RC51 Forums banner

1 - 15 of 15 Posts

·
Registered
Joined
·
58 Posts
Discussion Starter #1
I have small cracks around the mounting studs near the back of the seat. I am looking for a method of preventing the stress from causeing this problem. I am thinking there is not enough support points for the tail cowl and each bump in the road causes stess at that point... eventualy to it's breaking point. Im sure this is a common problem. Is there a cure ?
 

·
Super Moderator
Joined
·
6,485 Posts
Actually no, I've not experienced this problem after thousands of miles.

Are your cracks at the upper mount point near the cowl panel?
Do you have an aftermarket undertail installed, and if so, how is the undertail supported, especially at the rear?

Also, what sort of fasteners are used to mount the rear cowl?
Some photos of the problem may help as well.
 

·
Premium Member
Joined
·
8,335 Posts
I have experienced this on my first RC. It was due to the bolts being over tightened at some point. The cracking accelerated when I lost one of the bolts with the spacer and used a regular bolt with stacked washers.

I have also had issues with the front two mounting bolts for the rear cowl too.

Now I keep a spare set of each bolt in the tool box. Bolts are way cheaper than a new cowl.
 

·
Super Moderator
Joined
·
6,485 Posts
I also use a set of the front shoulder bolts also for the upper rear cowl mount bolts.
Works great and gets rid of the frankenstein bolts.
 

·
Registered
Joined
·
58 Posts
Discussion Starter #5
Yes my undertial is after market. Seems like it is only held on by two tiny screws from underneath. Is the stock mount more substantial? I will Check into that because the tail section extends so far past the " frankenstien" bolts that it has quite a bit of leverage at the point where it is cracked. Thanks for your thoughts.
 

·
Registered
Joined
·
58 Posts
Discussion Starter #6
Yes I could see how over torque of the front bolts could damage the plastic as well, fortunatly I don't have problems there. I saw the potential for damage and used medium locktight on the threds so they would stay put even though the bolts are lightly torqued. My plan may be to replace my tail cowl with one of those fantastic carbon fiber units... I want to get the issue resolved prior to the replacement. Your input is helpful, thanks.
 

·
Super Moderator
Joined
·
6,485 Posts
Does your undertail have the OEM fender completely chopped off past the battery box?
If so, that leaves the undertail not supported very well.
On mine, I only removed the inner portion leaving the sides of the fender to support the undertail as well as leaving mounts for the relays.
 

·
Registered
Joined
·
58 Posts
Discussion Starter #8
Hey subsailer

Are you in the navy ? Submarines? Now then, ill post some pics... not sure how much I can post but I'll give it a go anyway. I pulled out the bolts and observed how far the cowl wanted to sag on it's own... too much ! I noticed there is a metal brace under the cowl sort of between the frankenstien bolts with a gap of about a quarter inch to the underside of the cowl. looks like it was put there for upward support. Is there a pad or bumper missing ? Yours have a pad there ? Well I had some rubber that thickness and gave it a trial fit. The holes lined up much better... perhaps a fuzz high without me on it so I put the bolts back in and the tail is much more solid. think I'm gonna leave the rubber in there. if that bracket was not made for tail support ... it should have been. Like I said here are a couple of pictures.
 

Attachments

·
Premium Member
Joined
·
8,335 Posts
The cracking I had was never that bad! I had cracks and bits fall off directly around the bolt hole but never that far out...
 

·
Super Moderator
Joined
·
6,485 Posts
Yep, I was in the Navy and on submarines some years ago.

You have got something putting a lot of stress on that rear cowl.
Here's my rear cowl upper cowl mount hole (inside and outside view) with over 2 years on it. Not a single crack.
The elongation of the hole is as it comes

Also there's no pad on top of the bracket that holds the rear cowl.
Only the four bolts and two lower clips hold the rear cowl in place.
That bracket you show is used for the rear cowl panel or seat to latch in place.

Are your mufflers impacting the cowl per chance?


 

·
Registered
Joined
·
58 Posts
Discussion Starter #11
Hey madbuyer

Yea it sucks... only one side looks like that. That picture was from about six inches so it looks its worst. When it's put back together it is easy to miss. Apart from that the bike is spot on... not a scratch... I take that back...Hardly a scratch. The tail section may get replaced later we will see.
 

·
Registered
Joined
·
58 Posts
Discussion Starter #12
No, the cans are in the clear. You asked if the stock undertail was sawed off short. Yes it was. Could have been done differently.
 

·
Super Moderator
Joined
·
6,485 Posts
Since the rear fender was cut short, the undertail is supported by the rear cowl.
If you carry any object of sufficient weight in the trunk, that may be the cause of the stress cracks. That's my guess.
To me, that rear cowl seems fragile, and I'm very careful when removing or installing it.

When I bought my bike back in 2008, the previous owner did the ultimate hack job on the rear fender and wiring.
The fender looked like it was trimmed with a hedge trimmer or chain saw.
It was so bad, he used zip ties to rig the sections he mis-trimmed.
I have the photos to prove it, and they ain't pretty.

I replaced the rear fender (actually all the bodywork) and this is how I trimmed the rear fender.
The tabs were made from scrap plastic from the fender and secure the rear of the undertail.



The fender now supports the undertail and not the cowl.
It also still holds the relays as they should.
 

·
Registered
Joined
·
58 Posts
Discussion Starter #14
Hey I was gonna use that chiansaw line too but a hedge trimmer paints one heck of a picture.... To funny. Hadn't thought of that one. What you said about the undertail adding load as well as cargo in the box is a valid point. The efforts you have made to support your undrtail are worthwhile without a doubt. I will put some of those ideas to work. To bad it is after the fact that my cowl is cracked. Oh well it was cracked when I bought it. It can be fixed and it can be fixed well with the right plan.
 

·
Super Moderator
Joined
·
6,485 Posts
This is what greeted my eyes the first time I opened the rear cowl panel.


Note the wires cut off with bare ends just waiting to short somewhere.
I managed to tidy it up a little, but knew I had my work cut out for me.
I had to replace the wiring harnesses, rear fender, undertail, and all the bodywork.
Cost a bit of money but it's now all good.
 
1 - 15 of 15 Posts
Top