[Jeffjmu1908]

I just ordered a front sway bar from UUC yesterday and it is scheduled to be delivered tomorrow. Reading this thread has me worried. I'm sure I will get a part, however now I'm concerned it might not be the right part! I don't have a way of knowing because I'm not scheduled to have it installed until March 23.

[NJE90xi]

I have the front UUC sway bar. Lowered on V1's. Great handling upgrade. You MUST LUBE the sway bar every 30 k and when initially installed or it will rattle and creak loudly!!!

I have the rear seat bar if anyone is looking one. It is a 3-4 hr install as the subframe needs to be dropped. PM me if interested

[Jeffman]

Originally Posted by NJE90xi

I have the front UUC sway bar. Lowered on V1's. Great handling upgrade. You MUST LUBE the sway bar every 30 k and when initially installed or it will rattle and creak loudly!!!

I have the rear seat bar if anyone is looking one. It is a 3-4 hr install as the subframe needs to be dropped. PM me if interested

Thanks for letting us know. So just to confirm, you have an Xi with KW V1 coil overs with only the front UUC sway bar? What improvements in handling do you notice above just the V1s? Less understeer? Less body roll? Better turn-in? Thanks in advance as I'm thinking of doing this myself.

[ajsalida]

Just installed the front UUC bar onto my e92 335xi.

Install was pretty easy, as mentioned a couple of small hose bracket bolts were a little hard to get to. Pretty straightforward once you are under the car and looking at things. Perfect fit. Maybe not enough grease for the poly bushings but no creaks so far on the test drive.

Mainly wanted to highlight the difference between the stock bar and the UUC. See the following pics of stock front bar vs UUC:





Note the stepped diameter of the stock bar. I got my dial calipers out and measured. Outer part of the bar is in fact 26.5mm, but the inner section is 22.5mm. The UUC bar is of uniform diameter, 25.5mm.

This is very interesting. As everyone knows, torsional stiffness of a steel bar varies to the 4th power of its diameter. The stock bar behaves quite a bit more like a 22.5mm sway bar than a 26.5mm one. If we calculate the ratio of the UUC fixed diameter bar to the inner part of the stock bar, and take that to the 4th power we get approx 1.65. IOW the UUC bar is as much as 65% stiffer than the stock bar.

Now this is not exact because some of the thicker part of the stock bar does contribute a bit of torsional stiffness. But not much I wager.

Driving wise you can really feel the extra front roll stiffness, not too harsh which is what I was worried about. Zero slop which is partly the bar and partly the poly bushings. Also does not over power the rear M3 bar I already have on the car. Steering is crisper, more direct, the car just turns in sharply like right NOW with nearly zero roll.

To recap my other mods to this car, Koni yellows set 1 full turn off soft front, 1/2 turn rear (more on this later). Front Eibach pro kit, rear ZSP D2. Rear 22.5mm M3 bar + whiteline rear subframe bushing inserts.

Did not go on a very long test drive yet but I like the balance and esp how tight the steering feels now. After putting the D2 ZSP springs in the rear, it felt like a bit too much weight transfer in front diagonally on turn in. Now it is perfect or at least much better.

With the weight coming off the back a bit and the stiffening up of the front bar and shocks, the rear damping seems a little jiggly. Next mod and last (I hope) before winter sets in will be crank up rears to 1 full turn off soft.

[thegrinchboy]

Originally Posted by ajsalida

Just installed the front UUC bar onto my e92 335xi.

Install was pretty easy, as mentioned a couple of small hose bracket bolts were a little hard to get to. Pretty straightforward once you are under the car and looking at things. Perfect fit. Maybe not enough grease for the poly bushings but no creaks so far on the test drive.

Mainly wanted to highlight the difference between the stock bar and the UUC. See the following pics of stock front bar vs UUC:

Note the stepped diameter of the stock bar. I got my dial calipers out and measured. Outer part of the bar is in fact 26.5mm, but the inner section is 22.5mm. The UUC bar is of uniform diameter, 25.5mm.

