Author Topic: pinch bolt (Read 6153 times)

jartist · **on:** October 15, 2011, 09:48:47 pm

I was changing the tires out on my G5 yesterday and I noticed that the front axle spun freely with the pinch bolt still tight. That's a big chunk of aluminum on the front fork to squeeze with only a 6mm 8.8 grade bolt- a bit optimistic at best to expect from a bitty little bolt! I drilled it out to 8mm and replaced the bolt with an 8mm 10.6 grade one for 3.5 times more clamping power. Put it all back together carefully and the improvement is quite noticeable with smoother fork operation and no sticktion at all!

I thought for sure I read of someone else coming at the same conclusion about the pinch bolt on this forum but I couldn't find it so I figured I'd post my findings anyway.

Arizoni · **Reply #1 on:** October 15, 2011, 11:12:52 pm

I don't recall who it was but someone had broken the small bolt several times trying to tighten it enough to cause the fork to actually pinch the axle.

Tri750 · **Reply #2 on:** October 15, 2011, 11:48:42 pm

We started upgrading to an 8mm last year.
With the 6, the speedo drive be able to rotate around and break the speedo cable.
The factory has started using the 8mm as a running change from what ive seen. (not the official word)

Arizoni · **Reply #3 on:** October 16, 2011, 12:19:24 am

If they have changed the size it was after the 2011 production began.

My reading on the Indian Team-BPH site indicates that Royal Enfield has started producing front forks without the axle offset that has been a traditional feature of the RE since their first introduction of a telescopic hydraulic fork in 1947.

I haven't seen a picture of the new fork but I assume it will have caps to retain the axle.

Ducati Scotty · **Reply #4 on:** October 16, 2011, 02:19:41 am

Quote from: Tri750 on October 15, 2011, 11:48:42 pm

We started upgrading to an 8mm last year.
With the 6, the speedo drive be able to rotate around and break the speedo cable.
The factory has started using the 8mm as a running change from what ive seen. (not the official word)

Do you need to drill to fit that? Sounds like a worthwhile upgrade.

Scott

jartist · **Reply #5 on:** October 16, 2011, 03:21:34 am

I drilled it out with a 5/16" bit from the bottom so I didn't have to remove the fender. Really easy to do.

I should add that it's really important to understand how the parts fit together. The big nut on the left side bolts the axle to the left fork solidly. That leaves the right fork floating at the axle which is where the pinch bolt comes in to lock down the right fork laterally. My order when assembling is big axle nut medium tight then turn axle with a wrench on the right side to free up the right fork. Then bounce the fork with the bike off the stand to make sure the forks are free and there's no sticktion. Then fully tighten the big axle nut and pinch bolt and recheck the whole thing for sticktion.

When the axle is inserted and tightened it hangs up on the right fork and pulls it left which binds up the forks in that they arent parralell. That's why it's important to does all the steps to free up the right side when reassembling.

This process has been posted before but I always have to visualize what's happening. Once I understand it it becomes easy. Scotty, your fork tutorial you posted a while back is the gospel on this stuff.

BRADEY · **Reply #6 on:** October 17, 2011, 02:05:53 pm

here is a picture of the new front forks without the offset. yes RE did it after all these long 60 years

GlennF · **Reply #7 on:** October 17, 2011, 02:34:47 pm

Quote from: BRADEY on October 17, 2011, 02:05:53 pm

here is a picture of the new front forks without the offset. yes RE did it after all these long 60 years

wow ... that looks quite odd on an Enfield

t120rbullet · **Reply #8 on:** October 17, 2011, 03:48:50 pm

Quote from: BRADEY on October 17, 2011, 02:05:53 pm

here is a picture of the new front forks without the offset. yes RE did it after all these long 60 years

Maybe this is an answer to the rake change they did to the C5 that made it twitchy.
IMHO the old bikes that they made for those 60 odd years handled soooo good. Why would you want to change anything ?
CJ

bittercrick · **Reply #9 on:** October 17, 2011, 04:34:21 pm

Hey RE if that takes care of the wobbles I want a set.can't wait to hear more on this change. bittercrick

Ducati Scotty · **Reply #10 on:** October 17, 2011, 05:45:49 pm

Wouldn't that give you less trail and make it more twitchy? Unless the headstock angle or csaquette is different. Remember, the original reason for long forks on choppers was more high speed, straight line stability.

Scott

barenekd · **Reply #11 on:** October 17, 2011, 06:15:04 pm

It gives you more trail. The trail is measured from a line down from the steering head pivot to the ground, paralleling the fork tubes (usually parallels the tube, some forks differ) to the ground. Drop a vertical line to the ground from the axle center and the distance from where the steering axis line and the axle line are on the ground is the trail. Hence, move the axle back increases the trail. Gives a more stability and slower steering.
As for bittercreek's query. It should improve things on the C5.
Bare

Ducati Scotty · **Reply #12 on:** October 17, 2011, 07:21:10 pm

Thanks. Forgive me, hadn't had enough coffee yet

Scott

Desi Bike · **Reply #13 on:** October 17, 2011, 07:42:59 pm

Quote from: BRADEY on October 17, 2011, 02:05:53 pm

here is a picture of the new front forks without the offset. yes RE did it after all these long 60 years

Interesting, This is the IDM, I wonder if the Export Version will also have this new fork?

Arizoni · **Reply #14 on:** October 17, 2011, 10:17:04 pm

From a manufacturing standpoint it wouldn't make sense to have two different configurations in production at the same time.

Parts are least expensive when a lot of them are made without changing the machine setups.

jartist · **Reply #15 on:** October 17, 2011, 10:42:23 pm

It will be interesting to see if the G5 and B5 get the new fork treatment too or if increasing the trail is just an attempt to gain back a little more stability lost on making the head rake angle steeper.

