635CSI -88 Bronzit

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kasra
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635CSI -88 Bronzit

Post by kasra »

Hi everybody.
First of thanks everybody participating on this forum. I have learned alot by reading archives =D>

The E24 has always been one of my favourite cars.
Having looked around last year I finally got bitten.
I bought the car last year @ 107000km. The car came with full service history and have been more than well taken care of.
It has rolled almost all that distance in Swiss were it was sold new 1988.
So far everything on the car works(yeah... even SLS that was fully serviced 2003).
~2006 the car moved to Sweden, and here it has been living since.


Things that deviate from original specs:

-Front suspension which consists of Bilstein sprint & H&R(green colored ?) springs. Recently installed.
-Y-rondells, front 225/45, rear 265/40 -> yes works fine with the SLS.. so far anyways.
-///M markings on front and back
-Rear window tint.
-Head unit changed to a Blaupunkt unit.

The interior is Buffalo Havanna #0298. Seems to be quite rare as I have yet not seen another car with it. More pics of that later.

Here are a couple of shots of the car from my summer place:

Image

Image

Image

Image

Another favourite car design, coup? of course is the Ferrari 400. Preferably with carburetors :oops:

A couple of weeks ago I filled the R12 spec. A/C with Enviro-Safe Hydrocarbon gas. So far no loss in pressure and A/C blows cold and nicely.

First project about to be presentet here is about the car stereo.
Last edited by kasra on Sat May 26, 2012 7:23 pm, edited 2 times in total.
kasra
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Location: Sweden

Re: 635CSI -88 Bronzit

Post by kasra »

The stereo project:

The car has all original speakers in place and came with the basic speaker configuration [2+2 4x6"]. The head unit has at some time been changed to a Blaupunkt CD-unit:

Image

Needless to say something needs to be done.
My criterias are the following:
-speakers in original locations without modifications or cutting. Visually it must look original!
-Head unit with cd and aux input that looks stock.

The head unit was an easy pick - BMW Business CD CD43.
Rear speakers that needs to be shallow: Lanzar VX460s 4x6"
Front speakers Critical Mass SS46 4x6"
Last edited by kasra on Sat May 26, 2012 7:17 pm, edited 1 time in total.
kasra
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Re: 635CSI -88 Bronzit

Post by kasra »

The head unit with modifications:

The CD43 is regarded as a good stock head unit. Having studied the schematics of the CD43 I soon found ways to improve the unit.
Considering the 4x6" spekers and their locations modifying the head unit could be considered overkill. :mrgreen:
But hey, why make it simple?

First of there are polar electrolytic capacitors in series with the audio signal - both in the amplifier stage and the aux input circuit.
These capacitors was changed to polypropylen capacitors which are much better suited for coupling purposes.
Other electrolytic caps in critical power supply parts were also changed for better speced ones.

The big mod is the total rebuilding of the amplifier stage.

The original amplifier stage consist of 2x TDA7376b ic?s.
Nothing special here, the specs are quite average - quite high?ish distortion.
The TDA?s are controlled with a mute & standby signal from the digital circuits of the CD43.

Pic of the original output stage.
Image

The goal was here to build an output stage with more "Audiophile" quality sound.
Tripath TAA4100 is 4-channel Class-T Digital audio amplifier IC with good specs.
This IC is also possible to controll with an mute & standby signal. In short meaning one could integrate it within the head unit and still be possible to use all the mute functions + amplifier stage will go in standby whenever you turn off the head unit.
-> No need for a physical power switch for the new amplifier stage - its simply controlled from within the CD43 head unit.

In theory one could just tap the audio signals from within the head unit and couple them to an external amplifier. But then you would miss out of the finesse with auto mute, power and so on.

For amplifier output stage I choose to get a board from 41hz.com called AMP9-BASIC. This board utilizes the TAA4100 IC and is usable with a little modification.

The PCB will obviously not fit within the CD43 head unit so it needs to be mounted in a separate housing.

So here is how the modified head-unit looks:

Image

Image

In the first picture you can see that the original amplifier output stage ic?s are removed. You can also see the blue things which are capacitors for the AUX input.

The box beside the CD43 is the new amplifier stage. There are 3 cables between the units. The 2 black cables carries audio signals for 4 channeles - front and rear.
The white cable controls Mute & Standby.

