We all know about these, and how they are used to help save a worn damper with a groove from high miles. If your putting together a daily driver engine that is going to see a lot of miles, or using an expensive damper would it not make sense to install a speedi sleeve on the new balancer right at the start? Never seen anyone do this on a new engine build, and yet it seems like it would have no drawbacks? SS is harder than cast steel or cast iron that most balancers are made of so it should last much longer or maybe even forever? Anyone ever wear out a speedi sleeve before?

on semi trucks that get thousands of miles. Birdtracker

It takes a long time and lot of miles to wear a groove in a balancer, plus depending on what brand seal you are using, most replacements are made with the seal lip in a slightly different location. I have seen old balancers with two or three grooves in them. No issues with a stainless-steel sleeve I would think a little overkill on a new balancer.

Maybe I'm misunderstanding what I am seeing but I'd swear that a sleeve on a balancer wears a groove faster than the balancer itself.

This is true. I put a bunch of speedy sleeves on Allison output yokes and they eventually wear a groove in the sleeve and leak.

Wonder if that is due to the larger diameter of the sleeve making the seal fit tighter so it increases the amount of friction? I've never installed one of these and was just curious if this was a good idea or not to use one right off the bat.

Larger diameter does increase friction, plus dirty oil causes wear. If you can find one give a shot, just use a fine point pick to get the seal lip over the edge of the sleeve or it will get cut.

I have a damper from Damper Doctors that came back with a sleeve on it. I've had it on a couple motors and there's no wear on the sleeve yet, but it's drag race only.

I'm sure cast iron is harder than stainless, and has better wear properties.

it all depends on the grade of stainless or cast iron the item is made out of.
having machined all grades of both over my 45+ working career, i have run into cast iron that was so hard it was a real task to find the right cutting insert grade to plow through it.
and although stainless grades can be super tough as well, i have cut several grades of it as though it was made of butter.
just my personal life experiences as a machinist. your mileage will vary.

speedy sleeves are soft. If they were hard they would split when being stretched onto the parent part. If you had cast material as thin as a speedy sleeve, it would split as soon as you started to press it on.

I've used 4 or more speedy sleeves on several different Mopars brands motors and the other brands engines from NAPA and Auto Zone parts stores and had no issues with either brand
I lube up the seal and balancer snout with H.D black moly wheel bearing grease
I use Anti seize on the snout of the crankshaft and the inside sealing surface of the balancer also

Yes, it's good to lube those up so the new seals don't run on dry metal on the first start. I use assembly lube and also put it on transmission front pump seals where the convertor goes in too. Just a light coat does the job.