[Chilliman]

DANG AGAIN !!

My C5 is a July 2009.
I just looked at the front forks and the axle sits forward of the centreline of the fork tube.
It mounts into, I guess a 45 degree angle, inclusive casting at the bottom of the forks.
I hope THAT is some good news   

[gashousegorilla]

  Mine is April of 09'... same front leading axle and front end.  I think earlier in this thread , it was mistakenly said the wrong way around.   A couple/ few years AFTER the C-5 came out , they switched from our front leading axle forks TO the straight forks with the axle right under the forks... also they went to a 19" front wheel at that time and changed the rake angle.  I believe they ALSO went from a 110 to a 120 rear tire .    This was to make the bikes more stable.   But don't worry... just because you have that front end, does NOT mean you can't get it right. There are plenty of Enfields out there with that front leading axle.   The G-5 for one.....

  With the pillion seat off, if it is on there.   Straddle your bike with you hands on the bars and both feet on the ground.   As you are looking over your shoulder,  give the bike a shake with the bars and see if that rear end shakes like a ducks ass....

[Kevin Mahoney]

I might be missing something...The first iteration of the C5 in 2009 had about 3.5 degrees of rake removed. It also had a straight fork. The net result is that if you look on a line from the headstock to the axle it is a straight line. Had they left the 19 inch from tyre AND not removed the rake it would have been fine. Given where the weight on the axle landed the front end became unstable.  In some cases scary unstable.

Couple this with the fact that no two frames were made the same. While that was always the case for RE's during this time period and for many years after the company doing the frame welding was not using jigs (not kidding). This didn't much matter when the front end was designed correctly. This is also when a happy accident happened that propelled RE into the high volume company it is today. This meant that production was ramping up rapidly.

On later bikes it is not a straight line from the headstock to the axle and the axle is in front of the fork line giving it good stability.

You have to be very careful when you look at pictures on the net or elsewhere because the 350 did not have the fork change. All of the publicity shots were done in India were with 350's. The export markets were always forgotten about and this happened right up until I left RE.

I have some Power Point presentations about the design of the "new" C5 from 2008 but am too tired to dig around and find them. When I do I will post them as they are interesting.

gashousegorilla is quite right when he says that you can sort your bike out if it is unstable. If it isn't unstable then forget about it. Some were, some weren't. One unorthodox and even frowned upon item was to slightly overtighten the steering head bearings. It is usually fixed by a combination of many small things.

[gashousegorilla]

  Ummmmm..... Maybe I'M missing something?         I'm looking at my 2009 C-5 made in April of 2009.   It does NOT have a straight fork... it is offset.   It came originally with an 18" front wheel.   Every early C-5 that I have seen has this configuration... either from guys right here on the forum or in person ?   I'm not going crazy ,  am I ?!          I know my friend around the corner bought a 2012 C-5  and that sucker has the straight front fork and the 19" front wheel .....

[cstorckiii]

And just to add an extra data point, my January 2011 C5 has the leading axel and 18" front wheel.

[ROVERMAN]

You are not going bonker's Arizoni. Yes the originals were leading axle/18" wheel. The 2011 introduced the straight fork/19" combo, er.... I think.

[Desi Bike]

April 2011 build here. 
Leading fork and 18 inch.
Rock steady for me at all speeds.  18psi in the tire up there and 28 out back.

[Arizoni]

You are not going bonker's Arizoni. Yes the originals were leading axle/18" wheel. The 2011 introduced the straight fork/19" combo, er.... I think.

Ah,  I think it was gashousegorilla that thought he's going bonkers.
Up until now, I've been quiet. 

I stayed out of this because I own a 2011 G5 and that model never had a instability problem.
My 2011 G5 has the axle displaced ahead of the center of the fork downtubes.

The front forks with the axle displaced forward of the downtubes centerline dates back to some of the first hydraulic forks made by Royal Enfield starting with the 1947 Model G and Model J.
The leading or offset axle continued thru the entire Bullet production until it ended in 1964.  Needless to say, the 1955 based Indian production also used the leading axle design for all of the Bullets it produced up until the change was made to fix the new UCE C5 Bullets problem.

I suspect some of the problem here is there are several ways of talking about this "leading" design.

There is the offset axle with the axle ahead of the center of the downtubes and there is the axle location relative to the point on the ground where a line thru the steering head bearings centerlines meets the tarmac.

I think most of us are thinking of the relation to the downtubes and Kevin is talking about the point on the ground made from the steering head bearings centers.

That point on the ground has a lot to do with how the motorcycle handles and its stability.