The cables are routed from the underside of the CD43 pcb. The three unused holes in the amplifier box is meant for power lines and speaker cables.

Next step is to find out which cables are what from within the car.
AusE24

Re: 635CSI -88 Bronzit

Post by AusE24 »

kasra wrote:Hi everybody.
First of thanks everybody participating on this forum. I have learned alot by reading archives =D>

The E24 has always been one of my favourite cars.
Having looked around last year I finally got bitten.
I bought the car last year @ 107000km. The car came with full service history and have been more than well taken care of.
It has rolled almost all that distance in Swiss were it was sold new 1988.
So far everything on the car works(yeah... even SLS that was fully serviced 2003).
~2006 the car moved to Sweden, and here it has been living since.


Things that deviate from original specs:

-Front suspension which consists of Bilstein sprint & H&R(green colored ?) springs. Recently installed.
-Y-rondells, front 225/45, rear 265/40 -> yes works fine with the SLS.. so far anyways.
-///M markings on front and back
-Rear window tint.
-Head unit changed to a Blaupunkt unit.

The interior is Buffalo Havanna #0298. Seems to be quite rare as I have yet not seen another car with it. More pics of that later.

Here are a couple of shots of the car from my summer place:

Image

Image

Image

Image

Another favourite car design, coup? of course is the Ferrari 400. Preferably with carburetors :oops:

A couple of weeks ago I filled the R12 spec. A/C with Enviro-Safe Hydrocarbon gas. So far no loss in pressure and A/C blows cold and nicely.

First project about to be presentet here is about the car stereo.
What an Awesome car. Love the ride height and wheels.

Regards
Greg
GazM3
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Post by GazM3 »

very nice. any pics of the interior
BMW’s
84 E24 M635csi
90 E34 M5 3.6
94 E34 540i/6 SC E85
97 E36 M3 euro SC U/C
97 Z3 2.8 widebody

OTHERS
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kasra
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Location: Sweden

Re: 635CSI -88 Bronzit

Post by kasra »

Greg: Thanks! Regarding the height I would prefer a little lower on the back. I know the reference ride height of the SLS is adjustable. The question is what the lowest height possible is...

GazM3: Thanks mate! I will for sure add a couple of pics of the interior soon.
SWE635
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Post by SWE635 »

Fruktansv?rt snygg bil. N?stan s? att man ?ngrar att man gick p? den r?da linjen!

And for all of you that doesen't speak Swedish:
Daaaaamn, that's a beautiful car! Almost makes me regret that I went down the "red road".

...and don't worry. That's the only Swedish that will ever be posted by me!
---
'89 635CSiA; Zinnoberrot
'11 VW Golf Variant TSI160; Bronze
'15 Nissan Juke; Ink Blue
kasra
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Post by kasra »

SWE635, tack f?r de sn?lla orden!


So a new season is approaching here in chilly Sweden.
Some work is under progress, so im starting up front:

-changing all the bushings, arms, links etc. up front.
-hopefully also the motor mounts. :-k
-Adding Mwrench support for the steering box.
-adding Mtech short red springs in front to lift it up a little.
-22mm swaybar up front from M6 with powerflex bushings.



Here are the strut assembly up front with the old ~45-50mm drop springs. Very good condition considering its age. Still I will clean them up and add a coat of color for protection.

Image
kalkan

Post by kalkan »

very nice car, and unique CD43 mod.

good work!
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Ozibimmer
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Post by Ozibimmer »

Great car and great colour really like the stance of the car.
_________________________
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fazerman
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Post by fazerman »

Stunning car, very nice colour, looked at one that colour a few years back... :D
kasra
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Post by kasra »

Front legs now assembled with Mtech short red spring. Which is actually made by Eibach.
I also went through changing the motor mounts. The old ones, original dated 1987. Green to the color, came out in 2 pieces, not much life in them.
New "HD" ones installed in ~ 1H work, pretty straight forward as described in the archives.

Pictures to follow.
kasra
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Location: Sweden

Post by kasra »

Hard to see but yes they once were green:

Image


Sway bar links & rubber seats for the springs are Lemf?rder.

Image
kasra
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Post by kasra »

More parts for the front suspension ready to go in:

Image

Steering arm and control arm torqued up.
Tire rods and steering arm torqued up.

