Watts Link Question - a.k.a., Geometry Test

[EburgE]

Got stuck assembling the rear suspension. The guide says to attach the Watts Link to the DiDion tube first. Since the bellcranks were missing, I went ahead and assembled the rest of the suspension first thinking the Watts Links could be bolted on last. Now the parts arrived but the bellcranks do not line up with th holes on the flanges if the DiDion tube.

 

Any suggestions?

 

I tried putting the tires on and lowered the car off the jackstands, but it did not change much. Also double-checked the length of the Watts Link arms. The photo shows the holes that need to line up on the bellcrank and the tube. The tube still needs to come up and slightly back. I'd rather not have to take everything apart. Is there any way out?

 

http://www.usa7s.com/aspnetforum/upload/1994257755_WattsLinkProblem.JPG

[bsimon]

Don't know if this will make the bellcranks line up with the ears, but the dimples in the rear links go towards the chassis, not the tyre. The forward links should have the dimples outward towards the tyre.

 

On a second look at the assembly guide, I see that the rear link arm has an offset bushing trunion. Turning the rear arm around will move the bellcrank outwards to get it in line with the Dedion clevis ears.

[Alaskossie]

EburgE,

 

I went through this exercise recently also (though my bellcranks were not missing, and I was able to assemble the Watts links in the build-manual sequence). I recall removing and reinstalling the Watts-link parts several times, until I got all the components right. The build manual is confusingly opaque and ambiguous on this little assembly task.

 

Are the bellcranks "handed" themselves? (I mean, does the bushing extend farther outward from the crank face on one side of each arm, than on the other side? If so, can you swap them around?

 

I seem to remember that one hole on each bellcrank is spaced farther away from the bushing than the other. Have you tried flipping them end for end?

 

Do you have the forward Watts-link arm trunnion bolted into the correct hole in the chassis? (The "Watts-link" hole, not the "trailing arm" hole).

 

Bob S. is correct about the dimples (narrowed sections) of the forward Watts link arms facing the tyre, and the dimples in the rear arms facing the chassis. Doesn't seem logical for the rear arm dimple to face inward, but Nathan at RMSC confirmed that this is correct (facing it outward would seem to give more tyre clearance). Orienting the rear arm in this way changes the centering of the arm slightly vis a vis the bell crank, since the trunnion that is bolted to the chassis is not centered lengthwise on the arm.

 

I don't have my build manual in front of me, and my car itself is on Bob S.'s sawhorses several thousand miles down south, at present. Wish I could more accurately go through this step-by-step with you.

 

Tom Meacham

[Alaskossie]

EburgE,

 

Looking at your photo closely again, it appears that you have the rear arm dimple facing outward toward the tyre, not inward. Turning the dimple inward on each side may solve your problem.

 

Tom

[EburgE]

Are the bellcranks "handed" themselves? (I mean, does the bushing extend farther outward from the crank face on one side of each arm, than on the other side? If so, can you swap them around?

The bushing does extend outward on the outboard side of the crank face.

 

I seem to remember that one hole on each bellcrank is spaced farther away from the bushing than the other. Have you tried flipping them end for end?

The longer hole extends downward.

 

Do you have the forward Watts-link arm trunnion bolted into the correct hole in the chassis? (The "Watts-link" hole, not the "trailing arm" hole).

I believe it goes in the upper hole. Will double check.

 

Bob S. is correct about the dimples (narrowed sections) of the forward Watts link arms facing the tyre, and the dimples in the rear arms facing the chassis. Doesn't seem logical for the rear arm dimple to face inward, but Nathan at RMSC confirmed that this is correct (facing it outward would seem to give more tyre clearance). Orienting the rear arm in this way changes the centering of the arm slightly vis a vis the bell crank, since the trunnion that is bolted to the chassis is not centered lengthwise on the arm.

Good catch! Will do this after breakfast and see if it helps. Thanks!

[EburgE]

Here are the diagrams.http://www.usa7s.com/aspnetforum/upload/2137978453_WattsLinkDiagram.JPG

[EburgE]

Turned around the rear arms, which improved things a bit.

 

Disconnected the forward arm from the bellcrank and attached the bellcrank to the DiDion tube first. Used used a floor jack to coax the DiDion tube up while rotating the bellcrank to line up with the forward arm. Reconnected forward arm.

 

Disconnected the anti-roll bar during the process too. Not sure if that mattered.

 

Thanks again for the hints! :cheers: