Weakest link of a Banjo? Hotting them up?
#1
Posted 19 July 2010 - 04:07 PM
I'm interested because I've heard people very briefly talk about putting bigger diff components into Banjos, and now I can kinda imagine it after working with them a little.
The fact that they only have two pinion gears probably makes the standard centres a bit limiting. I've never blown one up before but I gather they often shear the pin or strip the teeth off the planetary gears?
Heat is probably a pretty significant problem with such a small diff, particularly if you're doing standstills, but you can always run thicker oil or use a diff cooler in more extreme cases
Has anyone here ever made up a set of axles for their car? What material? Can you weld a flange onto the axle and then machine it? or does it have to start off as one piece of billet?
In a very extreme case, if you were to make up a full spool and even more-so willing to look at using a different type of wheel bearing (something with the same O.D. and bigger I.D.), you could probably upsize the splines and the whole axles. There isn't that much to limit you then. How strong do you reckon it could be? Still using the standard 3rd member, diff housing, pinion, crown wheel, bearings etc, just put a decent crush tube on the pinion for good measure.
I know, I know... "why would you bother"
#2
Posted 19 July 2010 - 04:43 PM
Edited by Heath, 19 July 2010 - 04:44 PM.
#3
Posted 19 July 2010 - 05:28 PM
#4 _gearex_
Posted 19 July 2010 - 07:32 PM
#5 _rorym_
Posted 19 July 2010 - 07:43 PM
R
#6
Posted 20 July 2010 - 12:17 AM
Other than the above, the centres themselves aren't too bad considering the small size, however once you fix those problems you start destroying axles. Coarse spline axles twist (and break) at the spline, fine spline are a lot better but still only toothpicks.
If you manage to get a good combination of centre and axles, you start to put strange loads on the poor Banjo design (the removable diff head). The main housing isn't solid enough and you end up with twist that moves things around where they shouldn't be, end result broken bearing caps, cracked and bent housing.
Gearsets are OK (again given the size), but they get a hard time when all of the above starts happening.
#7
Posted 20 July 2010 - 12:21 AM
Leave them out.
You'll never break one then.
#8
Posted 20 July 2010 - 12:30 AM
The fact that they only have two pinion gears probably makes the standard centres a bit limiting. I've never blown one up before but I gather they often shear the pin or strip the teeth off the planetary gears?
Your not trying hard enough, try driving the crown wheel out the back of the housing (third member)
Heat is probably a pretty significant problem with such a small diff, particularly if you're doing standstills, but you can always run thicker oil or use a diff cooler in more extreme cases
HEAT HAS NOTHING TO DO WITH IT
Has anyone here ever made up a set of axles for their car? What material? Can you weld a flange onto the axle and then machine it? or does it have to start off as one piece of billet?
The axles are the strongest part...
How strong do you reckon it could be? Still using the standard 3rd member, diff housing, pinion, crown wheel, bearings etc, just put a decent crush tube on the pinion for good measure.
Weak as piss.
"why would you bother"
If you have to ask, you will never know...
#9
Posted 20 July 2010 - 07:21 AM
If you manage to get a good combination of centre and axles, you start to put strange loads on the poor Banjo design (the removable diff head). The main housing isn't solid enough and you end up with twist that moves things around where they shouldn't be, end result broken bearing caps, cracked and bent housing.
Gearsets are OK (again given the size), but they get a hard time when all of the above starts happening.
Agree, pretty much a bad design and too small for any creditable power, the salisury bango is far superior in design.
wot179 seems to have hit the nail on the head.
#10
Posted 20 July 2010 - 11:28 AM
No one seems interested (and rightly so) in spending money on something thats still going to break. Useable spares are cheap as chips anyway which pretty much takes any market away for your ideas.
R
#11
Posted 20 July 2010 - 12:28 PM
It would definitely save the hassle of fitting the queen mary 9 inch (added weight) or a commodore borgy.
The banjo fits, it works etc etc.
*touch wood* Ive never busted a banjo either, and Ive given both my old open centre and my LSD a pretty hard time (mainly through 205 or 215 tyres though)
it only seems to be the LH/LX guys that hat banjos (obviously the V8 thing and wider tyres makes the difference)
#12
Posted 20 July 2010 - 02:39 PM
#13
Posted 20 July 2010 - 02:42 PM
#14
Posted 20 July 2010 - 04:33 PM
.
http://www.youtube.c...h?v=1tqxzWdKKu8
Edited by wot179, 20 July 2010 - 04:47 PM.
#15
Posted 20 July 2010 - 06:01 PM
Absolutely agree. But I do find it funny how lots of people bag the design of a Banjo but don't bag the design of a 9"? If a 9" with all the "good bits" can handle like 700ft.lb then why can't a Banjo be made to handle like... 300ft.lb? I reckon it's just because people don't try - they'd prefer to put 40kg worth of unsprung mass in their rear end, after blowing up 20 unserviced centres. I don't view it as a commercial thing. People just upsize their diffs anyway. It's an intellectual mechanical exercise, my interest in cars is not monetary.the salisury bango is far superior in design.
I think the Salisburys are a nicer setup but building Banjos is definitely a more enjoyable activity. If someone wants to pay me good money to build Banjos then I might do it but that isn't my intention.
