5MT Torque bind confirmation help needed

shepherdfte

shepherdfte

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Joined
Nov 3, 2011
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Location
Hunter Valley
G'day all - just joined!

I'm hoping to get some confirmation of the fault with my Outback gearbox before I tackle the firm who fitted my recon 'box 18'000km ago :(

99% sure I know what it is after 2 nights reading up (including this awesome forum), but wanted to be 100%.

Car is a 5MT, open front and rear diffs, with a standard VC aided diff in the middle. The car has suddenly decided to start behaving like the centre diff is locked-up. Turning tight on tar the front wheels clunk and chatter, a bit like a CV joint (except they are new). When hot the car will actually stop rolling if you turn tight - needs significant power to move it. On the open road she now feels like she wants to go straight all the time - on sand it's actually hard to turn at all (it used to be easy). On tar you can physically feel that you're using the power steering to force it to turn. Gets worse after a decent drive - it's not all that noticable cold.

My main way of confirming my diagnosis was to jack up one side of the car (both wheels). In neutral, the wheels both turn effortlessly in the same direction - no issues. But once the input shaft is locked by putting it in gear, it was VERY hard to turn the wheels against each other. And this was cold.... I.e. if I turned the front wheel forwards, the rear turned backwards (correctly), but the force was so high I could almost not do it even with the tyre as leverage. Even very slow movement was highly resisted. I thought the VC would be quite loose unless turned fast. I "think" the one in my old 'box was much looser, but can't be sure now I no longer have it.

So can anybody confirm just how hard it should be to (slowly) turn the f/r axles against each other with a stock VC?

Thanks and sorry for the long first post!

Andy
 
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Not sure what your problem is but sounds like the center is rs, at least it's easy to get to so not a massive job for them to check, though I can't see you getting warranty after 12,000K's.
 
Sounds like the centre diff even though I have not heard one doing that before. At first I thought someone may have put a different gearbox and stuffing up the ratios, but it seems like the box had been in there for some time.
 
Thanks guys. Seemed a fairly common problem when searching the www, but not an everyday one. Interestingly I too worried that I might have got the wrong ratios in the recon box. After fitment I checked it by counting wheel rotations for drive shaft rotations, but plan to check again!

Anybody know how "stiff" if should feel when trying to turn f/r axles in opposition?

I hope I can get warrantee having paid for two years of cover, but not too hopefull :/

Andy

PS - glad to hear it's easy to get at. I assume the rear of the box only has to come off?
 
Yes- the rear of the box is all that needs to come off- plus the removal of the tailshaft, etc. I don't remember trying that test you asked.
 
plus one for centre diff
Ive only seen 5 or 6 come through our dealership in the last nine years that needed centre diff replacement, but it does happen occasionally and I think 4 or 5 of the few Ive seen was most likely due to differences in tyre size from my observations at the time
pm me your vin number and gbox number and I will price the job for you if you like

regards Andy
 
I've been thinking about all the people I know with Subarus- and I know quite a few- I can re-call only 2 centre diff failures in the last 10 years- and one was on ORS. The other was in the WRX Club- and that was traced to competition use when the driver did not realise the perils of full throttle and using the handbrake simultaneously.

Of course, if the gearbox has the wrong ratios that will also kill the centre diff
 
Well I'm going to check the ratios one last time on the weekend before I tackle the reconditioner. Thanks for the offer greentreefrog :) tbh if I can't get it under warrantee I'll just do it myself (I'm pretty handy). Would be tempted to fit the helical out if the 5-speed sti - I believe they fit. But I'll chase the supplier first!

Funny really that the centre seems to be jammed. On my old 'box the centre diff had done the usual and become totally open. Got the car stuck once with three wheels on tar and one (spinning) on wet grass LOL. This box could just drive out....
 
No helical in the STI center usually just a 4kg center diff or maybe a 12kg in some RA/s, best option is a DCCD if you can find one.

If you're going to split the box you can get a front helical from the US landed for about $440.
 
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That would be tempting too, but I'm hoping not to split the box.

Yeah I meant dccd. I believe that's a helical (but not biased 50/50) with a computer clutch pack to get close to lock-up when needed. More research needed, but I had in mind either running it as helical (no wiring) or manually controlling the pack. Car gets used for gravel roads, sand etc so centre helical is fine. A locker f+r would be awesome, but of course not available.
 
I've got one sitting at a mates place waiting to go in, un-powered they are split 35f-65r they are powered 0 - 12v so we are going to get something from J Car, a sparky friend is going to work it out and power it through the voltage range, apparently they are pigs on bitumen when set at 50/50.
 
There are DCCD's and DCCD's. The earlier 5 speeds available on the 22B and JDM STI's allows for manual adjustment only of their settings. I forget the internal workings, but they apparently use a lot more current than the later 6 speeds. The 6 speeds also have an auto function and to be frank that is where I leave mine- be it on the road or in competition. More investigating there though. The standard splits vary from model to model- even within the 6 speeds. With the later 6 speeds, it is a default LSD- but I forget if it is VLSD, helical or plated- I really do need to pay more attention! (I doubt it is VLSD!) The auto function and manual adjustments come on top of that.

I used to think that having the DCCD and plated diffs would be pretty close to locked diffs, but I don't think so much that is quite the case after more experience. You certainly have better grip than standard, and the centre diff can lock up so hard you think something is going to break. But you'd need your front and rear diffs to be pretty tight to be a like a proper locked diff. I guess what I really need to do to get a definitive answer is jack up the Impreza and go off roading in it!
 
Yeah that all sounds about right. I believe the earlier ones were (when unpowered) 35/65 but later ones were 60/40, however not yet sure how that relates to to 5/6 speed or models etc. Technically if you can get it nearly locked when powered it's 100/100 LOL.
 
I think the advantage would be in getting power to both ends instead of a weak 4kg viscous sending the power to the end with least resistance which in my case would be the rear as the front is mechanical LSD & the rear is viscous therefore the spinning wheel is probably receiving much more than 50% of available power.
 
Well I checked the ratios on the weekend. They match, so at least I'm not at fault. This time..... :)

Checking the ratios on the front diff is DAMN hard with a faulty centre. With one side jacked (car in gear to lock the centre diff input) I could barely turn the wheels in opposition with a 1m socket wrench. But after 20 sweaty turns, both wheels were still a dead match. The diff is so stiff that even in neutral, the wheels still matched after 100 (very easy) revolutions in the same direction. Good job the f/r diffs are both open or I'd never have been able to do the tests!
 
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Well the place that did the box said they'd fix it if the fault is as-described. Fingers crossed for next week and a trip to Sydney.

Then I can sort the wheel bearings, TPS.......etc :)
 
All fixed. Full marks to Alldrive Subaroo who did the recon box originally. They didnt try to fob me off, agreed the diff was at fault, and fixed it. Mind you it was cooking hot when i got there thanks to Sydney traffic, so they got to experience the fully locked diff first hand.... They worked to 6:30 at night, and dropped me at the shops for the day. Awesome, and very knowledgeable.

Apparently the front uj on the prop shaft is stiff, so there's a bit more fun for me.

Thanks heaps for the advice.

Andy.
 
shepherdfte said:
All fixed. Full marks to Alldrive Subaroo who did the recon box originally. They didnt try to fob me off, agreed the diff was at fault, and fixed it........
.......They worked to 6:30 at night, and dropped me at the shops for the day.
Awesome, and very knowledgeable.
Click to expand...

Great to hear you got it all fixed.

Regards
Mr Turbo
 
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