This is very interesting. As everyone knows, torsional stiffness of a steel bar varies to the 4th power of its diameter. The stock bar behaves quite a bit more like a 22.5mm sway bar than a 26.5mm one. If we calculate the ratio of the UUC fixed diameter bar to the inner part of the stock bar, and take that to the 4th power we get approx 1.65. IOW the UUC bar is as much as 65% stiffer than the stock bar.

Now this is not exact because some of the thicker part of the stock bar does contribute a bit of torsional stiffness. But not much I wager.

Driving wise you can really feel the extra front roll stiffness, not too harsh which is what I was worried about. Zero slop which is partly the bar and partly the poly bushings. Also does not over power the rear M3 bar I already have on the car. Steering is crisper, more direct, the car just turns in sharply like right NOW with nearly zero roll.

To recap my other mods to this car, Koni yellows set 1 full turn off soft front, 1/2 turn rear (more on this later). Front Eibach pro kit, rear ZSP D2. Rear 22.5mm M3 bar + whiteline rear subframe bushing inserts.

Did not go on a very long test drive yet but I like the balance and esp how tight the steering feels now. After putting the D2 ZSP springs in the rear, it felt like a bit too much weight transfer in front diagonally on turn in. Now it is perfect or at least much better.

With the weight coming off the back a bit and the stiffening up of the front bar and shocks, the rear damping seems a little jiggly. Next mod and last (I hope) before winter sets in will be crank up rears to 1 full turn off soft.

Good review. Glad you like the bar. I still need to put the whiteline subframe bushing inserts, as I am still trying to dial out the jiggliness, along with a seeming outside edge body "dive/shift then catch" on cornering. This maybe the same as the weight transfer shift issue as you described above. May also be the ZSP springs characteristics under load, which according to some on this forum are progressive instead of linear. Anyhow, I am now seriously considering Dinan or Swift springs, or going to coilovers e.g. KW Street Comfort or V3.

[Doyle]

Glad to know another person recognized the same things I did. UUC + M3 bars combined with stock-like natural frequency bias is great. UUC + H&R M3 bars combined with proper coilover rates is even better! The extra roll resistance helps address some of the bump travel issues, as well as load transfer (particularly at turn in and corner exit).

Also, of note: I believe the stock bar is hollow, whereas the UUC bar is solid.

[ajsalida]

Thanks for chiming in. I looked at both bars a long time and could not figure if either were hollow or not. I know the rear M3 bar is. If the UUC is solid and the OEM front is not, then it is even stiffer relatively.

What is good and a relief was I have ruined quite a few cars street handling with giant sway bars but did not here. In this case (what many don't know it seems) the stock XI springs are quite stiff, and moving to either Eibach or ZSP springs represents softening the spring rate quite a bit and lowering the natural frequency (and of course the ride height so roll center). Overall maybe too soft with stock bars. Stiffer bars then get that back in balance.

BMW really messed up the XI suspension. Far too tall, far too stiff springs, far too weak dampers in compression and rebound, and then those awful RFT tires. Oh and sloppy bushings everywhere to try and compensate for all that under-damped over-stiffness.

[Doyle]

Yeah. The x-drive system forced the ride height to be where it is ( front driveshaft). And then BMW's obsession with rft force the tire to have a stupid high spring rate, which then needs to be compensated for in the bushings and valving. And if you lower it slightly, you end up riding on the bumpstops.

This whole bmw awd endeavor is like their confusion about the US market and wagons. If we supposedly don't want wagons, don't give us useless, ugly GT monstrosities. If Subaru and Mitsubishi can do it, why can't bmw?

[ajsalida]

Originally Posted by Doyle

Yeah. The x-drive system forced the ride height to be where it is ( front driveshaft). And then BMW's obsession with rft force the tire to have a stupid high spring rate, which then needs to be compensated for in the bushings and valving. And if you lower it slightly, you end up riding on the bumpstops.

This whole bmw awd endeavor is like their confusion about the US market and wagons. If we supposedly don't want wagons, don't give us useless, ugly GT monstrosities. If Subaru and Mitsubishi can do it, why can't bmw?

Agree completely esp on the RFT's. I saw an interview with a "green" BMW exec and he was touting how good they were for the environment. What rubbish, even if it were true. Which it isn;t as people are having to replace them every time they hit a slight bump and bubble them . I bubbled several on simple pavement transitions, unbelievable. I doubt the engineers liked that decision. Rant off.

