[skier_du]

Rear Rebound Extenders DIY

On many previous BMW chassis, such as E9x, the top of the rear shocks are accessible in the trunk since the towers have a hole in the top. However on the F30, and I'm assuming other Fxx chassis cars, the rear towers do not have a direct hole with access to the top of the shocks. There is a hole at the mounting point of the top of the shocks, but there's a second layer of sheet metal over this with space between.
Naturally, I can't leave well enough alone, so I got a set of VKW V3 shocks for my F30. I would set and forget, but I track the car so I need to able to easily adjust the shocks rebound as well as the bump. So I set about figuring out how to route some KW extenders into the trunk for easy adjustment. For my F30 the KW 300mm length was perfect. It's a actually fairly easy install. Not to mention it and looks almost looks like BMW intended something to be passed through there. There is clearly a raised circle on the top sheet metal, directly above where the shock mounts. Anyway, enough background, it's a short DIY (compared to other projects like changing the turbo or putting in the coilovers) so let's get to it.

Tools you'll need:
* Flat screwdriver and/or interior trim tool
* T40 torx bit
* E14 torx socket (for upper shock mount but I'm not 100% if this is the same size for all Fx chassis cars, but you should have an assort to work on BMW cars either way)
* 18mm socket and wrench
* Extension for your chosen racket
* Drill and assortment of bits (I recommend cobalt for drilling metal but it's not hard metal, just may take more effort with regular or titanium bits)
* 90 degree adapter for drill
* Punch or similar tool if you want to use it to mark the location of the hole (or very steady hands with the drill)
* Needle nose pliers
* Step bit (cobalt recommended but not necessary, I got my "cobalt" step bits from Amazon and they worked fine)
* Zip ties

1. Once you have the rear of the car securely on jack stands or a lift you'll need to remove the rear wheels to have access to the wheel well.
2. Next you'll need to take out the rear shock. There's one bolt (18mm) that connects it to the rear "roll over strut" and 3 torx bolts (e14) that connect it at the top.
3. You'll need to compress the shock and work quickly to remove it before it extends. I do this manually but I'm also open to suggestions.
4. Now we move to the trunk. You'll need to remove the lining panels on either side. The floor has to come out to remove them, but other than the anchors (T40 torx bit), it's primarily just the expanding rivers to get them out. There is the socket on the left side, but you should be able to disconnect the wire for that. Or just move it out of the way, the shock tower is more accessible from the back seat.
5. Next you'll need to pull back the sound deadening/insulation to have access to the upper shock towers. I used zip ties to hold them.
6. You can refer to the pictures to see the raised circle of sheet metal. It's directly above where the shock mounts. Use a punch to put a dent in the middle of it. Then use the 90 elbow adapter for your drill and a small drill bit to make the pilot hole. Then a little larder bit. If you need to you can go up again, but this should be big enough to start using the step drill bit for the final hole. It's up to you how large you want to go, but I went just large enough to get the connection end through, not enough for the knob to fit through.
7. Next go under the wheel Well and enlarge the hole that is already there. Use your step bit here again and make the hole to the same size as the one in the trunk.
8. You may be thinking about not reusing the plastic top on the shock, but I thought it was a good idea to reuse them. they help hodl the paperish insulater and plug the hole up partially. My thought behind that is my car is a street car used in the northeast. Meaning winter and salt and everything else could get up in there. So I wanted to keep the paper insulator and cap to keep as much of that junk as possible out. So, if you're like me, pop the plastic cap off the top of your rear shocks. Drill a hole in them from underneath. Then use the step bit again to make it large enough to fit the extender conection on through and on the shock.
9. If your extenders fit through the holes on both ends, go ahead and attach them now and skip to the next part of reinstalling the shocks. Otherwise, now it's time to fit the extender through the new openings. If you have a hard time getting it through the second hole, this is where needle nose pliars, or something similar, will come in handy to grab it from underneath. Also having someone help with that comes in handy if you can find help. Sometimes a little extra beer helps with getting help.
10. Once through the holes, attach your extenders to the shocks. If you're extenders don't fit through the holes completely, don't forget to slide the plastic caps on and paper insulators on attaching.
11. Reinstall the shocks the reverse of taking them out. However you'll need to cut a hole in the trunk lining for the extenders. I don't know what the torques are for the bolts, perhaps someone knows. But be sure to firmly tighten the top 3 bolts, with extra caution to not over tighten. You can crank on the lower bolt and not pretty hard without working about stripping the threads.
12. Put the interior back together. You will see the extenders in just the right spot. If you close you can mount something to secure them in place. I did at first. But I found it wasn't necessary.
13. Put the wheels on and drop the car or finish other projects. Don't forget to torque your lug nuts Enjoy!
14. Enjoy your custom work and ability to easily adjust your shocks!

