Another Bilstein B6 vs. B8 Thread, Side-by-Side

PrematureApex · 11-16-2016, 07:20 PM

So I blew a B6 (HD) in a pothole the other day. Ordered new front B8s (sports) from Tirerack (on sale vs. the B6).

Unfortunately, I was in a rush, so I didn't pull the cartridge/bump stop out of the B8, but the housings, shaft lengths, and stroke appear to be identical between the two.

So the widely asserted "body is 25mm shorter" isn't correct. Pics:

thetyrant · 11-17-2016, 09:39 AM

Interesting, so is there a difference in compressed length ? as in different length internal bumpstop etc to limit travel ? would be good to see them both pulled apart to see any differences.

Ian

PrematureApex · 11-17-2016, 10:05 AM

Quote:

Originally Posted by thetyrant

Interesting, so is there a difference in compressed length ? as in different length internal bumpstop etc to limit travel ? would be good to see them both pulled apart to see any differences.

Ian

No difference in compressed length that I could see. But it was much more difficult for me to get an accurate measurement of that by just compressing them until they felt like they hit the stops.

Yup, I was in a rush...really should have pulled the cartridge out and checked the bump stop of the B8, the B6 was already apart.

In any event, maybe it winds up having a shorter bump stop, or perhaps just a softer one allowing a bit more travel. In any case, it's definitely not a shortened body as we've all been thinking.

thetyrant · 11-18-2016, 02:03 AM

Yeah shame but I know what its like when you just want things back together, have you a picture showing the B6 cartridge and Bumpstop disassembled ?

Over here in UK I had the Birds BMW B1 Bilstein setup on my last 130i, they are meant to be custom spec B8 dampers with matched springs but I didn't like them, main issue for me was front end and there seemed very little free travel before it was onto the bump giving a jiggly ride at low speed on uneven roads, fine when attacking the road but normal drive not pleasant!, I think they are supposed to shorten the front bumps as part of custom spec but I never pulled it apart to check and just sold it on and went Koni, far superior damping and ride imo.

dojk · 11-18-2016, 04:33 AM

Did you notice a difference in damping and/or rebound?

John_01 · 11-22-2016, 09:29 PM

So what exactly is the difference between the B6 and B8?
Are you saying the bump stop and compression characteristic is the same for both of them?

asbrr · 11-24-2016, 10:26 AM

Quote:

Originally Posted by John_01

So what exactly is the difference between the B6 and B8?
Are you saying the bump stop and compression characteristic is the same for both of them?

I think Washington335 is saying they ARE different, just that in this case OP didn't see a difference because the original B6 was blown/shot. Hard to believe Bilstein would make two parts that are the same and call them different things....

Olgeezer1 · 12-04-2016, 01:52 PM

Quote:

Originally Posted by Washington335i

Correct. B8 shaft is about 3/4" shorter than the B6. Use B8 for factory sport springs, BTW. Seems to be a lot of misinformation about this.
Best regards, Chris

That's interesting. As I recall, Bilstein recommends B6's for factory Sport Pkg. springs. That's what I went with and other than maybe raising the car 1/4", works great.

Mr Rooty Von Tooty · 12-08-2016, 01:42 PM

Bilstein has a great tech department which will answer your questions.

On my Mercedes with the Sport Pkg, it uses the Bilstein Sport Strut/Shock(B8?). I believe the M-Sport is slightly lower, so I suspect it uses the Sport too.

I doubt I'll ever replace the struts and shocks, but if I did, I'd check the tech guys first.

ShocknAwe · 12-09-2016, 05:12 PM

If I remember correctly when I was on the Bilstein wagon, B4 is the stock damper, B6 is their performance damper "stock height" replacement, and B8 is for lowering more than 20-30mm. Bilstein changed their opinion on what they sell the B8 for after I purchased the B6. I have no idea why they did that, maybe they saw failures with mild-moderately lowered vehicles, or maybe they just weren't selling enough of them. I suspect the latter based on my, and other car buddies who ran the same suspension setup, anecdotal evidence.

