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79 series diff gear problems, "urgent"

Posted: Sat Oct 24, 2009 3:36 pm
by hoppy's79
Has anyone had any problems braking 79 series diff centres. i've already destroyed 2 standard sets and now have busted the tips off a couple of teeth on a set of terrain tamer gears. If anyone has had similar problems do you have a solutions to rectify it with a stronger set of gears, i'm also looking to reduce the ratio while i'm at it.
If anyone has a soultion could you please pm me or write it on this page, you can also contact me on 0400712903 as i have a comp coming up in 2 weeks time and need a solution asap

Posted: Sat Oct 24, 2009 4:53 pm
by dank
mate i'd seriously consider how you drive the thing. You are obviously driving it beyond the limits of the gear to be breaking so much stuff. OEM seem to be the toughest gearsets out there followed by the terrain tamer stuff. 35s aren't a big tyre for your diffs.

Think about other things like your coil conversion. Is it supporting the diff well enough under power to stop the housing rotating forward under acceleration? This is a sure fire way to destroy C&Ps. common on leaf sprung vehicles a good coil setup won't have any axle wrap.

Check your pinion angle as well..it should be the same angle as your transfer output.

there are guys grafting GU centres into cruiser housings and getting custom axles made up...a lot of work and not sure if its worth the effort. Good luck with it I'd be interested to see how you solve your problem.

Posted: Sat Oct 24, 2009 6:21 pm
by Towie
mmmmmmmm X2 Dank something to do with the right foot aplication & diff angles etc as Dank said..... oh & dont put 37's on it yet!

Posted: Sat Oct 24, 2009 7:49 pm
by dow50r
U will notice the gear teeth are missing where the window in the centre is...because the centre doesnt hold onto the gear very well...an arb locker is solid steel, so holds the gear fron flexing better. The std spacer between the bearings in the pinion is crushable...if you buy a solid one that strengthenes the pinion 200% stops it flexin too.
Andrew

Posted: Sat Oct 24, 2009 8:29 pm
by hoppy's79
Yeah i give it a bit of a hiding but not more than it should be able to handle, mates drive their cars as hard and don't break stuff that's patrols and cruisers. the OEM stuff is shit from my experiences stripped all bar 9 teeth on the OEM gears. thought terrain tamer was holding up good till i pulled it out to put in my longfields and just the tips of the gears was broken. was talking to chris from locktup and he said lowering the ratio's will help because less stress on everything. i know of comp guys who have gone as far as changing the whole diff to a patrol unit. also the coil setup has nothing to do with it because it is breaking the fornt centres and it is a standard setup as coil in the front

Posted: Sun Oct 25, 2009 7:48 am
by thrashlux
I am running after market gears i bought in the states from www.ringpinion.biz

they have all the ratios and good qualitly not sure if you can get the rear gears from them though
i am running 5.29 gears in my 80(with lux body) same diff center as yours

aslo running 400+ HP my wheel speed regularly exceeds 80 kph at a stand still i keep smashing my free wheel hubs and studs
the long fields will actually help with the breaking of diff gears
thats why its a good idea to get the axles and cv's they can twist up to 90deg acting like a big spring or shock reliever for your drive train

jonathan