When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The torsional stiffness of 41mm forks is awful, by which I mean the wheel can twist sideways at the axle and the top tree allows the tubes to rotate inside it. The design is flawed, but salvation is at hand, although the only effective cure I know of at present is the CCE Tour Trac Tree kit - and yes I have one!
I've said this for years. You see it happen on wideglide conversions when hitting turns hard as well. The wheel could and would flex under stress.
The 41mm HydraGlide forks date from 1949. The Wide Glide as a model wasn't introduced until Willie G got his hands on a drawing board and came out in 1980.
Last edited by grbrown; Nov 3, 2016 at 05:43 AM.
Reason: Spelling!
I've said this for years. You see it happen on wideglide conversions when hitting turns hard as well. The wheel could and would flex under stress.
When was the 41mm wideglide designed? The 50s?
Well you won't get any argument from me on tube flex on a DWG.. Especially since the fork tubes are 4 inches longer than a bagger. I will say that I had a softail that had 4" over tubes over a DWG tube and it handles great even tho the handle bars would twist when grabbing a handful of the single disk front brake. They do flex..
BTW Technically the fork are 1 5/8 and not 41mm.. 41mm is about 1.614 inches and the fork measure about 1.624 which puts then close to 1 5/8.. Just everyone calls them 41mm..
That top-hat and bolt design cannot be turned from a sow's ear into a silk purse! There is no way on Earth that the top of the stock 41mm fork tube can be adequately clamped in the stock top tree - it ain't going to happen, no matter what we do! What is required is substantial metal-to-metal clamping, not a rubber seal.
The torsional stiffness of 41mm forks is awful, by which I mean the wheel can twist sideways at the axle and the top tree allows the tubes to rotate inside it. The design is flawed, but salvation is at hand, although the only effective cure I know of at present is the CCE Tour Trac Tree kit - and yes I have one!
If you look at the stock 41mm setup nothing is clamped between rubber for assembly.. I've had those forks apart many times and fail to see where is can happen except for one place and that is the seal that goes between the top nut and the fork cap.. Some after market seals are too large and won't let the bolt clamp the fork. It's the same issue is you cut an O ring groove too shallow and allow the O ring to support the clamping force. It won't work.
Sounds like you were assembling the stock forks either with the wrong parts or incorrectly.
BTW going to top clamp 41mm forks only potentially strengthens torsional stability of the upper fork tubes. Let say you create a clamp that grabs the top of the stock fork tubes to keep them from twisting. Would the handling be better?
BTW Technically the fork are 1 5/8 and not 41mm.. 41mm is about 1.614 inches and the fork measure about 1.624 which puts then close to 1 5/8.. Just everyone calls them 41mm..
Our forks are Japanese and as they have never used the inch, I suspect they also call them 41mm.
Originally Posted by bwoltz
If you look at the stock 41mm setup nothing is clamped between rubber for assembly.. I've had those forks apart many times and fail to see where is can happen except for one place and that is the seal that goes between the top nut and the fork cap.. Some after market seals are too large and won't let the bolt clamp the fork. It's the same issue is you cut an O ring groove too shallow and allow the O ring to support the clamping force. It won't work.
You're the one who introduced rubber to this discussion! Whatever O rings are used will have no affect or benefit on the torsional nature of these forks. That top design cannot provide adequate torsional support to the fork legs.
Sounds like you were assembling the stock forks either with the wrong parts or incorrectly.
You have no grounds on which to make that statement.
BTW going to top clamp 41mm forks only potentially strengthens torsional stability of the upper fork tubes. Let say you create a clamp that grabs the top of the stock fork tubes to keep them from twisting. Would the handling be better?
Here is a picture of a new stock HD sealing washer on the left and an aftermarket sealing washer on the right.. The HD sealing washer is soft and is made from closed cell foam so it compresses. The right side one is non-foam and oversized. Being non foam and oversized, the rubber seal really has no place to go other than between the small gaps between the flats on the fork cap and the top tree which is not much space. Not enough for the fork nut to pull tight on the top tree. Fork bolts loosen and the forks can twist.
Holding the 2 seals and roughly squeezing the with the same pressure.
Top - HD
Bottom - aftermarket.
Sorry for the poor quality pic.
Our forks are Japanese and as they have never used the inch, I suspect they also call them 41mm.
You're the one who introduced rubber to this discussion! Whatever O rings are used will have no affect or benefit on the torsional nature of these forks. That top design cannot provide adequate torsional support to the fork legs.
If you tighten a bolt into the end if a tube you can't unscrew the tube unless you overcome the frictional clamping forces. I'll agree it not as good as band clamp around a fork tube but what is needed.
You have no grounds on which to make that statement.
See my previous message. Not trying to insult, I mess stuff up and figure out what I did wrong later, message shows it..
Yes.
So something like this right below the upper tree should make a difference? Like this?
After about 10000 miles I pulled it out and didn't notice anything on the install or when it was removed.
This is the product I have, from Custom Cycle Engineering. An entirely new top tree, machined from solid, plus longer fork tubes, to enable them to be clamped. It's about as good as we can get, without going to a full 49mm conversion:
The kit:
Last edited by grbrown; Nov 3, 2016 at 03:37 PM.
Reason: Extra photo
This is the product I have, from Custom Cycle Engineering. An entirely new top tree, machined from solid, plus longer fork tubes, to enable them to be clamped. It's about as good as we can get, without going to a full 49mm conversion:
Have you got your front end finished? Have you put many miles on it?
I'm seriously thinking of the CCE top tree, just a bit hesitant. I've been waiting to see your impressions of the product....
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Slideshow: The bar-and-shield logo shows up on far more than motorcycles, some of the company's most unexpected products have nothing to do with riding.
Slideshow: From the troubled AMF years to modern misfires, these bikes earned reputations for reliability issues, questionable engineering, or disappointing performance.
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Slideshow: The Swiss custom shop has taken a Harley Softail and stretched it into something so long and low that it looks closer to a rolling sculpture than a conventional motorcycle.
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Slideshow: A standard cruiser becomes an intricate metal canvas in the hands of a Swiss custom house known for pushing Harley-Davidson platforms far beyond their factory brief.
Slideshow: Harley-Davidson's challenges aren't abstract; they show up in dropping shipments, shrinking dealer traffic, and strategic decisions that aren't yet translating into growth.
