Clonks and Bonks...

[peterux]

Originally Posted by MartinClan

Thanks Chris. They seem to be 24mm. The next problem is where to get them from. They are
way bigger than anything Namrick supplies and most of the on-line shops that do stock them will only sell a minimum of 100. Hmm

Robin

Hi Robin,
I always thought it was odd not to have a lock nut or 'grub' screw to lock the spring seats in position. I think you might have fallen out with Mark on said subject?

I've often wondered if they are likely to rotate and move up due to vibration but if yours are loose after only a relatively few miles then they clearly need locking in place.

Are you sure they are M24? If yes, then there's a few sellers on ebay selling small quantities of M24 nuts for a couple of quid plus postage.


...peter

[MartinClan]

Thanks Peter

You know I didn't think to check Ebay - DOH.

I am pretty sure they are M24 or if not some funny imperial size.

It seems M24 are commonly available in two thread pitches so I need to also check this. Looks like I shall be crawling under the car again tomorrow...

Robin

[MartinClan]

I checked over the w/e and it seems the thread has a 3mm pitch which fits in with the standard (coarse) pitch for M24. I ordered some nuts from Ebay so I will soon know if I am correct!

Robin

[MartinClan]

Well I fitted the lock nuts - so I did get the size right!

While I was at it though I think I may have found the root of the problem. When I removed the springs there were some signs that they have been binding - that is collapsing enough for the coils to touch. Fortunately when I moved the lower spring plates I also made the lower bump stops adjustable. So for a quick fix I can tweak these up a bit so that the bump stops come into play before the springs bind.

Long term I have two options:

1. Get some new springs of a different rate made.
2. Use the new Marlin springs which I believe involves chopping the top part of a standard spring off and welding the remainder to the upper spring plate. I think Jason has these. Jason - any feedback as to how well they work? Any pictures?

Robin

[GreatOldOne]

They work fine - I've not had any issues with them, and no odd noises that I'd attribute to the springs.

Marlin cut the springs down and then collapse the top most coil only, to form the upper spring seat:

Before:


After:


Spring Seats:


Painted and on the car:


As you can see, they're not welded to the upper spring mounting 'cup'. I cut the old rubber pads that the upper springs sat on (the witches hat one) so that It fit the cup, and I had the pointy middle section on the threaded stub

[MartinClan]

Thanks Jason - all is clear....

Robin

[peterux]

Originally Posted by MartinClan

Well I fitted the lock nuts - so I did get the size right!

While I was at it though I think I may have found the root of the problem. When I removed the springs there were some signs that they have been binding - that is collapsing enough for the coils to touch. Fortunately when I moved the lower spring plates I also made the lower bump stops adjustable. So for a quick fix I can tweak these up a bit so that the bump stops come into play before the springs bind.


Robin

So you mean the springs can compress so much that the they touch before the bump stops hit?
I'll have to take a look at mine and see if that possible.
I'm using Apex aftermarket lowering springs for an BMW e30 which is much heavier than a Sportster so i'd be surprised if that is the cause of my occasional 'clonk'.
But my clonk does only occur when I go over a big bump followed by a dip in the road so I guess this could be the cause. It is quite rare.
Was the thread standard M24 and do you think its worth put on some lock nuts?

cheers

Peter

[MartinClan]

Originally Posted by peterux

So you mean the springs can compress so much that the they touch before the bump stops hit?

Yes - that's exactly what I believe is happening. Because my springs were new and are powder coated you can easily see where the coils have touched. (Marks in the coating). I think I confirmed it today. I stiffened up the dampers (so the springs don't compress so readily) and I only had one clonk on an 80 mile trip.

So as a first step I will increase the height of the lower bump stop (Mine is a large nut with a bolt screwed into it. Then I think I will get some new "proper" springs and get Marlin to make me some of the new fangled upper spring plates and shorten the springs as Jason's are done.

Nuts are M24 with a 3mm pitch thread which I believe is standard for M24. Got mine off ebay.

Cheers
Robin

[peterux]

Robin,
these might solve your clonk problem?

http://www.orange-tuning.de/shop/sup...s-p-16513.html

...peter

[MartinClan]

Thanks Peter - I ordered some. Worth a try and a lot cheaper than new springs!

Robin