Jump to content
SAU Community

Recommended Posts

So..... I have a s15 Silvia that we converted awd by chopping up a gts-4 shell.. 

Car makes about 500hp to the wheels... 

Cars fitted with a  twin disc spec clutch and the awd is controlled by a ets pro.. 

Awd works perfect... Launched the car couple of times while the awd controller was in auto mode and all was fine.. Launched the car manual mode full awd  front diff survived 2 launch.. Replaced the spider gears that were damaged launched the car again and still managed to strip the spider gears again.. 

 

At this point I'm looking at getting a os giken lsd....  I've never heard of these diff breaking this easily.. At the time of launch the car was down on boost only making around 380hp.... 

The diff front and back ratio are the same.... Can something else be causing the gears to break so easily or I'm I just having bad luck with 2 worn out differential 

Edited by crashsvg

They don't survive abuse bwith big power and a lot of AWD, but 285kw should not be an issue.

I'd be looking for any sloppyiness between the driveshaft at the xfer case all the way to the front hubs, I think something is moving that is causing additional shock and the diff is the weak link

As Duncan said there is something more likely fundamentally wrong with the setup, as the big power usually destroys the crown wheel and pinion not the centres. 

You have nowhere near enough power to break a centre so it definitely points to something else, like possibly never actually disengaging the front torque. If everything mechanically checks out, it's really the only thing as they are not designed for constant use.

Maybe you have just been unlucky

I'm getting the feeling something is wrong also.. With the initial set up of the car I've had a issue where the car doesn't roll freely as it should..  So for example I parked on a gently sloping hill and when I got back in the car to move it with the hand break down and foot off the breaks the car didn't move at all while in neutral.. I had to put it in 1st and give it a Lil gas for it to move.. I've had similar experience other places where the car is on an incline and refuse to move unless it's given a Lil throttle.... 

I've never driven a stock gtr so I'm not sure if this is something normal... 

Also a few times this happend I turned off the ets awd controller and the car would sometimes unlock itself and roll Foward .. I notice this but I assumed the awd controller was doing because it sense the car was on an incline through the g-sensor and sent powers to the front which somehow caused it to lock up... I'm confused to what's happening through because I know the ets controller also needs a tps signal to activate the awd pump and with my foot off the throttle that didn't make sense... 

Hope I'm making sense here. 

Some additional info.. 

The first gears that broke the car had stock ratios from the gts4 4.375.. 

We them fited the car with a 4.08 gearing  front and rear diff (I counted all the teeth on both diff several times to varify the markings) ... They were both 49:12.... 

Everthing was torqued to spec. 

 

I'll upload a pic to show where the spider gears are breaking... The second one broke in a pattern That suggests the gears are stripping because the passenger side axel isn't moving..  When i tried launching the car when it broke the second time  it was almost as if I was doing a fwd open diff burn out because I could see the tires smoking  front and rear on my driver side. 

IMG_20211024_074746.jpg

It sounds like 4wd "wind up" you get when front and rear diff ratios are different. If the ratios are the same, then do the wheels have the same rolling radius front/rear? If they were a long way out you might get something like this.

Also, would be crazy, but... that front diff looks pretty dry, you are putting oil in there aren't you?

Same size tire all around, same diff ratio and ofc it had oil... Filled up until it over flowed... 

One correction also.. It's a full race awd controller installed.. 

Looking at both diffs and the fact they both broke the same place I'm thinking the awd controller may have been turned up too aggressive.. 

This only started happening since I started launching the car in manual mode.. The car had made over 25 launches previously in auto mode and never had a problem... But in manual mode it keeps striping the teeth. 

Maybe leaving the line we with  launch control and the twin clutch just is a bit too much for the teeth.... 

 

Have considering welding one of the broken diffs back together until I can get my hands on a osgiken.. Not sure how it would drive tho. 

 

Hey crashsvg, we're based out in Gold Coast AU and specialise in diagnosis and remanufacture/repair of differentials. Are you happy for someone to give you a call and see if we can find a long term fix and improvement for you?