Having the axle in line with or ahead of or even behind the actual downtubes has much less of an effect.  If you stop and think about it, the old BMW Earles Fork didn't even have real downtubes but it did have that point on the ground created by the tarmac and the center of the steering head bearings.

Anyway, now that I've bored over half of you, lets get back to the discussion. 

[gashousegorilla]

  Wait a minute ?    Now I'm really corn-fused .   Who am I now ?!       Hehehehe ! 


    Yeah... In a nut shell, if one DOES have one of the early C-5's WITH that axle out front AND those 18" wheels front and back.. AND IF it is unstable....Don't sweat it .   It CAN be cured , right up to as fast as you can go with that stock motor. 

  IF one is having problems with stability with one of them ?    FIRST !! thing to check is Tire pressure ..... Tyre pressure?.... Tire pressure ?....   Did I say TIRE PRESSURE ?!        DO IT !
Do NOT go by the pressures that are marked on the DOT plate on the front down tube... they are too high and  wrong.  DO like desi says above... run the lower tire pressures like the book says.  18-20 PSI  front and 26-28 psi rear... and your in the ball park.

  IF !.. If no matter what you do , tire pressure,  alignment, steering head adjustment ,alignment, fork braces , steering dampers even ! and etc  and etc. and etc.!  AND it STILL wants to shake you off of that bike at higher speeds ?   I would take a hard look see at how that tail section and fender is mounted.  Unplug the tail light and unbolt  those few bolts that hold the whole thing on .... remove it in one piece .  Then take the bike for a ride and see if your problem has all of a sudden disappeared.   Then take it from there by refitting your tail section, fender stays and fender so that there is no stress back there and that it is firmly secured like it should be.

   Fenders can't be forced in and twisted between the fender stays.... screws should not be flying out across the garage when you go to loosen it up..... or the whole thing suddenly shifts when you start to disassemble it and etc.  Or... you MAY have to remount your rear fender between the fender stays without any stress and in a way that it is better secured.   You can do this by moving the fender forward , so that the notch on the front of that rear fender DOES go into that rubber bushing. Then... re-drilling new holes through the fender for this new position, at the fender stay mounting tabs.   Doing this will make your bike rock solid.... IF you are having a similar problem like mine did.   

[wildbill]

so  i'm in Australia and my first new bike was a late 011 plated chrome/black C5 with the front offset fork. a few months later I read that the straight forked model 012 C5  was arriving soon and ordered the maroon/chrome C5  and actually bought the very first bike....lol

[ace.cafe]

My suspicion about the low tire pressure on the C5 front tire is that it was spec'd by RE purposely to slow the responsiveness of the front end, due to the geometry. I  suspect they knew it all along, and that they had all the production set up and much cost on the line, and they went with it. After they moved the original parts out the door, they made the change on the production line.
Those tires come with higher pressure recommendations from Avon, and they work great at the higher pressure on the pre-unit Bullets. It's when they made the frame change that this all came up.

[gashousegorilla]

  Could be ?  Avon DOES spec them at higher pressures.   Like what was found on my DOT plate.  VERY confusing for a new owner at the time, with the differences in the book and what it said on the bike ... WHO would believe 18 feckin' pounds ?!   But I can tell ya in my experience riding these UCE bikes .... the 18" wheeled offset forked first C-5, the 19" front wheeled straight forked newer C-5  and a the G-5.    They all like the lower pressures at higher speeds, with the Avon Roadrider's or K-70's at least.  The 18" wheeled original C-5 by far being the most sensitive to it.


 

so  i'm in Australia and my first new bike was a late 011 plated chrome/black C5 with the front offset fork. a few months later I read that the straight forked model 012 C5  was arriving soon and ordered the maroon/chrome C5  and actually bought the very first bike....lol

  Why does that not surprise me brother ?  LOL !     And your impressions between the two were... ?   What does it say in the book about tire pressure for the gorgeous shiny new bike of yours ? 

[Kevin Mahoney]

We came up with the lower pressure recommendation as well as suggesting a change to a 19 inch tyre for our customers and dealers. The pressure is way low, but it was somewhat helpful. A series of small changes is usually what it took. The whole thing was an engineering debacle as far as we were concerned.

You have to realize there was a complete disconnect at that time between RE, its engineers, marketing people and the export markets, importers and export bikes.

I think it is better now that RENA is actually RE.

[ROVERMAN]

Are you Arizoni? Or GHG? I think my Aprilla has sucked out the last of my brain!
Roverman.......I think.

[Kevin Mahoney]

I checked an old parts book and then consulted the Oracle of RE parts Tim about the forks. As has been pointed out I had it backwards. You were all very polite pointing that out to an old man. At any rate it was an engineering mystery but can be solved by owners using the methods pointed out earlier