E39 Coilovers Into E34 Complete Guide

[szacsi72]

Hey folks.

So as most of you know, getting coilovers (CO) for an E34 isn’t easy nor cheap, and while you can buy high-end ones nowadays, there really aren’t any budget versions (that perform at least medium-well.) So what do we do? There are plenty made for E39’s that cost a lot less. In this thread I am going to explain and show you the way you can install them.

I am installing FK E39 Gewindefahrwerk. I got the kit from Germany for a steal, couldn’t resist.
Oh, and they have TÜV papers, that make it legal in most of Europe.




THE REAR

Let’s start it off with the rear of the vehicle, since this is much easier.
The E39 rear COs are almost a bolt on. Well, they do bolt on on the lower side, because they use the same diameter bolts. The rod/stanchion is 1mm thicker than the one on the E34, so you need E39 bottom-out rubbers.
[PN: 33531091031]




On this picture, there arent any springs pads on the CO. DO NOT use it this way, this is just the pic I had.
For the top, there are two methods. The E39 springs are just a touch bigger. You can use your E34 top mounts (TM) , but you have to enlarge it and cut the side rubber. Personally, I prefer the other method, since its a good idea to replace the TMs anyways. You can get E32 7 series TMs and spring pads, those will fit perfect.
[PN: 37121129717 & 33531133048 ]

NOTE: some E32 TMs are 1-2mm bigger than E34 TMs, so you MIGHT have to enlarge the holes in the strut tower 0.5-1mm.




THE FRONT
This is where things get interesting. If you are bad with tools, miss mechanical skills, STOP. Take it to someone who knows what he’s doing.
We are going to modifiy the front heavily. Is it worth it? Well, even E34 specific COs need welding and cutting, such as BC Racing, so yeah. It is.



To start it off, we have to remove our stock front struts, and take them apart. We also have to take apart the new front COs. First, we need to cut the stock struts apart, to get rid of the spring plate.
I used a disc cutter for the inital cut. I then added a hose clamp, and grinded down the rest for a smooth, straight cut. You have to cut above the stabiliser bar link’s mount. You can cut whereever you want, depending on how low you want to go. I cut as low as possible, for more suspension travel. With my setup, the complete unit is now 4cm shorter than originally.
NOTE: if you go too low, your tire might hit the inner wing on a bottom-out.



Then, we take the new struts. We have to machine them down to fit inside the stock ones. Some use a grinding disc. I prefer machining, for a perfect fit- this means less (or in my case, basically no) sideways movement, which results in less stress on the whole unit and the welds.
I can’t tell you exactly how much material you have to take off, as the two different version struts on the E34 have slightly different inside diameter. We are talking 1-2mm.
Once this is done, give both a good clean and place the E39 unit into the E34 one. Give both sides good measures so they are equally placed. (measure from a fix point, not the cut you made.)




I then used my MIG welder to hold them in place. Its a POS, and could not make a stong bead. Therefore I asked a professional to get them done. I recommend you do this too. If the welds let go, bad things may happen.



Next, clean the heat affected area, and give it some paint for rust protection.



I just re-used my stock TMs for now, the camber plates I ordered hadnt arrived in time.
If you are having a hard time finding some for an E34, or they are too expensive, you may look at E30 TMs. They work too.
E36, E39, E46 use different layouts for the 3 screws- they need drilling.

NOTE: check for clearance. The secondary springs will probably stand out more than your stock struts, therefore it might rub.

The kit i bought came with bottom-out rubbers. If you dont get any, you probably need E39 ones for the front too.
[PN: 31331124449]



Now all that’s left is to re-install your new COs, set the rideheight and go for a test drive. Drive moderately, but on bad quality roads for around 100-150kms to help the springs settle in. Re-adjust the rideheight, and look for cracks or other failures. If there arent any, you can go enjoy your new suspension.

-Dave

[szacsi72]

Update: the rear maxes out at about -60mm/2.3", the front about -120mm/4-7".
(Note: DON'T.) But this could also be a good setup for someone who wants to go for airride.

[Jarods17]

Update: the rear maxes out at about -60mm/2.3", the front about -120mm/4-7".
(Note: DON'T.) But this could also be a good setup for someone who wants to go for airride.

Do you weld the front in the same way you would with e34 BC's? Its hard to tell in the post.