Monaro gearbox

[mfp4073]

Just a couple of quick questions on the T56 as fitted to Monaro's.
For those of you that have had them rebuilt, do they now shift from gear to gear smoother without balking or having that bloody awful (slight) crunching noise as the gears start to mesh? and can they be rebuilt to a tighter tolerance, so you can reduce the (PIA) huge amount of back lash from the output shaft?

Regards John

[mfp4073]

TBH, I'm hoping the gearbox will last a while yet, the car will be off the road in October. (I expect its past redemption anyway)
My ultimate plan is to get the gearbox built up to a... way better than new standard.
I want to be able to change gear without the usual cringe factor! i.e get rid of crunching noise and sort out the back lash. These two issues are spoiling the whole damn car.
Now obviously to get the job done right it's going to cost.....
Any ideas how much a professional rebuild would cost?
I did consider saving for a brand new box, but I suspect it will probably be just as crap as the original one anyway...unless they have improved the build quality of course?
Before I forget.
I have been using Royal Purple oil for a few years, and I have driven a couple of other Monaro's, but it was such along time ago I cannot remember the shift quality of the gearbox.

Regards john

[mfp4073]

stevieturbo said:

Oil can sometimes make a good difference.

Whether a rebuild will help, really depends how bad your current one is. There should never be any crunching regardless.

And if the problems are bad, they could be clutch related....so rebuilding the box to any spec wont fix the shifting problem.

And most lash you're feeling will be from the rear diff, not the box.

I had the diff rebuilt last year and fitted a truetrac. The car had a large amount of back lash both before and after fitment. So I then checked the propshaft and that seems in order. If I turn the prop by hand, it clunks big time from the gearbox.
I sometimes wonder if the pilot bearing has worn and damaged the gearbox.

regards John

regards john

[mfp4073]

I forgot to mention I don't hammer the car, and I have never considered the clutch might be part of the problem? but you never Know. The clutch fluid is always clean.

regards john

[mfp4073]

stevieturbo said:

There isnt really anything in the box that can clunk as you describe, the gears are always in constant mesh so unless there was serious gear wear, there simply wont be any lash worth talking about, at least not enough to ever make loud noises.
And if gear wear was that bad, it'd be screaming its tits off.

If you're rotating the propshaft and feeling lash/clunks, it will be the diff. And fairly normal at that too.

what gear was it in, if any when you say you heard or felt this clunk/lash ?

The clunk happens in all gears even reverse. The box itself is not particularly noisy and it is not a screamer!
I think it will be better to check out another Monaro before I start pulling the car to bit's!!!!!
I think I will take up your offer V88Dicky if thats OK.
Raving sorry to ask but what brand of oil would you suggest?

Thanks again John

[mfp4073]

wormus said:

I'd start by looking at the clutch. The slave cylinder doesn't move much on these so there's a risk that it's not fully disengaged and dirty/old fluid makes it worse. I have an LS9 clutch and slave in mine which has extra movement and I couldn't believe the difference it made when it was first fitted. No wrestling with the box and you can change gear with 2 fingers it's that light.

Thanks Wormus,
I plan to fit the LS9 in the future as I'm still running the factory set up at the moment.

regards John

[mfp4073]

OK, so it looks like the LS7 clutch and all the extras that need doing at the same time, is a straight swap. That sounds like the way to go.

Thanks all John

[mfp4073]

I forgot about this old thread...I had a new clutch fitted, and the gearbox is now way better.
I must admit I would never had put the clutch at fault since I don't hammer the car,and it had less than 60000 on the clock. But it was worn and never came close to actually slipping.. so there you go!

Johm

[mfp4073]

[quote=stevieturbo]

Any "lash" you think you're feeling from the output shaft is nothing to do with the gearbox, and everything to do with the propshaft/diff.

Thanks for info steviturbo,

The only bit of gear crunching I get now is shifting from 1st to 2nd gear when it's stone cold, but it is hardly noticeable. Once warm it's fine.
The diff has been totally rebuilt so that's in order, which leaves the prop. The rubber donuts look OK, but I might change them at some point together with the centre carrier bearing as they are all original. Hopefully it will then be a little less clunky....or not!

Thanks again......John

[mfp4073]

Aitch 'H' said:

The T56 is always clunky when cold. It's the old Borge Warner T5 'box that used to be fitted to Cosworths etc that the rights were bought for and made into a 6 speed, hence the T56 name. Mine was clunky and feeling like it was shot but a change of oil and a new LS7 clutch fixed it just like yours but they are notchy and a little stiff when cold, then when they warm up they free up

Thanks that's good to know, I think as a T56 goes I have a good one after all...

John

[mfp4073]

stevieturbo said:

I would be ensuring 100% your clutch is not dragging before pulling anything apart. And then I'd be exploring oils.

If the problem was only with 1 or 2 gears, then yes you could envisage a box issue. If it's more gears, all the gears....or worse going down the gears ( when synchros/baulk rings work hardest ) again, this should give a clue as to where a problem may lie.

From a standstill, how does the car go into gear....any gear ? including reverse ? It should go very easily.

And if not...with the engine off does it select a gear any differently ? ( allowing for fact parts are not moving and may not be aligned first try )

And the clunking...large rwd diff and heavy propshaft, to a degree there will always be some lash. The rubber donuts on the shaft should help absorb some of this though and mask it from the driver. You could maybe have the CWP lash set on the tight side of things as this will remove some of the free movement the prop sees during on/off drive, but there will always be some

In September of this year I had a new clutch fitted (LS7) together with new gearbox oil (Royal Purple) and two new Pedders half shafts.
I can select all gears easily with the engine running, but for reverse it is better to select second gear, then put it into reverse. If I try to go in reverse straight away it will go in but with a loud thump.
Without the engine running gear selection is as you have stated, 1st gear is a bit awkward, but everything seems OK.
The only noise issue I have is the slack in the drive train, I really can't get my head around that.
I have always had RWD cars and this is the only one that makes a loud thump when on/off the throttle especially when driving around town.
I have considered a one piece prop shaft or even solid replacements for the two rubber donuts, but my knowledge about this comes stops right there!(not to mention the cost of buying something that may not make any difference)

John

[mfp4073]

Thanks, I will look into that.
There is always something new to learn about these cars.

John