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Go Back   Madabout Kitcars Forum > Mad Build Area > Marlin Sportster, Cabrio, Berlinetta and Roadster builds

Marlin Sportster, Cabrio, Berlinetta and Roadster builds Enthused or Confused about your vintage Marlin build? Ask away here or show off your build.

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  #41  
Old 23rd April 2011, 17:11
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Right, I've just had the front end off Vikki, looking for options. I thought I could attach something via the old ABS sensor mounting holes (They're tapped to M8)... But no. Looking at it it would just flex as much as the main stays.

I think it's going to have to be (if anything) something welded to the current stays over the flange portion, taking into account the clearances required for the top wishbone.

I'm glad I was poking around the front though - Whilst investigating I found that the lower ball joint on the upright had worked it's way loose, and the steering was acting around the threaded portion of the joint, not the ball!

If I'd left it, and it worked all the way loose at high speed....
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  #42  
Old 23rd April 2011, 19:43
timbo timbo is offline
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I'm no engineer, but I've always thought that the 'third bar' should run parallel to the body of the car not perpendicular to it like the other 2 stays. If this was attached securely to the hub it would help prevent the rotation which I think causes the wobble (some sort of triangulation based theory I think).
Not had a chance to try it out yet though....
Tim
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  #43  
Old 23rd April 2011, 21:22
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Quote:
Originally Posted by GreatOldOne View Post

I'm glad I was poking around the front though - Whilst investigating I found that the lower ball joint on the upright had worked it's way loose, and the steering was acting around the threaded portion of the joint, not the ball!

If I'd left it, and it worked all the way loose at high speed....
Not those dreaded 'metro' ball joints again!!
If you recall my first pair failed the MOT just the week before my SVA test. I had thread locked them in and had a devil's job getting them out.
I broke a 1/2" extension bar, if I recall before heating them up to get them out. The second pair fitted were left in the wishbones when I sent them back to Marlin for my replacements as they wouldn't come out.
I don't recall if I thread locked the third set, probably not
I guess the steering movement back and forth has undone your one?
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  #44  
Old 23rd April 2011, 21:48
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That's what I'm guessing.

I put it back in and used my ball joint socket and a breaker bar to do it 'fudging tight' again.

I think I may have inadvertently caused it to come loose as I smeared the thread with a little copper grease, in an effort to stop corrosion. In retrospect, not a very clever idea, as I guess it eased it's rotation back out of the socket.

What's also worrying is that it passed it's MOT with it like it, as I can't believe it's happened in the handful of drives I've had since she got her ticket renewed.

I'll give the other side the once over tomorrow, but it looks fine at first glance, with the joint tight against the socket, and I can't see it moving with steering input (unlike the loose one)
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  #45  
Old 23rd April 2011, 22:15
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Quote:
Originally Posted by GreatOldOne View Post

I think I may have inadvertently caused it to come loose as I smeared the thread with a little copper grease, in an effort to stop corrosion. In retrospect, not a very clever idea, as I guess it eased it's rotation back out of the socket.
I think British Leyland design them to rust in and that stops them rotating on a metro

My MOT man always seems to take a very keen interest in my ball joints? I think he is just of a very suspicious nature or maybe he recognised them as BL bin ends? But he did completely miss that my fuel tank was leaking!
My third MOT is next month so we'll see what he finds this time....
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  #46  
Old 23rd April 2011, 22:15
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Quote:
Originally Posted by timbo View Post
I'm no engineer, but I've always thought that the 'third bar' should run parallel to the body of the car not perpendicular to it like the other 2 stays. If this was attached securely to the hub it would help prevent the rotation which I think causes the wobble (some sort of triangulation based theory I think).
That's what I was trying to find a mounting point for today - but the problem is anything on the hub ends up inside the line of the wheel, so it needs to bend back toward the car (like the main stays) to clear it and the tyre. If you take it off the current stay anchor point, you'd need to bend it so it goes into the wheel and then out again to clear the top wish bone:

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  #47  
Old 24th April 2011, 07:53
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Now I see the problem, which is maybe why Mark never designed a third stay for the e30 based car.

The e36 suspension geometry looks quite different...



Marlin demonstrator car Easter 2004 by marlinpeter, on Flickr

If you bolted a small length of angle extrusion (~20x20mm) across the top u-bolt (on the wheel side) could the third stay then come of the top of the centre of the angle extrusion. At an angle but keeping it straight?
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  #48  
Old 24th April 2011, 09:32
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Possibly... I'll have a look today at some point, as I have some metal angle left over.