I opted for Meyle HD and Lemf?rder parts. The lower control arms have aluminium bodies.
kasra
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Location: Sweden

Post by kasra »

Installed brake cooling vents behind the front air dam.
[51711822440]
[51711822439]
Dont know if they actually will bring anything performance wise, but they are very cool! :wink:
SWE635
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Post by SWE635 »

If ever you feel like selling the car...
---
'89 635CSiA; Zinnoberrot
'11 VW Golf Variant TSI160; Bronze
'15 Nissan Juke; Ink Blue
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Brucey
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Post by Brucey »

Good work there!

Some comments;

- I just looked at your 'before' front strut picture. Those green springs have 5-1/2 turns. All BMW-specced front springs for these struts have an integer number of turns, (e.g. 6 turns for the M-tech) because otherwise the top hat (which along with the spring and lower seat is angled vs the strut centreline) finishes up at the wrong angle. With this arrangment and old top mounts, it is possible for the top hat to touch the underside of the mount in use. It might even be that you can see a mark from this in your photograph.

Changing to M-tech springs is a good move; even if some people prefer the lower ride height, I prefer suspension that works properly!

-Re the brake ducts; IIRC these were fitted with the first 635CSi models. These cars do not have foglights integrated into the front spoiler; the slots in this version of the front spoiler extend full width and allow good airflow through to the ducts. It may be that the ducts will only provide any large benefit if you install a similar spoiler, or delete the foglights or something.

-Re Swiss spec. If your 6er was originally supplied as a Swiss specification car, you may find that there are all kinds of slight differences in the mechanical specification. Reversing or deleting some of these may well liberate some more power.

-re speakers. The 6x4 setup is seriously lacking in bass. You can fit larger speakers (up to 6x8) to the later/highspec rear pods (with the larger central speaker grille), and/or fit a subwoofer. Subwoofer installs can go under a front seat, or be hidden behind the armrest, or go below the rear seats.

A P.O. had already cut holes in the kick panel below the rear seats in my 6er, so I made the holes bigger, fitted 6x8s and to finish it off fitted reflex ports as well. You can see what I did here;

viewtopic.php?t=2154&start=0

BTW there is plenty of room for aux amplifiers and so forth under the rear seats, and it is easy to run wires under the centre console/carpet into this space.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kasra
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Post by kasra »

Brucey>>

Re springs:
You have a sharp eye for details. Yes I have read your thread about top hat angle. One of the many reasons I decided to change the front springs.
The Mtech springs specially made for M535 [31-33-2-225-645] have good spring rate, and brings some additional drop compared to regular M5/M6-
One who lives will see...

Will it sit to high I may try a 10mm drop hat made for E30/Z1. for example Bonrath 9208S.


For rear im going for special lowering springs made for SLS, more on that later. :D

Re: disc vents
The world spoiler; while the sides sits flush with the fender, the whole front has a 10-15mm(?) column between fender and spoiler. I was hoping for some flow through that column.

Re Swiss cars:
What power limiters do you know of? I know about the catalytic converter.
Factory papers read 208 or 212 bhp, will have to recheck.

Re speakers:
This one gives me real headache, being an audiophile and all. My goals are to make non-invasive installations. Probably DIY bass + ampli under the front seats. The nutria/havanna upgraded pods are still avail, I may look into that. But I must admit I like the looks of the older pods better.
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Brucey
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Post by Brucey »

Re the top mounts/spring hats; my top mounts are admittedly a bit old and a bit saggy, but there is not 10mm clearance between the top of the hat and the underside of the top mount flange. I shall be interested to see how you get on if you try a different top hat.

Re the rear shocks; If you have OEM-type Bilsteins (with a BMW part number on them as well as a Bilstein part number), they have just one groove in the shock body, and are not height adjustable.

However it is possible to add further grooves to the shock body, and therefore convert them to height-adjustable spec, like the aftermarket Bilstein shocks are.

You need to find someone who has a good lathe, ideally with a >50mm throat in the headstock. One word of warning is that (unlike a twin-tube shock) a monotube shock has the piston running to a close clearance against the inside of the tube that is the shock body. Therefore any significant deformation of the shock body will ruin the shock.

This means that both holding the shock in the lathe and/or a slightly blunt tool (that 'pushes' too much) may risk damage to the shock. But it can be done, anyway.

