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Derek's 308 engine rebuild

Discussion in '308/328' started by derekw, Oct 16, 2016.

  1. derekw

    derekw Formula Junior
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    Sep 7, 2010
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    The end mill on my drill press to deepen the valve pockets was a crap idea. It would bite and release, bite and release, so very hard to control. I found a mini router with a grinding stone followed by a drum sander on my Dremel tool worked best. I must have done 8-10 test assemblies with playdoh, heads, cams, belts to get all the clearances where I wanted them. I also did the squish landings to get .050 with piston rock. A bit less would have been better but the compression of the head gaskets over time and retorques, liner movement, etc. made me a bit conservative.
     
  2. derekw

    derekw Formula Junior
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    #377 derekw, Aug 16, 2017
    Last edited by a moderator: Sep 7, 2017
    We retorqued the heads this morning and will now test for leaks. Fingers crossed! We put a very thin smear of copper Permatex around both sides of the holes which had no sealing rings. Should work well... says he hopefully. I need to take the cars to Montreal tomorrow and Friday. Dead Forest Motors is shutting shop and moving on to wetter climes.
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  3. Brian A

    Brian A Formula 3

    Dec 21, 2012
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    1983 US 308 GTS QV
    Best wishes to you, family and cars on this next leg of your great adventure.
     
  4. derekw

    derekw Formula Junior
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    Just a quick update to say my cars arrived safely in the UK and are now stored in Surrey. I plan to go down now and then to slowly get the 308 put back together. The storage looks rough but is sealed, dry, and secure (being in someone's back yard.)

    On a sadder note, my erstwhile assistant Matt Maggio-Tremblay is either unable to answer his phone or email (I hope he is ok), or he has decided to keep my roof spoiler that he said he would drop at the shipper (and my Image Unavailable, Please Login Image Unavailable, Please Login ´61 Jaguar Mk 2, heads, carbs.) If anyone sees either for sale in the US or Canada, please let me know.
     
  5. Ferraridoc

    Ferraridoc F1 Veteran
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    Jun 20, 2012
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    That is sad. The world is a very small place nowadays - I'm sure that pressure can be brought to bear. On a lighter note, if it gets done by xmas, I will substitute the Moosehead with Dog Bolter Real Ale
     
  6. derekw

    derekw Formula Junior
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    Just an update to let anyone following this tome that Matt did get in touch in December and I was able to get my parts back this summer.

    One of the funnier things that happened to us in those last couple of days in the dead forest garage was pressure testing the water system before we closed up the engine and mounted it onto the transaxle. We blocked all the other inlets/outlets, clamped a length of water hose to the thermostat housing, plugged it with the end of a rubber mallet that fit well, tightened the clamp, filled the engine with water and then pressurized it to about 15psi for 30 minutes. One tiny leak on the one inlet manifold so we disconnected the pressure, loosened and evenly re-torqued the manifold nuts and re-tested for an hour. No leaks. Bumped up the pressure to 20psi and the mallet head plug shot across the garage with a helluva bang, narrowly missing Matt!
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  7. Ferraridoc

    Ferraridoc F1 Veteran
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    Do you know what this means? You owe me a carton!!! Merry Christmas, Derek!
     
  8. derekw

    derekw Formula Junior
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    ... I've been half expecting that for a while. They have pretty good beer here in Pommiland if you ever make it over :)
     
  9. Ferraridoc

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    Maybe next year. At the moment, I'm so busy, I have to book a half an hour two weeks from Tuesday just to scratch my arse :eek:
     
  10. derekw

    derekw Formula Junior
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    While sorting boxes (now that my torn shoulder ligaments are a bit better) I came across my alternator so decided to pull it apart as it wasn't turning smoothly and looked very grimy inside. I found this good post from jmaienza which helped: https://www.ferrarichat.com/forum/threads/bosch-alternator-disassembly.343680/

    Using a thick flat screwdriver and some penetrant I got the 4 long screws to move after a few light taps with an impact screwdriver. Once they were out, I supported the two front mounting lugs on the two sides of a vice and tapped down on the back casing with a wooden drift and a plastic mallet. Careful when it comes apart as the stator ring (red oxide coloured) must go down and off with the back casing. If not you can damage the wires connecting the stator ring to the diode plate.

    Once the back casing is off you can hold the rotor (wrapped in cardboard) in a vice and remove the big nut on the fan, then take out the 4 screws behind the fan, rest the front casing lugs on the vice jaws and tap the shaft down and out of the casing with a plastic mallet. Three screws hidden on the diode plate come out to allow the diode plate and stator to be separated from the back case. It was really dirty and had lots of oxide inside.

