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E24/2&3 OE Front Spring guide, version 1

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Brucey
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E24/2&3 OE Front Spring guide, version 1

Post by Brucey » Wed Dec 14, 2011 9:33 pm

Stimulated by Madridcab's helpful post in the 'invisible numbers' thread, I've been collating information re OE front springs. Below is a first draft of a guide to OE front springs, how to use them, and some places you might find them in the boneyard...

There are yet further OE springs which might fit and be useful, if information becomes available it can be added. When I first looked into this I was fairly baffled by the complexity; but when I looked at
other springs (e.g. E34 springs) I realised we have it easy; a typical E34 fitment list for just one model has over thirty part numbers in the first phase of production alone....

If there are not typos and omissions in my list I shall be amazed, so please do call them out if you see them.

cheers

Brucey
----------------------------------------------------

Front spring guide: Ride height adjustment and suspension modification using BMW OE springs.(Version 1, Dec 2011)

Front springs:5/82 to 2/88

Tall to small;

31 33 1 129 653
31 33 1 127 662
31 33 1 126 024 (old number 31 33 1 126 025)
31 33 1 126 904
31 33 1 125 726
31 33 1 127 503
31 33 1 125 341

Dropping one down on the list above lowers the car by ~7mm (thanks to Madridcab's useful posting, to which I have added). The final items on the list above are suggestions which have been added by extrapolation from BMW fitments on various other cars, not E24, so must be regarded as approximate (at best) until shown otherwise.

To maintain front ride height, you should think about dropping down one if changing from Boge to Bilstein struts, doing an auto to manual conversion, or maybe dropping two if stripping out the AC. The 'points system' and the examples later should help decide this.

If lowering; spring rate remains about the same with these springs, so you lose a little travel lowering this way and/or work the bumpstop harder, earlier, on bumpy roads. However, on good surfaces, ride comfort should be preserved, provided lowering is not excessive.

If choosing aftermarket springs, or alternate hats, note that the top of the spring is only correctly angled if the original E24 hat is used, and the spring has a whole number of turns. Other arrangements will most likely cause the top end of the spring to be badly cocked, which is never a good idea in the long run.

-----------------------------------------------

2/88-on E24 springs, Tall to Small;

31 33 1 134 188 (listed as NLA)
31 33 1 134 187 (believed roughly equivalent to 31 33 1 127 662)
31 33 1 134 186
31 33 1 134 185 (also NLA on ETK)

going one down on the list is believed to drop the car by ~7mm. These springs will physically fit in place of the 82-87 ones, but are not used on any other BMW. These springs weigh less than the earlier springs, but are believed to be a similar spring rate.

---------------------------------------------------------------

M-technic springs (both stiffer and lower than stock)

31 33 2 225 646 ( '644' without red marks, use when AC fitted normally )
31 33 2 225 645 ('644' with red marks on two coils, also with orange stripe on all coils?)
31 33 2 225 644 (stamp marking for -645 and -646 springs; does not exist as a separate part)
31 33 2 225 643 (M-technic spring for 520i, 524TD etc)

the '645' spring is believed to give ~20mm drop vs a 31 33 1 126 024 spring (starting at stock height)
the matching rear spring is 33 53 2 225 654 but NB this is meant for E28 so may not give the correct ride height on E24 without adjustment.

-------------------------------------------------------------
M5/M6 springs. (tall to small). Front rates believed comparable with M-technic springs. Comparative ride heights uncertain (anyone?).

31 33 2 225 115 (18 or more points with M5, M6 with AC)
31 33 2 225 024 (7-17 points with M5, M6 without AC)
31 33 2 225 233 (0-7 points with M5, lowers M6 below stock)

Points as follows: AC = 16pts, Glass roof = 4pts, electric seats = 4pts, steel sunroof = 3 pts, Headlight Wipers = 3pts, Front spoiler = 3 pts, Electric Windows = 1pt, Fire extinguisher = 1pt, Independent Heating = 1pt, OBC = 1pt, Radio = 1pt

---------------------------------------------------------------
Edit; Rob's info (thanks Rob!) M635CSi springs (marked 2225 020 241 B11C, so probably 31 33 2 225 024 ?) 325mm free length, 7 turns, 13.5mm wire diameter, blue stripe. Thus they are ~30mm shorter (free) and 16% stiffer than stock 13.0mm wire springs. This translates to ~18mm drop vs typical stock spring.