#16
Posted 20 July 2010 - 06:17 PM
Ok.One wheel burnouts with open centres seize the spider gears to the pin which then breaks the roll pin and spins in the housing, chewing it out and effectively creating a heap of backlash as the holes become oval.
I'm not convinced.HEAT HAS NOTHING TO DO WITH IT
#17
Posted 20 July 2010 - 06:37 PM
But I do find it funny how lots of people bag the design of a Banjo but don't bag the design of a 9"?
the salisury bango is far superior in design.
Doh, their bigger, they can handle more but still suffer from the same inherent design of the banjo.
I think the Salisburys are a nicer setup but building Banjos is definitely a more enjoyable activity. If someone wants to pay me good money to build Banjos then I might do it but that isn't my intention.
There is no difference in building either.
#18
Posted 20 July 2010 - 06:54 PM
I'd prefer to just yank my centre out and take it to the shed
#19 _stu.slr_
Posted 20 July 2010 - 09:29 PM
bloke who built my diff said he has seen alot of banjos with falcon centres, not sure whether he meant the old fairlane 8.8 or the b/w 78.
yeh, B/W spider gears, but fine spline only i guess
#20 _HQ SS_
Posted 20 July 2010 - 10:16 PM
I have blown up heaps of banjo's and snapped numerous axles over the years but all the banjo failures have been from the centre out.
Either spiders splitting in half or loosing teeth and overriding each other (then splitting the centre carrier in half.) or the small spiders
overheating on the centre pin causing a failure as described above.
But has anyone here actually had a banjo crown wheel and pinion fail on there cars.
What I mean by that is a actual crown wheel or pinion that has had the teeth fail.
I do not mean as a after affect to spider gears being spat into them or centre giving way and breaking but a out and out tooth failure.
If you have can you describe in what circumstance.
The reason I ask is that I have seen a fair amount of salisbury and hilux diffs where they have suffered out and out pinion or crown wheel
failure but not a banjo gear set.
Also in fairness to the banjo as well, a centre that has wear in the carrier which allows the spiders to move further apart, therefor giving
less tooth contact is a lot more likely to go bag than a a carrier with no wear/ movement.
This may be a lot more common problem than a lot of people may think.
For example in the last big clean out of banjo centres I did I tossed out twenty odd carriers and kept two, all the rest were flogged out.
So with the diffs that everyone has had fail how many were actually in good condition to start with.
I am of course talking about the open wheel centres above from past experience the LSD centres are worse for blowing up because of the
even smaller spider gears in them.
On another note the longest lasting banjo diffs I have ever owned were all cig lockers which solved the spider gear problems.
Cheers Paul.
#21
Posted 20 July 2010 - 11:52 PM
They really are not worth the effort unless you have a stocko six and drive like a granny.
#22
Posted 21 July 2010 - 10:43 PM
How so, the Borg Warner is 25 spline but Banjo is 23 (or 10 for the coarse axles)?
bloke who built my diff said he has seen alot of banjos with falcon centres, not sure whether he meant the old fairlane 8.8 or the b/w 78.
yeh, B/W spider gears, but fine spline only i guess
#23
Posted 21 July 2010 - 11:40 PM
This was behind a not quite 1hp per cube 308 with crap low grip 205 street tyres.
The bits are simply not made to withstand much load.
#24
Posted 22 July 2010 - 12:43 AM
The bits are simply not made to withstand much load.
As already mentioned, grey motor technology.
A billet bit that the carrier bolts into (3rd member?) and another billet bit the the crownwheel bolts onto (carrier?) and a press fit spider gear shaft (rather than interference fit) would be the only way that I can see to make these near bullet proof....................?
Then all you need to fix would be the chewy gum axles.
Dowelling the carrier cap bolts and fitting 4 housing to banjo dowell bolts would be a start. (same as pressure plate dowell bolts)
Sleeving the spider gear shaft hole to make the spider gear shaft a press fit would also be a step in the right direction.
A small salisbury (UC) might accomodate a cradle between the carrier caps?
But.....then.......you've still got chewy gum axles?
Edited by rodomo, 22 July 2010 - 12:52 AM.
#25
Posted 22 July 2010 - 04:38 AM
I run a fine spline LSD and would like to point out the following,
A course spline open centre is weak as piss.
However a fine spline LSD is very strong.
I run soft compound race tyres but not slicks. I dont give stupid abuse but will do long straight burnouts that keep both wheels spinning at equal speed.
I can bust course spline axles in 2 secs and open centres break very easily. You will break either the spider gears or work the pin lose to the point it slides out and destroys the gears.
However I have never ever broken a 23 spline axle or crown and pinion. The only time I damaged spider gears was when I tramped it at the drags but this is expected for any diff. However I have found that the Lsd cones do wear quickly.
One time I got the car airborne and accelerated as it landed and busted the carrier caps and totalled the diff. After this experience I had a heavy steel bar machined to support both caps and I feel this has made the diff much more stronger.
However the biggest problem I have is bending housings into a banana shape over time. The shear torque of the engine will bend the housing and when I have time one day will have extra ribbing welded to give strength.
So whilst I give respect to the capabilities of this diff, the LSD fine spline is not as weak as some make it out to be as they are transferring their experience from the course spline axles and open centres and generalising about the LSD fine spline.
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