    My bigger (front) bearing was very good (type 6303ZS) but my smaller back bearing (6201C3) was not very smooth so I got a long, flat punch behind it and tapped it off. I then held the bigger bearing (gently) in a vice with the rotor vertically above it and pointing up. I put a drill onto the other end so I could spin the rotor to polish the slip rings (fine sandpaper, then scotch pad.). I also used some medium sandpaper on the outside of the rotor which had some surface rust. I'll paint the rotor with some rust converter paint.

    To clean the very dirty housings (forty years of oil, grime, some oxide), I put a dish washing tablet into half a bucket of very hot water and let them soak for an hour, then used a nylon dish brush, and finally a brass brush. Took about 10 minutes of brushing and worked like a charm. I cleaned the diode and stator ring with a dry brush and compressed air then tested the diodes. Put one multimeter lead onto a stator wire where it is soldered underneath the negative plate and then check continuity to the negative plate above and then to the positive plate next door (with the long, threaded positive power output.) On one plate should have a low resistance and on the other no flow (open circuit.) Then test the other two stator wires in the same way. All good.

    My brushes were down to 12mm long so I ordered some new ones (8mm x 5mm x 19mm.) If they are too long I'll file them shorter. £6 on ebay. I also ordered a new SKF bearing for the back with two seals and high temp grease (6201 2Z/C3HT51 for only £3 from georgelodgedirect.co.uk.) On a roll I ordered some red oxide enamel for the stator from ebay. When I get the parts I'll report on the brush change and reassembly.





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  11. marklintott

    marklintott Formula Junior
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    Your description and the linked post are the best I've seen on this - thank you. I ended up getting a rebuilt unit from ebay as at the time I wasn't sure what I was getting into once or if I managed to get the long bolts removed. Some ali/steel corrosion in evidence.

    Anyway, I have an old one needing re-furb if anyone is interested....

    Mark
     
  12. derekw

    derekw Formula Junior
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    I decided to order the big bearing too, a Timken 6303 2Z/C3 from George Lodge for £3. Probably not needed but "while it's apart..." I forgot to mention checking the rotor coil continuity test (I got 3.5 ohms between the slip rings.) Also test for short circuits on the rotor and stator. There should be no flow from the slip rings to the rotor shaft or poles or from the three stator coil ends to the iron stator ring.
     
  13. derekw

    derekw Formula Junior
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    The bearings just arrived today which reminded me to post a description and some pictures of the alternator going back together. Putting the new brushes into the housing was straightforward. Use a soldiering iron to de-solder the wires, lift the tabs clamping the wires at the back, pull the brushes out, fit the springs on to the new brushes, feed the wires through into the housing, trim the insulation sleeve, solder the wires on and clamp them with the tabs, and then trim excess copper wire.

    I sprayed the field coils and rotor with high temperature clear varnish once they had been cleaned and the rotor painted with rust converter. The high temp varnish is probably not needed but I thought a little extra insulation can’t hurt. I also sprayed the iron field coil ring with the red oxide enamel. I’ll go and press on the new bearings and take some photos of the alternator going back together. Before you put the field coil back into the rear housing, check that the three field wires are not touching the bunches of windings (they could rub and wear through) and also not sticking out too far so that they rub on the housing. Once I had put mine into the rear housing and screwed in the 3 screws, I noticed one field wire touching one of the diode plates so i used my finger to lift it away a couple of mm. Again, it could rub through the insulation sleeve and short.
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  14. derekw

    derekw Formula Junior
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    #389 derekw, Sep 29, 2018
    Last edited: Sep 29, 2018
    Removing the larger front bearing was a little tricky since I don’t have a thin bearing puller. I supported the bearing seal plate with two thin spanners (wrenches) across the vice jaws, put the four screws in to protect the threaded holes, filled any gaps with washers, and then tapped down hard with a flat steel punch. Nothing! After heating up the retaining collar with a heat gun it moved and after a few millimetres I was able to fit my bearing puller behind the plate and remove the collar, bearing, and plate.

    The new bearings tapped into place without any problems. I found a 12 mm socket which fit the inner race of the small bearing and a spark plug socket that fit the inner race of the big bearing (and then collar.) Remember to put the plate on first with the concave side facing forwards.

    Two things to remember are the white insulator sleeve into the rear housing for the long threaded power output rod (before you put in the field windings and diode plate assembly) and then the wave spring which goes into the back housing bearing recess before the two halves go together.