There is precedent for bad BMW AWD suspension. If you recall the first X3's that came out the suspension was beyond terrible. If Porsche and of course Audi can make a sporty great handling AWD platforms even with RFT's, it really is a disgrace what BMW has done with the XI's.

Nothing a little home brew suspension tweaking can't fix but come on guys.

[jeffblue]

So UUC front bar plus oem m3 rear sway bar with m3 bushings is a good combo? I was planning on getting m3 rear sway bar and then eventually getting a UUC front sway bar when i can find one... Since supposedly buying them new doesn't really guarantee you will get them lol. Will the UUC front bar overpower the m3 rear bar? Or should I try and get UUC front and rear if possible?

[ajsalida]

Originally Posted by jeffblue

So UUC front bar plus oem m3 rear sway bar with m3 bushings is a good combo? I was planning on getting m3 rear sway bar and then eventually getting a UUC front sway bar when i can find one... Since supposedly buying them new doesn't really guarantee you will get them lol. Will the UUC front bar overpower the m3 rear bar? Or should I try and get UUC front and rear if possible?

That last bit is actually a good question. I got the M3 rear bar first, had heard all the UUC stuff and wanted to stay away. Then after some other tweaks (replaced rear eibachs with OEM ZSP D2) I found the car had a bit to much rear roll stiffness. Happened to stumble across a sale on the UUC bars couple of weeks ago and thought why not. Plus they were selling front bar separately.

Zero issues shipping, shipped next day in fact, no BS or waiting, bar arrived and everything was fine. Having gone through that painless experience I'm wondering if I should have gone with both front and rear form the beginning. But I am very pleased with the set up as is. M3 bar is 22.5 mm, but hollow. UUC bar is (I think) 19.5mm but supposedly solid.

I got the M3 bar with the nicer OEM delrin bushings and brackets, shipped for $200. UUC bar with their yellow poly bushings @ 15% off but expensive shipping was $290 total.

Either way, what I think is a big rear bar is just too much bar for stock XI front bar, esp since I went to softer springs (Eibachs are softer than stock).

So I think really it doesn't matter which way you go, just be aware the UUC are available and might as well get a matched pair if it is within budget. M3 bar is a nice piece but not sure it is any better. It MAY be a tad stiffer depending on the hollow vs solid 22.5 mm vs 19.5mm.

[jeffblue]

So wait, you ordered brand new UUC sway bars and you got them right away? Where did you order them from? Are you saying i should just go with front and rear UUC sways instead of doing the rear M3 bar with front UUC?

Originally Posted by ajsalida

That last bit is actually a good question. I
got the M3 rear bar first, had heard all the UUC stuff and wanted to stay away. Then after some other tweaks (replaced rear eibachs with OEM ZSP D2) I found the car had a bit to much rear roll stiffness. Happened to stumble across a sale on the UUC bars couple of weeks ago and thought why not. Plus they were selling front bar separately.

Zero issues shipping, shipped next day in fact, no BS or waiting, bar arrived and everything was fine. Having gone through that painless experience I'm wondering if I should have gone with both front and rear form the beginning. But I am very pleased with the set up as is. M3 bar is 22.5 mm, but hollow. UUC bar is (I think) 19.5mm but supposedly solid.

I got the M3 bar with the nicer OEM delrin bushings and brackets, shipped for $200. UUC bar with their yellow poly bushings @ 15% off but expensive shipping was $290 total.

Either way, what I think is a big rear bar is just too much bar for stock XI front bar, esp since I went to softer springs (Eibachs are softer than stock).

So I think really it doesn't matter which way you go, just be aware the UUC are available and might as well get a matched pair if it is within budget. M3 bar is a nice piece but not sure it is any better. It MAY be a tad stiffer depending on the hollow vs solid 22.5 mm vs 19.5mm.

[ajsalida]

Originally Posted by jeffblue

So wait, you ordered brand new UUC sway bars and you got them right away? Where did you order them from? Are you saying i should just go with front and rear UUC sways instead of doing the rear M3 bar with front UUC?

I bought them from UUC, they have a website. Just type UUC Into Google. I'm not saying what you should do otherwise, just relating my experience.

