MKI_GT6
MKI_GT6 New Reader
8/19/14 9:50 p.m.

I'm researching different designs for the bell crank I'm going to build for the rear pushrod suspension on my GT6. It seems like there are quit a few different methods of pivot, from bearing, to uniball, to oil filled nylon, to rubber bushing, to just rotating on a through bolt. I wanted to get some opinions on what you guys thought might be the best way to allow the bell crank to pivot.

Thanks

stafford1500
stafford1500 Reader
8/28/14 3:37 p.m.

There is a needle roller bearing that incorporates a needle thrust bearing on one end (Nadella) that is designed to take the loads you are looking at. The best option beyond that is to get individual needle rollers for the pivot around the through bolt and add needle thrust bearings at the ends (all with hardened races). This is the way to keep the components cheaper, despite having more physical parts to keep track of during removal/replacement. Also cheaper to buy the individual components. The preload is the challenge, so be prepared to spend some time doing some serious measuring and shimming.
I have done the individual component method on all four corners of my project with pushrod/rocker systems. The complete assembly moves very smoothly, as long as there is not too much of-axis loading, but that is what the thrust bearings are for...

erohslc
erohslc HalfDork
9/6/14 7:56 p.m.

Or, look at how an OEM did it (rear suspension on PT Cruiser), and perhaps 'repurpose' some bits.
You can also examine the rockers used on some motorcycle shocks, these see high loads.

bgkast
bgkast SuperDork
9/6/14 9:23 p.m.

The PT Cruiser doesn't use any sort of push rod suspension (that would make it about 200% cooler)

It uses a Mc struts in the front and a beam axle with a watts link in the rear:

bgkast
bgkast SuperDork
9/6/14 9:26 p.m.

Pushrod suspension:

erohslc
erohslc HalfDork
9/7/14 11:04 a.m.
bgkast wrote: The PT Cruiser doesn't use any sort of push rod suspension (that would make it about 200% cooler) It uses a Mc struts in the front and a beam axle with a watts link in the rear:

Yes, you DO realize that every Watt's linkage uses a BELLCRANK, right?
(that would be the 'bellcrank shaped thingy' in the middle of the Blue components in your picture)
The OP question was about bellcranks.

But speaking of pushrod suspension, here are pix of a couple of versions of the Yamaha R1 shock and pivot linkage, not bellcranks per-se but perhaps useful:

https://search.yahoo.com/search;_ylt=ArO7yTzuipXJemVy1SgoWpObvZx4?p=yamaha+R1+shock+pivot&toggle=1&cop=mss&ei=UTF-8&fr=yfp-t-901&fp=1

https://search.yahoo.com/search;_ylt=ArO7yTzuipXJemVy1SgoWpObvZx4?p=yamaha+R1+shock+pivot&toggle=1&cop=mss&ei=UTF-8&fr=yfp-t-901&fp=1

The problem with any pushrod system on a Spitfire/GT6 is lack of room. But once you shed yourself of orthogonal up-down thinking, you can find lot's of place to put coilovers, the challenge then is to craft a set of linkages connecting them to the vertical links. With careful planning, you can wind up with a nice rising rate result.

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