----------------------------------------------------------------

Spring fitment examples, key;

E = European model
US = North American model
Aus = Australian model
Swe = Swedish model
MT = Manual transmission
AT = Automatic transmission
AC = Air Conditioning
TR = Tropical Spec
OF = Official spec
B = Bilsteins


All E24 5/82-6/87 unless otherwise indicated. Springs are listed small-to-tall here.

31 33 1 125 341 (colour code?)
E30 Various-too many to list!
E28 typically with lower spec


31 33 1 127 503 (colour code?) (two blue stripes on last two turns -thanks to "OnTheFritz")
E28 525i E, MT, B
E28 528i E, MT, B.
E30 various with M20/M21 engine and full spec

31 33 1 125 726 (orange stripe on last three turns)
E28 525i E, MT,
E28 525i E, MT, B, AC.
E28 525i E, AT, B.
E28 528i E, MT
E28 528i Aus, B.
E28 528i E, MT.
E28 528e (3/83-9/86) US, AT, AC.
E28 528e (9/83-9/86) US, MT, AC.

31 33 1 126 904 (pink strip on one turn? edit; probably not)
E28 525i E, MT, AC.
E28 525i E, AT.
E28 525i E, AT, B, AC.
E28 528i E, MT, AC
E28 528i Aus, MT
E28 528i Aus, MT, AC, B.
E28 528i E, AT
E28 528i Swed.
E28 528i Aus, AT, B.
E28 528e (9/86-on), US, AC.
E24 635i ( 6/87- 2/88 ) E, MT.

31 33 1 126 024 paint code 'long yellow mark on last turn'
E28 525i E, MT, B, OF.
E28 525i E, AT, AC.
E28 528i Aus, MT, AC.
E28 528i Aus, AT.
E28 528i OF, B.
E28 528i Aus, AT, AC, B.
E28 535i US, MT, B.
E28 535i US, AC.
E24 628i E, AT.
E24 635i E, AT.
E24 635i ( 6/87- 2/88 ) E, AC
E24 635i ( 6/87- 2/88 ) E, MT, TR.
E24 635i ( 6/87- 2/88 ) Aus, MT.

31 33 1 127 662 (colour code? edit: pink stripe on one turn, thanks Madridcab)
E28 528i Aus, AT, AC.
E24 635i ( 6/87- 2/88 ) E, AT, TR. (Note 1.)
E24 635i ( 6/87- 2/88 ) E, MT, AC, TR.
E24 635i ( 6/87- 2/88 ) Aus, MT, AC
E24 635i ( 6/87- 2/88 ) US, AT.


31 33 1 129 653 (colour code?)
E24 635i US (5/85), AT.
E24 635i ( 6/87- 2/88 ) E, AT, AC, TR

---------------------------------------------------------------

Note 1. post 2/88 springs; the suggestion is that

31 33 1 127 662 is roughly equivalent to
31 33 1 134 187

Europe 6/88 635

31 33 1 134 185 (*NLA) E24 635i MT
31 33 1 134 186 E24 635i AT
31 33 1 134 187 E24 635i AT, TR
31 33 1 134 188 (*NLA) E24 635i Aus AT

31 33 1 134 186/7 E24 635i MT, AC
31 33 1 134 187 E24 635i AT, AC
31 33 1 134 188 (*NLA) Aus, AT, AC

Japan 6/88 635 (all auto w a/c) -187 spring

US model 6/88 635

187/188 manual or auto (all AC ?)

----------------------------------------------------------
Last edited by Brucey on Fri Sep 14, 2018 7:13 pm, edited 6 times in total.
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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Jon Ackermann
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Post by Jon Ackermann » Thu Dec 15, 2011 2:19 am

Brucey:

You need to sit back and pour yourself a nice glass of wine. You must be exhausted.

Good work.

Jon
1987 635 csi Sold but not forgotten
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Brucey
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Post by Brucey » Thu Dec 15, 2011 9:07 pm

right-ho, best idea I've heard all day..... :wink:


cheers

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madridcab
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Post by madridcab » Thu Dec 15, 2011 9:49 pm

Good work, that?s a comprehensive encyclopedia on springs.. I did not realize they used the same strut set up on the whole model range (E30, E24, E28) should be useful for bone yard hunters. This also should give us a chance to figure out what we are likely to have.

