Drivetrain woes - a case of too much power?

[AM04ARO]

Driving back from Brands I heard a familiar whine - the diff was whining again. Was a bit peed at the time as I was doing the NSL on the M3 doing little over 2k of revs .

Reason for posting is for those with more than 450BHP (I have no idea what I have but am guessing around 550) have you had any issues with your drivetrain? I uprated my clutch as suggested and think that this caused the latest problem - I was getting clutch slip and now I am getting full power from the SC etc through.

What makes me feel a little 'annoyed/confused' is I know other cars are running a lot more power than me but have not heard of any issues. Could it be my driving? I use it as a daily driver and am quite often sat in heavy traffic. Pretty sure my driving Sunday was like everyone else (less the tramlines that Boss left behind). I don't tend to wheelspin much, don't practise drifting or donuts.

Is the 'ro a Tvr in disguise.........

[Le Sarthe]

I am at circa 490hp/470 torque std clutch and 3.9 diff - no probs what so ever in 60,000miles.

Bit like yourself no mad wheelspins etc. but it gets a good workout. 40mph in 2nd, 60mph in third and 80 in 4th and hold and.....nail it. Major kick in the pants and off you go.

That extra torque you have though....I believe Tiler never had any probs when running at that level with a 3.9 diff.

[sid447]

A quick surf through LS1.com.au,

Will confirm the same issue that you have,and other drivetrain problems. These cars are not exactly over engineered.
A smaller 2" dia. propshaft was fitted from MY2001 production which made it the weakest part and usually the rubber donuts start to split depending on use (VT-2 had a 2-1/2" high tensile steel propshaft with U-jays at each end; much stronger but this left the diff as the weak point.
Usualy the driveshaft output flanges crack or the driveshaft stub axle in the diff.

[eatthis]

whats a 3.9 diff??
i thought the 3.9 refers to the final drive which has bugger all to do witha diff

[yorkkie]

diff can change final drive ratio

[AM04ARO]

sid447 said:

A quick surf through LS1.com.au,

Thanks for that.

Thought it was just me but it would seem they have had issues over there too.

3.91 diff is an excellent but of kit (when it works) that really improves acceleration with no engine mods. Think it may be slight overkill with the sc tho.

[stevieturbo]

sid447 said:

A quick surf through LS1.com.au,

Will confirm the same issue that you have,and other drivetrain problems. These cars are not exactly over engineered.
A smaller 2" dia. propshaft was fitted from MY2001 production which made it the weakest part and usually the rubber donuts start to split depending on use (VT-2 had a 2-1/2" high tensile steel propshaft with U-jays at each end; much stronger but this left the diff as the weak point.
Usualy the driveshaft output flanges crack or the driveshaft stub axle in the diff.

All of those items are weak links that simply break.

Whining is generally a build issue, or incorrect oil which cause premature wear of the crownwheel and pinion.

[stevieturbo]

Although if its std...maybe there are some other issues ?

www.ls1gto.com/forums/showthread.php?t=145873

[mackie1]

eatthis said:

whats a 3.9 diff??
i thought the 3.9 refers to the final drive which has bugger all to do witha diff

The diff is the final drive. The number of teeth on the crown wheel and pinion dictate the ratio.

[AM04ARO]

stevieturbo said:

Although if its std...maybe there are some other issues ?

www.ls1gto.com/forums/showthread.php?t=145873

Perhaps the early cars had a sub standard diff, hence the newer cars are not having the same problems.

[stevieturbo]

AM04ARO said:

stevieturbo said:

Although if its std...maybe there are some other issues ?

www.ls1gto.com/forums/showthread.php?t=145873

Perhaps the early cars had a sub standard diff, hence the newer cars are not having the same problems.

It would seem strange. Isnt the rear end the same as the Commodores which have been around for a good while ?

[crisisjez]

You forgot to say that you do push on a bit mate
Do you think that the racelogic T/C may be doing too good a jod and straining the axle instead of letting the wheels spin?
Just a thought. Oh and nice to meet you on sun.

[sid447]

AM04ARO said:

stevieturbo said:

Although if its std...maybe there are some other issues ?

www.ls1gto.com/forums/showthread.php?t=145873

Perhaps the early cars had a sub standard diff, hence the newer cars are not having the same problems.

Early cars had a stronger propshaft as mentioned my in first post. This was deemed to cause too many diff problems so from MY2001 GM-H fitted a weedy propshaft with rubber donuts at each end as a coupling in place of the U-jays.

[AM04ARO]

Think i answered my own question alas.

What I believe to have caused the diff to go appears to be the mix of power (SC +IC), Harrop Clutch, Race Logic all transferring to much power through the diff. Nice to be at the cutting edge providing it does not cost me........

Have opted back to the 3.41 diff with the harrop diff plate on my shopping list.

[stevieturbo]

AM04ARO said:

Think i answered my own question alas.

What I believe to have caused the diff to go appears to be the mix of power (SC +IC), Harrop Clutch, Race Logic all transferring to much power through the diff. Nice to be at the cutting edge providing it does not cost me........

Have opted back to the 3.41 diff with the harrop diff plate on my shopping list.

I would highly doubt traction control would hav any effect on these parts.

I would also be sceptical that too much power would do it too.

I put a lot of power through a crappy old Granada diff for an easy 8+ years, and never once did the diff unit, or the crownwheel and pinion complain.

As I said, excess power may break things like this, I dont believe it would causue premature wear on its own, which would lead to whining.

I would also hazzard a guess there are plenty of guys in Oz with a LOT more power than you....

Might be worth asking there ?

www.ls1.com.au/forum/forumdisplay.php?f=9

[AM04ARO]

Have asked the question stevieturbo (on the ls1 aus forum) but I think the power 'cooks' the oil therefore causing the damage. Tiler's car is the ony other one wth the same mods and he has the harrop cover.

[stevieturbo]

AM04ARO said:

Have asked the question stevieturbo (on the ls1 aus forum) but I think the power 'cooks' the oil therefore causing the damage. Tiler's car is the ony other one wth the same mods and he has the harrop cover.

Incorrect tolerances between the gear mesh will fry the oil in no time if they are bad enough.

A friend lost a diff in a Cossie within 200 miles when it was re-built by a local gear specialist....typical !!!!

I built it the next time.

The first time I built the diff for my current car, I did it wrong. It lasted maybe between 1-2k miles ?? not sure really.....when it went, boy did it go !!!! The noise was unreal, almost deafening ( 200+ miles from home, so just kept driving )
And the smell of the oil after....Eeewwwwwwww it was rotten. Totally cooked.

Not oil related, not power related. Totally my own fault for building it wrong. Pinion depth was wrong, and its a total PITA to measure and get right.
backlash is easy though..

Of course, you need both right !!

[pomona]

My ex GTSR ran 3.9 diff,s/c with i/c and Racelogic with no probs in 27k miles with trackdays included.Still ok as far as I am aware!!As Stevie says smell the oil as it tells the tale.

[well_fans]

is your's one of the "early" 3.9 diffs that Monkfish etc were installing as I understood they had a few problems with them and decided to take the work in house to ensure their reliability. You'd have to check with Roger exactly what the problems were they had seen but it could be worth a call.

[A57 HSV]

I've not heard of anyone else fitting one, but Mark (ex LSV) fitted an oil cooler to the diff. on my supercharged VX. This was really a "belt & braces" approach, as back then (2001) there were very few 500+ bhp cars. I never had any drivetrain/diff. problems. The car was the press vehicle & did quite a few 0-60 & 0-100 timed runs.
I'm not sure what the differences are between the Monaro & HSV VX drivetrains are, can't be too different though.