View original topic: DIY flywheel hub refinishing... Page: 1, 2, 3, 4  Next
dhaavers Fri Sep 21, 2012 8:53 pm

"DIY flywheel hub refinishing...for non-flywheel-hub-refinishers"


Anyway...the final step before feeling fully confident in my recent clutch replacement & reinstallation
was to deal with the obvious-but-not-terrible groove in the flywheel hub.

Sorry - I forgot to take a "before" picture, but if you've been there, you know what I mean.
The groove in mine was visible, but hardy detectable. I'd guess maybe a couple thousandths, no more.

[EDIT: misleading photo removed - [but you can see it quoted on p.2 if you like...] :roll: ]

I was convinced it could & should be done, based on several posts like this:
(Posted: Tue Nov 23, 2010 12:26 pm)

tencentlife wrote: ... if your flywheel has a deep groove on the seal hub it will leak (even with a new seal)...repositioning the seal at a different depth will not help; that will trash the new seal even quicker. If the groove is deep enough to catch your fingernail, it is too far gone and you should find a new FW or replacement in better condition; but grooves shallower than that can be improved:

The FW can be set up in a lathe or other device to turn it steadily (I have done them by hand bolted to a crankshaft and that laid in V-blocks, but made an adapter for my lathe) and the groove abraded out and polished by using successively finer grades of abrasive paper or cloth (emery is preferred for steel), lubricate generously with WD40 or something light. Start with a 40-grit, work up to 1200 or 2000. Take your time and get it to as smooth a finish as possible. Extra points for doing a final polish with a cotton buff and suitable polishing compound...
After thinking on this for a week or two, (and me without a lathe - what to do?) It came to me:

1) Got myself a $5 rubber 3M "Disc Pad" (used for circular sanding discs with a power drill):

2) Used it as an arbor to mount the flywheel (the rubber helps grip the flywheel & keep it centered):

3) The concave mounting washer provided also helps center on the pilot shaft hole:

4) In place of the small screw provided with the pad, I used a 1-1/4" stove bolt
to allow for the depth of the flywheel, plus a few washers to take up some slack.

5) Mounted my cordless drill to a spare work surface (did I mention I'm cheap? :wink: ):

6) Used a spring clamp to lock the trigger (using the slow clutch setting):

7) Just as described by tencent: a bit of WD-40 to float the swarf, and about 5 minutes with a narrow strip of each successive grit
(50, 80 & 150-grit emory cloth, then 220, 320, 440, 600 & 1500-grit "wet-or-dri"):

8 ) Here are results after the 600-grit, with 1500-grit yet to come:

I managed to kill both of my batteries in just under an hour, so I decided to call it a day and finish up tomorrow.
(By this time it was also a little past beer-thirty - another perfectly good reason to save some work for later...)

I plan to finish with the 1500 wet-or dri & then go completely anal with a round each of rubbing & polishing compound...


Ok - I admit it isn't perfectly secure and not entirely wobble-free, so I added a margin of safety as shown in pics #5 & 7:

- I screwed a plastic crate to the floor directly below the flywheel;
- fitted a heavy cardboard box inside the crate & reinforced the box with fiberglass drywall tape;
- stuffed the box with a bag full of plastic packing peanuts...

I figure if the flywheel DOES get loose, it'll have a tough time keeping much momentum through the loose peanuts, cardboard, fiberglass & crate.

Also it's unlikely to sustain any damage from these relatively soft materials...<crosses fingers>

Be careful working over your toes or concrete...YMMV.


Otherwise - it seems to be working, right?


Crankey Fri Sep 21, 2012 9:12 pm

I like it.
I've used drills as grinding lathes before. nice job on this one.

dhaavers Sat Sep 22, 2012 5:26 am

Thanks! I just know I'll sleep better without that groove in the flywheel...

Zeitgeist 13 Sat Sep 22, 2012 10:05 am

I like your ingenuity. You desperately need a drill press.

?Waldo? Sat Sep 22, 2012 10:42 am

I congratulate your ingenuity and hope it all works well for you. At the same time, if the disc breaks or the flywheel comes loose some other way and then drops into the cardboard box while spinning, what's to prevent it from rolling right out of the cardboard box and becoming a very expensive DIY project? I'm much cheaper than you are and so I have the machine shop do it or I install a redi-sleeve.

dhaavers Sat Sep 22, 2012 2:20 pm

Thanks for the kind words (& a smattering of hand-wringing - Andrew!)
I'm just doing what I can with what I have & letting y'all know it's working.

FWIW, tencent has posted a number of times on this process and mentions that
every machine shop turns him down when he's asked if they can dress the hub...
I even asked my guy yesterday & same story. Maybe eventually there'll be a
machine for this, but it doesn't exist now so this is how I took care of it.

Regarding your concerns for personal and material safety; isn't it clear that I thought about this ahead of time?
Plastic peanuts, double-layer cardboard containment and multi-layer fiberglass safety net, all secured to the floor
within another heavy plastic crate...lots of layers of redundancy & all chosen to be energy-absorbing...
I was very comfortable with what I was doing.

