Death Buggy Mk I repair

[Sand-Yeti]

Some of you may remember that I reported side rail cracking on my DB-I recently.

The buggy has done a few thousand kms and suffered a torsional fatigue crack at the rear of the left rail.

Looked like this:

http://i15.photobucket.com/albums/a394/Sand-Yeti/DB-I/DB-1Siderailfracture1.jpg

http://i15.photobucket.com/albums/a394/Sand-Yeti/DB-I/DB-1Siderailfracture.jpg

 

I made the side rails from rectangular mild steel 50 X 25 X 2 mm thick. I decided to use this section size as the principle side rail loading is bending.

 

However, this buggy has a rigid axle (my others are sprung) so while rolling around the dunes my rear axles was trying to twist the side rails,

The failure occurred at the rear behind the rear backrest. which is also the stabilizing tie between the rails. Note that the crack started at the edge of the triangular gusset.

 

I weld repaired the crack and added 4 mm plates of different lengths around the rear part of the rails. I purposely made the outer plate long so that it would be clamped by the back rest.

I then reinforced the right hand rail in the same manner.

 

While this repair is likely to work for a few thousand more kms, I wanted something more permanent, so welded on some lugs to hold some cross bracing. This will stiffen up the rear and reduce the torsional forces on the side rails.

I finished the welding, cleaned up my poor welding mess and have put a coat of primer on tonight.

Looks like this:

http://i15.photobucket.com/albums/a394/Sand-Yeti/DB-I/DB-IRepair04.jpg

 

http://i15.photobucket.com/albums/a394/Sand-Yeti/DB-I/DB-IRepair06.jpg

http://i15.photobucket.com/albums/a394/Sand-Yeti/DB-I/DB-IRepair05.jpg

http://i15.photobucket.com/albums/a394/Sand-Yeti/DB-I/Undercoat02.jpg

http://i15.photobucket.com/albums/a394/Sand-Yeti/DB-I/Undercoat04.jpg

 

I will post some final pics once I finalise the paint job & fitted the seat.

[thedogsbollox]

Wow that is ugly, and i mean the fabrication BTW, but i bet that will hold her together forever. That is one solid bit of kit, do you know how much she weighs?

[Sand-Yeti]

Wow that is ugly, and i mean the fabrication BTW, but i bet that will hold her together forever. That is one solid bit of kit, do you know how much she weighs?

 

Yeh! I know it's ugly but for me the most important thing is that it is functional and holds together. Nobody sees me in the desert so I don't have to impress anybody.

Haven't weighed it yet. but expect it to be between 50 & 55 kgs.

The wheels & tyres weigh 20 kgs alone.

I'd like a lighter buggy and Giorgio who buggies with us is in the process of building a composite buggy that with similar overall dimensions to the DB-I an expected total weight of around 32 kgs. I'm looking forward to how that works out in our patch.

 

You will note that the DB-I has a rigid axle. The rails incl. padding are tight on my body when squeezing in it. It more suited for riding at high speed across the sabkhas than running the dunes but I keep it as a spare mainly for visitors.

Visitors who are not afraid to ride in the ugly Death buggy will find it a nice buggy to handle.

[dubai_reddragon]

Dave, looks like the DB1 is about to reborn!! Can't wait to see it in the dunes.

[Sand-Yeti]

Dave, looks like the DB1 is about to reborn!! Can't wait to see it in the dunes.

 

I don't think you ever had a ride in it but you are always welcome.

Keep in mind it is called the 'Death Buggy' for a reason.

 

I can lower the seat, and you will crack the 60 kph barrier with ease on our bumpy sabkhas.

[dubai_reddragon]

Dave, I would love a go but I need to check my life insurance, I know exactly why its called DB1!!! See you soon

[Sand-Yeti]

I've finally finished the reinforcing & bracing of the DB-I tonight.

