balanced crank? do the rods need doing with it???

kiwicar · Post by **kiwicar** » Thu Mar 01, 2007 11:35 am

Many thanks for the reply Boosted
Yes I can weigh the rods end for end (to .1 gms) but will need to make a jig to do so (will do so over the week end).
These are Eagle H beam rods for an SBC so don't have the LE ballance pad (or any big end ballance pad) that the standard SBC rods have hence also the surface treatment on all surfaces (appart from the L/E and B/L very end surfaces about .75mm and these are a bearing surface themselves, I'll post a photo tonight. the pistons are fully coated so don't want to machine them if I can avoid it, I could weigh all the rings and locks and select those to bring in the last .2 of a gm or so on the pistons then match to the little end weight and get those to match. that would then just leave the big ends......
Is there any milage in the washer under the rod bolt approach or is this a real no no?

Any ideas of tollerences you would aim for? I was going to aim for +/- .2 grams on piston, pin pairs, (scales probably arn't actually better than that) then match them up with rod little end masses, then bring in the light rod as far as possable then pair these up lightest big end with heaviest and see if this gets the big ends on the crank with the same masses. it all really hinges on this light rod (unless it turns out the light rod has a heavy big end!

thanks again boosted I would really welcome your comment
Mike

kiwicar · Post by **kiwicar** » Thu Mar 01, 2007 11:36 am

And any and all other comment please, I am puzzled.
Mike

Boosted LS1 · Post by **Boosted LS1** » Thu Mar 01, 2007 12:10 pm

My scales weigh to a .10 of a gram but it's impossible to get consistency so I doubt you will either. They won't be accurate at that level. The jig you make will give you some stiction. Nowadays I try to aim for within .5 of a gram at each end of the rod. You could grind a bit off the rod cap where a pad would have been if you need to. It's not a stressed area or as suggested you could use a washer if need be. In fact I'd probably use a washer under both bolts to keep things equal. I'd go so far as to get a washer precision made to ensure flatness on both sides. As for the pistons, trimming a bit from within the skirts shouldn't be an issue even if they are coated.

Boosted.

kiwicar · Post by **kiwicar** » Thu Mar 01, 2007 12:23 pm

Thanks Boosted,
I shall go the washer route for the one rod and yes as you sugest I will use two, I will start with selecting washers once I have bought a big bag of them (was going to use un-coated mild steel) but may well end up having two made (any preferable grade of steel if I do?) I really want to avoid grinding the rods If I can. And try component selecting if I can. The scales appear fairly consistant, I have weighed then several (many) times in two sessions and the results for each rod have not varied more than once in 5 weighings (yes I am a sad git)
Thanks again
Mike

Boosted LS1 · Post by **Boosted LS1** » Thu Mar 01, 2007 1:54 pm

It's when you weigh end to end that you will experience variations.

As for the washers, you need something that's really hard from a precision engineering firm. Locktite it all together.

Boosted.

kiwicar · Post by **kiwicar** » Thu Mar 01, 2007 2:05 pm

Thanks again
I was wondering what I was doing with the weekend, now I know

. should be interesting

. Ill get some EN45 turned up and heat treated and see how it goes. Which locktight would I use for this? thread lock or one of the others?
Mike

Boosted LS1 · Post by **Boosted LS1** » Thu Mar 01, 2007 4:51 pm

I'd use an anerobic locktite. It's expensive but will set hard.

Boosted.

Post by **Coops** » Thu Mar 01, 2007 7:41 pm

RS got back to me today,

£130.00 + vat extra weight, extra work weight matching extra, will advise first.
and two - three week wait before any balance work can be done

may have to look around again

IainB · Post by **IainB** » Thu Mar 01, 2007 7:59 pm

Tony,
What about that other company that was mentioned in the old forum, one of the drag boys (edit Luke Bennett) had used them, will have a search, weird way of balancing though.....all will become clear in a mo

Ah Ha - I wasnt going mad http://www.vibrationfree.co.uk

Boosted LS1 · Post by **Boosted LS1** » Thu Mar 01, 2007 10:35 pm

thev8kid wrote:RS got back to me today,

£130.00 + vat extra weight, extra work weight matching extra, will advise first.
and two - three week wait before any balance work can be done

may have to look around again

Whats this all about Tony? I can do hand balancing within days not 3 weeks. Dynamic balancing depends on my outside source but usually within a week.

Boosted.

Post by **Coops** » Thu Mar 01, 2007 10:41 pm

whats your price mike?
as may pay you a visit if possible

Boosted LS1 · Post by **Boosted LS1** » Fri Mar 02, 2007 9:02 am

Tony,

I don't know exactly what you want doing. Do you want to give me a call sometime. Leave your landline number on the a/m and I'll get back to you.

Mike.

Post by **Coops** » Fri Mar 02, 2007 10:32 pm

i'll try and call you during the day saturday mike,

Boosted LS1 · Post by **Boosted LS1** » Fri Mar 02, 2007 10:46 pm

Mid morning or afternoon will be fine but as said, I'll call you back if I miss you.

Mike.

kiwicar · Post by **kiwicar** » Wed Mar 07, 2007 3:46 pm

Hi Mike
had a go over the weekend at trying to measure the weight of a big end of a rod, made a jig and every thing, compleetly inconsistant results, you are dead right, shame really had good highly consistant results on measuring whole items. Any sugestions on this, as without being able to compare end to end weight on the con rods it will be meaningless to ballance them further

Mike