Mudguard stay modifications.

[mlplatt]

Some may recall that I mentioned my breakage of one of my mudguard stays a few weeks ago.

Marlin finally offered to replace these at half price but now inform me that as they are very busy they cannot supply them "for a few weeks yet." Such an open ended delivery forecast may I fear become "a few months yet" and eventually "whenever."

So I am thinking of relying on friends locally. This has the advantage of allowing me to modify them slightly, allowing the longer mudguards (purchased from Styla) to be positioned further back on the wheel.

What I would be grateful for is any information on the modifications carried out by Marlin. Thickness and diameter of tube, structural differences etc. compared with their original faulty design.

Failing that any advice in general. What I do want to avoid is any repetition of the breakage which had it not occurred on a deserted country lane when practically stationary could have been highly dangerous.

Malcolm Platt

[Peterx]

Re: Mudguard stay modifications.

Malcolm,
I have a set of the later version which are made of solid bar. They are off the car at present, so I could photo and measure them up, if your interested. The issue of Sportster mudguard stays has been discussed elsewhere. One theory put forward by Robin Martin was that the Marlin design has both stay bars almost horizontal allowing the bars to twist like a torsion bar. I did a quick survey of lots of other manufacturers cars at a show and noticed that most manufacturers have one stay fixed at 90 degree to each other. This is worth considering when designing your own.
Keep us all posted on your new design as there are a few of out here that are interested.

best regards

Peter

[mlplatt]

Re: Mudguard stay modifications.

Thanks Peter. I would indeed appreciate a photo of your later stays. My Sportster is a Ford based one so a later design would be interesting to see as Marlin did tend to change things. Robin Martin's theory is interesting and is in line with David Sidall's thoughts on the subject. The problem is that things get in the way! The front stay has to curve round not only the wishbone but also at full lock has to avoid the headlight. So room for manoeuvre is limited. David suggests a cross piece to triangulate the stay. Another friend suggests webs to strengthen the bends. I will certainly keep you informed as to the outcome.

Best regards,

Malcolm

[mlplatt]

Re: Mudguard stay modifications.

Peter.

Can you tell me the diameter of the solid bar. Marlin inform me that it is smaller but do not specify its size.

Regards,

Malcolm

[Peterx]

Re: Mudguard stay modifications.

Hi Malcolm,
I forgot to mention that my Sportster is a BMW version so may be different to yours?
I measured up the bar and it's a tad over 12mm so it's probably 12mm bar plus the powder coating.
I've posted a couple of pictures here but you might get a better idea from looking at this...

http://www.flickr.com/photos/peters-bmwmarlin/2206893257/sizes/o/in/set-72157600024149736/

regards, Peter

[mlplatt]

Re: Mudguard stay modifications.

Hi Peter,

The Ford based stays are radically different. For a start they fasten with three bolts, two of which are direct on to the brake callipers. The two separate arms sprout from a central shaped angle iron section. It is difficult to describe but I will post a photo as soon as I have the modified ones made to show both. At the moment the plan is to keep them basically the same but with the front strut more upright and the rear strut straight. We think we can manage this if we reposition the headlights, reversing the bracket's position atop the shocks thus moving them back and giving more leeway on full lock.

Whether any of this can be adopted to the BMW set up I am not sure. You will be able to judge better from the 'before' and 'after' photos.

I think I will go for a rather larger diameter rod than 12mm though. Just to be on the safe side.

Regards,

Malcolm

[Peterx]

Re: Mudguard stay modifications.

Hi Malcolm,
yes, i've seen the Ford type, they are indeed quite different. Maybe just copy the original Marlin design with either thicker wall tube or maybe solid bar? The BMW ones used to be tubes and are now solid bar.
I'm no expert but I understand that bad welding can also cause the tubes to become brittle and weakend.

Good luck,

Peter

[andy-rogers]

Re: Mudguard stay modifications.

I thought I was immune from this problaem, as my stays are not the weedy Marline ones, but much more beefy. Yesterday One of mine (offside) broke - the 3mm thick plate that attached to the mudguard itself. This is a fatigue failure, due to constant vibration. Dave Siddall has kindly offered to fix it for me, but I think the best long-term solution is to mount the mudguards from the chassis as Dave has done.

[Peterx]

Re: Mudguard stay modifications.

I don't know who Dave is but has anyone got any pictures of how he has fixed his mudgards to the chassis?
thanks
Peter

[copperleaves11]

Re: Mudguard stay modifications.

Hi Peter.Here's a photo of my "solution".Aesthetically it may not be to every-ones taste but I feel that the original stay design was not up to the job and (to my knowledge, there have been four failures),though this can be remedied by using a combination of stronger/solid bar or tube,you end up with an increase in un-sprung weight.Surprisingly, the amount of debris thrown by wheels onto the rear wheel arches seems no worse than with the original mounting method. David

[Peterx]

Re: Mudguard stay modifications.