 

I'm knowledgable at designing stuff but am just an amateur welder and fabricator when it come down to the real work of actually doiing this kind of physical work.

 

This is all my own handiwork so just have myself to blame if it breaks again.

 

I figure now that it's beefed up in the right places, so let's see if it works. I haven't got around to polishing the stainles etc. & I'm certain I never will.

 

PTW you are such an expert in ultra brilliant finishing finishing on stainless, please come on over when you are bored, I might have a job for you. LOL

 

Pics of finished job (sorry I didn't clean the non modified bits).

http://i15.photobucket.com/albums/a394/Sand-Yeti/DB-I/DB_IFin2.jpg

http://i15.photobucket.com/albums/a394/Sand-Yeti/DB-I/DB_IFin8.jpg

http://i15.photobucket.com/albums/a394/Sand-Yeti/DB-I/DB_IFin4.jpg

http://i15.photobucket.com/albums/a394/Sand-Yeti/DB-I/DB_IFin7.jpg

[dubai_reddragon]

Hey Dave, it looks great, is it out tomorrow or Friday?

[popeyethewelder]

That look well beefed up now Dave....stainless ehh, I'll pass on the polishing thank you

[Sand-Yeti]

Hey Dave, it looks great, is it out tomorrow or Friday?

 

UDB tomorrow & DB-I on Friday.

We are planning to bolt Giorgio's new composite rear axle on the DB-I on Friday.

He's making two axles one stiff & one flexible. I get the opportunity to try & break the stiff one first. Off interest, the 1.45 m long composite axle weighs only 2 kgs. The 20mm tapping blocks to hol;d the wheel bolts are made of alu.

Giorgio offers no insurance should the Death Buggy live up to its reputation.

Side note Pete - P.M. me as I'm waiting to finish the backrest for your Libre. I need you and buggy to customise it to your body.

[Sand-Yeti]

That look well beefed up now Dave....stainless ehh, I'll pass on the polishing thank you

 

Pity because I was thinking about bringing it to Lincoln for a quick polish on the 30 August. You'd only have to do the forks, downtube & rear axle

The side rails are mild steel, hence the paint job.

 

I had a choice of Cat yellow or marine white (very high quality paint BTW).

I think you know why I chose white.

[popeyethewelder]

That look well beefed up now Dave....stainless ehh, I'll pass on the polishing thank you

 

Pity because I was thinking about bringing it to Lincoln for a quick polish on the 30 August. You'd only have to do the forks, downtube & rear axle

The side rails are mild steel, hence the paint job.

 

I had a choice of Cat yellow or marine white (very high quality paint BTW).

I think you know why I chose white.

 

 

Ok then Dave you bring it in your suit case and I will polish it while you are at mablethorpe having fun............I love polishing...love it I tell you..

[Orange]

 

Pity because I was thinking about bringing it to Lincoln for a quick polish on the 30 August. You'd only have to do the forks, downtube & rear axle

The side rails are mild steel, hence the paint job.

 

I had a choice of Cat yellow or marine white (very high quality paint BTW).

I think you know why I chose white.

 

 

Ok then Dave you bring it in your suit case and I will polish it while you are at mablethorpe having fun............I love polishing...love it I tell you..

 

Polishing what..

[Sand-Yeti]

 

 

Ok then Dave you bring it in your suit case and I will polish it while you are at mablethorpe having fun............I love polishing...love it I tell you..

 

Polishing what..

 

Rear axle, downtube & fork legs are all stainless. The two fork cross members are alu. and will polish up nicely too.

Car wax & good polish on the paintwork won't go amiss

 

Looking for a polishing job then Orange???

[Sand-Yeti]

 

Ok then Dave you bring it in your suit case and I will polish it while you are at mablethorpe having fun............I love polishing...love it I tell you..

 

Can't do that. I wouldn't want to break up your love affair with polishing.

No! you have to come to Maplethorpe and get bored riding your buggy in good onshore winds while I make one of your buggy's dirty.

