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  1. #1
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    Member No: 141374 eldon is an unknown quantity at this point eldon's Avatar
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    Newbie with novice questions

    Hi All – We purchased an E28 M5 back in Sept. of ’05. It has 170k miles; records back to the window sticker, Dinan chip and suspension upgrade, and checked out with a local (Seattle) E28 M5 junkie. It just needed some routine maintenance and love. Until then my automotive experience was almost exclusively limited to 911s. I figured its time to start consulting the experts, so here I am. I plan on performing all work myself, shy of alignments and projects that require super-specialized and expensive tool purchases. I have a few softball questions.

    1. What tech. literature should I pick up, e.g. manuals, trouble-shooting guides, part diagrams, wiring diagrams, etc. I already have, and appreciate, the E28 Bentley manual, but it obviously doesn’t cover the M5.

    2. Are there any dismantlers/wrecking yards that specialize in these early Ms?

    3. What is the reservoir and pump assembly under the spare tire? When cleaning up and re-installing the trunk interior after fixing a leak, I noticed this assemble. I found the grey relay, at least it looked like a relay, for the pump unplugged. Regardless of whether I plug the relay in or not, the pump sounds like it is running when the car was running. Is this noraml?

    4. I’m planning on selling my ’69 911 and am toying with the idea of using the M5 as the occasional drivers skill/track day car. Is tracking or otherwise significantly pushing an M5 with 170K a bad idea? While I don’t mind putting money into the M5, funds are not unlimited. If this type of use is the ultimate goal for the M5, should I start thinking about rebuilding another S38 or exchangeable engine?

    5. What is the “typical” life span of a well-maintained S38B35 (That is the variety of the S38 for the US E28 M5, right?)?

    Thanks in advance.
    eldon


  2. #2
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    Member No: 136776 Mark_88_M5 is on a distinguished road Mark_88_M5's Avatar
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    A few answers / opinions

    1. A factory M6 manual if you can find one will have the S38 engine section and the SLS section. I never have gotten a strait answer if those sections are in the E24 Mobile Traditions CD.

    2. Not very many of these cars were brought into North America; I can't come up with the numbers right off hand. I don't know of any yards that specialize in the early M5's.

    3. SLS pump and reservoir. Check in the rear wheel wells for hydraulic tubing, nitrogen balls and Green bodied shocks. If you have those you have the original SLS suspension. If you don't then the SLS has been eliminated and you have a conventional rear suspension.

    4. Depends on the maintenance records and current condition of the engine. Has the timing chain, guide rails and tensioner been replaced. What do the current compression and leakdown numbers look like?

    5. The bottom end of these motors are pretty bulletproof with regular oil changes. High RPM excursions can be detrimental to the front crank hubs. Most will recommend timing chain and associated hardware replacement around 100K miles.

  3. #3
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    Re: Newbie with novice questions

    You will really like it on the track. However, it takes a bit more skill to boggie through the tight turns. On the longer turns you will do very well. On that note the stock brake set up is not the best. I used my stock brakes with hawk hps pads on the track (with a brake cooling kit) and after 4 hot laps I had total brake fade. If you do not drive the car for a few weeks the front 4 piston calipers might or will freeze up. To solve this problem I upgraded to the e34 m5 calipers and rotors for the front and rear of the car. Not only did the fadding go away but my stopping power increased quite a bit.
    The braking bias on the e28 is not so good I believe the stock brakes are like 73% front and 27% rear. That being said the e34 m5 brakes on the e28 change the bias to 64 front 36 rear. If you are going to track the car I would recomend doing this conversion. The cost is about 1k and worth every penny. Good luck with your car and remember to get the valves checked every 20k.

  4. #4
    Andy
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    Re: Newbie with novice questions

    I never pushed the stock brakes at the track but at the auto-x at least I didn't like the heavy front bias which, combined with the stock suspension, was nose dive city.
    I've since upgraded just the rear brakes to the 540/M5 rears and the brakes have been fade free at HPDE's at LRP and NHIS lap after lap using street pads (Porterfield R4) and no brake cooling ducts. I'm not that fast but my last time out I ran down plenty of cars with more rubber, more hp, bigger brakes, and less weight without any fade so I'm pretty happy with my set-up (and the rear calipers and rotors were a relatively cheap upgrade).
    That said, when I drove my first event ever in the rain, I rode the brake a little more than usual I think and depite the cold wet day I experienced substantial brake fade so perhaps my set-up is just barely adequate and a bigger set-up all around might give a little more room for safety.