FWIW, I used the B6 (HD) with Swift-Rs for a while. Worked wonderfully. Still have them sitting in my workbench actually. Need to find the setup a new home.

John_01 · 12-09-2016, 06:35 PM

Sometimes a shock/strut with less drop travel is necessary to prevent the springs becoming loose at full droop.
I don't see that being an issue with M-sport springs, as they are installed from the factory with standard length shocks and struts. It doesn't make much sense to me.

ShocknAwe · 12-09-2016, 06:38 PM

Quote:

Originally Posted by John_01

Sometimes a shock/strut with less drop travel is necessary to prevent the springs becoming loose at full droop.
I don't see that being an issue with M-sport springs, as they are installed from the factory with standard length shocks and struts. It doesn't make much sense to me.

B6 didn't become loose with springs at full droop even with Swift-Rs installed. No way they would have an issue with stock M-sport springs.

Hops128i · 04-07-2017, 09:32 PM

Quote:

Originally Posted by ShocknAwe

B6 didn't become loose with springs at full droop even with Swift-Rs installed. No way they would have an issue with stock M-sport springs.

I just installed B6's on my factory sport springs, then read all this discussion on how i should have installed B8's. I'm sort of concerned, but i think everything is OK, the springs seems firmly planted at full extension.

I haven't found discussion with sport springs becoming unseated with b6's.

ShocknAwe · 04-08-2017, 06:38 AM

Quote:

Originally Posted by Hops128i

I just installed B6's on my factory sport springs, then read all this discussion on how i should have installed B8's. I'm sort of concerned, but i think everything is OK, the springs seems firmly planted at full extension.

I haven't found discussion with sport springs becoming unseated with b6's.

You're fine.

dojk · 04-09-2017, 09:57 PM

I contacted Bilstein directly.

They replied that my stock 2008 E82 135i N54 with factory M-sport suspension should use the B8 instead of the B6.

Hops128i · 04-10-2017, 07:44 PM

Quote:

Originally Posted by ShocknAwe

You're fine.

With a few days on the B6's, they are fantastic, feels better than new. It's like i can feel the car again!

The last suspension work i did was a camber plate install, and vowed to never do any suspension work again as the car was on jack stands for a week. But this time around... it wasn't so bad. Had a shop move the springs and plates over to the new struts, that really helped!

All i can say is don't wait like me for 75k miles to accumulate before you replacing the shocks/struts!

11-16-2016, 07:20 PM	#1
PrematureApex Colonel 840 Rep 2,402 Posts Drives: N55 X1, N54 135, s54 m3 Join Date: Jan 2008 Location: Philadelphia iTrader: (0)	Another Bilstein B6 vs. B8 Thread, Side-by-Side So I blew a B6 (HD) in a pothole the other day. Ordered new front B8s (sports) from Tirerack (on sale vs. the B6). Unfortunately, I was in a rush, so I didn't pull the cartridge/bump stop out of the B8, but the housings, shaft lengths, and stroke appear to be identical between the two. So the widely asserted "body is 25mm shorter" isn't correct. Pics: __________________ '02 S54 M3 (500/500 GC/Koni) '08 N54 135 (JB4, DCI, BMW PS/Bilstein B6s, H&R M3 FSB, Strongflex FCABs) '14 N55 X1 (JB4, BMS DP, BMS Intake, Alpina TCU reflash, H&R Sports, Bilstein B6s, E93 M3 RSB, Strongflex FCABs, baby seat) '08 N54 535xi touring (Bilstein B6s, Downpipes, MHD tune, baby seat) Last edited by PrematureApex; 11-17-2016 at 10:09 AM..
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11-17-2016, 09:39 AM	#2
thetyrant Enlisted Member 6 Rep 48 Posts Drives: 2011 F25 X3 30d Join Date: Jul 2010 Location: Cumbria UK iTrader: (0)	Interesting, so is there a difference in compressed length ? as in different length internal bumpstop etc to limit travel ? would be good to see them both pulled apart to see any differences. Ian
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11-18-2016, 02:03 AM	#4
thetyrant Enlisted Member 6 Rep 48 Posts Drives: 2011 F25 X3 30d Join Date: Jul 2010 Location: Cumbria UK iTrader: (0)	Yeah shame but I know what its like when you just want things back together, have you a picture showing the B6 cartridge and Bumpstop disassembled ? Over here in UK I had the Birds BMW B1 Bilstein setup on my last 130i, they are meant to be custom spec B8 dampers with matched springs but I didn't like them, main issue for me was front end and there seemed very little free travel before it was onto the bump giving a jiggly ride at low speed on uneven roads, fine when attacking the road but normal drive not pleasant!, I think they are supposed to shorten the front bumps as part of custom spec but I never pulled it apart to check and just sold it on and went Koni, far superior damping and ride imo.
	Appreciate 0 Quote

