I just got off the phone w/ Bilstein tech dept. I had called them to ask about revalving my B6 (HD) shocks for use with Dinan/Mtech lowering springs on my e23. The B6 HD e23 shocks are part #s 34-002315 and 24-007214. I had read on this forum and others that you could send e23 B6 shocks in to "have them revalved as sport (B8) shocks". The tech told me that they did not typically revalve the e23 B6 shock for lowering springs, and that they also typically did not revalve many B6 applications for lowering springs - that the stock valving was still valid for a lowering spring as long as the rate was within 20% of stock. He said that the only modification that Bilstein would perform if I shipped them the shocks was to adjust what he called spring pull-down, which sounded like it was for limiting the strut rod travel in droop. He said this was unnecessary for this application and that I was fine to use a mild lowering spring w/ stock B6 shocks and it would not damage the shock or cause unwanted performance issues. He said that a general rule w/ the Bilstein line was that B8 (sport) shocks could never be used with stock ride height springs, but B6 shocks can be used with lowering springs. He said that sending my B6 in for the pulldown spring mod would be, in his words, "a gigantic waste of money" for 127.50 per shock. I guess I am going to run the B6 w/ my Dinan springs and see how it goes.
Last edited by BONDOSPECIAL; 11-06-2018 at 08:31 PM.
Steve H.
I always thought it was something with the piston length up front and the rears were okay dimensionally inside.
Could they explain the difference in their shocks versus 'Dinan' setup units or BMW Mtech?
I make E23 parts.
09/1983 745i (stolen spring '13 around Houston, TX Achatgruen on nutria buffalo. 8481080)
10/1984 745i
11/1984 745i
11/1984 735i (10:1-265/6)
Ford, MB, and GM round out the pack.
Nope. The guy I talked to did not sound that excited to talk to me (and he doesn't even know me yet to have a reason!)
Steve H.
I've been running the sport front/hd rear for over 20k now with no issues on Bavauto springs.
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I should have at least bought the B8 sport front when they were still available - they haven't been available for a few years now.
Steve H.
Man, time flies. I guess that's the major problem with most parts for the E23 now.
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I'm running HDs all around with Vmaxx springs. HDs hold up really good but I've only driven 100 miles since Friday's install.
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Last edited by 7THRTY2; 11-06-2018 at 02:29 PM.
Make sure to post a pic a thousand miles later to show how they settle.
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Who did you speak with?
I didn't ask for a name. Is there someone you'd recommend I call back and ask for?
Steve H.
Those look like the Bavauto ones I have.
I just went thru this scenario with my 81' 745i. Shipped a set of struts for rebuild with paperwork & called to t/w Bilstein rep. I just called the 800# and asked some questions. The person I dealt with... I'm probably a bit more critical than most since I work in the service industry & have very high expectations. He did ok. They were fairly knowledgeable & assisted to the best of their ability (i think), but didnt bend over backwards. From what I can recall, he echoed what you said about HD vs Sport valving being the same. They build both differently just to space down the extended length of the shaft to accommodate lowering springs. I'm sure mainly so the spring doesn't droop during install & takes up the full length of the strut. He said their struts are apx 10% stiffer than stock to accommodate a wide range of lowering springs. Coincidnetally the Vmaxx springs I'm running are 'supposed' to be !0% stiffer than stock as well. Rather than go thru all the trouble of measuring spring rates & having struts re-valved to match, I took the gamble that a stock rebuild to spec would suffice. So far I'm satisfied having put apx 100 miles on my new setup both with the car empty & weighted. On my 10/83 745i car I'm running R&D greens with sports/front & HD/rear. Car rides awesome! I did have some extra grooves cut by local machine shop for flexibility. This car/setup has seen at least 10k miles minimum & multiple 'extended' spirited pulls at 140mph+ as witnessed by HitmanX. Though this wont hold up in a court of law.
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Interesting that several vendors chose red for their springs. Vmaxx are manufactured in the Netherlands & custom made to order. I nabbed 2 sets.
These HD struts only have a few thousand miles on them. I'm sure I will only ever put another few thousand miles on them. It sounds like people saying you can have B6's "revalved to be sports" are misunderstanding what Bilstein does to these struts. It also sounds like anecdotes that running B6's with lowering springs is going to result in blowing them in a few thousand miles are also questionable. I would still send mine in to have the strut extended length adjusted if it was necessary or would accomplish anything (if the spring becomes slack and moves around every time I have the car on the lift and I have to worry about the spring clocking itself wrong when I set the car back down, that's a problem). If it won't accomplish anything, I'll use them as is.
I will try to talk to Bilstein again later today, armed with the clarifying information I have gained, and see what they can tell me.
