1886 replies to this topic

[mr5000]

It's funny looking at the photos because the car sits pretty flat, looks like I'm not even going hard hahaha.

That's probably because you aren't going that fast.... It's a 202 on lpg Heath...

hahah need a like button

[Redslur]

You have certainly come along way Heath in the years I have been on this forum. Well done mate. The car is coming along nicely.

Gerry.

[Heath]

I'm throwing in the towel and getting a 9"!

[MRLXSS]

*Checks Date* - Not April 1st...



Once it's in and all sorted, you'll never look back!

[DanWA]

go the borgy heath..

[Heath]

Sorry, I know it isn't April 1st, but I was still taking the piss.

Banjo LSD coming, finally off my arse

Edited by Heath, 31 May 2011 - 01:57 PM.

[MRLXSS]

Lucky you have an underpowered 6cyl on Gas! The Banjo LSD might be enough for you then!

[Heath]

Nah Graybo mate the diff I was running was going fine, but Stew wanted to borrow a diff and it was a good excuse for me to get off my arse and put the diff I've wanted for a while in this car. Matt my car has been punishing a lot more rubber than yours has for the last year lol. Rather have a nice loud bright fun to drive Torana than a shed ornament, even if it is fitted with a sickomatic and a twin exhaust system

Well mid last year I bought a fine spline 2.78:1 LSD Banjo centre on eBay.

I pulled the LSD carrier out, swapped it for an open coarse carrier, set that up and sold it off to someone. I slipped some spare axles into the centre, chocked everything in place on the floor in my crappy little shed and tested the slip torque by leaning on my breaker bar jammed between the wheel studs. Excuse the unflattering photo I got my mate to take but it's worth including incase you didn't get the procedure.


Pretty agricultural looking but produced very repeatable results just with some bathroom scales and a ruler, love a good back of the envelope calc! The result was 73N.m => 54ft.lb. That was below workshop manual specs so I assumed the LSD was pretty stuffed. I got onto gearex via PM and picked his brains a bit, he pointed me in the right direction. I cracked the LSD hemispheres apart and had a geeze. Jackpot, I was so scared I'd spent heaps on a stuffed old LSD but I opened this one up and it looked pretty tidy! I posted some detailed photos back to Jay and he said it looked to be in excellent condition. I could put a shim down under the cone in its seat and the shim stayed loose so I knew it hadn't bottomed out or anything (not that the surface suggested it had, but it was all new to me)


Anyway I needed to tighten it up, I asked around and couldn't buy any shims so just bought some shim stock and cut some up haha


Chucked a .006" shim between the spider gear and the cone on each side, bolted it back together and re-did the test

This time the result was 107N.m or 79ft.lb, which IIRC was about the factory spec according to the GM-H workshop manual. But I knew I could do a bit better than that haha.

With another .006" shim added either side, I tried bolting the hemispheres back together and it was feeling a bit spongy, so I put it on the ground and started doing the test, then tightening up the bolts and repeating. The torque was flatlining and then I snapped a bolt. So I went and got some new high tensile bolts and went again with a total of .012" extra preload per side


156N.m or 115ft.lb, double what I started with. Good as!




Then I had to set it up in a centre. This was a centre I was basically given by Torunya 3.08:1 ratio with a V8 yoke I just swapped for a 6cyl unit. You've already seen one Banjo diff build documented pretty comprehensively in this thread, so I'll try and show a few things that I didn't cover last time...

The bearings were already fine, the surface finish on the teeth was good, no heat treatment problems or abnormal wear, I didn't have to do that much... I put one of my CNC'd crush tubes in it and had about .003" end float, chucked it on the lathe, took a .005" deep cut giving me .002" preload like the last diff and that was done.

Then I just stripped it apart again, deburred everything, ran a dienut down the pinion thread, blew it all clean with compressed air and degreaser, gave it some assembly lube and chucked a new oil seal on the pinion, and some markings so I could identify the centre. Bolted my yoke holding tool on and held that in the vice so I could tighten it up as tight as I could with my metre long breaker bar


Got an old screwdriver and welded a protrusion on the side of it as a little tool to easily adjust the screw adjusters

Gave it .005" backlash (bit tighter than last diff) and a bit over 2 notches of carrier preload



Made up a custom long stud to put in my housing to suit the tall ratio centre design.



And bolted it in the car this arvo, we've all seen a banjo centre swap so not gonna bother with photos. No burnouts yet because I had crap in the boot but, but it all seemed good to drive on.

To summarize. 3.08:1 Fine Spline Banjo (GU4, 23 spline). It's got a solid steel crush tube on the pinion set up with .002" bearing crush and huge torque on the nut, there is .005" backlash measured from the outer end of the drive side tooth on the crownwheel, the LSD has original springs and .024" extra preload in the way of shims. Axles are marked left to right so the torque reversal is minimised, and they have a straight lines linished down them so you can pull them out and inspect them to see if they're twisting.

Let's see how long this Bango lasts hehe

Edited by Heath, 01 June 2011 - 11:56 PM.

