Frame sliders/engine guards

[LikeAfox_imp]

I have crashed at 65 mph, while sporting SW Motech guards and they saved my crankcase. Left guard was twisted like a pretzel and was missing about 50% of metal, but it stopped the important parts from touching the road. Basically, get those if you want to survive. DO NOT buy the ebay copy guards, yes they cost less, but they are made from pot metal. Original part is solid steel.

Having said that, I'm currently rocking this set Honda CB1100 2010-2018 Crash Bars | ruchkagaza

They are hollow, but run the entire height of a frame. They are excellent for mounting foot pegs and other nonsense. I'm going to make plates to block wind to my lower body, come winter time. $200 shipped to my door from Russia.

 

[Bazbro_imp]

Yup! This is what happens in even a minor spill...

My favourite bars are the Hepco & Becker, very strong, subtle, but most importantly, they bolt straight onto the frame/engine mount, rather than onto a flat piece of metal that only then bolts to the frame. I see this as a weak point.

You're right, Likeafox - the Chinese copies are too insubstantial to be effective.

 

[max]

These look very nice Bazbro actually the least intrusive look, however we may differ in opinion slightly but i can see them breaking the aluminium cast engine mount on impact because the engine guard looks stronger than the cast mount.
This is what happened to my cb919 by the previous owner who probably mounted frame sliders directly onto the alu cast engine support and they had to aluweld the engine support back on after a crash, a bit of a job.
Just something to consider.

 

[Houtman_imp]

I still like my Over stainless steel engine protectors for the reason you mentioned.

 

[Bazbro_imp]

That's a good point, Max.

 

[2017EX_imp]

I have SW Motech on mine. I dont know if the H&B bars have purpose specific long engine bolts included included or not. SWM includes the two long engine bolts that are designed to fail instead of breaking an engine mount, or bending a frame, if an impact severe enough to damage those components takes place. Quite a while back I did a lot of research on bars before I bought. At the time some members were using the stock Honda long bolts instead of the included SWM long bolts. Here is the thread, what I discovered, and torque values. http://cb1100forum.com/forum/showthread.php?tid=8360

Among other pluses, the SWM have three points of contact with the bike. The supplied long bolts will absorb energy and fail if necessary. I have also seen pictures of these bars after a crash, whereby the flat pieces of steel that mount the front frame bolts and engine mount bolt, bent, but still protected the engine. Here again, energy absorbed and the flat steel bent before transferring enough energy to damage the frame and/or engine mount. Naturally we are talking worst case here, as much of the time the end result will probably be just a scraped up engine bar. I am certainly not throwing shade at any other bar brand or option, just explaining why I went with SWM.

Back in the day, I had case saver bars on my 1974 CB750 Four. The bike slid out from under me during a slow left turn from a stop at a stop light. The case savers were aftermarket, and bolted on at two points. The mount points were flat steel, and bent, but saved my engine case. Ever since then I have been a believer in engine guards.

 

[max]

Thanks for posting your explanation 2017EX, i have also followed the link provided and read the whole thread.
Most of it makes sense to me and is easy to understand with your posts and i can appreciate why you made the decision to choose these bars and how to mount them; again, they are the nicest ones to my taste.
The washers between the bars and the aluminium frame mount are a good way to spread the load when it comes to the point of stripping the threads of the provided softer bolts, bending them and thereby absorbing the force of the impact and maintaining support even if the bars come in contact with the engine cover, i understand that and agree with it.
Ironically it seems to me that the tighter the bolts are torqued the less force is left to absorb energy before stripping the threads.

Here is where i loose track of your statement;

" I have also seen pictures of these bars after a crash, whereby the flat pieces of steel that mount the front frame bolts and engine mount bolt, bent, but still protected the engine. Here again, energy absorbed and the flat steel bent before transferring enough energy to damage the frame and/or engine mount."

Whilst i agree with the statement i have trouble understanding which flat pieces got bent and how the cast engine mounts remained intact.
Could you enlighten the members and possibly provide the pictures you mentioned or point in a direction so we can find them?
Not trying to be picky but trying to understand what keeps the engine intact.

Very much appreciate the helpful and detailed information you provided, thanks.

 

[2017EX_imp]

No worries Max. The front most ( closest to the front wheel ) mount is a vertical piece of flat steel welded the the round bar stock. That piece of flat steel has two holes to bolt to the frame down tube. Moving toward the rear of the bike from there, the next mounting point is a vertical piece of flat steel welded to round bar stock. This piece has the mounting hole for the engine bolt. During my research I saw some pictures of SWM bars that had been in a crash. Those two flat steel mounting points showed some bending (twist ) toward the rear of the bike, but were not bent enough to hit the engine, or allow the engine to hit the ground.

