"Normal" Press Fit

[Barry Donovan]

a lot of years to mix in aftermarket, decipher tricks.
Nothing is the same on my own project from the 80s.

if a pro complained of too loose back then, there ya have the answer..it altered the numbers forever.

Nothing to get uptight over.

I found the Subaru has the same pilot bearing as an alternator. the Mercedes may have a trick number elsewhere, an original.
I'd keep working in the tight one..ther is a smart reason somewhere.

Remember a diesel is a big torque number on old steel...I'd want too tight as well.

there is also a trick to add high temp wheel bearing gease with a pin greaser to lube the new one. I don't mean slick it up to press fit, I mean the bearing itself, internal.

[BKBridges]

Dan,
A "soft" journal bearing would be a .002 interference, but a ball bearing should be put in per old machinists customers wishes... .0002 interference max (in your size range). Hardened races into a hard crank flange don't give much. We do a lot of ball bearing assembly and we use a tapered bore with a .0002 clearance at the top and a .0001-3 squeeze at the bottom (giving away the secrets...) Not something you'd do with your crank though. IMO its time to get out the brake hone and hone out the crank to the OD of the bearing. If you were able to install the ball bearing with that much interference (.002) it would clobber the bearing's tolerances and surely make for a short ride on the races.
BKB

[DanStokes]

BK - Good Idea on the brake hone. However....... The hole isn't deep enough to keep the stones straight and a dingleball would hit the wrapped wire area on the bottom of the hole (where the twisted wires come together) so the balls would only minimally engage.

What I'm doing is using a Tootsie roll on the die grinder followed by a less aggressive flap wheel to take the grinding marks out. The Tootsie roll is pretty stiff and I pay a lot of attention to keeping it moving radially and straight to the bore so I don't think I'm too far off. I'll see if I can dial indicate the bore to see if it's concentric but I'm not sure if I can get my indicator in there.

Great ideas - keep 'em coming, please.

Dan

[Mr4Speed]

Does it have to be a bearing? If you could find a bronze bushing that was bigger on the o.d. and smaller on the i.d. you could get it turned to size to fit, and they're a lot more forgiving on assembly, and misalignment during use.

[rightpedal]

Hey Dan just spit balling but.... How would a mag drill work? Use the existing hole to line up the drill and step up drill sizes. Now that I am thinking about it would a mag drill fit on the current flywheel. I saw it done on a caddy 500 motor that they were changing over to manual trans.

Just thoughts.

Steve

[DanStokes]

It's done now and SEEMS OK. I hope to bolt the trans up today (yesterday got too busy).

Here's a pic of the bore after I hogged it out with the die grinder and one of the bearing in place.

Dan

[Beagle]

man they REALLY didn't want that flywheel coming off!

[DanStokes]

There are so many bolts that I just ran 'em in by hand and anchored them with marker paint - should be fine. Especially as they're grade - um - maybe 2,000 or something - it's written in metric.

Typical M-B over-engineering.

Dan

[phitter67]

Official M-B marker paint? I believe it has to be metric as well.

[DanStokes]

You bet. Though I cheated a bit and bought the generic German brand instead of the M-B branded stuff - it was 1/2 the price - got it down to $247.85 (if you guys have bought German parts you'll know what I'm teasing about).

But seriously - those numerous bolts tighten to 30 lb-ft then turn another 90*. The bolts are special and have a reduced neck just under the head.

Dan

[BKBridges]

Dan,
Skilled die grinder usage. Nice work!
BKB

[DanStokes]

Well, I hope so BK. This has yet to be proven as I don't know how concentric it is. I think not TOO bad though - I kept the die grinder moving and tried to start and stop at the same point while keeping the Tootsie roll 90* to the bore. Worst case is that the input will travel in a bit of an orbit but I don't expect it to last 100K (miles OR klips).

Dan

[Caveman Tony]

nice job Dan!

Although, personally... I woulda just gone down to the big local liquor warehouse and picked up some dry ice.

If it works for military aviation engine building, its good enough for me.




I used to work in a AF jet engine rebuild shop.... Lol, and guess where we sourced our dry ice...

[DanStokes]

Interesting thing is - when I DID manage to force the first one in there the bearing got so tight it wouldn't spin freely. Evidently it all sort of crushed into the center hole. So hogging it out was, ultimately, the right thing to do. I still think it's stupid for M-B to make 2 slightly different sized crank holes (stick and auto) when the could just make the converter nose the same size as the OD of the pilot bearing, which is a standard bearing. Typical Benz.

Dan

[CTX-SLPR]

Interesting thing is - when I DID manage to force the first one in there the bearing got so tight it wouldn't spin freely. Evidently it all sort of crushed into the center hole. So hogging it out was, ultimately, the right thing to do. I still think it's stupid for M-B to make 2 slightly different sized crank holes (stick and auto) when the could just make the converter nose the same size as the OD of the pilot bearing, which is a standard bearing. Typical Benz.

Dan

Odd but not unprecedented. I remember reading that Ford did something similar with the MEL engines so you that you'd have to actually counterbore the back of the crank to put a pilot bushing/bearing in it. It wasn't even machined more than the ~3/8in needed for a torque converter pilot.