Thanks, Dave, that looks a very interesting design. Do you get spray from wet roads when you go round a corner?,
thanks, Peter

[copperleaves11]

Re: Mudguard stay modifications.

Hi Peter. Truth be told, I don't go out in the rain if I can help it. However in a straight line I would envisage no difference from conventional mounting.If cornering at any moderate to high speeds, the wheel angles are relatively small, that was the reason I extended the mudflaps inboard slightly.At slow speeds the momentum of debris thrown from the tyres is less.Over the time I've had the car, I've(6 years from sva)found that cycle wings offer sporting looks with compromised efficiency and unless any mudflaps leave a gap of only 1/2 inch between themselves and the road,missiles from the front tyres seem to find there way past.For what it's worth that's my theory anyway.
regards David.

[Colin Barratt]

Re: Mudguard stay modifications.

Hi All,
My offside mudguard bracket broke for the second time recently on the lower stay at the angle nearest the guard on my BMW based car. It was on the way down through France so I removed the guard and the broken section and drove on to my destination where a local carrossier did a neat job welding it up.
I have always noticed that the offside one bounced around more than the nearside one and it still did it so when I got home I took a look to see why. I found a hairline crack across the plate between the two mounting holes. A friend suggested that I grind a shallow grove along the crack which he then ran weld into. I ground it almost flush and then refitted it. It still bounces more than the nearside one. I think that the angle bracket of which the plate is part has "lost its temper" (if it ever had any).
I am considering making an auxiliary support running from the front caliper bolt to a "Stauff" pipe clamp https://www.hydraulic-supply.com/htm...uff-clamps.htm bolted around the straight section of the front stay which will give triangulated support rather than having it in one plane only. For symmetry's sake I'll do the other side as well.
What do you think?
Colin Barratt.

[peter.crowther4]

Re: Mudguard stay modifications.

Hello Malcolm,
I have a Ford based Sportster that has suffered a few stay failures in the past. The car is used for Endurance events across Europe and is therefore a very good proving ground for mods. The original stays were strengthened post the first failure but minor Bulgarian roads saw that off soon enough!. The originals were only thin section mild steel with small diameter bosses which on inspection were cracking in several places (apart from the already failed part). My own solution has been in two steps: 1/ Lighten the mudguard itself to reduce the bending moment at source. The guards are very heavy at 1.4 kilos each and were easily reduced to 1kg each with plenty of meat left. Obviously the material was removed from inside the arch. Could have taken more but wanted to retain durability. 2/ re-design of the brackets and upgrade the materials. I used T45 tube of greater (20mm dia and 2mm section) and used larger bosses/braces. greater width mudguard fixing plates were made (another failure point across the fixing bolt threads) and the whole ensemble bronze welded. Bronze welding is a very good solution frequently used in aircraft airframes and avoids the potential for localised crystallising of the material as the heat applied is less. A rough calculation showed the new design/materials to be not less than 6 times stronger without resort to solid bar!!! An alternative would be the more modern 4130 chrome moly tube. I have photos of the brackets if you want to see them and I'll measure up the various thicknesses and diameters if that helps. Send me an E mail at: [email protected] and I'll post them to you. It's now 2.5 years since fitting and no signs of distress anywhere.

Regards

Peter C

Some may recall that I mentioned my breakage of one of my mudguard stays a few weeks ago.

Marlin finally offered to replace these at half price but now inform me that as they are very busy they cannot supply them "for a few weeks yet." Such an open ended delivery forecast may I fear become "a few months yet" and eventually "whenever."

So I am thinking of relying on friends locally. This has the advantage of allowing me to modify them slightly, allowing the longer mudguards (purchased from Styla) to be positioned further back on the wheel.

What I would be grateful for is any information on the modifications carried out by Marlin. Thickness and diameter of tube, structural differences etc. compared with their original faulty design.

Failing that any advice in general. What I do want to avoid is any repetition of the breakage which had it not occurred on a deserted country lane when practically stationary could have been highly dangerous.

Malcolm Platt

[Colin Barratt]

Re: Mudguard stay modifications.

I consulted a friend who suggested that the weakness is in the design of the right-angled section which bolts to the hub carrier. This flexes and fatigues across the weakest line which is between the three holes. His solution was simple ................ weld a triangular plate onto each end of the right angled section, effectively half boxing it in, so that the two parts cannot move in relation to each other. It works!!! The muguards are now as rigid as one can expect for two pieces of rather heavy fibreglass mounted on bars of spring steel bouncing at high speed over potholes and dead badgers. My only plan for the future is to replace the fibreglass guards with aluminium versions. More of this later.
Colin Barratt.