    To hold the brushes in the retracted position for insertion, I used two match sticks hooked behind the wires (see pic) and was then able to fit them into the back housing. Re-assembly was quite easy and only took about 10 minutes. Remember to tighten the fan nut before you put the two housings together so that you can hold the rotor while tightening the nut. I used blue Loctite just for insurance and also to reduce galvanic corrosion on the long screws. I'll phone around to see if anyone can test it for me before I fit it.
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  15. thorn

    thorn Formula 3
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    Those stator windings look brand new. How'd you get them so clean? (I see you said a dry brush and air, but dude... stellar results.)
     
  16. derekw

    derekw Formula Junior
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    Coat of high temp varnish makes them nice and shiny!
     
  17. derekw

    derekw Formula Junior
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    So I managed to get some parts off the 308 to work on at home-- brakes, front suspension, and the original magnesium wheels. First job was to rebuild the calipers and even though I plan to use Wilwood calipers up front (inside both 14" and 17" wheels) I am rebuilding all four.

    Starting with the front calipers, ATE 48mm 2-pots, same as early Porsches, I battled to get the pistons out despite lots of penetrating oil, heat gun, levering etc. Normally I'd just pump them out with the brake system but the car is an hour away so I skeptically tried a bike pump and it worked! Once one was out I put it back in a bit, clamped it and pumped out the other one. The hollow threaded tube from a light fitting fitted the brake inlet nicely.

    Bigg Red on ebay.co.uk has all four front 48mm pistons/seals for £40 (part No. BRKP86.) I first bought the seals from buycarparts.co.uk (autodoc.de) for £5 each side (248030) but I got the kit with pistons as I had damaged the piston lips trying to lever them out.

    The original finish was clearly silver plating and in a few places there was surface rust so after a good clean with a wire brush, strong alkaline wheel cleaner, and a pressure washer, I dried them in a warm oven and then painted on a thin coat of rust converter just to stop any further corrosion. I cleaned the bores with green scotch pad, cleaned the bores and passages with brake cleaner, dried it with a hair dryer, lubed bores and pistons with brake grease, put in the new seals, and assembled them using the good info on the Pelican Parts forum:

    https://www.pelicanparts.com/techarticles/911_caliper_rebuild/911_caliper_rebuild.htm

    It's important that the cut-out section of the piston faces into the oncoming brake disk's rotation. This increases the clamping force on the trailing edge of the brake pad which makes the pad wear more evenly and reduces squealing. A simple rule for the 308 calipers is that the middle of the raised ridge points towards the bleed nipple on both calipers and the end of the raised ridge that is closer to the wheel axis is in the center (i.e. in line with the brake inlet or between the mount bolts-- see my pics below.)

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  18. derekw

    derekw Formula Junior
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    I have been waiting for two weeks for a warm day in London to paint the original magnesium wheels but eventually gave up and have cranked up the heat in our one bathroom. The chromate paint is nasty stuff so I got the wheels nice and warm, ran outside to spray one, brought it back in to dry.

    The real work was the 4-5 hours of cleaning, brushing, wire brushing, acid cleaning, brushing, neutralising, cleaning... I first used a pressure washer and then a good scrub with an alkaline wheel cleaner. Once the dirt was off I cleaned off the oxide where the wheels had scratches or the paint had come off using a 12% acetic acid that every proper Swedish home has (Ättik Sprit.) You can see the metal and oxide bubbling and coming off. A stainless steel wire brush helps break it free. Then an alkaline rinse to neutralise the acid (teaspoon of drain cleaner in a few litres of warm water (wear gloves.) There were black bits in the pitted surfaces-- either slag from the casting or some oxide reacting to the chemistry but they came out with more brushing and a sharp knife-tip. The inside diameters that sit on the hubs were the worst corroded and took a lot of brushing plus acid to clean up.

    Once the bad bits were properly cleaned and neutralised, I put a good key into all the surfaces for the new paint to stick. Lots of elbow grease and green scotch pads. Final clean and then a couple of days in the hot bathroom to fully dry. I've now done 2 coats where needed of Cessna Green chromate primer and was lucky to find some (bought 6 cans just in case.) It is no longer being made (try LAS Aerospace, about £6/can.) I'll let it dry for at least a day and then fill the blemishes and do the silver + clearcoat.
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  19. Einsteiger

    Einsteiger Karting

    Oct 9, 2014
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    Kevin
    Incredible amount of work. Well done!
     

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