I didn't see the need for making a bracket like you get with pineapple or tweakit kit (both are excellent kits). I just made a custom pulley using some bearings i had laying around (30mm OD). The pulley OD is around 38-40mm. Then I used a 42" 5rib belt. I probably should have ran a 41.5" long belt since the adjuster is maxed out, but the belt is tight. Hope this helps someone who's trying to do it themself

 

Hope that thing holds up and doesn't end up snapping on you

 

why would it snap? its got a grade 8.8 bolt through it.

 

It is not the bolt you need to worry about, it is the cast aluminum you have it bolted to.

 

I estimated the strength of that rib using this:

sigma = F/A, ~.75in * ~Pi*(.314in) = .742in^2

sigma = ~140lb max/.742in^2 = 188 psi of pressure on the threaded hole. cast aluminum has like 10kpsi+ tensile strength. its a good approximation without having to go into all the calculations for shear etc, it will be fine.

 

Too small of a brain to make anything of your equations. But if it works without issue, it would probably a nice alternative for the single turbo guys too.
And if adjustment is maxed, then you may end up buying another belt eventually anyway. Seems like they stretch a bit from new.

 

Have you had any instances where this has happened?

 

Actually I have personally seen the cast iron front plates crack the "ears" off behind the water pump housing with much less stress/force than is being applied to that cast aluminium "ear".

If it works long term for you, good deal. However, if it breaks off I hope you update this thread with a warning not to do this mod.

 

It looks like it would be pretty easy to incorporate support in as well if necessary...Lets see what homemade stuff I can come up with.

 

i think i could weld a bracket to the bolt seen above the pulley if more support is needed. i will update the thread on how its working out

 

There is a lot of pull leverage on the pulley end. Even if it holds it may bend just enough over time which will cause the belt to come off. I was getting ready to suggest the above to you. Get-er-done!!!!

 

remade the whole thing to be safe! used 2 bearings this time

https://www.rx7club.com/showpost.php...3&postcount=11

 

The first set up was a time bomb!

 

Here's mine that I made a while ago, still works just fine. I made it from a stock alternator pulley.
http://www.rx8club.com/showpost.php?...3&postcount=34

 

looks really good!