howitzer85 Member 241 Member For: 17y 8m 12d Gender: Male Location: The marsh... Posted 11/10/10 07:40 AM Share Posted 11/10/10 07:40 AM Hi Guys,I seem to be having no luck with my diff at the moment, I just broke the diff bolt for the 3rd time...First time was the typical shagged stock bush and the bolt went with it. I then had the superpro bush fitted with an unbrako bolt, this lasted over a year till my next round of power mods before it snapped taking my diff cover with it. It did give me warning though as it was clunking like hell for a few months prior.So I had a strengthened diff cover fitted, new bolt went in (bush was still good so they re-used) and 2 months later when shifting into second I heard that all too familiar BANG! I was driving like a granny at the time too!There was no warning this time I thought everything was sweet until it happened. I originally thought it just came loose so I tried to tighten the thing but that didn't work. So I dropped the cradle for a look and found the thing was broken again.So my question is what bolt are the guys with heaps of power using? I'm only just on 300kW, granted it is a manual but surely there is something capable of handling that load.I'm really considering fixing it and turning the power down and leaving it, but then I read about other guys well into the 400kw bracket and no problems, has got me buggered...can anyone offer some advice?Cheers. Link to comment Share on other sites More sharing options...
dat_40l Donating Members 997 Member For: 19y 4m 11d Gender: Male Location: newcastle NSW Posted 11/10/10 09:33 AM Share Posted 11/10/10 09:33 AM M16x100, 12.9 grade socket headed cap screw, and may want to upgrade to stronger superpro or nolathane bushes to help reduce the movement back there. Link to comment Share on other sites More sharing options...
arronm Dropping a turd Gold Donating Members 9,520 Member For: 17y 5d Gender: Male Location: Perth Posted 11/10/10 04:41 PM Share Posted 11/10/10 04:41 PM This is the bolt to use. Drill a hole in the spare wheel well and change the bolt regularly. They fatigue over time. The more power you have and the more you beat it the more often you change the bolt. Link to comment Share on other sites More sharing options...
GMKILLER Donating Members 77 Member For: 15y 4m 13d Posted 11/10/10 07:52 PM Share Posted 11/10/10 07:52 PM so the same thing has hppend to me..too and its bugging me. MY cars a bf mk2 with 105k on the clock its auto so stock rear bush went so went for the duks nuts bush plus replaced bolt at 95k then 3 months later snap.. replaced rear diff housing PLUS cradle because it had cracked.and diff bush then now just before weekend snap.. dont know what dammage was done but its snaped maby all ov the above again..what should I do too any mob out there making solid HIgh tensile bolts.. Link to comment Share on other sites More sharing options...
senna_T Forged Member Lifetime Members 15,818 Member For: 17y 8m 25d Gender: Male Location: SW Sydney Posted 11/10/10 10:49 PM Share Posted 11/10/10 10:49 PM Its interesting that this is happening - I've still got the same bolt in my car that came from the factory, no breaks running 500rwhp in a manual.I think it may also have somehting to do with the front diff bushes allowing alot of movement after the single poly bush is replaced - could be creating a pivot point on the bolt. Link to comment Share on other sites More sharing options...
howitzer85 Member 241 Member For: 17y 8m 12d Gender: Male Location: The marsh... Posted 11/10/10 10:56 PM Author Share Posted 11/10/10 10:56 PM (edited) I was thinking the same thing senna, so I'm planning on replacing the front bushes while I'm at it.I was actually thinking about replacing the bush I have for the non-high performance one. Maybe abit of give would be a good thing for the bolt? Edited 11/10/10 10:59 PM by howitzer85 Link to comment Share on other sites More sharing options...
senna_T Forged Member Lifetime Members 15,818 Member For: 17y 8m 25d Gender: Male Location: SW Sydney Posted 12/10/10 01:54 AM Share Posted 12/10/10 01:54 AM Probably not a bad idea, I've been running the comfort one for a fair while now and no dramas at all Link to comment Share on other sites More sharing options...
dat_40l Donating Members 997 Member For: 19y 4m 11d Gender: Male Location: newcastle NSW Posted 13/10/10 10:12 AM Share Posted 13/10/10 10:12 AM yeah last time I snapped mine the place that did the bushes for me put to long a bolt in it and didn't pull the bush hard up against the diff they used a m16x130 then my mate and I replaced it last time did teh measurements and only needs m16x100 pulled the bush 30mm up against the diff so hopefull its better now. Link to comment Share on other sites More sharing options...
Smoke them tyres Member 557 Member For: 16y 10m 11d Gender: Male Location: Brisbane Posted 13/10/10 12:03 PM Share Posted 13/10/10 12:03 PM (edited) I think it may also have somehting to do with the front diff bushes allowing alot of movement after the single poly bush is replaced - could be creating a pivot point on the bolt. Very valid point Pat. I think they should be replaced as a set. The nose of the diff will want to come up under power and vice-versa on back off. Std front bushes and a stiff rear bush would not be a good combination for the bolt.......I think it would be seen by the bolt as an "unrestrained" bending load, given that the rear bush is now comparatively stiff.Unfortunately, Dana in their infinite wisdom has chosen to use bolts as locating devices, not purely tensile devices that they should be. Ford should have corrected them as well.... Edited 13/10/10 12:15 PM by Smoke them tyres Link to comment Share on other sites More sharing options...
shmitt Member 76 Member For: 15y 6m 24d Posted 16/10/10 12:13 AM Share Posted 16/10/10 12:13 AM Hey fellas well just broke the centre diff bush bolt. It snapped probly 60 or so mm from the end so a faor bit is still stuck down the hole. Just wondeting how you guys got the rest out? I dont realli want to drop the cradle down an already have a hole big enough in wheel well to get the bolt out. Was thinking drill an ezyout but drilling that bolt will be a headf*ck. Any advice be god Cheers Link to comment Share on other sites More sharing options...
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