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Oldtimer BMW 745i (1981)
I bought the vehicle in 1992, after a very long search. The love has lasted ever since. This inspired me to create unique motor control electronics. I hope that the ROTREX compressor replacing the turbocharger will be installed soon.
The engine management in this car uses original BMW 745i injector nozzles which are low impedance.
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The exhaust
In 2007 I bought 1 SUPERSPRINT cylinder header made of acid-proof material for my car, because I want to replace the turbo with a compressor. After a recent engine rebuild due to a broken crankshaft, I had to have the exhaust system professionally rebuilt. So I took my car to a specialist workshop, the same one where the exhaust was fitted and all the other necessary ancillary work was done. I was completely satisfied, as were others in my circle of acquaintances. That’s why I hired them again. The installation took about 1 hour and they charged me 20000 forints. Didn’t sound good, cold start up you could clearly hear a gasket leak somewhere in the front. The mechanic claimed he was sure it was sealed and took offence at me criticising his work because he said it was perfect. I asked for a blow at the rear drum exit so we could decide whether I was right (obviously I was) or not. I was blocked. I saw no point in arguing, this workshop is not what it used to be. What could I do, I went home. I blew in the back, it was whistling somewhere in the front. Besides, the car was already a bit loud before the breakdown, but I ignored it. With the help of family members, I managed to find that the stitching on one side of the “SUPERSPRINT” emblem, which was stamped into the factory welded plate on the 5th cylinder exhaust afterwards, was completely worn around. The fault was repaired by a friend of mine at the age of 78, with about 5 hours work. A man’s worth is the product of his talent, his diligence and his morality…
engine control wiring harness
The wiring harness is completely made of silicone-insulated LappKabel cables, even the shielded wires, including the transformer cable. All its parts are new, reinforced with LOCTITE 9220 adhesive at the branches, and the connectors are also reinforced with this material / fully waterproofed. The outer covering is TESA adhesive tape.
The front shock absorber
Suddenly the oil spilled. I was taking the vehicle in for a roadworthiness test. The day before I hadn’t seen or felt any signs of it, but there it was all oily on the left sternum. Of course, the roadworthiness test failed. I bought 2pcs MONROE MG-971 shock absorbers and a SACHS ” Protection-Kit”. I disassembled it. The tower bearings were hanging (1996 production), the rubber bearing was a bit worn. I bought 2 of the “WEISS-HART” type a few years ago. I knew I would need them one day. I decided to install them now. The springs, spring plates went into a sand blaster, then into the galvanizer. I ended up painting the springs with the same paint I had used on the previous installation (2009). Of the spring beds, only the bottom two were new, I couldn’t buy the top one, but they were still in good condition. The bearing seals and other small parts were original BMW. I assembled it so that the tower bearing has a slight negative clearance. The rocker arms and couplings are in perfect condition at the moment.
brake caliper
Replacement of the front shock absorbers required the braking system to be deflated, while the outer bleed bolt on the left front caliper broke. For the repair I used a factory brake hose dutch and a 4mm brake hose end piece. An M6 thread was made in the original 5mm hole on the inside of the Dutchman. As a repair, I made a 10×1 thread from the 7×1 torn thread, sealing the Dutchman with loctite 243 threadlocker, and the 4mm brake pipe end underneath to form a sealing surface. Here I use an M6 threaded bleed screw with a 7 keyway, so the bleed key remains the same size. All metal parts have been cleaned and galvanised, except the pistons which are new and factory chrome plated. The saddle castings were also painted for maximum corrosion resistance. The rebuild kit is original ATE, and I used a special silicone grease with graphite content that is heat resistant up to 260 C for assembly. Brake pads and mounting kit are BREMBO. Of course the right caliper was also rebuilt.
