DZUS Fastener Question

[PortRS]

I’m checking my car (310S) prior to starting it after winter, first time removing the nosecone, and both lower Dzus bolts are missing. Can I replace just the bolts? 
 

The Caterham UK parts site shows a different fastener for the upper and lower, what is the measurement so I can order them locally? Thanks. 

[wdb]

I’m not familiar with newer cars but on my 1995 the bolts are attached to the frame for the bottom fasteners. The “S” springs are on the nosecone. The top fasteners are the opposite, more or less. 

[fastg]

It looks like that was probably once a Self-Ejecting Dzus fastener. Checkout https://www.pegasusautoracing.com/advcat.asp?CategoryID=DZUS

 

Graham  

[MV8]

I'll assume you want one of the aftermarket fasteners which are similar to the aviation type but are measured differently for ordering.

Generally, the aftermarket self-ejectors are not offered as individual components. If you want to replace just the fastener (no retaining groove for the ejector type snap ring), for the shank size, using a six inch dial caliper, measure the center hole size in the plate or find a known size bolt that is a little smaller in shank size. There are also metric fasteners available.

For the "grip", with the dial caliper, as you open the jaws with the thumb wheel, a rod extends from the square, far end of the caliper. With the nose installed and pressed inward toward the chassis mounted fastener spring wire, place the far end of the caliper across the plate (not over the rivet area) and extend the rod to touch the spring wire. The "grip" ordered will be the first grip length size LESS than this distance. They tend to come in bags of 10 so keep some in a glove box. The spring is pulled out of position by the fastener to hold the panel and prevent falling out from driving.

Self-ejectors also come in different grips and may have different rivet spacing. I think the spring wire thickness is fairly standard/universal.  

[IamScotticus]

When you know what you need  replace everything with stainless steel, if it isn't already stainless. 

[PortRS]

Thanks for the helpful advice. The one thing I don’t want to do is remove the rivets and replace the whole fastener. Wonder what happened to the bolts?

[IamScotticus]

I will suffer the embarrassment for your benefit. 

Here is what happens after years of neglect and why Im recommending stainless here.

 

Also,  although your Dzuz are reversed in order, the captive concept is the same.

 

Your screw should not have fallen out unless there was a constant pushing force on it for a long time.  If they had released from the S springs or were never fastened to begin with, its possible they could have been worked through the holes.

 

The winged screws are my addition.  I drilled out the old rusty flush ones and riveted these in.  Its really easy.  You're working on fiberglass so make sure the rivits are light duty aluminum.  You gotta know how to rivit if you own a seven.

Edited April 1, 2023 by IamScotticus

[bball7754]

FWIW, I stopped fastening the bottom dzus fasteners about 10 years ago, and that includes lots of track sessions.  YMMV. 😊

 

Steve

[Vovchandr]

55 minutes ago, bball7754 said:

FWIW, I stopped fastening the bottom dzus fasteners about 10 years ago, and that includes lots of track sessions.  YMMV. 😊

 

Steve

 

Mine were missing an I've never used the bottom either. 

 

With that said there is some damage from vibration and extra stresses on that lower lip (can't be seen but concerning)

[IamScotticus]

Yep.  not happy with Dzuz down there and very fidfly to align.  I will be considering altetrnative solutions going forward.

Velcro?  Rubber bands?  Duct tape!

Edited April 1, 2023 by IamScotticus

[Vovchandr]

You can always try the 620R style mounts. You'll need new mounts welded or attached but they are more sideways and higher 

[fastg]

Aircraft Spruce sell the individual fasteners. 

 

https://www.aircraftspruce.com/categories/aircraft_parts/ap/menus/ha/fast_1dzus.html

 

Graham 

[IamScotticus]

2 hours ago, Vovchandr said:

You can always try the 620R style mounts. You'll need new mounts welded or attached but they are more sideways and higher 

I remember being more sideways and higer...

Im stuck in the 90s.

could someone put up a pic of those please?

Edited April 2, 2023 by IamScotticus

[MV8]

Here is a way to add adjustable side mounts without welding. Also, Skybolt makes very nice dzus type fasteners.

 

Edited April 2, 2023 by MV8
Drew spring on the wrong side of the bracket plus the cat brkt is better/lighter.

[Taber10]

Wow, the idea of being able to operate all four Dzus fasteners without getting underneath the nose is really appealing.  Thanks for posting.

[JohnCh]

Here are a couple of pictures of a lower 620 nose cone mount.  The first shows the location near the lower radiator mount, the second is an overhead shot that highlights the angle in relation to the lower A-arm's front mounting bolt.

 

 

 

-John

[Vovchandr]

45 minutes ago, JohnCh said:

Here are a couple of pictures of a lower 620 nose cone mount.  The first shows the location near the lower radiator mount, the second is an overhead shot that highlights the angle in relation to the lower A-arm's front mounting bolt.

 

 

 

-John

 

This post made me realize that I've never bought the brackets yet. Granted I'm still quite far away from mounting/painting the nose 620 nose cone as I haven't settled on the stripe style. 

[IamScotticus]

Side mount?  Easy?

Sacrilege!