An alternative DIY solution is to source some 50mm ID tube, and to use that to support the spring perch. The tube can be cut to length and will need to be supported on a shoulder that is added to the shock body. This can be added near the bottom of the shock by welding, if you are careful; the shock contains a floating piston which sits about 50mm up from the bottom of the shock; there is oil above and gas below the piston. In use this piston moves about 10mm. You can weld onto the bottom part of the shock body (about 4-5mm thickness) or to the side of the shock body (~2mm thickness). It is a very bad idea to allow the welds to penetrate very far because the gas inside has a high pressure.

Another approach is to take a 'Rally Design' coilover conversion kit, and use that to support a (modified, with a larger central hole) standard size spring perch. The only problem with this is that you will not be able to refit the standard protective sleeve to the shock. However, unlike a full coilover conversion with a 2-1/4" spring, the stock spring is large enough inside to allow you to fit a different cover, or perhaps a full gaiter of some kind.

BTW I agree about the non-invasive audio install; I probably would not have fitted the speakers as I did, had there not already been holes there.

Another (non invasive) potential speaker install position is in the bottom of the doors. I think that there is enough room for some 120mm units, or a small sub unit behind the standard cloth trim panel; you might not even be able to see speakers mounted here if it was done carefully. If necessary a fibreglass enclosure could be made to fit inside the door trim, so that the whole speaker mounting can be bolted rigidly to the metal parts of the door. Here, a potential risk is speaker damage if the doors are slammed hard, but I guess it would be worth a try.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kasra
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Post by kasra »

Now the front suspension and steering is ready.

Thust- and control- arm were tightened under preloading as per bentley, with the car standing on four steel rims.
Its recommended to have the car higher up than regular rims, in order to have space to torque the thrustarms. Lesson taught for next time. :oops:

Now on to the rear suspension:
The SLS is working good and recently serviced, I dont have the heart to rip it out.
--> Im going to install a Dinan spring made to work with SLS.
They will bring 0.75" drop, matching the fron M-techs. They also bring alot more spring rate. Its said to balance out some understeer...
Probably no the best solution but hey, lets try it. They will be mounted with all new bushings.
-replace Subframe bushings
-replace trailing arm bushings... :-k
-replace diff mount...
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Brucey
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Post by Brucey »

a good trick is to have the car up on stands, then jack the upright into the correct attitude for normal ride-height. This way the Upper TCA bushing bolt can be torqued in the correct attitude.

There is however a risk with this; that the car might come off the stands, and/or that the jack might spit out. So be careful!

Stock (and E32 upgrade) BMW TCA bushings should be torqued in the normal ride height; otherwise they see a permanent twist (not good). With PU bushings, it doesn't matter.

BTW the spring rates and ARBs will dominate the feel at turn-in (not enough low-speed compression damping to make a big difference with most stock shocks) but mid-turn the roll stiffness is greatly influenced (especially with lowered suspension) by the 'supplementary springs' (bump stops). Boge struts use external bump stops front and rear. Bilstein uses stock bump stops at the rear , and hidden bump stops (that are inside the base of the insert) at the front. Either sort can be trimmed if necessary, provided you don't lose the fit at each end of the stop.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kasra
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Post by kasra »

The method you describe sounds a bit risky. With steel rims under the regular wheels was a good way of getting the car up on all four in a neutral loaded position. But you will need wiiide rims to get proper height, otherwise PITA.

I have read your comments about trimming the bump stops.
By trimming you mean cutting its length? How to find out appropriate length?
Fwiw I have new ones ready to be installed.

Also more improvements for the rear end:
-18mm M5 sway bar + poly bushings.
-Wiechers rear strut brace.
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Brucey
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Post by Brucey »

kasra wrote:The method you describe sounds a bit risky.
I've done it a few times; it is OK if you do one side at a time I think, but on such occasions I dream of having a four poster ramp...
I have read your comments about trimming the bump stops.
By trimming you mean cutting its length? How to find out appropriate length?
Good questions.

For stock (Boge) bump stops; On balance I think it is best to cut the top of the bump stop because the bottom has a hollow shape giving a soft transition which is best retained. However if you cut more than 10mm from the top then the bump stop may slide down the shaft (not so good) in use. So in this case something (many turns of insulating tape, or a piece of a synthetic wine bottle cork with a hole cut in it?) should be added to the shaft to make the bump stop a snug fit. The correct retaining diameter at the rear is ~18mm, and at the front (Boge or other twintube insert) is 27mm.

