are concerned you can always add your own bump stops.

[KnifeySpoony]

That's a good idea I hadn't thought of that.