308 suspension bushings | Page 2 | FerrariChat

308 suspension bushings

Discussion in 'Technical Q&A' started by docweed, Jan 14, 2006.

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  1. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
    4,212
    Black Forest Germany
    Full Name:
    Martin N.
    Hi Andrew,

    happy to read, that my infos were useful. You're correct with the MB2025DU, but there are different versions. Get the PTFE ones.
    And you need the thrust washers too.
    Meanwhile they are no more called 'Permaglide'. And regarding supplies in NZ a quick google search for 'Schaeffler New Zealand' gave me this result:

    https://www.bayengineerssupplies.co.nz/products/brands/***-bearings/P90

    I am sure, they could help you sourcing the needed parts.

    Talking about the "hardened" inner bushings. I'm not sure, whether they are really hardened. But sure, they are hard-chromed. Therefore some knock-offs from independent parts dealers made from stainless steel without further treatment are useless.
    Sometimes you can reuse them. If the hard-chromed surface is not damaged like rusted through, clean them, give them a polish with fine sandpaper and check their roundness. Mine were still o.k. after 100.000kms and I reused them.
    The same with the big steel washers which slide on the thrust washers.

    Best from Germany
    Martin
     
  2. Andrew McLaren

    Aug 21, 2020
    33
    Auckland
    Full Name:
    Andrew McLaren
    Wayne - could you give me any clues as I must be looking in the wrong place!

    I did have a troll through the 308 xref listing, but didn't find anything there - there is a lot of posts, so was trying to pull out anything with bush, suspension, and now gone back with your name, but still haven't found anything? I assume you are referring to the 308/328 xref sticky thread?

    Martin - I thought the DU prefix denoted PTFE? Once I had a generic part, it appears that my normal bearing supplier here (ABD) does have them. 7 of the inners bushes cleaned up easily but this last one definitely has scoring. I had noticed most of the aftermarket ones referred to stainless, so assumed this was adequate. I do have access to a pretty good machining facility (children can be useful...), so definitely possible to manufacture a new one. One thought was to get a hardened bush with the right 20mm OD then sleeve this inside to get back to 12mm. I'll talk to the bearing people tomorrow.

    Regards - Andrew
     
  3. Crowndog

    Crowndog F1 Veteran
    Rossa Subscribed

    Jul 16, 2011
    7,042
    Fairfield,Pa
    Full Name:
    Robert
    When redoing my suspension bushings I discovered that original oem rubber ones came in two hardness levels. It was recommended that the harder rubber be used in the rear components. The softer in the front.
     
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  4. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
    4,212
    Black Forest Germany
    Full Name:
    Martin N.
    You're correct. I looked once more. The bushings with different thermoplastics have the prefix DS or DX.

    Best from Germany
    Martin
     
  5. Andrew McLaren

    Aug 21, 2020
    33
    Auckland
    Full Name:
    Andrew McLaren
    I've cleaned down the inner bush, and its definitely damaged. The other 7 bushes come out unmarked after a clean, and still mic at exactly 20mm all round. The 8th has had definite metal to metal contact in two places, and these mic to around 19.95. Not so good, and ideally the inner bush should be replaced. I'll add a picture - the worst damage is shown, there is also some minor scoring on the diagonally opposite surface.