For front bilsteins, the bottom of the internal bumpstop is the place to trim, since the top (nose) of the bumpstop is shaped.

If you want the car to ride over small bumps very well, then it is a bad idea to have the bumpstop very much compressed in the first 15mm of suspension travel above the normal ride height.

If you want the car to feel 'sporty' then it is OK to have a little static compression of the bump stop, but this will give a more jiggly ride.

Roughly speaking the standard springs and the M-tech springs will give these two set-ups with no other changes, but yours will be different to this because of the SLS.

What would be a bad thing would be if the front and rear bumpstops compress at different times and by very different amounts. During hard cornering, the force on the bumpstop can be similar to the force in the spring, especially with lowered suspension. Because the bumpstop gives a powerfully rising rate action, if the bumpstops are not compressed equally front and rear, the car may transition violently from understeer to oversteer as you corner more quickly or go over bumps mid-corner.

I don't know if you have seen it, but on Top Gear a few years ago they all bought tatty M30 cabrios and drove them round the track. They all had been lowered to some extent (I think) and they all did the same thing on the limit; went from mild understeer to strong oversteer. This is what can happen, and it can easily be made much worse. Do note that this is probably much more aggressive driving than should ever be attempted on the road.

So check the bumpstop clearance at the standard ride height, then again at the new (lowered) ride height. The stock bumpstops are approximately the same length front and rear, and (as standard) there is a similar amount of suspension travel front and rear too. If you retain equal available suspension travel front and rear, and a similar balance of coil spring (and ARB) rate, cutting the bumpstops equally front and rear would make some sense, but if you want a 'sporty' ride and you are only lowering 15-20mm then no cutting may be necessary.

When estimating available suspension travel, please note that the travel can be limited by the compression of the bumpstops (e.g. bilstein fronts; you never get the last inch of travel) the shock travel, or the springs going coilbound. IIRC several stock rear setups are limited by the spring going coilbound. It would be a bad thing if the spring went coilbound before the bumpstop was seeing much load. I don't know what an SLS setup will do because I've not looked at one in enough detail.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kasra
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Post by kasra »

Thanks for the reply Brucey.
So this is really good information, you have really given this some thinking. Fwiw it has kept me awake the whole weekend.
I have looked at the bumpstop for the rear. Based on its anatomy best way of shortening as I see it, dissect a piece of the midsection and reglue it. This would give the best stability with maintained shape.

Whats the length of the bumpstops in front Bilstein sports?

The rear SLS Dinan is supposed to give an equal amount of drop compared to M-techs.

Dinan spring for SLS e24/e28 is really rare and not much is known about it.
Here are the specs of Dinan rear springs for SLS:
Spring length: 10,5"
Coil diameter: 3.99"
Wire diameter: 0.5"
Total coils: 7.25
Active coils: 6.25
Said to bring 60% more spring rate compared to regular SLS spring.

The Dinan diameter is less than regular SLS spring. This way the spring can bring a drop and have the increased spring rate.
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Brucey
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Post by Brucey »

that spring is a bit like a standard front spring, but wound a bit shorter and with an odd 1/4 turn.

You can work out the exact rate using formulae. The wrinkles are that;

a) the wire diameter needs to be measured very carefully (it appears cubed or to the fourth power depending on which formula you use)

b) the number of active turns changes all the time.

Very many springs have a variable pitch near the ends, over the last 1- 3/4 turns. Probably you have between 5.5 and 4.5 active turns between static and 1" of suspension compression.

BTW you may find that the spring goes coilbound at the end of the stroke. It is good if the bumpstop is well ramped up by then.

BTW front Bilstein bumptops are available in 85, 82, 73mm lengths, and different compounds/profiles. The standard ones I have found are the 82mm ones -in the struts where they have been identifiable, that is....

Cutting and gluing bumpstops might work, but I worry about the glued joint failing; it all depends on the Poisson's ratio of the bumpstop material, and how flexible the adhesive layer is. I fancy cutting the top of the external bumpstop instead, and using a collar on the shock shaft to retain the bumpstop.

Probably you will get close to the setup you want with a little calculation, but experimentation is what will get you all the way.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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