[76lxhatch]

Nice detail Heath, just one question - with the back lash did you set it based on the tooth contact pattern? Although there is a spec for the starting point (and min/max) the end setting should really be determined by gear mesh.

[Heath]

I don't understand exactly what you mean. The pinion went back into the same centre that it came out of, I never even pulled the big bearing off it - whatever shim stack (if any) was there to determine the wipe pattern was not measured and remains unaltered. On the last diff I checked the wipe pattern with marking blue, but the look of gears suggested to me that this one was already sweet how it was, so I didn't change much

[orangeLJ]

Well you basically lost me!

Im impressed heath, that seems like some pretty technical stuff, and something I wouldnt try my hand at simply out of the fear of busting an LSD centre (especially with the $$ they seem to pull)

Whip me one up and post it up will you!

[76lxhatch]

I don't understand exactly what you mean. The pinion went back into the same centre that it came out of, I never even pulled the big bearing off it - whatever shim stack (if any) was there to determine the wipe pattern was not measured and remains unaltered. On the last diff I checked the wipe pattern with marking blue, but the look of gears suggested to me that this one was already sweet how it was, so I didn't change much

The back lash is adjusted by the screw adjusters, you said you set it a bit tighter than usual to 5 thou. The back lash also has a bit of effect on the tooth pattern and on a worn gearset in particular you should set it back to however it has been running (because it was good) - better to have back lash a bit out of spec that gives good tooth contact than vice versa. I assumed that's why you changed it?

[DanWA]

One thing i have never tried to battle is diff centres, i've banged heaps and tend to just change the whole lot over, find it much easier this way haha

Big props to you Heath, you take anything on!

[Heath]

Oh I get what you're saying now mate, in that respect I guess it may be less-than-ideal. I heard someone say since my last diff that a bit tighter lash adjustment (than factory specs) would be better than looser lash adjustment as far as diff temperature and efficiency is concerned and the adjustment was getting pretty coarse with what I was chasing so I just opted for the tighter setting. Thanks for pointing it out - I did neglect that aspect

[mr5000]

they the fine spline axles i had lying around

[Heath]

Yeah they're the ones in the photos missing half the studs and shit hahaha. I put some others in the car though

[76lxhatch]

Oh I get what you're saying now mate, in that respect I guess it may be less-than-ideal. I heard someone say since my last diff that a bit tighter lash adjustment (than factory specs) would be better than looser lash adjustment as far as diff temperature and efficiency is concerned and the adjustment was getting pretty coarse with what I was chasing so I just opted for the tighter setting. Thanks for pointing it out - I did neglect that aspect

With a bit of luck it will be sweet anyway, but it would be nice to check the tooth pattern (don't forget to load it up a bit) to confirm it after all the hard work you've done. I didn't want to be negative but you've done a really nice job of building it up that it would be a real shame to have it whine, or worse, when you put it back in the car. Not many people spend the time to get the finer details right but that's what you've done here and is exactly what makes all the difference when building a good diff.

I had a slapped together unit that whined like you wouldn't believe (was getting sick of breaking Banjos and building new ones!) - anything over 85km/h and rear seat passengers couldn't hear themselves think, I never realised such a noise was possible without straight-cut gears!

[Heath]

Well I've done a few ks in it now. The diff isn't as tight as I expected it would be (probably good as far as axle life is concerned) but it seems quite good. There is no detectable backlash and no whining or anything. The car is stepping out nicely when it's pushed, but it's completely manageable.

In general though this beast has been neglected for ages. I topped up the gearbox oil today and put some more oil additive in it too, I tried to fix the speedo inaccuracy with no success. And the reverse lockout in the shifter started playing up a few months ago, the spring loaded socket wasn't sliding like it should have (still lasted for heaps of hard, hard ks and non-stop going for reverse delivering pizzas), so I pulled the shifter all down, replaced that sliding socket and the housing that it sits in because the bore was damaged, thankfully I had spares. Anyway put it all together with fresh grease and a few other alterations and took it for a quick skid, seems good.

I want to do heaps to this car soon... Brad came around the other day, probably just to make me jealous of his car. Anyway we spent some time talking through some electrical mods we've gotta do to get it a bit more sorted. So that shouldn't be too far off...

[MRLXSS]

So.... how is it?????

You all ok?

[Heath]

Well it wouldn't be an 'epic' story without an ending.

Don't know what to say. Balling my eyes out doing this but I'll try and make it read alright. Building this car was the best thing I've ever done, bar none. When I got it (aged fourteen) I'd never lifted a bonnet so it's fair to say it's taken me on a bit of a learning curve. The stories I've got, knowledge I've gained, friends I've made and longterm pride & satisfaction I've been rewarded with make it all justified. Thanks to everyone who gave advice, leant a hand or provided bits that I needed. I could list a hundred people that played a part but the main one that needs to be mentioned is Rob. You deserve to feel appreciated - sorry I f***ed up mate!



Gonna miss you baby