Modifiying standard con rods
Turbo Mini Forums

Hi all. A few years back I read an article (I think it was Mini world keeping your mini alive) about modifiying con rods. What was said is that the standard rods have a lot of roughness to them with casting lumps still on them, so by grinding them off and polishing them with a wire wheel would improve their oil drip off. I really hope this is true as I've done this to my rods and hope I haven't weakened them. Does anyone have any ideas on this. :) Gav

as long as you have ground up and down the beam and not side to side.
make sure they are the same weight.

i would now advise having them shot peened, now that you have worked them

What does shot peening involve. I think I've done a good job on the rods. They look the muts nuts. Really polished. :)

fantastic, why don't you post up a pic and we may be able to advise,

carl

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

Failed parts often show evidence that the failure began at an imperfection in the surface, called a stress riser. Polishing removes a lot of imperfections, so the idea is that the polished part could take more stress before failure, or take similar stress for more cycles. The polishing that we can do with simple tools needs to be along the major stress axis.

Early automotive and aircraft engines could not rev high, the valve springs failed. Then one WW1 aircraft engine parts supplier started shot-peening the springs, they did not fail. Hmmmm. Plenty of science since then, proper shot peening impacts the surface in such a way that surface molecular bonds are stronger than unpeened surfaces, end result is it will increase the life of the part and/or increase the stress limits.

On this subject,has anyone modified rods to fully floating pins,at home ?.

VERY nice work ! I,m starting with Midget rods so dont have to machine away the huge lumps on the caps.
Sorry if I sound stupid,but I assume that you just ream the end for a sliding fit on the pins and let them run in the rod without any bushes?.
Have you got a foolproof way of holding the rod and reamer dead square, which is pretty critical.

I had a local engineering company put a bush in the end of my rods, to make them fully floating.

Luke

i was/am going to do this to my rods, but wasnt going to bother with a bush

the plan was to hone the little ends out, as there is probably only a few thou to remove, but when i came to do it, i wasnt happy about a few things, i.e. alignment, uneven honing etc, so going to ream them instead

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

Wow Thanks for your interest guys in this topic. My rods look a bit like Vegards but he looks like he's spent more time on his. I'll put some pics on as soon as I work out how to do it I was really worried that I'd sprapped em.

http://s603.photobucket.com/albums/tt113/madcatminis/


Yeah this is my rod. The photo actually looks shit compared to vengards but i have only polished the sides of the rods as I read not to do the inside of the h shaped bit. (if that makes sense?)

Edited by madcatminis on 10th Apr, 2009.

if you copy the bit that says IMG code and paste it in here you get the pic up as above mate. todays tip for you

Cool. Cheers for the tip james.

Sorry to bring this thread up again, but if I've fully polished the rods by grinding is shot peening also needed or can I get away with just the polishing. Is both processes really needed?? I do hope that I can just get away with the polishing as my pistons are now fitted. The chap at the engine centre said that the shot peening would be a waste of money unless I was revving the nuts off my motor and the fact that they are for a turbo motor where the power is at lower revs. I'm also using a standard turbo cam. What you guys think????

Edited by madcatminis on 22nd Jun, 2009.

Any comments chaps????

Looks like you've done a nice job, not sure how much difference it will make but hey they look nice. Regarding your comment about camshaft, the standard turbo cam is junk if you are after power, it is nothing more than a standard 1300 Metro cam! Ditch it ASAP! Good replacements are the MG Metro normally asp cam, or one of the turbo specific cams such as the Avonbar Ph 2.

I think that you need to shot peen the rods after that. That's because you've now removed the hard "skin" from the forging. Also, you need to check the rods for straightness. Removing the skin might bend rods. I've seen it.

I've just done another eight. Next time, I'll get them from Carl. Damn, I hate working on rods...

Edited by Vegard on 19th Nov, 2009.

Is there something wrong with me as i get a little bit excited when i see rods that are all polished!!! :)

Thats probably quote worth but am too lazy today.

If something is worth doing, it's worth doing half of.