DIY: Whiteline rear subframe inserts

[DougiesGoinDeep]

Anyone seen this in stock recently? Everywhere I order from cancels the order immediately because they are out of stock.

[ShocknAwe]

Try these guys, got mine from them. Super fast and cheap shipping.

http://www.fcpeuro.com/products/bmw-...ubframe-kdt918


Edit: just saw they are unavailable from them too. Maybe a manufacturing issue...

[rod.bearings]

What's the difference between this and KDT918 and KDT917?
The KDT917 seems to be more expensive

[gap]

Originally Posted by CAVU

I installed my inserts in May. Like you said, the improvement is noticeable, but I need stronger medicine. I'm thinking of biting the bullet and going with M3 bushings.

Had the inserts for a few months and as many have said it is a improvement but not a total cure. Had the m3 inserts installed a few weeks ago and that is the way to go.

[_Ryan_]

Originally Posted by gap

Had the inserts for a few months and as many have said it is a improvement but not a total cure. Had the m3 inserts installed a few weeks ago and that is the way to go.

A year in, I'm looking at the Turner solid bushes. Inserts aren't enough.

[rod.bearings]

Do I need alignment after I install these?

[Fidiman]

No need to do an alignement : you're not moving camber arm or whatever !

[Freon]

I did not get a realignment. I'm not that concerned about it since the subframe really shouldn't shift when dropped and put back.

As mentioned before, the inserts do not actually relocate or place the subframe further down as some have questioned. The inner metal collar of the the bushing still makes direct contact with the metal of the frame. There is no static tension added when placing the inserts, they just slide in by hand (with the help of the grease).

[MightyMouseTech]

Originally Posted by krazi3azn

What's the difference between this and KDT918 and KDT917?
The KDT917 seems to be more expensive

KDT917 is a full bushing replacement, like installing the M3 bushings. The 918 are just inserts into the stock bushings.

[02rsxpilot]

Got everything installed today. @CAVU 's writeup was a big help getting the front inserts in. You really do just have to get comfortable with manipulating the subframe. Even though the install is really a 1/5 difficulty, I think its helpful to have someone with some experience on suspensions assisting if its your first time. There's a fair amount of tricky wrenching and the E18s can be really tough to break loose at first, so knowing when to compress the suspension and when to let it out can help a ton.

I'll wait to report any of my reactions until spring when I've had a chance to get the car on track. Last year at Laguna Seca the car felt really wiggly under hard braking into T8 so I'm hoping I see gains there this year with this mod. I will also have M3 front LCAs installed though so hopefully I can differentiate.

All-in-all it's definitely worth a shot for $50 and a DIY versus M3 subframe bushings at $1,000 parts + labor. If it doesn't cut it, you can always uninstall them and sell them here on the forum and go for the real deal.

[BeastMode335i]

wonder if this would be the same for an E92 335i?

[02rsxpilot]

Originally Posted by BeastMode335i

wonder if this would be the same for an E92 335i?

The instructions that come with it are actually for an E92. In fact, I think there's one less step for the 3-series (No cross braces in front of the rear wheels. At least they aren't mentioned in the instructions).

[BeastMode335i]

Originally Posted by 02rsxpilot

The instructions that come with it are actually for an E92. In fact, I think there's one less step for the 3-series (No cross braces in front of the rear wheels. At least they aren't mentioned in the instructions).

Sweet, thanks brother!

I just bought my E92, and I'm going the suspension route first so I'd love to perform this modification.. May team them up with some H&R springs and I think that will give me a much better ride, and with ditching my RFT's haha..!!

[02rsxpilot]

Ok I lied. I said I'd wait 'til I'd been on track to review, but that was mostly because I only expected the effect of the inserts to be truly noticeable on track. However, after several weeks of driving, there are a couple of clear changes to the car.

1) Absolutely the rear end doesn't wiggle as much. To me, this translates to better handling because the suspension no longer has to manage as much weight transition (in terms of volume/duration, not actual weight).

You can imagine this on a larger scale by picturing how it would feel if the entire car rocked side to side while going through a corner. It would be very unnerving! In reality, the stock rear subframe bushings let the rear of the car do this on a much smaller scale, and the suspension has to try to even that out while going around a corner. The bushings remove a lot of that compliance, which equals better/more consistent handling. I think this is also why folks talk about the subframe bushing mod/replacement improving front grip. If the rear isn't wiggling around as much, it's not trying to twist the car which lets the front tires use more grip to turn.