Last edited by BONDOSPECIAL; 11-06-2018 at 08:33 PM.
Steve H.
If sending them in due to needing rebuilt, I'd advise either a stock rebuild or getting your spring rates measured prior & then having them valve to match. You can also note how much you want them to shorten the extended shaft length. Custom valving drives the price up though. Almost makes coilovers look like a better option. For now I'm sticking with the simplicity of springs.
I am the original purchaser of the struts and they have maybe 3, 4 thousand miles on them. They don't need a rebuild, I was only going to send them in to have them modified in any way they saw necessary for the Dinan coils I have. Did you have any issue w/ the lowering coil springs being loose between the top and bottom strut mounts & rubber isolators at full extension, or was the coil still preloaded?
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I suppose I can go check this since I have the springs and struts although they are all boxed up
Steve H.
My rears didnt pre-load on install & had maybe 1/4" gap. On the work order sheet I sent in, I noted to have the rear strut length shortened by 3/4". I need to check the receipt to see if they did this or not. If they didnt, then I should've used 1.5" to give a bit more margin.
Hmm, I need to find a set of 'Dinan' E23 struts.
I have E23 front sports here, HDs, Comforts, and Twin Tubes I think even. Rears I only have HDs. I am wondering if the Dinan ones are just shortened rods and nothing more.
I make E23 parts.
09/1983 745i (stolen spring '13 around Houston, TX Achatgruen on nutria buffalo. 8481080)
10/1984 745i
11/1984 745i
11/1984 735i (10:1-265/6)
Ford, MB, and GM round out the pack.
I talked to Bilstein again and still didn't get a clarification on reducing the strut length for Mtech/Dinan lowering springs. I guess I will mock up my Dinan springs, note how much of a gap there is if any for the front and rear, and then send them in and request the strut length be shortened by a little more than I need.
Steve H.
Nebraska, I talked to Bilstein further and they indicated that it was not an issue if a lowering spring was not preloaded in an HD strut off the car as long as it remained preloaded with the strut installed on the car w/ the suspension at full droop. Did you notice if your springs lost preload at full droop on the car?
Steve H.
When car is lifted in the air, my rears to lose preload. I could move the perch up 1 position but that would give too much rake in my opinion. This makes me wonder if they did shorten the extended length or I just miscalculated.
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By specs are you referring to different valving or extended shaft length?
There is no different valving for the sport strut, the only difference is the extended shaft length over the HD.
Good to know your rears lose preload, I want to avoid this. I doubt that hurts anything but I am going to have this car up and down on my lift a lot and I don't want to worry about that.
Edit: I talked to Bilstein again. They assured me that "unless you plan on getting the car off the ground while driving, sending in B6 HD struts to add droop limiters for lowering springs is not a cost effective solution. Lifting a car on a rack and the springs unseating is not all that uncommon and will not cause damage to the shock or spring."
I asked if they could reference the B8 part #s and shorten my B6 accordingly and they said to just fill out a service sheet and inform them how much I am lowering the car if I want the droop limiters added and they will figure it out.
The long and the short of it and why I started this thread is, don't mail Bilstein a set of B6 struts with the instructions "Make these sport spec" because you are not going to get what you think you are getting. Definitely talk to them first.
Does anyone know how much the Dinan e23 spring set I have is supposed to lower my car? Something like 1/1.5"?
Last edited by BONDOSPECIAL; 11-07-2018 at 01:42 PM.
Steve H.
Tons of good info right here. I think you made a good decision that will hopefully prove cost effective. The only unknown is if the Dinan spring rate is something crazy high which I doubt. elGuappo on mye28 is running Dinan IIRC so you could ping him for height. Also for reference: http://www.mye28.com/viewtopic.php?f=2&t=142556
Mind posting a pic of your springs for reference? I have a set I'd like to compare with.
Last edited by gixxerboy; 11-07-2018 at 02:51 PM.
I believe the extend shaft length is the HD shock/strut insert, the sport being shorter.
One issue with using the HD shocks with lowering springs is hitting the internal bump stops in the strut insert and doing the same with the rear external bump stops since the shock does not have internal stops. Yes, this reads that the front does not need the bump stops when using the Bilstein strut insert.
Now if someone has a pair of like new Hartge shocks and strut inserts, maybe I would sell my Bilstein sport set from the H7.
I just saw the mye28 thread. The previous owner of my 745i is in there, and he is the one who bought these Dinan springs. I didn't see a drop distance listed. From those pictures it does not look like much of a drop from my stock 733 in my signature picture, less than an inch. That being the case, I think I'm worrying about nothing using stock B6 shocks. This is an extremely tame drop compared to what most people would consider lowering a car.
Steve H.
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