11-18-2016, 04:33 AM	#5
dojk Private First Class 19 Rep 179 Posts Drives: E82 135i Join Date: Nov 2010 Location: Malaysia iTrader: (0)	Did you notice a difference in damping and/or rebound?
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11-22-2016, 09:29 PM	#6
John_01 Colonel 232 Rep 2,643 Posts Drives: E90 325i, E82 135i Join Date: Mar 2009 Location: Sydney, Australia iTrader: (0)	So what exactly is the difference between the B6 and B8? Are you saying the bump stop and compression characteristic is the same for both of them?
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12-08-2016, 01:42 PM	#9
Mr Rooty Von Tooty Banned 117 Rep 460 Posts Drives: 2013 BMW 135i M-Sport Join Date: Jul 2015 Location: Dayton, OH iTrader: (0)	Bilstein has a great tech department which will answer your questions. On my Mercedes with the Sport Pkg, it uses the Bilstein Sport Strut/Shock(B8?). I believe the M-Sport is slightly lower, so I suspect it uses the Sport too. I doubt I'll ever replace the struts and shocks, but if I did, I'd check the tech guys first.
	Appreciate 0 Quote

12-09-2016, 05:12 PM	#10
ShocknAwe 1Addict 3234 Rep 7,894 Posts Drives: E82 Mutt, M57 Truck Join Date: Jul 2012 Location: Charleston iTrader: (22)	If I remember correctly when I was on the Bilstein wagon, B4 is the stock damper, B6 is their performance damper "stock height" replacement, and B8 is for lowering more than 20-30mm. Bilstein changed their opinion on what they sell the B8 for after I purchased the B6. I have no idea why they did that, maybe they saw failures with mild-moderately lowered vehicles, or maybe they just weren't selling enough of them. I suspect the latter based on my, and other car buddies who ran the same suspension setup, anecdotal evidence. FWIW, I used the B6 (HD) with Swift-Rs for a while. Worked wonderfully. Still have them sitting in my workbench actually. Need to find the setup a new home. __________________ 2010 135i 6MT Jet Black N54/3 FE82 Mutt \| BUILD THREAD \| GARAGE SALE
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12-09-2016, 06:35 PM	#11
John_01 Colonel 232 Rep 2,643 Posts Drives: E90 325i, E82 135i Join Date: Mar 2009 Location: Sydney, Australia iTrader: (0)	Sometimes a shock/strut with less drop travel is necessary to prevent the springs becoming loose at full droop. I don't see that being an issue with M-sport springs, as they are installed from the factory with standard length shocks and struts. It doesn't make much sense to me.
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04-09-2017, 09:57 PM	#15
dojk Private First Class 19 Rep 179 Posts Drives: E82 135i Join Date: Nov 2010 Location: Malaysia iTrader: (0)	I contacted Bilstein directly. They replied that my stock 2008 E82 135i N54 with factory M-sport suspension should use the B8 instead of the B6.
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