We have decades of experience in this and would be happy to have a look for you.

Antonio

National Assessing & Engineering

https://nationalassessing.com/mechanical-services/mechanical-diagnostics-and-repair/

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Hi, is the HKS  Tower Bar still available ? negotiable ? 🤔
    • From there, it is really just test and assemble. Plug the adapter cables from the unit into the back of the screen, then the other side to the car harness. Don't forget all the other plugs too! Run the cables behind the unit and screw it back into place (4 screws) and you should now have 3 cables to run from the top screen to the android unit. I ran them along the DS of the other AV units in the gap between their backets and the console, and used some corrugated tubing on the sharp edges of the bracket so the wires were safe. Plug the centre console and lower screen in temporarily and turn the car to ACC, the AV should fire up as normal. Hold the back button for 3 sec and Android should appear on the top screen. You need to set the input to Aux for audio (more on that later). I put the unit under the AC duct in the centre console, with the wifi antenna on top of the AC duct near the shifter, the bluetooth antenna on the AC duct under the centre console The GPS unit on top of the DS to AC duct; they all seem to work OK there are are out of the way. Neat cable routing is a pain. For the drive recorder I mounted it near the rear view mirror and run the cable in the headlining, across the a pillar and then down the inside of the a pillar seal to the DS lower dash. From there it goes across and to one USB input for the unit. The second USB input is attached to the ECUtec OBD dongle and the 3rd goes to the USB bulkhead connected I added in the centre console. This is how the centre console looks "tidied" up Note I didn't install the provided speaker, didn't use the 2.5mm IPod in line or the piggyback loom for the Ipod or change any DIP switches; they seem to only be required if you need to use the Ipod input rather than the AUX input. That's it, install done, I'll follow up with a separate post on how the unit works, but in summary it retains all factory functions and inputs (so I still use my phone to the car for calls), reverse still works like factory etc.
    • Place the new daughterboard in the case and mount it using the 3 small black rivets provided, and reconnect the 3 factory ribbon cables to the new board Then, use the 3 piggyback cables from the daughterboard into the factory board on top (there are stand offs in the case to keep them apart. and remember to reconnect the antenna and rear cover fan wires. 1 screw to hold the motherboard in place. Before closing the case, make a hole in the sticker covering a hole in the case and run the cable for the android unit into the plug there. The video forgot this step, so did I, so will you probably. Then redo the 4 screws on back, 2 each top and bottom, 3 each side and put the 2 brackets back on.....all ready to go and not that tricky really.      
    • Onto the android unit. You need to remove the top screen because there is a daughterboard to put inside the case. Each side vent pops out from clips; start at the bottom and carefully remove upwards (use a trim remover tool to avoid breaking anything). Then the lower screen and controls come out, 4 screws, a couple of clips (including 3 flimsy ones at the top) and 3 plugs on the rear. Then the upper screen, 4 screws and a bunch of plugs and she is out. From there, remove the mounting brackets (2 screws each), 4 screws on the rear, 2 screws top and bottom and 3 screws holding in the small plates on each side. When you remove the back cover (tight fit), watch out for the power cable for the fan, I removed it so I could put the back aside. The mainboard is held in by 1 screw in the middle, 1 aerial at the top and 3 ribbon cables. If you've ever done any laptop stuff the ribbon cables are OK to work with, just pop up the retainer and they slide out. If you are not familiar just grab a 12 year old from an iphone factory, they will know how it works The case should now look like this:
    • Switching the console was tricky. First there were 6 screws to remove, and also the little adapter loom and its screws had to come out. Also don't forget to remove the 2 screws holding the central locking receiver. Then there are 4 clips on either side....these were very tight in this case and needed careful persuading with a long flat screw driver....some force required but not enough to break them...this was probably the fiddliest part of the whole job. In my case I needed both the wiring loom and the central locking receiver module to swap across to the new one. That was it for the console, so "assembly is the reverse of disassembly"
×
×
  • Create New...