Jump to content

- - - - -

Narrowed rear control arms

  • Please log in to reply
81 replies to this topic

#81 volkswagner



  • Senior Member
  • PipPipPipPip
  • 318 posts
  • Location:WA

Posted 20 October 2017 - 05:03 PM

Just make a new mount point and weld the damn thing onto the cross member where YOU want it. don't compromise on the design for sake of "bolt on". The 510 isn't a "bolt on" car. If someone can't weld they can have an exhaust shop weld it on for them...


Just sayin  :ninja:


Sucks cause this design won't work with my exhaust routing or solid mount diff setup  :blush:

Unfortunately we have to balance many more design considerations than just optimizing the suspension performance. Bolt-on reduces the amount of time we spend answering install questions so we can spend that time designing more parts  :thumbup:  Also, with bolt-on solution I can engineer all of the components with known constraints, I don't have to worry about variables like the booger welds that Bob the muffler guy puts the tabs on with. 

Bolt-on pays the bills.


Exhaust routing and diff. mounts are all the same. 


Very nice. I'm interested to see what happens with toe through the travel.


Suggestions: Box the upper portion of the Moustache structure. Bore a hole and insert a tubular sleeve (if needed) to provide access to the diff cover support studs.(or supply extra-long new studs.) Acceleration and brake forces are going to try to torque the mustache mount around each point where it mounts to the chassis. Boxing each side together will help  to control that stress.


If you want to sell these, consider squaring the arm to the angle of the mustache mount. This way, you can design around some existing O.E. rubber bushing, for those who want their car to remain somewhat civilized. The way it is currently angled, I don't think any rubber bushing would work. 


I've wanted to build a new structure that replaces the boomerang and mustache, but uses all the stock mounts. This is nice; cheaper and more attainable.



Predicted toe progression. Assuming the hub center is 115mm above the lower surface of the rear crossmemeber mount. (measuring ride height this way makes the measurement independent of wheel size), Aligned to 0.3 degrees toe-in per side at the 115 ride height. Also 0 camber. This keeps toe-in for over 2 inches of droop and compression. deviation from the alignment changes the rod lengths and so changes the progressions.


If you look the moustache-box is boxed around the suspension points and mounting points to transmit load, it is also boxed below to spread that load to the laterally. The diff mount section is single sheet to provide hand and tool access as well as to not clash with the spare tire well. This sheet is as thick as the stock mustache bar and so will handle the diff loads the same if not better due to the boxing on the ends.


No rubber, racecar. 



To maintain stability, structural integrity, stock configuration, and bushings, you could attach the trailing arm to a shallow member mounted to both points on the X member. That would giving it up down travel and have a left right and rotating only movement connecting the arm extending to the hub.


Although all these designs will theoretically solve camber issues, they'll do nothing about toe trail through. Not sure if that's a good or bad thing. I also believe the shallower the mounting triangle is, the greater the squat under power will be. 

The design allows good toe progression control. The camber control is actually more difficult. The key is that as the race rods arc they sweep in or out which changes track width slightly and adjusts toe.


Using the inner pivot results in ~1.5 times the upward force at the pivot during acceleration than the outer point. Should mean less squat. We'll see.

#82 paradime


    Datsun Mechanic

  • Senior Member
  • PipPipPipPipPip
  • 6,184 posts
  • Location:Easy Bay, 510 Area code
  • Cars:72 510 SR20 2 door, 01, Acura MDX, Valocci Electric Motorbike.

Posted 20 October 2017 - 06:11 PM



The blocked list is getting bigger-but you were the first.