    On the MB2025DU's, there is good news. They are readily available here in Auckland, and even at a quite reasonable sub NZD 6.00 each (not much more than 3 Euro). So the big question I have now is what I do with the inner bush. It looks like all the aftermarket ones are stainless, but some indications were that these were inferior to the originals (presumably based on these being softer). Here are the options I can see - I'd appreciate any comments or suggestions!
    1. Clean up and replace the damaged inner bush using a new outer bush. As the damage is isolated to the ends, there is still a solid bearing area in the centre of the bushes. Obviously loading would be higher, and inevitably the outer bush won't last as long. But these are cheap, and if I put the damaged one in one of the bottom wishbones, its easier to get back to later.
    2. Replace the inner bush with a stainless one, either making one, or using one of the aftermarket items. Any suggestions of what stainless would work best here. If I have to go the hardening route, its probably easier to just get a replacement bush mailed in.
    3. Make a new inner bush using a hardened sleeve as a basis. The bearing people here do have 20mm hardened sleeves, with a 15mm ID, and lengths of 26mm or just over 30mm. Its easy to sleeve one of these back to the 12mm ID required. If using the 26 mm sleeve, I'd flange one end of the sleeve, then finish this to the exact 26.7mm required (a question on this below!). If using the longer sleeve, I'd need to part this off, and probably surface grind the end to get it back to the correct length. Assuming everything in Auckland reopens this week, my son's workshop has all the capability to do this. The disadvantage with both options is that the sleeves are not plated, so I worry about corrosion, especially as these are assembled dry.
    4. Don't know if available here, but there are definitely hardened and hard chromed linear rods available with 20mm OD, and 12mm ID. These would still need to be parted and finished to a final size, but would only have the corrosion issue on the opened face, which is more manageable.
    On the length of the inner bush - I measure these at 26.7mm, which is a bit of a strange number. Does anyone know the basis of this? My guess is that it is critical, and is designed to limit the loading on the thrust washers - the outer bush is 25mm, and putting the 1.5mm thrust washer outboard of this, gives us 26.5mm, which means the inner bush is a whole 0.2mm longer. With the whole assembly torqued up, this leaves a miniscule clearance for the thrust washers at each side, but the washers themselves are not under the torqued loading. Does this sound reasonable?

    Thanks for any help or advice!

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  6. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
    4,212
    Black Forest Germany
    Full Name:
    Martin N.
    #31 Martin308GTB, Aug 23, 2020
    Last edited: Aug 23, 2020
    I love manufacturing parts myself as well. I even have a small mill and lathe. But given the price of the inner bush I would replace it with a genuine Ferrari part. They are around €6.00 incl. VAT from Ferrari UK.
    Also pay attention that the rubber rings are in good condition. They are all, what protects the dry bearing against dirt and moisture.
    If they look good and are tight, reuse the old ones. If not replace them. Though reusing the old ones is preferrable, because the rubber reproduction parts are crap. I learned that the hard way regarding the lip seal on the rear uprights for the wheel bearings.

    Your calculations regarding the bushing length/thrust washers are absolutely correct.

    Best from Germany
    Martin
     
  7. Andrew McLaren

    Aug 21, 2020
    33
    Auckland
    Full Name:
    Andrew McLaren
    Thanks again Martin. I hadn't even considered that these would be still available from Ferrari.

    I just had a talk to the Ferrari people here, and they would be importing one for me (ironically from the UK), at a total cost of ~ NZD 200 (about €110). Ferrari themselves list this as a stainless bush now. Would be interesting exactly what this is made from - if it was something like 440, they could still get it up to around HRC60.

    I had a peek at the Maranello UK website, and £32 there, so think your €6 might be a bit out of date!

    Superformance are just under £13. I've dealt with Superformance a lot, and never had any issues with them, so that's probably the route I'll investigate.

    Regards - Andrew
     
  8. ago car nut

    ago car nut F1 Veteran
    Silver Subscribed

    Aug 29, 2008
    5,246
    Madison Ohio
    Full Name:
    David A.
    Harder suspension bushings help handling, but beat out the pickup points on the chassis.
     
  9. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
    4,212
    Black Forest Germany
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    Martin N.
    We are discussing the bearings on the uprights.

    Best
    Martin
     
  10. Andrew McLaren

    Aug 21, 2020
    33
    Auckland
    Full Name:
    Andrew McLaren
    Thanks to all and especially Martin.

    The rear end is going back together. Wishbones have been cleaned off and repainted, new inner bushes, new split sleeves and thrust washers on the outer bushes. I'm still waiting for a new hardened insert for one of the outer bushes - this is on its way from the UK, so I've gone ahead and reassembled it with the damaged insert. I won't use it like this, but does keep everything aligned, so I can go ahead and get the calipers mounted and bled. I'm hoping I can replace this insert with the wishbone still in place, but that remains to be seen. The outer bushes were missing 3 of the thrust washer locating dowels, which would allow the non teflon side of the thrust washers to turn. Not good, but easily resolved with some cut down 3mm needle rollers.

    The rebuilt outer bushes are much tighter - I probably shouldn't be surprised! I found these were a bit of a hassle reassembling dry, as there is nothing to hold the bits together. A couple of extra arms would help. I ended up building up the bush set for each side, and putting a bolt through each side to hold the bits together. Once the assembly started to slide over the hub, and get held together by that, the bolts could be removed one at a time and replaced with the single through bolt.

