5 series based sportster help

mcramsay · #1 11th January 2014, 12:38

Hey guys, I was wondering if any one knew of any other builders building a sportster based on the rear subframe suspension of a e39 5 series, I am having some trouble working out of the rear shocks bolt up to the chassis and some pictures would really help. Sadly the build is completely different from the 3 series none of the build blogs I have found are much use for this part of the build!

peterux · #2 13th January 2014, 20:39

Quote:

Originally Posted by mcramsay

Hey guys, I was wondering if any one knew of any other builders building a sportster based on the rear subframe suspension of a e39 5 series, I am having some trouble working out of the rear shocks bolt up to the chassis and some pictures would really help. Sadly the build is completely different from the 3 series none of the build blogs I have found are much use for this part of the build!

Hi Craig,
you are the only e39 chassis builder that I have heard off so I guess a call to Marlin will be required.
But I'm sure if you post some pictures someone on here might be able to offer some suggestions. Looking at realoem the e39 rear shocks are like McPhearson struts so I would guess that the top just bolts up to the Marlin chassis like in the original car?
This video I found may help?
http://www.youtube.com/watch?v=iSD_FvkVOoc

Maybe I've misunderstood your question?

......peter

mcramsay · #3 13th January 2014, 21:00

Sadly not that simple, the only part of the suspension set up not is not used from the 5 series is the shocks. These are supplied by marlin, they are the same gaz shock units that are used on the front suspension. Marlin supply a threaded adaptor that screws into the e39 hub for the shock lower mount. The gaz shocks are fitted with 1/2" ID rose mount joints, that allow movement of the shock, basically so it can sit at an angle. My problem is as follows,

With the shock bolted up to the lower mount, there is at least a 2" gap to the top mounting bolt as shown below:

To get over this problem I need to mount the shock at a slight angle, the rose mount joints will allow for this. The problem is spacing the shock to hold it in position. I can't use washers as the OD is too large and then hits the shock housing ( that holds the rose joint) and thus stops it being mounted at an angle. This pic shows the lower mount

I think what I have to do is machine a spacer for the top and bottom mounts which will hold the shock in place and take up the gap between the top chassis mount and shock absorber, but the spacer has to be a small enough outer diameter to allow the rose joint to pivot, I was thinking of stainless tube, 13mm ID and then 17mm OD this will sit flush on the rose joint and not the outer casing of the shock, but I will have to weld a large thick washer to the end of the spacer where it meets the chassis on the top mount, to better spread the load when the bolt is tightened up.

Kind of hard to explain! I have emailed marlin so just waiting for there advice! It can take a few days for them to respond to emails though!

You can follow my build on this photo bucket album!
http://s223.photobucket.com/user/mcr...in%20sportster

peterux · #4 13th January 2014, 21:15

Quote:

Originally Posted by mcramsay

Sadly not that simple, the only part of the suspension set up not is not used from the 5 series is the shocks. These are supplied by marlin, they are the same gaz shock units that are used on the front suspension. Marlin supply a threaded adaptor that screws into the e39 hub for the shock lower mount. The gaz shocks are fitted with 1/2" ID rose mount joints, that allow movement of the shock, basically so it can sit at an angle. My problem is as follows,

With the shock bolted up to the lower mount, there is at least a 2" gap to the top mounting bolt as shown below:

To get over this problem I need to mount the shock at a slight angle, the rose mount joints will allow for this. The problem is spacing the shock to hold it in position. I can't use washers as the OD is too large and then hits the shock housing ( that holds the rose joint) and thus stops it being mounted at an angle. This pic shows the lower mount

I think what I have to do is machine a spacer for the top and bottom mounts which will hold the shock in place and take up the gap between the top chassis mount and shock absorber, but the spacer has to be a small enough outer diameter to allow the rose joint to pivot, I was thinking of stainless tube, 13mm ID and then 17mm OD this will sit flush on the rose joint and not the outer casing of the shock, but I will have to weld a large thick washer to the end of the spacer where it meets the chassis on the top mount, to better spread the load when the bolt is tightened up.

Kind of hard to explain! I have emailed marlin so just waiting for there advice! It can take a few days for them to respond to emails though!