[Sand-Yeti]

After any major work comes the test after repair.

 

Additional to the repair, reinforcing & cross-bracing, Giorgio manufactured a composite rear axle.

I suggested he make it 1.45 m long but somehow or other he made it 1.6m long.

He brought it round my house yesterday morning complaining that it was too heavy at 2.1 kgs. Seems he wasn't happy about the alu. tapping blocks at the end with the M20 threads because these weighed 600 grams.

2kgs was nothing as far as I was concerned but wondered if it would break. He proceeded to jump up & down on it to prove how strong it was.

 

Pic of finished buggy & ready for desert run:

http://i15.photobucket.com/albums/a394/Sand-Yeti/DB-I/DB-I-3.jpg

 

As Fluffywoo is much better to look at than me, she sat in it while I took pics

 

http://i15.photobucket.com/albums/a394/Sand-Yeti/DB-I/DB-IW.jpg

 

http://i15.photobucket.com/albums/a394/Sand-Yeti/DB-I/DB-IW02.jpg

 

http://i15.photobucket.com/albums/a394/Sand-Yeti/DB-I/DB-IW03.jpg

 

I added a 3 litre Camelbak of drinking water in my insulated brown bag that you see just behind Fluffywoo, which kind of made a mockery of the 2kg axle.

 

I got off steadily at first but was soon bumping over the rutted floor at 60 plus kph wondering if the axle would break.

The back end of my buggy was so rigid that the front was jumping around rather like the old saying of the tail wagging the dog.

I noticed this as my GPS mounted on my downtube was shaking from side to side.

There was some very slight flexing in the axle as Giorgio had built it to withstand high dynamic downward forces. However I sensed that when hitting ruts or small bumps unevenly, the axle tended to flex forwards & backwards. Giorgio explained that he hadn't designed it to accomodate that type of loading but figures he can fix that easily enough.

A good feature about the DB-I now is that it is very light to lift on to my trailer at the end of the day.

 

I could chuck this buggy around as hard as I wanted and it stayed pretty much on the ground. I was spinning it around from very high speed and hardly had the wheel lift.

The downside to the long axle was the reduced clearance as I ran along dune ridges. I felt the characteristic bum drag through the reinforced seat.

 

Giorgio reckons the composite axle will not suffer from fatigue but the material is sensitive to UV light that will reduce the life. A good dolloping of paint will fix that problem.

 

In conclusion, the steelwork did its job and the axle did as well. In general I'm well pleased with the results.

 

As a side note, I suffered a rear wheel puncture about 9 kms from the ghaf tree. I rang Brig to drive over with a spare wheel.

Giorgio was worried when I rang as he thought the axle was broken but was much relieved to hear that I'd only punctured a tyre.

[Draggin]

SY, did you try the db1 with your own steel axles?? Just wonder what the comparison would of been with the original axle and the extra stiffness in the rear?

 

One final comment, can you make sure fluffywoo is in all your pictures in future rather than that old wrinkly guy :D :D much more pleasing on the eye.

 

Tim

[Sand-Yeti]

SY, did you try the db1 with your own steel axles?? Just wonder what the comparison would of been with the original axle and the extra stiffness in the rear?

 

One final comment, can you make sure fluffywoo is in all your pictures in future rather than that old wrinkly guy :D :D much more pleasing on the eye.

 

Tim

 

Not yet Tim. I didn't get started until mid afternoon and managed only 90 minutes of buggy rolling time. It was bad enough watching all that good wind go to waste waiting for the Mrs to bring my spare wheel after the rear wheel puncture.

I didn't want to waste that good wind changing axles as well.

I may try out my stainless axle on the DB-I next week. It will certainly be interesting to compare.

 

The wrinkly old bloke is me and totally agree that Fluffywoo makes my buggies much more pleasing to look at.

[popeyethewelder]

Fluffywoo makes my buggies much more pleasing to look at.