[Logicoeur]

What does it look like with all the carpet reinstalled?

[andino]

Originally Posted by Logicoeur

What does it look like with all the carpet reinstalled?

2nd to last photo has one with the carpet back. I missed it the first time I looked through the photos as well.

[skier_du]

Originally Posted by andino

2nd to last photo has one with the carpet back. I missed it the first time I looked through the photos as well.

Originally Posted by Logicoeur

What does it look like with all the carpet reinstalled?

I can try to grab another photo for you. Just let me know if there's anything you need.

[soundwave9]

What settings are you running your v3's?

Also, do you know the torque spec for the E14 bolts?

[DreamerJoe]

nice, I thought about doing that exact thing on my ST XA's, running the KW extension just like that, but decided I'd rather not put a hole there.. kinda wishing I had tho, looks good man!

[skier_du]

Originally Posted by DreamerJoe

nice, I thought about doing that exact thing on my ST XA's, running the KW extension just like that, but decided I'd rather not put a hole there.. kinda wishing I had tho, looks good man!

Thanks!

Originally Posted by soundwave9

What settings are you running your v3's?

Also, do you know the torque spec for the E14 bolts?

Depends on track or off. Also still tweaking things as I always seem to do. I've had to play with it because the rear did like to come around suddenly. So I've increased traction in the rear. Also had mid corner understeer. So far It's decently balanced with maybe a touch of oversteer mid to exit of corner. But currently as follows:
Street bound: front 5 clicks from full firm, rear 6 clicks from full firm
Street rebound: front 3 clicks from full firm, rear 4 clicks from full firm
Track bound: front full firm, rear 1 click from full firm
Track rebound: front full firm, rear 1 click from full firm

Also of note, when it's in track mode, I have north of 3* camber in the front. This actually lowers the front and changes the balance of the car. It feels good, but I've been adjusting the suspension and tire pressures to compensate. I don't have a current picture to show the front to rear balance though.

The e14 torque specs, don't know off the top of my head. I just tighten them by feel. Lol

[rallakias]

I want to thank the topic starter skier_du for sharing with us his DIY for adjusting the rear shocks.
I have a 2017 F30 330e and have bought a KW Street comfort kit with code 1802000J . I also used a pair of 30cm long extenders that are the perfect length for our platform! The adjusting knob is barely seen when opening the trunk but your arm gets easily to it .The only thing is I have to fix them somewhere because they make a noise when the cars goes over bumps.
I chose KW instead of Bilsteins B16 thanks to this DIY because it solved the problem of adjusting the rear shocks and made it even easier than the B16 that the adjustment ring is under the shock.Now I have to find the right setting to my liking although the rear shocks seem to have only 13 available clicks ,while the front have 19 (!) instead of the 16 advertised.

[skier_du]

Originally Posted by rallakias

I want to thank the topic starter skier_du for sharing with us his DIY for adjusting the rear shocks.
I have a 2017 F30 330e and have bought a KW Street comfort kit with code 1802000J . I also used a pair of 30cm long extenders that are the perfect length for our platform! The adjusting knob is barely seen when opening the trunk but your arm gets easily to it .The only thing is I have to fix them somewhere because they make a noise when the cars goes over bumps.
I chose KW instead of Bilsteins B16 thanks to this DIY because it solved the problem of adjusting the rear shocks and made it even easier than the B16 that the adjustment ring is under the shock.Now I have to find the right setting to my liking although the rear shocks seem to have only 13 available clicks ,while the front have 19 (!) instead of the 16 advertised.

Glad this helps rallakias ! Only takes a little planning and a few extra minutes. Makes a great difference and opens the option for KW and similar suspensions to be a good choice since adjusting them is so easy this way.

[rallakias]

This is how the 30cm long extender looks .
It was making some rattling noise while driving so I used a tire up.

[cfm56d7b]

One of the best and relevant DIY projects for KW coilovers owners. Thanks for sharing!

[MacklinUSOB]

This is a DIY for me this year for sure!

[Pelekanos]

skier_du rallakias

thanks for the DIY! is here where the hole on the plastic top should be done?

[skier_du]

Originally Posted by Pelekanos

skier_du rallakias

thanks for the DIY! is here where the hole on the plastic top should be done?

[img]"]https://i.ibb.co/rQx9J2N/suspension.png[/img]

Happy to help.

Yes, the cap hole goes right where the little spike is. I drilled from the underside with a regular bit. Then used the step bit to get the right size opening.