You can follow my build on this photo bucket album!
http://s223.photobucket.com/user/mcr...in%20sportster

Hi Craig,
OK, I get the problem. Check with Marlin but I think you need "rose joint misalignment spacers"
Try searching on ebay or have a look at this...

http://www.therangerstation.com/Maga...008/joints.htm

...peter

P.S. nice build photo's!

mcramsay · #5 13th January 2014, 21:22

You Are a complete god send. Got some ordered up!
Cheers mate

peterux · #6 13th January 2014, 21:37

Quote:

Originally Posted by mcramsay

You Are a complete god send. Got some ordered up!
Cheers mate

No problem, I hope they work!
I must be spending too much idle time reading other peoples build sites!!

BTW some years back I spoke to GAZ who were adamant that their shocks should not be mounted upsidedown but I know Mark supports this method of mounting.

Keep us posted on your build updates

MartinClan · #7 14th January 2014, 12:19

Hi Craig

Personally I would still check with Marlin. Surely they should be supplying everything you need?

Also don't assume everything is correct. The rear spring mounts on my E30 based Sportster were in the wrong place (over 25mm out). Several builders of the same era had this problem. Rather than take the chassis back to Marlin for correction I moved the spring plates on the suspension arms so they lined up.

Whatever solution you choose, as you have coil overs, remember the complete weight of the rear of the car and the dynamic load from suspension movement is taken on the top mount.

Happy building!

Robin

morris · #8 14th January 2014, 17:10

Following on from Robin, if it was me I would want the bolt through the top mount supported on both sides if it was not tight against the chassis otherwise even with spacers, there will be quite a bit of leverage on that bolt. The other thing to bear in mind is how the shock will be angled when the suspension is compressed as if it's angled over on the build stands it will get worse on the ground and even more so when you hit a bump.

I also ended up getting some rose joint spacers from EDS motorsport on Ebay though they won't completely solve your problem

I couldn't get my front shocks to mount the right way up because the spring cup fouled on the mount arm. Nigel managed with his build even though we both have the same design, which is odd.

mcramsay · #9 14th January 2014, 21:36

I did find it odd that the top mount for the shock is a single bolt at the top. I thought it would be a bolt through bracket. I have ordered the tapered spacers. And I will use one of these each side of the rose joint on both too and bottom, this should hold the shock at a fairly good angle. I have emailed marlin the above pictures so I will see what they say, as for the orientation of the shocks, I mounted them as per the pictures in the manual, if GAZ say this is wrong then I will turn then up the other way!

morris · #10 15th January 2014, 18:43

The other thing you could do (if I understand where the shock is positioned) is make up a steel plate a few mm thick that the other end of the bolt goes through (you'll need a longer bolt). The plate could then be bolted onto the outside of the chassis rail that sits above top of the shock or even better, welded and then bolted. This would at least hold the bolt both ends but you'd still need some long spacers

Thinking again, if you made a |_| shaped bracket about same width apart as the brackets on the front suspension, it could fit over the top of the rose joint with the bolt going through both sides but itself be bolted up through the underside of the chassis rail above. If the main bolt came through the chassis, one side of the bracket, the rose joint (and smaller spacers) and then the nut on the other side of the bracket, that would be pretty secure and have the advantage that loading on the bracket mount bolt is down it's axis so very unlikely to break. I can draw a picture if that doesn't make much sense.

Cammy · #11 15th January 2014, 19:32

Hi Craig,
I have been meaning to get in touch with you for a while as it seems you and I are the only two guys out there building an E39 based Sportser. Looking at your photos I might be a bit ahead of you in the build process but not much as I changed engine last year and have only just got it in its final position - very long storey which I will happily share with you! I also had the same issue as you regarding the spacer problem. Marlin sent me some spacers, eventually, and I stuck them on with some washers to get round the problem but it still doesn't look right to me and I am planning to get them checked out/fitted properly at a local garage in the next few weeks - same place that did my engine and who will be moving the servo to the passenger side as a result but that's another storey!!

I need to get the car back on its build stands and get the wheels off so that I can get some decent photos and will post them asap - its about time I revealled my efforts via Fickr!

Cheers for now

Cammy

P.S. To all those interested in installing an M52B28TU - I may have found someone who can delete the EWS! Will post a thread when I get some more info/confirmation.

peterux · #12 15th January 2014, 19:46

Quote:

Originally Posted by Cammy

P.S. To all those interested in installing an M52B28TU - I may have found someone who can delete the EWS! Will post a thread when I get some more info/confirmation.

Cammy · #13 15th January 2014, 21:31

Nice one Peter!

peterux · #14 16th January 2014, 14:07

Hi Cammy,
just joking.

But seriously, if you have found someone who can really do it that that would be a major breakthrough in being able to use the dual Vanos M52 engine range which is now becoming an affordable option.
Do keep us posted on your progress...

...peter