Syncro Upper hinge pins loosening

[Klappars]

Syncro 4 upper hinge pins keep coming loose.

I keep re-securing them with the 1.5mm set screws but these often come loose even when tightened properly

Any fix or upgrade for this?

 

[Nelson.81]

Bit strange that the upper The hinge pin is threaded & also has set screw to hold it. Maybe the threads are stripped in the hole I would try different set screws 1st see if they hold . I don’t know of any upgrades so if new set screw don’t work I would just try bit of blue loctite on threads of upper hinge pin & set screw see if it holds if not replace the part it screws into unfortunately only option I see. Cheapest on eBay if you uk

https://ebay.us/m/Ja6nS3

 

[Klappars]

Bit strange that the upper The hinge pin is threaded & also has set screw to hold it. Maybe the threads are stripped in the hole I would try different set screws 1st see if they hold . I don’t know of any upgrades so if new set screw don’t work I would just try bit of blue loctite on threads of upper hinge pin & set screw see if it holds if not replace the part it screws into unfortunately only option I see. Cheapest on eBay if you uk

https://ebay.us/m/Ja6nS3

I have very recently replaced the upper top plate/front chassis brace part which the hinge pins screw into.

The set screws do but down on the pin threads but despite that the hinge pins still loosen quite often.

I am aware that thread lock cannot and shouldn't be used on plastic as it can degrade plastic.

For now, I have wrapped some PTFE tape on the hinge pin threads to give more of a friction fit.

I was hoping that parts from the Spark or another Corally vehicle could be swapped to fix this design weakness.

 

[Nelson.81]

loctite used in other areas like the diff cases which are plastic don’t be afraid of using a little bit. Unfortunately with the chassis brace being part of the upper hinge pin holder on Syncro no parts from other vehicles are compatible not unless your willing to loose the chassis brace. If you sacrificed it you could use the top deck/upper hinge pin holder from a different model like the Asuga as it uses same upper hinge pins as Syncro.

 

[Klappars]

loctite used in other areas like the diff cases which are plastic don’t be afraid of using a little bit. Unfortunately with the chassis brace being part of the upper hinge pin holder on Syncro no parts from other vehicles are compatible not unless your willing to loose the chassis brace. If you sacrificed it you could use the top deck/upper hinge pin holder from a different model like the Asuga as it uses same upper hinge pins as Syncro.

The diff casings have nyloc nuts in them don't they, so safe to use thread lock?

Will look into Asuga top deck and hinge pin holder.

Would it still be possible to fit another front chassis brace?

 

[Nelson.81]

No no nylon lock nuts in diff cases just screw into plastic diff case. No other chassis braces fit unfortunately & if you installed Asuga top deck would need to change shock towers also(like one in pic) I would just try changing the grub screw or use a bit of loctite.

 

[Atomic Skull]

The diff casings have nyloc nuts in them don't they, so safe to use thread lock?

Will look into Asuga top deck and hinge pin holder.

Would it still be possible to fit another front chassis brace?

You won't find anything that can dissolve nylon in a consumer product you have to get into the scary stuff like formic acid or dimethyl formamide to affect it.

EDIT: Goo-gone might but I won't have that stuff in my house way too dangerous for a consumer product imo.

 

[danl]

Vibratite VC3

 

[Klappars]

So, applying some thread lock which won’t damage the plastic could help here?

Might try that if the PTFE tape doesn’t work.

 

[Nelson.81]

So, applying some thread lock which won’t damage the plastic could help here?

Might try that if the PTFE tape doesn’t work.

No just don’t go crazy with it, if your worried you said you already replaced the part try it on the original part see how it holds.

 

[Atomic Skull]

So, applying some thread lock which won’t damage the plastic could help here?

Might try that if the PTFE tape doesn’t work.

Stripped holes in plastic are almost always because you are over tightening the screws.

EDIT: I see you have already replaced it with a new part so the holes should be fresh. For holes in plastic you should use "plastic thread lock" which is basically the same thing as gap filling "thick" super glue with blue dye added and a huge price markup. You can just use locktite thick superglue or gorilla super glue (any "gap filling" super glue will work) and apply a bit to the threads before screwing it in (you do not want to apply it to the screw as it would then get on the inside of the suspension arm hinge). Use a toothpick or similar implement and don't go nuts with it just squeeze a drop out into the toothpick (have a piece of paper underneath when you do this to catch spillage) and then apply it to the inside of the screw hole.

The hinge pins are not intended to be fully torqued down, if you are getting some back to front play you need to add a caster clip to take up the space. "two finger tight" only.

Also the holes in the arms are slightly oversize and will always be a bit loose on the pins, for a fix see this thread: https://www.corallyforum.com/threads/repairing-a-split-upper-front-suspension-arm.1585/

To fix a stripped or overly loose hole this has worked for me, clean out the screw hole with alcohol and a dental brush to remove any grease and allow it to dry (wick it out with a rolled up piece of paper tower and let it sit for a while). Then apply a drop of "thin" super glue to the threads with a toothpick or similar implement and work it around so it coats the inside of the hole and let it cure. Apply the glue to the toothpick and then stick it in the hole and work it around the inside you want to coat the inside but don't overdo it. This will bulk up the threads so that they hold the screw more tightly. Cut the point off the the toothpick it makes it hold the drop of glue better, or just use square ended toothpicks.