[ajsalida]

Small update here, the rear end really felt underdamped after several more spirited test drives, so I cranked the konis up to 1 full turn off soft. Very pleased with this balance for street. However I am driving more aggressively with it (it is fun after all) and with all the rough roads out here have bottomed a few times (front).

There is a real issue with lack of front travel on these XI's when you lower them, mainly due to the higher strut housing. We;ll see what I do about this if anything. I may swap in some D6 ZSP springs and slightly taller ZSP bump stops. I have eibach pro kit front springs now with e36 m3 stops.

[jeffblue]

Originally Posted by ajsalida

Small update here, the rear end really felt underdamped after several more spirited test drives, so I cranked the konis up to 1 full turn off soft. Very pleased with this balance for street. However I am driving more aggressively with it (it is fun after all) and with all the rough roads out here have bottomed a few times (front).

There is a real issue with lack of front travel on these XI's when you lower them, mainly due to the higher strut housing. We;ll see what I do about this if anything. I may swap in some D6 ZSP springs and slightly taller ZSP bump stops. I have eibach pro kit front springs now with e36 m3 stops.

you have the m3 rear with the UUC front right? how is the balance?

[ajsalida]

Originally Posted by jeffblue

you have the m3 rear with the UUC front right? how is the balance?

Very neutral, slight bias to oversteer. M3 rear bar does not overpower the UUC front at all.

[Doyle]

Originally Posted by ajsalida

Small update here, the rear end really felt underdamped after several more spirited test drives, so I cranked the konis up to 1 full turn off soft. Very pleased with this balance for street. However I am driving more aggressively with it (it is fun after all) and with all the rough roads out here have bottomed a few times (front).

There is a real issue with lack of front travel on these XI's when you lower them, mainly due to the higher strut housing. We;ll see what I do about this if anything. I may swap in some D6 ZSP springs and slightly taller ZSP bump stops. I have eibach pro kit front springs now with e36 m3 stops.

Yup, that's why shortened front struts and higher front spring rates are the money ticket on the e90xdrive. I hate to say it, but I think you might be drifting into coilover territory. You can try the swift spec-r springs and maybe shortening the Koni's.

[ajsalida]

Originally Posted by Doyle

Yup, that's why shortened front struts and higher front spring rates are the money ticket on the e90xdrive. I hate to say it, but I think you might be drifting into coilover territory. You can try the swift spec-r springs and maybe shortening the Koni's.

Yeah I figure I'll hack something up for this winter and then make up my mind if I want to do the TC Kline kit. They are the only folks I've seen so far that have the proper solution for lowered XI in terms of extra travel in front via shortening the struts.

Here's the kit I want Santa to bring me

http://www.tcklineracing.com/webdocs...Details690.cfm

[Doyle]

Originally Posted by ajsalida

Yeah I figure I'll hack something up for this winter and then make up my mind if I want to do the TC Kline kit. They are the only folks I've seen so far that have the proper solution for lowered XI in terms of extra travel in front via shortening the struts.

Here's the kit I want Santa to bring me

http://www.tcklineracing.com/webdocs...Details690.cfm

Nice choice. Some smart guy must have pushed TCK to put that kit together

You'll be very happy with 400/700 and your sway bars.

[ajsalida]

Originally Posted by Doyle

Nice choice. Some smart guy must have pushed TCK to put that kit together

You'll be very happy with 400/700 and your sway bars.

Was that due to you? Nice work!

[thegrinchboy]

Adjusted Koni's (F/R) a few times over the weekend and the rear end no longer seems to be kicking out. Spring loading issue is still present but less prevalent. The ZSP springs may just be too soft for xDrive. The ride is flatter and firm, but not jarring. Less general body undulation. Subframe bushing not squirrely (yet) from everything being tightened down again, but coming close.

Current configuration: UUC sways F/R + Koni Yellows (F @ 1-1/8, R @ 1 turn from full soft) + ZSP springs (D6/D5) + M3/Z4 bumpstops + 15mm spacers (R).

Will be installing 12mm spacers in front when I find some used on the forum. Need to let this setup settle out for a while. May install M3 subframe bushings, M3 controls arms, and Dinan springs (TBD) next year.