Sportster front suspension beginner's questions
 

I have just started working on the front end of my Sportster and have a couple of beginners questions.
The ball joints for the lower wishbones and modified struts seem excessively tight in their threads. I haven't really tried to force them yet but have cleaned treads etc. How tight should these be? It almost feels like a thread mismatch to me.
Secondly, when I offered up the lower wishbones to the chassis the mounts don't seem to line up, see photo attached and on my Flickr album. If I line up the front mount then the leading edge of the rear mount is against the metal of the wishbone eye. It isn't as if it looks as though the bush just needs to be compressed to squeeze it in, it is metal to metal. Any ideas? Can someone check the dimensions of theirs to see if I have a manufacturing issue. A quick look doesn't seem to show any bend brackets.
Thanks

I remember having a similar problem with the wishbone fitment on one side of the chassis, but I don't think it was quite as bad as shown on your photos. I overcame my problem with a hammer to belt it up into the bracket on the underside of the chassis. I don't know if that is possible in your case.

The best measurement I could take (not easy with the car on the ground) between the inner brackets was 19.5 cm. That is for wishbones based on re-using the E36 struts chopped down. If you've gone for the more modern setup Marlin were promoting a few years back, this may be different.

The only thing I can suggest for the ball joints is either there is weld splatter in the thread (which will not be easy to get out given the size of tap you'd need) or it's just the powder coat. Have you measured the thread pitch on the ball joint and in the threaded insert to see if they match?

Ball joints should ideally go in without much force, some of them are a bit tight. I seem to remember needing to clean the threads quite a bit. These days I use an impact gun and a big socket to remove them.

The lower wishbones didn't fit on mine either - needed some manipulation of the mounts to get them fitted.

The balljoints on mine were a tight fit. But not all balljoints are made equal. Assuming Marlin are using the same ones still (metro?) there are some pretty crummy ones about. Several of us had issues with the taper as well.

My wishbones fitted fine. But mine are fitted with some rather more flexible metalastic bushes. Don't remember the source....

Cheers, Robin

Thanks
 

Thanks all. I will go back out tomorrow and get some decent measurements etc and investigate some more in better light.
I don't know where Marlin sourced the balljoints. There were a couple of weld splashes which I cleaned off but thought it odd that all 4 tightened up in exactly the same way. I'll get the thread gauge on them tomorrow.

My balljoints were tight due to weld splatter but OK once I'd cleaned up the threads. I came to the conclusion that genuine Quinton Hazel ones were the best quality. (I think QH are now bankrupt but there are still old stock around).

My second set of wishbones (after the wishbone recall) didn't fit like yours. I tweaked the wishbones by putting a threaded bar through the bushes and spread the wishbones with some nuts and washers on the inside. It was quite easy to adjust them to fit, but it may be best to check with the factory to see what they recommend.

...peter

Hi Chris, Nice to see one more E39 BMW donator in this forum - When I tried to fit my set it was not without controlled forces to fit them right - I have not really tried the movements yet because of thinking that I have mounted it wrong - but I am going to take it down and lubricate some of the key components so I am sure that I don´t get some trouble later on.
It is all about to clean it up well before fitting it. I sat for a long time and made my cleaning....and it still felt very tight when I mounted the ball joints.. mostly I think it was from the powder coating that made my problems. Then it is a lot of welding nearby and it also will effect on this...

I'll go out and look for what measures I have in my chassis, but I do not know if Marlin has other measures of wish bones if it should fit BMW uprights there..

I took some measurements this morning. 52mm between front brackets, 197mm between mounts and 50mm between rear brackets. Rear bracket is tighter than front but nothing that a little encouragement won't deal with.

Spoke with Kev at the factory this morning and sent him dimensions and photos. His initial reaction was that it was a bigger error than normal and he was going off to check dimensions before recommending next steps.

So I can go back to thread cleaning while I wait.

Chris - my measurments are left/right front - 50/51,5, rear L/R 50,7/50,4 and between mounts L/R 191/192,8 -I can understand it needs some power to squeese them in place.

I added some pictures on Flickr - https://www.flickr.com/photos/our_ma...h/23059908349/

Rickard,

Thanks for this, a very useful comparison. The gaps between the brackets on the front and rear mounts is very similar to mine, and as you say I am happy I can get the bushes to fit into these with a bit of encouragement.

The distance between your front and rear mounts is 5-6 mm less then mine and I think that is the issue. It means the mount lines up against the actual eye not the bush.

Fingers crossed I will hear from Kevin at the factory.

Did you get my answer on the subframe bolts?

My wishbones were a similar amount out to yours. At the time Mark recommended 'forcing' them in but in the end I got the tabs re-welded.
Tim

No - I have not found any ...yet - where did you post it? So many different places to keep track of... Can you send a PM on this forum..?

I think every sportster owner has run across this issue.

I managed to get mine fixed by spreading the wishbone slightly - opening my vice between the two arms. Then, with the bushes in it tapped into place with a plastic mallet, rather than having to use a big 'fine adjustment tool'

Good news, I think.

Firstly balljoints now fit nicely into the modified e36 struts. A patient couple of hours thread cleaning did the trick.

Also I can delay the thread cleaning on the lower wishbones. The error is greater than Kevin was OK with me just spreading the wishbones, so he is going to make me a pair to match my measurements. Just off to triple check them before he gets started.