Taking out ALL THE SLOP in A-arms ...

[Big Kid]

Ok, I'm new here and coming aboard to help me with getting ideas while sharing ideas already applied to better our 2 TYPHON buggies & a KRATON.


I may get to some pictures loaded as i get familiar with the format here and size limits ....
Having some machines in the shop ( lathe & mill etc ... ) along with tooling doing these mods are pretty easy tho really something not practical for most ... sadly.

What we did was place an A-arm in the mill vise holding it vertical. Then using a drill of the same size as pivot pin get the hole in A-arm perfectly lined up. Removing the pilot drill replacing it with a 1/4" 4 flute end mill.
Then we bored out the outer ends on both sides @ .150" deep. This created shallow counter bores where we're going to press in custom made sleeve bearings.
* This done ( So Far ) on the Top front A-arms, Lower rear bearing carriers, 8 in total right now.

Next was to go onto the LATHE and using some high grade material known as PEEK make up the sleeve bearings that will be pressed into the ends of A-arms. The I.D. hole of the bearing is only a few .001's bigger than the pivot pin O.D. and the bearings O.D. @ .003" larger than the bored out A-arms counterbores creating a press in fit.

Once bearings were pressed into the counter bore of A-arms. Using the OEM pivot pin ran it into the bearing of one side and out the other. A bit of wiggle to get the bores aligned and the A-arm flops freely on the pin.

** The rear Bearing carriers which sit between the tabs of A-arms got the same treatment getting a bearing on each side.

Final trick was THROWING AWAY !! the clip in C shims on front top A-arms and making simple Delrin washers to fit the gap specs wanted on each end. *This removed any fore & aft motion of arms on the pins.
Also tossed away the rear lower carrier washers using BIGGER diameter delrin washers sized to gap & offset wanted.

All said the A-arms and Carriers have virtually NO WOBBLE on the pins now what so ever !!
Wheels stay in perfect tracking alignment and suspension is vastly tightened up !

Onto the track along side my sons stock Typhon the handling is so much improved with the buggy so much more planted with more predictable tracking in & out of the corners, jumps and whoops.

* After now @ 10 packs run threw it the A-arms, Carriers are still just as wiggle free while my sons OEM stock car continues to degrade as it get looser and looser in these critical areas.

Scott

 

[Big Kid]

OK ... here a few pics of thrush washers and bearing mad to fit A-arm / carrier block.

 

[FreddyBrady]

I applaud the time invested to fix this problem right. I have an old bridgeport and a lathe and will probably be copy catting this idea as i to am getting the jiggly, wandering wheels and its driving me nuts. I have never heard of peek till now and it Looks Like The People Who Make it Are Proud Of It. how much Longer Would the Peek Last Than Delrin Or Bearing bronze? Ive Got that Stuff Laying Around.

 

[Big Kid]

I applaud the time invested to fix this problem right. I have an old bridgeport and a lathe and will probably be copy catting this idea as i to am getting the jiggly wheels and its driving me nuts too. I have never heard of peek till now and it Looks Like The People Who Make it Are Proud Of It. how much Longer Would the Peek Last Than Delrin Or Bearing bronze? Ive Got that Stuff Laying Around.

Bearing bronze while CLEAN works great ... sadly R/C buggies are not clean.
Delrin in the ( acetal actually ) AF grade or glass filled will work OK, just happen to use a lot of PEEK in my air gun hobby where this material is proven TOUGH !!
Peek is pricey but your not using much either.

Once A-arms & rear carriers are modified and you keep the counter bores .150" or so deep, extracting bearing sleeves as they slop out is easy enough with some pin & wobble action to R&R as needed.

 

[FreddyBrady]

Ill order some peek and test it out. i've got a kraton and I notice alot of steering slop through the bell crank and rod ends also. Probably worth it to find some tighter rod ends and make some servo saver bushings aswell.

 

[Big Kid]

Ill order some peek and test it out. i've got a kraton and I notice alot of steering slop through the bell crank and rod ends also. Probably worth it to find some tighter rod ends and make some servo saver bushings aswell.

Yup, measure up the servo bell crank oil-lites, up size the fit a tad on O.D. and make em wider to take out the vertical slop ... you will be golden !

 

[Mongoose]

Nice choice on the PEEK. We use that as an insulator when they need to be rigid over the softer and cheaper green glass alternative on our EDM machines.

Would you be willing to sell some of these bushings?

 

[Big Kid]

Not in the parts biz and making them one at a time on a manual lathe is not cost effective.
other issue being, pending size of the counter bores and there depth ... bushings get made to fit said counter bore in O.D. & depth.

Being my OP is starting to get some interest, want to elaborate more on the making of the counter bores within the a-arms and carriers.
While doing my first ones on the front A-arms had used the 1/4" end mill and it did fine ( so long as everything stays lined up in the mill )
When doing the Rear carriers had thought about a Piloted cap screw counter bore tool ??? ... hey i have some and found the 8-32 size was perfect having a .161" pilot and .285" flutes ** requires using turned down 5/16 PEEK rod and not 1/4"

Still needs to be done in a mill, but the pilot keeps chatter minimal and makes sure the counter bore follows true to the pin bore while giving a more consistent size & depth of counter bore.

 

[Tankman]

I have no idea how you do this lol but impressive. I just got an Outcast and was wondering if you'd sell these if I paid for material via PayPal. Would using RPM A-arms be even better?They're not much more than stock.

 

[WTF MIKE]

Is peek harder than ipe?