 

You're not kidding she can grace my buggies any time , saves me having to polish them

[philpig]

i hope your bringing fluffywoo over to mable when you come sy

[Sand-Yeti]

i hope your bringing fluffywoo over to mable when you come sy

 

Better talk to her fiancee about that. She engaged to the Dubai Red Dragon.

[dubai_reddragon]

Dave, dont worry about it, so long as he guys fund her kites and buggies, its fine with me. Plus if she goes to Mable with you, that we leave me with some peace and quiet for a while.....;-)

[FluffyWOO]

Hummm... I can recommend Mr Sheen to do the job...

[jimmy221599968752]

i like the axle Yeti, basically making the axle braced in the horisontal plane will stop the toe in/out and still allow it to flex vertical . you are noticing the front end bounce now because the back is so good, maybe you could take you back axle to popeyes and he can lend you the front Carkeek suspension rig on your return . popeye will probably notice the oposite now , he will have rear bounce due to the smooth front . p.s. your bracing would be twice as strong if you joined the cross together in the middle, it looks seperated currently . good luck in England.

[Sand-Yeti]

i like the axle Yeti, basically making the axle braced in the horisontal plane will stop the toe in/out and still allow it to flex vertical . you are noticing the front end bounce now because the back is so good, maybe you could take you back axle to popeyes and he can lend you the front Carkeek suspension rig on your return . popeye will probably notice the oposite now , he will have rear bounce due to the smooth front . p.s. your bracing would be twice as strong if you joined the cross together in the middle, it looks seperated currently . good luck in England.

 

Thanks for your comments Jimmy.

The composite axle was built to accommodate the serious downward bending moments but nothing much on the sides with the result that it was noticeably moving to & fro.

It was this to & fro movement that was exciting the front of the buggy.

 

I can confirm this as I ran with my 1.4+ m st. steel axle last Friday and the front end shaking was back to its normal self. I even ran at a higher speed of 67.5 kph compared with 62.4 kph on the composite axle.

 

Giorgio is making a new composite axle that will be 1.5 m (the test one I used was 1.6 m). It will also have additional stiffness on the sides to prevent the to & fro flexing.

 

The reason I beefed up the back of the buggy side rails and added the cross bracing is that I hadn't anticipated the rails to suffer that much from torsional loading. Most of the loading on my rails comes from downward bending.

 

However, with the rear end of the buggy running on a rigid axle in the dunes, both rails were effectively trying to twist around each other particularly when on slopes that caused uneven loading on the rear wheels.

 

It took a couple of years buggying for the steel to fatigue to the point of breaking.

I beefed up the rear rail behind and including the area where the rear backrest is clamped. This is probably enough to prevent further breakages. However, to reduce the twisting effect on the frame, the cross bracing does do this well. e.g. say the right rear wheel lifts trying to turn the right rail over the left one, the brace will partially transfer the load to the left hand rail trying to lift that as well which effectively reduces the torsional loading on the rails.

I have noted that some people weld the cross bracing but this doesn't actually double the strength but it does make the area more rigid.

The downside of welding in the middle is that heat applied during the welding process affects the structural integrity of the parent metal so this is an area, which could then become suspect.

In my case I used fairly thin tubing and do not have a facility with my electric welding set to weld that particular thinness. This is the prime reason that I didn't weld the bracing in the middle.

Making a nice weld in the middle of the bracing is definitely more aesthetically pleasing but I believe I have redesigned it sufficiently to prevent a further failure for along time to come.

 

One thing is apparent when I buggy and that is that the cross bracing has made the rear more rigid.

 

I have been running my UDB, which has a suspension axle much harder than the rigid DB-I axle. The suspension takes out the shock loading & these rails on that are still in a tip top condition.

 

I'd love to take my buggy to the UK to fit the front suspension but the airfreight cost is just prohibitive. I going have to build it here after my hols.