510 Idler Arm Bushing replacement

[RoadRace]

hey - this is just a cautionary note as i have never seen this happen. I was getting "death wobble" while driving straight, felt like the front wheel was coming off, but everything was tight. some research pointed to the idler arm bushings.

I got the DP Racing Delrin bushing kit with needle bearing thrust washer (PN 224-2101)

When i got the idler arm off, you could clearly see the bushing rubber was melting and dripping out, the drip had congealed - there is no heat source near the idler arm, the melting was coming from shear friction as the arm itself was cycling. this car is only driving on race tracks.

 

i also got the DP racing Idler frame channel doubler kit - and that's a good idea because when i took this one off (and it clearly had been on there for 40 plus years) the washers on the wheel well side were distorted and 'coning' into the bolt holes - this was also surprising.

 

this is stock as removed, note drip at bottom

 

 

this is a close up of the melted rubber coming out

 

new DP racing bushing installed, note Torrington needle bearing thrust washer

 

both bushings and sleeve installed, ready for re-assembly.

[datzenmike]

Is there a grease fitting for the idler? My 620 ball joints had the rubber looking like black caramel or toffee. I imagine the ball joints had been replaced some time in the past and the grease was softening and dissolving the rubber.  By 'rubber' I don't mean actual rubber as that will dissolve in petroleum products but some form of synthetic silicon rubber compound. Maybe these were cheap knock off joints?

 

Synthetic rubber does not melt and you could never physically generate the temperatures needed to cause it to decompose. What looks like a drip could be fine particles from chafing mixed with a lubricant, surely bushings in the idler arm are not run dry. They may be lubed and sealed?

[RoadRace]

There is no grease fitting at all. the drips were pliable, glossy rubber. its quite bizarre. during disassembly, the washer was found to be partially bonded where the rubber had actually re-vulcanized onto approx 25% of it. 

i used a drill bit to drill out the rubber and then press out the remaining bushing/sleeve and it came out pretty clean. when drilling, the rubber bushing did what drilling rubber normally does with no surprises. this is a rather strange scenario. 

[datzenmike]

There has to be some kind of lubricant in there I would think. Sealed for life?

[ggzilla]

The lubricant is grease. It's not sealed for life, you can remove the nut and re-lube it. However it is not a maintenance item, and they generally last more than 150,000km before needing re-greasing

 

Datsun used to sell new bushings for $10 so it wasn't a big deal just to replace them