Ducati Scotty · **Reply #16 on:** October 17, 2011, 11:21:45 pm

Quote from: Arizoni on October 17, 2011, 10:17:04 pm

From a manufacturing standpoint it wouldn't make sense to have two different configurations in production at the same time.

Parts are least expensive when a lot of them are made without changing the machine setups.

The export bikes are already different. Different tires, different ECU/exhaust with the O2 sensor, different front wheels on the C5 (19" for IDM now), and I think a few other little things.

Scott

Arizoni · **Reply #17 on:** October 18, 2011, 12:56:37 am

True but the fewer things that are different the easier it is to produce on an assembly line.

I found this quote on the Team-BPH forum about the new 2012 front fork.
The individual who posted it said it came from a review by Adil Jal Darukhanawala from an article on zigwheels.com

"...the internals and their construction are all new. The revised geometry this brings in its adoption sees the trail hiked to 101.49mm from the previous 72.54mm while the centre shift of the forks measure 26mm at a rake angle of 26.09 degrees..."

Ducati Scotty · **Reply #18 on:** October 18, 2011, 01:03:44 am

Over an inch change in trail! That' huge! I bet it feels like a totally different bike. Do you know if it's the same frame (head angle) and casquette? What's the trail on a G5?

Scott

BRADEY · **Reply #19 on:** October 18, 2011, 02:09:29 pm

This subject needs to be investigated in detail, before coming to a final conclusion. May be Kevin M would be the right person to bring in the "factory perspective"
Or may be he is just waiting for all the brainstorming to end

barenekd · **Reply #20 on:** October 18, 2011, 04:42:36 pm

Reminds me of an early '70s Kawasaki Big Horn (Big Hoax). It was set up so you could mount the axle in front, or the center or behind the fork sliders.
They were horrible handling pigs. I guess Kawasaki couldn't figure out how to make them handle, so they left it up to the customer! I guess the customers couldn't figure it out, either, they didn't produce that version very long.
Bare

Tri750 · **Reply #21 on:** October 18, 2011, 05:49:40 pm

To clarify, the 2012 C5's (US) we got still have the leading offset front end. No change.
The 8mm change in pinch bolts started showing up in the last batch of 2011's.
To convert your early model to 8mm, we just drilled them with a hand drill. 2 minutes to fix it.
Maybe we should all mention where we are from as there are numerous differences around the world.

Ducati Scotty · **Reply #22 on:** October 18, 2011, 05:56:59 pm

And there's not guarantee that the next batch of 2012's you get in will be the same. The warranty explicitly states that they can make changes and improvements at any time with no obligation to retrofit existing bikes.

Ducati and lots of other manufactureres do the same thing. You can have identical models from the same year with different parts. I guess it's a combination of improvements and what supplier has parts at the time.

Scott

Tri750 · **Reply #23 on:** October 18, 2011, 06:02:00 pm

Guarantees? In the motorcycle biz? Please.
Yea, well you get used to that. So far, with the RE's the few tweaks we have seen have been for the better. The last military we got, the paint was much prettier than the first. nice bit of gloss, it looked deeper if that's possible.

TWinOKC · **Reply #24 on:** October 18, 2011, 10:29:46 pm

Quote from: Ducati Scotty on October 17, 2011, 11:21:45 pm

The export bikes are already different. Different tires, different ECU/exhaust with the O2 sensor, different front wheels on the C5 (19" for IDM now), and I think a few other little things.

Scott

Will a 19" wheel and tire fit the C5 without any modifications to the front fender?

Just wondering, cost would probably too great for me.

Ducati Scotty · **Reply #25 on:** October 18, 2011, 11:13:59 pm

Yes, mostly. One person who did it reported needed to enlarge the holes in the fender struts a little as I recall.

And there's a kit: http://nfieldgear.com/enfield-store/c5-19in-wheel-kit.html

Scott

Desi Bike · **Reply #26 on:** October 18, 2011, 11:50:36 pm

Why go through the expense of a new rim when some of available tires for the 18 inch rim have the same or very close outside diameter as what one can shoehorn onto a 19 inch rim under the fender?

TWinOKC · **Reply #27 on:** October 19, 2011, 03:39:25 am

Quote from: Desi Bike on October 18, 2011, 11:50:36 pm

Why go through the expense of a new rim when some of available tires for the 18 inch rim have the same or very close outside diameter as what one can shoehorn onto a 19 inch rim under the fender?

You are right, it makes more sense to get a bigger tire for the front. Thinking about a winter project of replacing with the Kendra K265 3.50x18 for both front and rear per r80rt's and some others suggestion. I like the look of the Kendra's.

Thanks Scott for the Nfield Gear link. I should have looked there before I posted.

PAndy · **Reply #28 on:** October 21, 2011, 10:10:25 pm

Arizoni, it was me. I broke 2-3 of the 6 mm bolts, which was beyond absurd.

I had a horrible highish (60 mph) wobble and found out the front axle wasn't pinched at all even though the pinch bolt was plenty tight. I guess ample play in the front axle can lead to high speed wobbles, what a surprise!

Ducati Scotty · **Reply #29 on:** October 21, 2011, 10:34:42 pm

Now I really want to replace it!

Scott

gashousegorilla · **Reply #30 on:** October 22, 2011, 07:05:40 pm

No clearance issues with the 19" rim, or fitting to do, when matched with a Avon Roadrider 90/90/19. Just another option is all...... You could continue to use a lower profile front tire if you like, for some great handling street use, with the benefits of a 19" wheel. Also you can retain the stock rear tire. There may also be a wider selection of 19" front tires, then 18" .... BUT, if your gonna do any gravel or off road stuff, or a combination of all... I think r80rt hit the nail on the head with those K70 tires.