    So its close to running again. Thanks again for the help and advice.
     
  11. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
    4,212
    Black Forest Germany
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    Martin N.
    You noticed the tiny pins, which position the thrust washers?

    Best
    Martin
     
  12. Andrew McLaren

    Aug 21, 2020
    33
    Auckland
    Full Name:
    Andrew McLaren
    Those were the dowels I was referring to. 3 of the eight were missing (and pretty certain they hadn't just fallen out on disassembly as the holes were full of muck). Pretty sure at least one of the thrust washers was in the wrong way round as well. I got some 3mm needle rollers from the bearing store, and parted these by turning them in the lathe while using a cutoff disc on a Dremel to cut to approximate size, then ground them to final length (around 4.5mm but just done so that the final stick out was just less than the thrust washer). Used Loctite to set them in place. They are fiddly!
    Both hubs have been off in the last few years to do wheel bearings, and both places should have known better...
     
  13. Andrew McLaren

    Aug 21, 2020
    33
    Auckland
    Full Name:
    Andrew McLaren
    It's all back together, and just taken it out for a drive.
    I ended up replacing all 8 inner bushes (what it came apart for), all the teflon split sleeves and thrust washers in the outer bushes, plus one of the inner hardened sleeves that run inside the split sleeves. All the others were fine, as were the hardened washers the thrust washers bear against.
    While the rear end was apart, pulled the calipers off, cleaned these up and put new seal kits in. Pistons were fine, and no sign of any leaks from the handbrake adjusters. One of the pads was noticeably worn compared to the others, so guessing there was a sticky piston in there, but not any more!
    Also found a problem with one of the inner CV circlips having come adrift (seperate thread), so ended up with one of the driveshafts out as well.
    All feels good!
    Thanks for the help and advice
    Andrew
     
  14. miketuason

    miketuason F1 World Champ
    Owner Silver Subscribed

    Feb 24, 2006
    15,517
    Cerritos, CA.
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    Mike
    #39 miketuason, Dec 6, 2020
    Last edited: Dec 6, 2020
    Ok I was just messaging Martin about this, I just got the A arms back from the powder coating shop, I did not remove the PTFE bushings and they did a bad job masking the bushings, the shiny piece would not fit (tight) so I had to sand it down using my dremel tool and now it goes in but loose, in the process I probably took off the PTFE lining too and probably better to get new ones.

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  15. Andrew McLaren

    Aug 21, 2020
    33
    Auckland
    Full Name:
    Andrew McLaren
    They are trivial and cheap to replace, so I'd just go ahead and do it. If you have access to a lathe, a stepped drift to press these out and the new ones in helps a lot. I have one I made here you would be welcome to, but it's in NZ?

    Andrew
     
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  16. Andrew McLaren

    Aug 21, 2020
    33
    Auckland
    Full Name:
    Andrew McLaren
    BTW, I just used a 125mm vice as a press, which worked fine.
     
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  17. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
    4,212
    Black Forest Germany
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    Martin N.
    Mike asked me about the bushing and washer dimensions. You have a PM. But just for archive purposes, I write them down here as well:

    Bushing: ID 20mm, OD 23mm, length: 25mm
    Thrust Washer: ID 22mm, OD 38mm, Thickness 1.5mm

    Best from Germany
    Martin
     
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  18. waymar

    waymar Formula 3

    Sep 2, 2008
    1,321
    Northeast, PA - USA
    Full Name:
    Wayne Martin
    Check out post #386 & 390 In the cross reference sticky thread. Went through this already. Cheap off the shelf items.
     
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  19. miketuason

    miketuason F1 World Champ
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    Feb 24, 2006
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    Mike
    Great info, thanks for that Wayne! Today I just found a great source and excellent price form this Co. American Sleeve Bearing ( a s b) and I just ordered 8 pieces. I also added this to the Parts Cross Reference under 308/328 section. Image Unavailable, Please Login Image Unavailable, Please Login
     
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  20. miketuason

    miketuason F1 World Champ
    Owner Silver Subscribed

    Feb 24, 2006
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    Mike

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