I don't know if any of you folks follow the TerraTrike Owners group on Facebook. I find it an interesting group of folks. Yesterday during a discussion of a fellow's question regarding stiff steering on his Rover I posted the solution I found and Gary Greenway posted the thrust bearing upgrade that he implemented. Seems to me that it would be quite worth the while since it used bits readily available from McMaster Carr and the cost is only about $33 plus shipping. The necessary parts are....
2 ea 5909K15 Thrust needle roller bearing for 20mm shaft diameter
2 ea 5909K75 1mm thick washer
2 ea 5909K87 2.75mm thick washer
These are sandwiched together with the thick washer on the bottom then the bearing and the thin washer on top. The assembly then replaces the existing flat washer at the bottom of the kingpin. Suitably lubricated, of course.
Combined with the very good lateral support offered by the plastic bushings in the headset the needle bearing assembly should significantly improve wear resistance.
Comments
Debating now whether I should bother to order a set of BB7's since I will have to take the front wheels and brake assemblies off to do the upgrade anyway.... not that there is any problem with my Alhongas.
Definitely would be nice to have someone like @goldmember chiming in here from time to time.
"Thinner washers may be out of flat due to distortion in hardening in the free state (expected to flatten out under load)."
http://www.timken.com/en-us/products/bearings/productlist/roller/thrust/needlethrust/Pages/NeedleRollerandCageThrust.aspx
I had Phil Woods hubs on my DF back in the day. In fact, they were the second set of Phil Woods hubs in Hawaii. Supposedly lower rolling resistance and better reliability. I didn't notice any change in rolling resistance... in fact the wheels didn't spin quite as long with them as before. They did, however, stay very, very clean. No problem with dust or water getting into them.
The bushings on my Rover are the same top and bottom. They are both black "plastic" and have quite a hard, smooth surface. The 2016 TerraTrikes with exception of the Rover are supposed to be getting an upgraded lower bushing which rumor has it will be bronze.
For a steering application such as this I also think TerraTrike's solution is the more robust. I have never had a great deal of faith in ball bearings in cups where the forces that act on them tend to drive the cups and balls into compression. Needle and/or roller bearings... we shall see... we shall see.
Anyone - is there an exploded diagram/picture of the entire assembly? I will be ordering a new Rover in 2 weeks.
This is a great forum!!!
My camera up and died on me... I'm reposting here what I just finished posting on the Facebook TerraTrike Owners group page...
Cleaned
the cosmoline(?) off the bearing and washers with some alcohol. Laid my
trike on its side, removed the steering cap screw and upper washer,
loosened the steering arm bolt then lifted the steering arm off and let
it hang out of the way. Pushed down on the kingpin until it slid out of
the bushings, removed the lower washer then cleaned the kingpin and the
bushings with alcohol. Assembled the new parts onto the kingpinwith
thick washer on the bottom, then the bearing (after a liberal coating of
lithium grease on both sides), thin washer on top. Liberally coated the
kingpin with lithium grease and pushed it up through the bushings. Set
the trike back upright so its weight would pre-load the assembly. Put
the original top washer back on, cleaned the excess grease off the top
of the kingpin, reinstalled the steering arm, put the cap screw assembly
back on and snugged it down. Set the steering arm position the way I
like and tightened the clamp bolt good and tight then loosened and reset
the cap screw to "thumb tight" plus a couple degrees snugger. Repeated
the process for the other side. There was no need to remove the wheels,
mess around with the tie rod or the brakes. Took Honu for a test ride...
steering a liitle bit heavier than before probably due to the amount of
preload I put on the assembly. Still much lighter than when I first got
my trike and absolutely no trace of "stickiness" when steering left or
right crossing dead center straight ahead. On the way back I did a
"hands off" test at 12mph for almost 1/4 mile. No peddle steer, no
tadpoling, no twitchiness, no wander... straight arrow all the way. The
cap screws tightened down about 3 1/2 turns so getting longer ones would
be a good idea. The stock ones are m5-20. McMaster Carr has m5-22 p/n
92095A482 at $10.69 for a box of 50 or m5-25 p/n 92095A216 at $5.60 for a
box of 25. Sorry no piccies... the cellphone I use as a camera up and
died on me last night. Hopefully my description of the procedure is
adequate to any who may want to do their own Rover steering upgrade.
The bushings in my Rover were some sort of dark grey composite(?) material. Nylon, delrin, something else I don't know... but definitely not metal. I didn't change them... I just replaced the stock lower washer with the bearing assembly I described.
I like the way TerraTrike is going about upgrading their lineup. Address those things that can significantly enhance the rider experience on the current products. I have a suspicion that the Tour II will be upgraded or redesigned for next year... maybe with suspension(?).
Two
things have bothered me since doing the bearing upgrade to my Rover.
One - progressively stiffer steering the further one goes from straight
ahead. Two - a more pronounced tendency to self-center when rolling.
Some research showed that these are both charactistics of strongly
positive caster. What would cause it... the roughly 5mm increase in
height between the steering knuckle and bushings due to the new bearing
stack. Combine that with the fact that I am running Schwalbe Big Apple
tires on the front which have a much larger tire contact area on the
pavement due to their 1/2" greater width than the stock tires... it's no
wonder the effect was so noticeable to me. Today I took the headsets
apart again, removed the 2.75mm thick washer at the bottom of each stack
replacing it with the original TerraTrike washer that is about 1mm
thick. Everything wiped clean and regreased upon reassembly. Took Honu
out for a test ride and now it is much better. I can still detect some
off-center resistance and some of the self-centering behaviour (the
latter being a good thing if it's not too pronounced) and my steering is
once again able to go lock to lock. I would have to say that it is not
as sublimely light as before the bearing upgrade but still pleasantly
light and precise.
The impression I have of my Big Apples at 40 psi vs the CSTs at 40 psi is that the Big Apples don't reduce the initial impact all that much... they simply extend the time it takes for the impact to transfer to the frame. IOW, they act more like dampers than absorbers.... or maybe I should liken them to being slow absorbers. They also feel like they offer better traction than the CSTs. That's to be expected. I don't plan to put my CSTs back on just for comparison sake.
There is a big difference in the shock absorbing and damping characteristics of the Big Apples at 40 psi versus at 60 psi. The ride at 40 psi is much more comfortable than at 60 psi. OTOH, I think pedalling effort required to accelerate to and maintain speed is less at 60 psi. I'm running at 40 psi now but I think I will be going back to 60 psi. There is an additional advantage to running the higher pressure... if I forget to check pressure before a ride it's less likely that I will be under-inflated.
The only thing that I changed was the stack height which was reduced by about 1.75mm. All other parameters remained the same... tires, tire pressure, assembly procedure, using trike weight to pre-load the bearings... all the same.
Serendipity smiled on you with that heel strike. Glad to hear you were'nt hurt.