I think it might have to come off the lower U clamp, as I'm not sure if the upper threaded portions would have enough length to pass through the back plate, the stay and the angle & still get a nyloc on.
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  #49  
Old 24th April 2011, 15:42
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Well, what a waste of an afternoon that was.

I tried peter's suggestion of some angle iron off one of the u-clamps. I went for the lower one, as there was still plenty of thread on the clamps to go through the extra metal.

Good idea, but doesn't really work. The rod or metal that you use as the third stay needs so many bends to clear stuff it's not funny - I got two attempts wrong by getting the bends either in the wrong place or to the wrong angles, so I gave up on that idea.

I have also tried taking a stay off the back of the upright, as the angle of travel from lock to lock is less than that if you had it on the hub side. This seemed to have some promise, as the bends weren't so complicated.

I got it up under the wing, but as soon as it was there, it was obvious that it was going to be a useful as a ashtray on a motorbike. It flexed just as much as stand still as it did without, so I can't see it being any good at speed, either.

So, unless someone can come up with a better idea, I'm just going to stick with the two stays and live with the wobbles - there doesn't seem to be any evidence of impending failure, and it's as rock solid on the upright as it was when I put it there.

C'est la vie...
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  #50  
Old 24th April 2011, 18:51
timbo timbo is offline
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Hi Jason
Sorry you didn't have any success. My intention, at some point when the expert in Caerphilly has actually fixed my car, is to try something like this:

http://www.flickr.com/photos/3310545...in/photostream

but I appreciate you don't have the same central mounting point as the E36.
Regards
Tim
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  #51  
Old 26th April 2011, 18:32
AndyDane AndyDane is offline
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I've had a problem with my E36 based wing stays as well. The problem on the E36 version is that the wingstay bolts to the upright with a piece of angle at the bottom. The 2 bolts that hold it on seem to create a weak point where the flexing causes it to crack through the middle making it flex more, making it crack more.... you get the idea.

I think its made worse by the length of the stays as well. I've tried a solution using an exhaust clamp, strip of steel and PClips - seems to work but the first P Clips were a tad too small and sheared so new ones are on order!

somehow it doesn't look as good as anyone elses solution but it has damped the wobbling quite a bit...

Andy
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  #52  
Old 26th April 2011, 22:34
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Andy, your solution looks similar to what I want to attempt, so I'm glad it works! My idea was to weld a bar to the existing stays but this may prove impractical/impossible to fit or remove.
Cheers
Tim
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  #53  
Old 2nd July 2013, 21:56
NigelB NigelB is offline
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Default Wing stay failure

I've resurrected this thread.

After just 250 miles both my wing stays have cracked in the same place. The crack is on the mounting bracket that bolts between the upright and the hub. 20/20 hindsight is great but I always thought that cycle wing struts which were as long as my E36 design were prone to a lot of flexing and possible failure. I just didn't expect it to happen this quickly ................ Here are pictures of the cracking. Its in the lower corner of the triangular end plate.


Wing stay failure by MarlinBuild, on Flickr


Wing stay failure by MarlinBuild, on Flickr

After searching Madabout last night I found Andy Dane's idea where the wing stays are braced to the top of the upright using an exhaust clamp and some P clips. I've done the same and it appears to work a treat. Not yet road tested but the flexing is significantly reduced when you give it a good old tap.


Wing stay brace by MarlinBuild, on Flickr

It will be good to get it back on the road tomorrow for a proper test. Certainly the knocking noise of what I now know to be the wing stay, against the rim of the wheel, should have now gone away
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  #54  
Old 2nd July 2013, 22:50
AndyDane AndyDane is offline
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Glad it helped Nigel. did your wing stays have that triangular end plate on when you got them or is that your own addition?

I've just had one of mine welded to include a bracing end plate like that as there was nothing there to start with...
andy
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  #55  
Old 4th July 2013, 09:09
NigelB NigelB is offline
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Quote:
Originally Posted by AndyDane View Post
did your wing stays have that triangular end plate on when you got them or is that your own addition?
My stays came with the end plates already on them so perhaps the weakness was identified and the end plates were the seen as the cheap and dirty solution. But its clearly not, particularly with both mine failing after such a short time.

Your solution however does the job. I have now road tested it. The wing bounce is greatly reduced and the associated noise of the stay hitting the inside edge of the rim has gone altogether.

How has your brace performed long term??

N.
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