The other way to describe it is the car "takes a set" quicker where before it would oscillate a bit until it set.

2) Remove compliance=add NVH (Specifically harshness. I haven't noticed noise or vibration). I know most folks talk about the M3 bushings or the inserts and seem to say that there is little impact on NVH, but that's not been my experience. I get some pretty good thumps from the rear of the car now that weren't present before. You won't feel it on good roads, but you definitely will on bad ones. I'm sure some better damping/springs could sort it out, but there's a reason this car didn't ship with stiffer bushings. I can't imagine what it would be like with the inserts and RFTs.

Is that harshness enough to make me regret the mod? Not really, but I do think it is a trade-off people should be aware of.

[2010MSPORT335i]

Originally Posted by TwinTurboed

For everyone replacing the bushings or inserts, I really recommend replacing the subframe bolts (PN: 33 32 6 760 340). They are aluminum and no one stated that they are stretch bolts, but when you torque the new ones, you can feel them stretch.

I thought the inserts firmness deteriorated overtime, but it was actually the subframe torx bolts. After I replaced them with the new ones, the rear is tight again.

About to order these for my e92.

Do you know if these will fit an e92? I would assume yes, but didnt know if they were the same P/N.

Also is this the same part # for all 4 of the subframe bolts?

Thank you!

[Freon]

Before ordering anything I would confirm compatibility list from the seller and/or manufacturer. While the outside dimensions of the bushings should be interchangeable, I'm unsure the OEM bushings have the exact same voids that the inserts rely on.

You can order the bolts from a place like ECS or GetBMWParts that have good website controls for searching. Roughly from memory they all seemed identical?

[loesch]

I just went under the car and stuck a magnet to all 4 bolts. Don't waste you money buying bolts unless the threads get bitched up.

[Gray_Panther]

Originally Posted by Freon

attention

Originally Posted by sliderpass

Simon

Originally Posted by _Ryan_

attention

Originally Posted by Naoto

attention

Quoting those "orignales" who did the install about two years ago. How have the inserts held up over time? Has the effect decreased? Any issues with the rear subframe bolts loosening?

I would love to install these while I am installing koni yellows and eibach springs.

[loesch]

I would like to comment on ride height since there seems to be some confusion. These DO increase ride height in the rear by about 1/2 inch. I'm pretty disappointed by that. When I first installed them I was on stock M sport suspension and I thought there was a slight difference but wasn't positive. I just installed a set of Eibach Pro-Kit lowering springs (2097.140) and you can definitely see about a 1/2 inch difference from front to rear.

[Freon]

Originally Posted by loesch

I would like to comment on ride height since there seems to be some confusion. These DO increase ride height in the rear by about 1/2 inch. I'm pretty disappointed by that. When I first installed them I was on stock M sport suspension and I thought there was a slight difference but wasn't positive. I just installed a set of Eibach Pro-Kit lowering springs (2097.140) and you can definitely see about a 1/2 inch difference from front to rear.

I'm sorry, but you are just flat wrong. The inserts do not affect the static location of the subframe. The metal unibody is still in direct contact with the center metal collar of the bushing.

You say you changed springs so I don't see how you equate your ride height to the inserts. You're basically telling us exactly why you are wrong, you're throwing several variables at the problem and claiming one of them is the cause.

If you just put in springs you probably either need to let the suspension settle. Drive it for a few days and check your ride height again. Or you have an installation issue and the rear springs are not properly located in the seats, or you changed them out, etc.

Finally, the front struts have rubber boots that you should probably be replaced when you change the springs. They wear out over time and this could be causing the front of the car to sit lower than expected. There are a million of other possible causes here.

[loesch]

Ok. Before I did the springs is when I first noticed the ride height difference. I just convinced myself it was in my head until I saw the same result after doing springs. It's easier to see the difference between front and rear now. Yes, I torqued the control arm while the suspension was compressed under the weight of the car. Is it possible the factory torque specs for the subframe bushings aren't sufficient to get the center metal collar your referencing to contact the metal unibody? Looking at it from the side it seems as thought the unibody and subframe now pinch the upper insert, adding to the space between the 2.

[02rsxpilot]

No ride height change for me. At least not a detectable one. Certainly not a 1/2 inch.

Car was excellent on track last week. Much more stable in corners and under braking.