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Discussion Starter · #1 · (Edited)
I was doing about 70 km/h (43 m/h) on a badly corrugated dirt road and picked up a wobble, which can be best described as a about 35% tank slapper. Luckily I got it under control. Now my Google search came up with a lot of possible causes.

Set up on the bike:
85 kg rider, tail bag about 5 kg. Fuel tank full.
Dunlop Trailmax Mission front and rear, tyre pressure as per manual (1.7-1.9 bar or 25-28 psi).
Rebound at 5.
Apart from a radiator guard no other accessories on bike.

So I think these are the most probable cause:
Soft front suspension.
Tyre pressure too high (I afterwards did let it down by .3 bar, but didn’t come across corrugated roads again, so couldn’t test it).

What do you think?

PS I never in many years riding dirt roads on the 800 / 1100 / 1150 / 1200 GSs experience this.
 

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I’d vote for soft front. In the wee bit I’ve taken my unit off tarmac, the front felt “heavy” causing issues in soft sand,excerbated by the hard tire with no traction. Lowering tire pressure smart move, it gives more bite and a wee bit more suspension. I’ve found the rear shock to be fine, if soft (I like soft). I believe a wise investment would be stiffer spring (or springs depending on choice). most likely change fork oil weight and or damping. I’m waiting for my finance minister to calm down some Before I make any changes. The rally raid solution seems sound and isn’t too pricey, (level 1). I’m leaning to dropping more coin and going with Adrenni replacement cartridges. About 2X =3X cost. Not sure why truthfully but I am finding the front suspension in need of improvement, street or off road. Too soft front affects spirited tarmac cornering negatively as well. As I break mine in I’m feeling this.
I your case, I’d try a better front tire before going crazy if funding an issue. The other approach too would be a steering stabilizer. But really deal with fork stiffness.
Of course, don’t forget your steering head bearings,600 mile run in service requires inspection of adjustment. I think TVS put in ball bearings! A negative first for BMW. Serious weak point. I pray I’m incorrect on this.
Good skill set to not panic and riding it out!
I hope you keep riding whilst waiting on parts, you now know where to excercise caution.
 

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Maybe you were too slow? with corrugation, you need to travel at the right speed so that the corrugations cause the least amount of discomfort. This may be more difficult on a bike, as you might cross through a speed were the bike becomes less controllable.
 

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Discussion Starter · #5 ·
@porth and @ARBOLMANO thank you for your reply and advice. I think I should play around with tyre pressures and see what happens.
Unfortunately the 310 is not a big seller in South Africa so aftermarket equipment is very limited. No suspension upgrades / spoke wheels etc.
 

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I’d think Rally Raid would ship to SA without issue. But I’d try a different front tire first. tire pressure can only help so much and too low causes other issues. Same size, tubeless but with more tread. Perhaps a softer carcass. What I found was thAt I had plenty “go“ to get up on the sand but the front struggled to be controlled like it was diving Then catch and swing to side. Perhaps going faster would have helped but I had already excedead my comfort zone on a new unit with no crashing bars etc. In same spot, my Van Van had zero issues and was fun, such that I did twice. Whoops (corregation) test your suspensions response time and traction of front tire. on an MX bike one just powers through, no big deal. 310 is not an MX bike. its a GS and in stock form, an 80% road, 20% light dirt. Might well be you’d lose the wobbles by simply going faster or much slower. Quite possibly if one shift weight to rear could help too. It’s the experiment part that would worry me as I’m old.
 
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Discussion Starter · #8 ·
I’d think Rally Raid would ship to SA without issue. But I’d try a different front tire first. tire pressure can only help so much and too low causes other issues. Same size, tubeless but with more tread. Perhaps a softer carcass. What I found was thAt I had plenty “go“ to get up on the sand but the front struggled to be controlled like it was diving Then catch and swing to side. Perhaps going faster would have helped but I had already excedead my comfort zone on a new unit with no crashing bars etc. In same spot, my Van Van had zero issues and was fun, such that I did twice. Whoops (corregation) test your suspensions response time and traction of front tire. on an MX bike one just powers through, no big deal. 310 is not an MX bike. its a GS and in stock form, an 80% road, 20% light dirt. Might well be you’d lose the wobbles by simply going faster or much slower. Quite possibly if one shift weight to rear could help too. It’s the experiment part that would worry me as I’m old.
Thanks for the advice, all valid points, will search for the best solution. There is always a way to avoid the corrugated sections, just stay on the edge of the road next to it, and take it slow :)
 

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Discussion Starter · #9 ·
I310 is not an MX bike. its a GS and in stock form, an 80% road, 20% light dirt. Might well be you’d lose the wobbles by simply going faster or much slower.
Correct, although I plan to use it 70% on dirt. I do not commute in the city, just occasional trips. I think if I plan accordingly, and rectify the above, the 310GS can be a great small bike tourer on dirt. Thanks again for your valuable advice.
 

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310 has potential to be crazy cool 100% off road. Different tires and lower gearing being starting point. I personally wouldn’t go with spoke rims until I had issues with the stock ones.
Just too much outlay for something that’s quite possibly a “non” issue, it’s not a 600 lb bike nor is the intent to win races. Many 1200 GS units came without spoke rims. I’d shell out for a stiffer front end long before spoked rims. Wait until you mash up a wheel. The BMW style tubeless spoked rims have proven less than strong, hard core riders seem to change them out for conventional tube type. Rear shock will not last long either, but wear it out before replacing, at least I would (will) I’m cheaper and less demanding than some. Well and have a dirt bike.
 

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I was doing about 70 km/h (43 m/h) on a badly corrugated dirt road and picked up a wobble, which can be best described as a about 35% tank slapper. Luckily I got it under control. Now my Google search came up with a lot of possible causes.

Set up on the bike:
85 kg rider, tail bag about 5 kg. Fuel tank full.
Dunlop Trailmax Mission front and rear, tyre pressure as per manual (1.7-1.9 bar or 25-28 psi).
Rebound at 5.
Apart from a radiator guard no other accessories on bike.

So I think these are the most probable cause:
Soft front suspension.
Tyre pressure too high (I afterwards did let it down by .3 bar, but didn’t come across corrugated roads again, so couldn’t test it).

What do you think?

PS I never in many years riding dirt roads on the 800 / 1100 / 1150 / 1200 GSs experience this.
I am recovering from a broken right clavicle, 4 broken ribs and an L1 vertebrae burst fracture with spinal cord injury that left me paralyzed from the waist down after experiencing tank slapping on a 2019 BMW R1200 GS.

I was completing a 2500 mi ride and only 6 hours away from home. I went through all kinds of weather and road conditions without issues. In fact the bike performed awesome. I decided to take a dirt road and within 20 minutes I came across loose dirt at around 35 mph and the bike went into tank slapping. I released the throttle, did not hit the brakes but made the mistake of fighting the steering. As soon as I fought the tank slapping the bike crashed instantly.

I have been riding for over 20 years, never came across this scenario and obviously handled it wrong. I do wonder about this particular BMW as a professional rider from the UK who test rode the new models died test riding this bike from tank slapping…aka Death Wobble.

I am fortunate that I am recovering after three surgeries and lots of therapy. While the doctors said in would never walk again I recently completed several great rides in northern Thailand. So I am walking and riding.
 

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Really tough with the big bikes, glad your back at it, sorry you had to go through. Even the wee bikes can do this but there’s just half the weight involved. Staying relaxed like everything is key, I find throttle application to be the fix always remembering to look where you want to go. That darn weight penalty can be fierce In application.
 
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