BTW, checked mine in the garage, for 9/87 build European spec AT, AA, TR, Electric Seats, sunroof etc spring number 31 33 1 127 662, 1 pink marking on one coil.

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Brucey
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Post by Brucey » Thu Dec 15, 2011 10:28 pm

-excellent, thanks for that, I've amended the first post in this thread accordingly!

-anyone else got spring colour code info to contribute? BTW I'm trying to collate rear spring info too....

cheers
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wattsmonkey
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Post by wattsmonkey » Sat Dec 17, 2011 7:42 pm

Thanks Brucey! Fascinating stuff indeed.

Here's a potentially stupid question: does it matter which way up springs are installed?

I've got a pair of M635 springs which I'm going to stick on to get some feel for the difference between them and the Eibach copies with their "wrong" number of turns (meaning having a half turn, placing the drop hat out of alignment). I had a look at them tonight, and the numbers are stamped as per other posts, but are at the bottom of the spring as installed.

I imagine that tops and bottoms are identical in non-progressive springs, but would be interested to see if I'm missing something obvious! Incidentally, there is a blue "stripe" on the top of each spring as installed.
"Most of it necessary; all of it enjoyable[!]" LJKS
'86 M635CSi #367 Bring the Noise.
'84 635CSi, dogleg fun

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Brucey
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Post by Brucey » Sat Dec 17, 2011 8:15 pm

with 'single ended' progressive springs there is a theoretical advantage in unsprung weight if the close coils are fitted at the top. In reality this effect is very small and it is probably best to fit the close turns at whichever end of the assembly stays cleanest, as the more dirt and rubbish get trapped in the close turns, the quicker the finish goes and corrosion starts.

BTW athough the OE BMW springs are symmetric top to bottom, they are also progressive, but in a more subtle way. Typically a 7 turn spring has about five active turns at normal ride height, but the 'lead-in' on the turns goes almost two full turns from the spring end before the pitch is constant. The spring does not go coilbound in one go, but loses active turns gradually as it compresses. Thus the spring can lose a further two active turns when compressed far enough and this means it has just three active turns just before it goes coilbound. The stock 13mm wire, 7 turn springs go coilbound if you manage to squash the bumpstops down to nothing; thus I reckon maybe 3.5 to 4 active turns is about it for this spring type when the suspension is fully compressed.

So which part number are your springs? Let me know and I'll add the colour code info to the list. If you have other spring data (turns, free length, wire dia, main diameter, compressed length etc) all could be very useful.

BTW I found a load of info on springs on MyE28.com but I don't necessarily agree with their calculated spring rates etc, in part because the measurements are not accurate enough; the wire diameter measurement has to be accurate to 0.1mm or better; any coiling deformation throws it out, even the paint thickness is a problem...

cheers



Cheers



So
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wattsmonkey
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Post by wattsmonkey » Thu Dec 29, 2011 11:44 am

A few measurements for you:

M635CSi front springs numbered 222 502 0241 (followed by either B11C or &11C). Not progressively wound, diameter 13.5mm. Uncompressed length 325mm. Seven complete turns. I believe these to be from a 1985 car. Blue stripe.

Eibach copies from Fritz's Bits, again not progressive (so not very Eibach-like then??), constant 13.5mm, 13.5mm diameter as per above, uncompressed length 295mm, five-and-a-half turns.

Cheers,

Rob
"Most of it necessary; all of it enjoyable[!]" LJKS
'86 M635CSi #367 Bring the Noise.
'84 635CSi, dogleg fun

bpoliakoff
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Post by bpoliakoff » Tue Apr 16, 2013 4:18 pm

I bought a new set of rears at the dealers 3-4 years ago for my euro 61 635. They were black with a bloe stripe. The ones that came off, in pieces, had a yellow stripe on them. Ended up using B&Gs all the way around.

Rainer are the springs you need for an early or late car? I have some fronts from an early car, used but in nice shape
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.

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Jdesign
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Re: E24/2&3 OE Front Spring guide, version 1

Post by Jdesign » Fri Sep 14, 2018 1:37 pm

This is an awesome list. Thank you!!
Image
BMW E24 633CSI - BMW M30B32
BMW E30 325IC - Toyota 1JZ-GTE
BMW E36 318i - Ford 5.0 FE302
https://www.instagram.com/_jdesigner_/

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