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    Re: Newbie with novice questions

    Weaknesses:

    Chassis - Brakes & front upper arm bushings. Brakes have been discussed - replace rears with e34 units to help balance load on fronts, or replace fronts with bigger units, such as the 750 or 850 units. Bushings can be replaced with larger ones from a 750 that have been modified by grinding. Finished units are available from Steve Haygood. Bushing upgrade is Well worth it!

    Interior - M5 leather is soft and thin. Keep leather moist using Leatherique Rejuvinator oil. Keep friction to a minimum; don't slide your tukish over the bolster.

    Engine - Valve adjustments (valves get tighter with use, leading to overheated cracked valves. Timing chain guides get brittle, break and impede movement of the chain, causing massive engine failure. Replace all components if in doubt. Crank hub fails due to poor quality construction. Many users recommend switching to Frank Fahey's modified unit made from tool steel. But probably not a major requirement unless you regularly wind it up past 6500.

    Exhaust - the factory cat is super expensive. Swap in a cheap cat or track pipe for daily use and store the factory cat for testing purposes only.

    The rest of the car is straight ahead BMW. Very tough stuff. Scottie Sharpe
    84 745i 15 lbs boost, BMWTurboPerformance.com MAF kit, 17x9 3pc BBS, clean underwear, Executive Interior
    88 Dinan-badged M5, M88 motor with 2 row conversion, Dinan Stage 4 suspention, Dinan 17x9.5 3pc wheels, 255/40 Conti Sport X 4, Racing Dynamics software, e34 rear brakes, B&B Stainless steel Exhaust, F&R LaDue stainless steel strut bars.
    67 1602 Ireland coil overs, brembo brakes, Dual Weber 45
    Do you BMWwikiwiki.com ??


  6. #6
    Bruce
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    Re: Newbie with novice questions


  7. #7
    Bruce
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    opinion on crank hub

    I would like to include my technical opinion on the crank hub issue.

    I have taken mine apart and learned how it is made and I see that there is potential for a failure in some cases.
    There is nothing wrong with the OEM design - (if you take a hard headed german stance). I believe the design is good and will work indefinelty if AND ONLY IF it is assembled correctly.
    The work and effort required to torque the nut onto the hub is difficult. You need specialized tools. A torque multiplier is best. You need to accurately fasten the nut. Many cars have been servied using huge breaker bars, impact guns, bumping the starter, clutch dumping when rolling for disassembly and re-assembly. I have also seen horrifying pictures of a torch being used turning the heat treated nose of the crankshaft into soft butter. It is no surprise to me as an engineer that there have been failuures here. There are large forces at play and they need to be controlled.
    The Fahey hub is not wrong, it is perhaps a better design in that it is more foolproof. It can be assembled without the fancy tools and does not seem to come apart.

    I still contend that the original hub will not fail when it is assembled according to the OEM specs. I do not accept that the original design is bad, my car is original and gets revved high often. I do accept that the Fahey hub is more ham-fisted tolerant.

    All I want is to take the mystery out of these types of failures and make sure we make good logical decisions. Mr Fahey charges a huge amount of money for the simple turned piece of steel, and gets many sales based on the fear mongering that comes from the unknown nature of the failures. I am not saying he is getting rich off of it.. I am sure that with the few parts he sells that he makes very little from it. But is is expensive compared to renting the proper tool to get the high torque.

    Hope this helps...

    Bruce

  8. #8
    lkfoster
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    Exactly how I feel on the matter

    Couldn't have put it better myself. As a mechanical engineer also I don't see anything fundamentally flawed with the OEM hub, but can't fault the Fahey hub either with exception of the price.

  9. #9
    Bruce
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    i thnk i love u.. hahahaahah


  10. #10
    Bruce
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    nobody agrees with me. it is

    so nice to have someone on the same wave length.............

  11. #11
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    Re: Newbie with novice questions

    I agree about the timing chain components.
    If it has not yet been performed, get that plastic chain guide replaced if you want to sleep at night.

  12. #12
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    Re: nobody agrees with me. it is

    At the risk of making Bruce squirm with discomfort over uncharacteristic concensus with his position, as a mechanical engineer, I agree with his position on the crank hub for road use.

  13. #13
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    Group hug time.....


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