 

[Bazbro_imp]

I am REALLY impressed with both SEMotech's thoroughness and your persistent research, 2017EX. So much so that I'm going to re-examine the H&B ones versus the SWM ones. If I discover anything significant, I'll post here

 

[Cqrlm911_imp]

Thanks for input....ordered the swm bars

 

[Cqrlm911_imp]

I just installed the sw motech bars. Very impressive fit and finish.....a little confusion on torque specs on front down tube bolts, but found old post with correct info

 

[Lord Popgun]

Congrats on that Cqrlm. I hope you NEVER find out if they work or not.

 

[max]

First of all you are all better off with the crashbars, of course, but i did find some info about the damage on the engine mounts.
this is from a cb1300 on" zam's channel " on youtube if you want to have a look yourself, the engine is strikingly similar to our cb1100 and mounts to a similar frame in the same way, and i have no idea why it broke off since he did not mention it but some time later i saw him mount frame sliders on the same bike, they were however plastic by the looks of it, here are some pictures i took of the video;

and the video;

Not to disagree here with anyone's choice but wanted to show the result of an accident.

 

[Bazbro_imp]

Well-spotted, Max.
I think these CB engine mounts are disgraceful for thesereasons...
1. They are placed too far to the outer edges of the crankcase where they are very vulnerable to being struck
2. They are grossly insubstantial. If I recall, my '72 CB750 mounts were bigger affairs that went right across the engine from one side to the other, with one big long bolt securing the two sides.
3. This is from a world-leading manufacturer, so you wouldn't expect these sort of errors.

As a result of 2017EX, Houtman and other's observations on crashbars (my preferred protection) I have switched my intentions to buy from Hepco&Becker to the SWMotech offering - very similar bars but with two main differences - an additional metal strip between engine mount and bar mount on SWM, that allows a little flexibility in an accident and reduces "shock", and a different attitude to the mounting bolt - rigid and inflexible on H&B or "sacrificial" in nature on SWM.

Here are my own broken engine mount pics:

 

[GoldOxide_imp]

Very compelling example. However, accident environments/situations are harsh. I suppose it is a matter of degrees of damage control.

 

[Houtman_imp]

Can you weld that broken mount ?

 

[Bazbro_imp]

Can you weld that broken mount ?

Yes, I could, John.
The best course would be to...
1. Take the engine out of the frame and replace the lower engine block. Or
2. Next would be an engine-out, strip-down alloy-weld repair. Or
3. Then an in situ alloy-weld repair, and finally
4. A JBWeld repair.
Removing the engine is out of the question - it would ALL have to be done at a dealer and the cost would be prohibitive! It ain't gonna happen, 'cos I can't do it myself.
I spoke to my welder (who coincidentally owns an old Honda Four!) and whilst he was prepared to look at the job and maybe have a go, he was unsure about doing it in situ because of the heat generated by the weld
. At that time I was going to take the 'bike for him to have a look, on my way bringing the 'bike home. My 'trailer plan' failed when the hitch broke so the 'bike was brought straight home here and the welder hasn't looked at it yet.
I decided to at least TRY the JBWeld - I'll be keeping a VERY close eye on it. If the product is as good as the reports, it'll be fine. If it's not, I will have to deal with it then.
The crack itself is UNDER the weight-supporting part of the bracket. It is totally supported on either side by big penny washers, clamped and torqued up, then clamped to the frame. The weight is downwards, onto the unbroken part and I can only see it breaking again if it gets an upward whack like last time. Of course, it may fail through vibration, heat, whatever but all reports suggest that will not be the case. No weight is being taken by the weld - just holding the loose underneath part UP onto the solid top part.
It is what it is and although not ideal, I'm keeping my fingers crossed. (And toes, and arms, and eyes!).

 

[max]

5. make the 5mm vertical drain hole in the mount bigger and closer to the front and tightly wind something strong like layers of piano wire or stainless locking wire used for racing around the whole boss ( like a hose clamp ) after the jbweld has cured, the more the stronger, the form is already there and paint over it.

Then if you don't like it it's easily removed with side cutters and if it is giving way it may do so gradually in the future.
If skillfully done this can be quite strong with high tensile steel wire ( and cheap ).

 

[Bazbro_imp]

Thanks Max.
I had actually considered a U-shaped metal "brace", much along the lines you've suggested, but I really don't think it will be necessary. The joint, cramped-up by the bolt and compressed between the large washers, is very well supported and braced - there will be zero movement and very little, if any, stress. I'm quietly confident it will be a successful repair.

 

[Cqrlm911_imp]

Speaking of the sw motech bars, the instructions suck. I had to go back through old posts on here to find the torque specs for the 2 stock engine mount bolts on down tubes being reused for the bars(36 ft/lbs). The supplied swm bolts(one on each side) are torqued at 28 ft lbs. I think/ hope I did it correctly.