Worn synchro rings

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iancoleman PCGB Member
2018/02/22 23:11:19 (permalink)

Worn synchro rings

Just thought I'd share this incase anyone might find it useful.  A few years ago I was concerned about how noisy my G50 gearbox was (70k miles) although working smoothly in all gears.  I went to a local independent who advised me that a noisy gearbox is a common thing that could be improved by putting swepco oil in it.  I was told the only downside was stiffer gear changes when the gearbox was cold in cold weather.  I went ahead with the oil change and it did make the gearbox a bit quieter, and the gear changes were indeed stiff when cold (I didn't use the car in winter so this wasn't a major problem for me).  A few years and a few thousand miles on and my gearbox is currently having a full overhaul and what I now know is that it was noisy because the bearings were worn (yes really!) and I also know that putting thicker swepco oil in the gearbox not only made the changes stiffer, but they have worn out the synchro rings for first and second adding considerable cost to the rebuild which would have otherwise only needed the bearings.  If I knew then what I know now, I would have put up with the noisy bearings until I was ready for the rebuild.

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    PCGB Member
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    chrishak PCGB Member
    Re: Worn synchro rings 2018/02/23 09:19:03 (permalink)
    A lot of 915 gearbox owners swear by Swepco oil, but as far as I'm aware, it's not widely recognised as being suitable for G50's, in fact, your experience sounds like it actually has a detrimental effect. A chat with the indy. who filled your 'box with it might be worthwhile, you never know, they may assist with the rebuild cost.
    Who did you finally decide on to do the rebuild?
    PCGB Member
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    benabrahams PCGB Member
    Re: Worn synchro rings 2018/02/23 09:27:16 (permalink)
    Thanks for the info.  Sorry to hear about the problems you have had.  Its very useful for me as my 3.2 is going in for a new clutch next week and I was going to change the gearbox oil at the same time.  My car has a 915 gearbox and I would be interested to hear other peoples experience with Swepco?  I'd read plenty of threads on various forums singing the praises of the stuff and have just bought some.  
    On a side note, I've not had the car long and it has a limited slip-diff, do people recommend an additive to the oil?
    PCGB Member
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    stuntmangb PCGB Member
    Re: Worn synchro rings 2018/02/23 11:13:08 (permalink)
    Hi thanks for the information I have a G50 box
    I  don't believe in additives in oil as I did read put the nice sticker on your tool box not additive in your oil , wouldn't add to a limited slip diff .
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    Grommett Guest of the Club
    Re: Worn synchro rings 2018/02/23 11:37:54 (permalink)
    I stopped using that particular Indy a while ago. Eddie at Silvertune is currently doing a full engine rebuild and Gearlink in Salisbury are doing the gearbox.
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    T911UK Guest of the Club
    Re: Worn synchro rings 2018/02/23 12:50:13 (permalink)
    Swepco is highly recommended for 915 boxes and has been for years. Not specifically recommended for G50 boxes, I cant see how a gearbox oil with the correct spec would damage parts inside the box!

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    Grommett Guest of the Club
    Re: Worn synchro rings 2018/02/23 18:33:38 (permalink)
    swepco is more viscous than spec, that’s why it makes gear changes stiffer(and gearboxes quieter).  The synchro rings don’t spin freely so the gear changes are not as smooth and the result is that the synchro rings wear prematurley.  If anyone is thinking of putting swepco in their G50, they might find this info useful. I would put the cost of an oil change towards the cost of that inevitable rebuild👍
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