Tips for prepping rods?

[mick08]

hmm ok will have a think about it. realistically they would only need to be 1/2 as thick going through the piston as through the rod. although with correct choice of material it probably wont matter (i think i actually have titanium bar stock in the right size already and its bloody light!!)

I don't know if titanium is the best material most good pins are made of tool steel, not 100% sure what elements make up tool steel but i do know i haven't ever heard of titanium pins, check it out, be interesting to hear what you come up with.

[oldcorollas]

are the lighter gudgeon pins same material just smaller or something stronger? i may as well knock a set of light ones up while im playing on the lathe. mmmm titanium anyone?

titanium = no.
not good for fatigue (VERY notch sensitive) and hard to machine without making crack starters...

not many titanium rods around.... and not much titanium in aircraft either

[andrew_mx83]

fair enough. we just got a bit of bar stock for shits and giggles, to see how it was to work with and what we could make out of it. turns out it cuts fairly easy with normal tool steel, the swarf comes off bloody hot though!!

i do like my new ring



its probably not the ideal material, but for laughs i priced up some bar stock to CNC some pistons out of, $2500 OUCH!!!

so what material for gudgeon pins? or just bore out standard ones?

[oldcorollas]

is it Ti6Al4V?

iirc, Ti in general work hardens hugely when coming off.. or something liek that...
so much so that for that new F35(?) joint strike fighter, some ppl in Aus developed a laser assisted maching process... the laser heats up the Ti just ahead of the tool, to make it easier to machine.
Ti typically has a 10:1 weight ratio, of material bought vs part made

anyway, enough OT

[andrew_mx83]

indeedy (but thanks for the info).

so i will clean up the beams/end of casting marks/ridges then polish, then check balance then peen.

is there any point at all in cleaning up the insides with a polishing stone on the die grinder?

[mick08]

Talk to your balancer but i would have them shot peened before going to him, he will take minimal material in the right places, just my opinion but i would let him be the last person to touch them before they go into the engine.(besides a good clean)

[andrew_mx83]

he did say to peen them first, but i then worry that if he takes any material off it will damage the hard skin from the peening

i might just get some whales and balance them myself as i go

[dangdang]

he did say to peen them first, but i then worry that if he takes any material off it will damage the hard skin from the peening

i might just get some whales and balance them myself as i go

Sorry I couldn't help myself

[oldcorollas]

he did say to peen them first, but i then worry that if he takes any material off it will damage the hard skin from the peening

i might just get some whales and balance them myself as i go

thats the irony of the car performance world
same as why everyone cryo-treats stuff that it has no effect on

edit: but the areas he does touch, can be peened again anyway

[mick08]

You will see he will take off a miniscule amount and it won't be worth a pinch of shit to the 'hard skin'.

[oldcorollas]

the "hard skin" is the layer with compressive stress, that closes the cracks... if you remove that layer in some area, then why shot peen at all?
the layer of compressive stress is not very thick, probably less than 1mm..

on the other hand, 1 gram of steel is abotu 1x11x11mm ....
if a rod is out by 1 gram, there is no way it can be balanced and not destroy the shot peened layer in that area

if they remove a miniscule amount... then they are not really doing anything are they?

[oldeskewltoy]

sorry.... not been around for a bit......

You CAN get titanium! I've enquired,BUT as the miles build the titanium pins will gaul and require a rebuild.

These pins are slightly tapered, and are of a different material. When I build my 4AGE using 80% stock parts, the pins was one of my few aftermarket choices to improve the engine.

Here are the links I have to my wrist pin "soap opera"
http://www.hachiroku.net/forums/show...2&postcount=85
http://www.hachiroku.net/forums/show...&postcount=124
http://www.hachiroku.net/forums/show...&postcount=126
http://www.hachiroku.net/forums/show...&postcount=131
http://www.hachiroku.net/forums/show...&postcount=132
http://www.hachiroku.net/forums/show...&postcount=135

[Sam_Q]

so who sells off the shelf 20mm floating gudgen pins for a 4age? from the links above it looks like only Ross have something close.

Also did you end up trying these out in your engine?

[andrew_mx83]

hmm i wonder what the coating on the titanium pins is..... this motor is race only and will never do 30,000 miles!!

[mick08]

the "hard skin" is the layer with compressive stress, that closes the cracks... if you remove that layer in some area, then why shot peen at all?
the layer of compressive stress is not very thick, probably less than 1mm..

on the other hand, 1 gram of steel is abotu 1x11x11mm ....
if a rod is out by 1 gram, there is no way it can be balanced and not destroy the shot peened layer in that area

if they remove a miniscule amount... then they are not really doing anything are they?

A Conrod is weakest where the beam meets the bigend and majority of rod failures i have seen have fractured there, when they balance rods they don't take off huge amounts of material its only to match all the weights to the lightest one unless your rods very old or maybe from a fucken Ford or something, the idea of removing the forge marking that runs down the beam with a grinding/flapper wheel is to get rid of any sharp/irregularities that could start a crack under stress, then it is common for people to put that hard skin back with shot peening process,when material is removed for balancing its usually done either on the cap between the bolts/nuts or over the top of the little end- Not removed from the Beam area.