The brake master cylinder
After the caliper rebuilds, we tried to bleed the braking system with the classic two-man solution, but failed. Sometimes some small or big bubbles appeared in the bleeder tube, the pedal never got hard. The master cylinder randomly sucked in air, audibly, more or less when the brake pedal was released. Replace master cylinder, but for what? The original is 22.2mm and the car has ABS. A new one is now available from csat ATE for at least 106.000 HUF. However, the later BMW E32-750i car is also ABS, the master cylinder fits perfectly, but the inside diameter is 25.4mm. I bought an A.B.S. one for 16700 HUF. I pulled it apart to look inside. I found it to be perfectly made. I took it in, had it degassed. Everything is flawless, the pedal force is perfect, but the pedal travel is obviously shorter. With that, the brake system repair was successfully completed.
Rear shock absorber
Since such parts are no longer available, with the help of my friends I bought a new E32 740i BMW rear MONROE from the new MONEYEE rear shock absorbers. The lower silencer blocks were machined on a milling machine, the piston rods on a lathe to the correct geometry. The spring plates are the correct size and position on them from the factory. The springs and upper spring plates were ground after cleaning, as were the bolts, washers and nuts. I purchased the “Protection-Kit” from KAYABA for my E32 BMW. I painted the shocks and springs. Replaced the strut bearings and upper silen blocks, spring plate seals and one of the damaged upper dust shields with factory new ones.
Rear axle carrier rubber mount
The rubber mount is a rather expensive part for this model, as it is an older version with a removable housing. There is no after production and never was. I wasn’t going to buy a factory one because I wasn’t going to get robbed. I did find 1 merci silen block that could be solved. I asked my friend Karcsi to do 1 small lathe job. I had the old silen block burned out of the case, then had the case and associated brace support cleaned off with a grain sander, then had them anchored down with the bolts and nuts. The converted Mercedes silencer block, which still gives a tight fit, was then assembled using a press machine with factory BMW body glue (the glue is the green stuff in the photo)
So it cost me about 20000 forints, compared to the factory 120000.
The Steering arm
The weakest point of the chassis is the steering arm bushing. I’ve bought countless original BMW replacements, but they’ve all broken in a short time. I am now trying to make a matched axle-bushing combo with a stainless steel bushing with 2 VITON O-ring seals. I use KLŰBER WOLFRACOAT C paste as lubricant. I have disassembled and checked the complete connecting rod. All ball heads are a little tight, the rubber bushings are flawless. On the post assembly test the chassis was perfect, but the internal noise was a little increased, as expected. I’m testing it for now. I may change it back to factory in the future to reduce internal noise. Stability, however, is certainly unmatched among e23 BMWs. Even from speeds above 200km/h, the car stops without vibration and arrow straight when braking with the steering wheel released.
The instrument cluster
The instrument cluster is an interesting topic. During production, cars were fitted with an instrument cluster with a service interval display containing two batteries. Over time, these can fail, or even burn out, causing an irreparable state of inoperability. I happened to find a 1993 instrument cluster with no battery. It contains a purpose oriented chip and a non-volatile I2C bus EEPROM that stores service interval data and configuration. The speedometer clock was scaled to 160 miles. I took it to a specialist (Mr. Haudek) to have it made into a reliable indicator up to 300km/h. He didn’t want to understand it. At first he thought I was a stupid kid, when I explained that the situation was completely serious, he refused. What could you do, do it yourself, as you have done so many times before. A friend of mine was repairing radio transceivers, he had a serious frequency generator. We disassembled the clock unit and managed to draw an authentic dial using the frequency generator, which another friend was able to transplant into a CAD program. Still, the printer failed to get it right in several places, several times. I must be too demanding. Finally, a graphic artist did a PICTURE job of drawing it, flawlessly in my opinion!!! It doesn’t exist, but it does. I can see it with my own eyes. The graduations are completely irregular as you can see in the photo, because this dial is the real thing, not like the factory ones. I was using 265/40r17 tyres in the rear at the time. Today you can only buy 255/40r17 from us. I am now recalibrating to this size and replacing the recently broken odometer drive gear. I also intend to repair the water temperature gauge that is flickering back and forth.