Of course, you can do what you want - I'm just documenting what I did, as I searched but
found no other topics addressing this and thought it might be of interest to the community.



FWIW - finished the process today and I'm very happy with results:

This after finishing with 1500-grit, plus rubbing- & (finally) polishing compound*.
It's clean & ready for a new seal and many more miles...

* (Also eagerly awaiting receipt of my "extra points" from tencent...!!!)

Happy Trails!

dhaavers Sat Sep 22, 2012 2:27 pm

Zeitgeist 13 wrote: You desperately need a drill press.
Yeah - and that's not all... :wink:

?Waldo? Sat Sep 22, 2012 5:29 pm

I'm glad it worked for you. As I mentioned in my previous post, IMO a much easier, faster (and cheaper if your time is worth anything) is to use a redi-sleeve. They cost about $20 and install in less time than it took you to go to the store and buy the sanding disc with virtually no risk of personal injury or property damage.

dhaavers Sat Sep 22, 2012 6:15 pm I know what a redi-sleeve is, too.
Today I learned that AND how to dress a flywheel hub.

So here's my question: why oh why doesn't Tencent suggest the easy fix?
Maybe I'll try the redi-sleeve next time...


?Waldo? Sat Sep 22, 2012 6:27 pm

I'm not sure, but I imagine Tencent has a lathe to chuck the flywheel, in making dressing the seal surface easy and risk free. I don't mean to rain on your parade. I honestly congratulate your ingenuity and hope the project works out for you. It's just not the method I'd recommend to others.

presslab Sat Sep 22, 2012 7:03 pm

I like your ingenuity! :D

Did you measure the O.D. before and after? Harbor Freight has cheap digital calipers that aren't too bad. Does the new seal feel tight when you test fit it?

dhaavers Sat Sep 22, 2012 9:30 pm

Nope - haven't measured anything & haven't got to fitting the new seal yet.

As I posted, this is a low-budget DIY project, as many of mine are.

Unfortunately it's a 2-hour drive for me to get to a decent tool store, or even a machinist
that could dress my "stepped" flywheel. I'm just doin' what I can with what I've got
or can reasonably get...all hopefully without breaking the bank (or my toes).

In my last pic you can see just the slightest indication of where the groove used to be.
It wasn't deep enough to catch a fingernail, but you could feel it.
It was probably a couple thousandths, no more.

You could accuse me of blind faith, but for this job I'm going with the advice I've heard
from guys like Tencent:

1) I worked out a shallow groove to give me a better chance of getting a good seal
on my perfectly servicable used flywheel; and...

2) I'm using the best recommended seal (Sabo from GW) which is better sized &
has a stronger spring to ensure a good seal on the slightly undersized hub.

I guess I'm just exploring what's possible on a budget, posting my results,
and happy to be having some success...

Peace out, girl scout.


dhaavers Sun Sep 23, 2012 6:49 am


I open my package from GW this morning and find that my 95-cent flywheel o-ring was
packed loose in the same box with the new axle w/CV 's...result being that it is banged
up enough that there are several spots that have lost their circular cross-section.

I don't like the look of it I'm hesitant to put it in.

Q: What are the chances I can find one locally & get on with this job?
Dimensions? Any special material here?

Of course, I can call GW & get another'll just add a week to the project...


tencentlife Sun Sep 23, 2012 6:49 am

Nice job! Resourcefulness gets it done.

insyncro Sun Sep 23, 2012 6:51 am

BusDepot and VanAgain should have one to you in a day 8)

dhaavers Sun Sep 23, 2012 6:54 am

tencentlife wrote: Nice job!
Thanks, man - that means a lot coming from you!
<dream come true>


PS: I'm hoping GW will do the decent thing & comp a replacement...

tencentlife Sun Sep 23, 2012 7:04 am

GW should comp you an overnight letter, it's their fuck-up.

Terry Kay Mon Sep 24, 2012 10:31 am

What I want to know on this Polish resurfacing act of insanity, What oversized seal are you going to use?

You took out the metal, now your going to have to replace it with something--and a bigger seal is going to have to be used.

This is where a wear ring would have saved you bunch of time & head scratching---

tencentlife Mon Sep 24, 2012 10:52 am

Well I guess you'll just have to go on wondering, genius-boy, some of us have work to do.

Crankey Mon Sep 24, 2012 5:09 pm

another reason to do it this way is, it's fun.

the flywheel seal dia does seem like a good point though.

build it back up with a mig and spin-grind it back with your drill-lathe and a 4.5" grinder. problem solved. :)

I would probably put the drill motor in a vice.

the safety measure assumes when things let go, they will go straight down to the ground. but actually, if the flywheel shifted off center enough to be a problem it would wobble until it flung itself sideways. often what happens is the arbor of that sanding pad will bend, because it's just wimpy mild steel. then it all goes south....err east or west. :lol:

not that I don't approve of the process. I might have used a grade 8 bolt/nut/washer and maybe a wooden disc.

would it have been possible to fill that groove with JB weld and sand/polish that ?

Powered by phpBB © 2001, 2005 phpBB Group