cocacolakidd

iTrader: (6)

So now I’ve heard of the 9 bolt rear end. As weak as my 10 bolt, 7.5, 26 spline rear is, it makes me want to find one. I have also heard that repair/upgrade parts are hard to find for them. Do any of the bearings, posi parts or other 10 bolt std. items fit these? Where would one find rebuild parts or upgrade parts for them. I have also heard them called the Australian 9bolt…are they made in Australia…or is somebody pulling my leg…thanx, Ed.

cam-

Yes made in Australia is true. Yes they are better than the ten bolt. No there are no parts that interchange between the two. Very hard to find parts and pricey too. diffsolutions.com is the only place i am aware of but good luck getting replies.

fireturd350

iTrader: (8)

Randy's ring and pinion also carries parts for the 9 bolt. I got my gears and install kit through them.

This post might get answered a little quicker on the the transmission and drivetrain board.

You can always check around at the salvage yards... main thing is to do a lot of research before hand. The 9 bolts need a certain series of carrier if you plan on using a different gear in them. So just don't plan on picking out any 9 bolt from a f-body and slapping a 3.70 or 4.11 gear in it.

Usually by the time you buy the gears and install kit it can be 300 to 500 bucks or so. And that's before the purchase of the rearend too. So most people look into other options like a strange or moser rear end.

cocacolakidd

iTrader: (6)

Is there a URL for "Randy's ring and pinion "...I will probably run the 3:23 R&P for a bit (I am assuming these are the Std. Gears for a 9Bolt) before up-grading later.

When I was in the Army I had some close friends from Australia stationed at our base camp, and have kept in contact with them for years now. I am going to contact them to see what they know of the 9 Bolt and available parts there Downunder. Could be a sourse of parts and upgrades.

ebmiller88

iTrader: (7)

If there's any standard gearing for a 9 bolt it's the 2.77...those are a dime a dozen. The better ratio is the 3.27 and the most desirable is the 3.45...good luck finding one of those for under $400. There's also a 3.08 but those are not too plentiful.


Ed

ebmiller88

iTrader: (7)

You may be better off just looking for a complete 3.27 rear with disc brakes and then upgrading the brakes to the good PBR setups and be done with it. Those can be had for around $200-250.

Ed

83 Crossfire TA

iTrader: (2)

You can use 10 bolt pinion shims for side gear shims in the 9 bolt posi. I think that the ring bolts are the same also.


As far as ratios, there are also 3.73’s and 4.10’s. All of the ones that I’ve seen (and the one that I own) have been 3.27’s or 3.45’s (305/5 speed cars). There is an RPO for 3.73s in f-bodies, but I’ve never seen one with it from the factory.

Strength… well the gears and axles are reasonably strong (supposedly better then a dana 44), but the posi isn’t. I’ve found that the posi is good for about 35 dragstrip passes before it needs a rebuild, and after about 3 rebuilds even with creative machining and much thicker then stock shims there is no way to get it to work (the ends of the case get thin and start cracking). I finally welded my cones to the side of the case, but made the mistake of leaving the lip on the sides of the cones that just ripped right off after about 6 months of daily driving, some racing and a lot of abuse on very sticky tires. I cut all the old welds out, cut the lips completely off the cones, welded them back in, welded the side gears in, welded up the cracks on the sides of the case, played around with running a bead around the inside to get the 2 sides to mate up correctly again, and now I have to clean it up and reassemble it. I suspect that I’ll break an axle or the gears next time (of course, I’ve broken 7 (I owned 3 f-bodies) 10 bolts since ’98, and I’ve owned this one for 3 years now and haven’t actually broken anything that wasn’t my fault, just worn parts out).

TTA 1387

The 3.73 factory geared cars were the '85 L69 5 speed cars. When I moved out of my parent's house, a neighbor in the same apartment complex had a 85 IROC with the 3.73 gears. My 84 L69 had 3.73 gears and we were identical rpm, shifting, etc. His car felt just like mine except being black and 16" wheels. I don't know what the RPO code was though.

As for strength of the 9 bolt. I had well over 200 passes on mine and never had a problem. Lots of 1.6x and 1.7x short times also. I used Mobil 1 with no additive. From what I've seen, its when you start running consistent 1.5x short times it becomes a problem.

cam-

These rears don't hold up to sticks very well at all. Some guys have had good luck with them but I sure didn't. 83Crossfire is right on about the posi units IMO too.

fireturd350

iTrader: (8)

http://www.ring-pinion.com/ is the website for randy's ring and pinion. Last time I called in, at least a year ago, they only carried one ratio for the 9 bolt... it was a 3.73 gear. Ran me right about 320 bucks or so I think for the gear and install kit.

83 Crossfire TA

iTrader: (2)

I’m not really stating an opinion here, rebuilt with it shimmed as tight as it will go, it will wear out the posi fairly quickly if used hard. I got 34, 37 and 36 passes on each rebuild over a span of about 2 years/12K miles before I would just start killing the passenger side tire trying to heat them in the ‘box. I suspect that regular autox would be worse for it. OTOH, I’ve rebuilt one for a friend that has seen probably 2 dozen track passes and 70K miles so far and is still working perfectly. The posi seems quite adequate for street use but not for hard racing use.

Rob, I don’t know how yours could still be happy without a rebuild, I know I’m hard on rear axles, and have broken a few 10 bolts, but those have always been gears or in one case axles, and I’ve never worn out a 10 bolt posi. Has yours ever been taken apart and rebuilt? I’m wondering if they might be happier if they are not shimmed as tight (I can’t see how, it would result in less case/cone wear on the street but more at the track).

FWIW, I’ve looked into using the 9 bolt ends/shafts with a different center section and found something weird, the splines are cut at a different angle then normal (it doesn’t help that mine are hammered to hell), so if you wanted to get creative, adapt someone else’s center section, spool or whatever you’d need to get custom axles.

Basically, I’m of the opinion that if you have one and need something more durable then a 10 bolt, then run it. If you _really_ need something durable, need to spend money to get it/get it how you want… then go aftermarket (by the time you buy gears, posi, install kit and pay someone to set it up right you’re at ½-2/3 the cost of an aftermarket rear, and if you end up paying $100-200 for the housing…). For that $320 (price listed above for a set of gears, though I haven’t seen them quite that cheap) you could get 2 sets of gears for a 10 bolt, and as long as you accept that they are basically disposable you're probably better running them in the long run (most people aren't nearly as hard on their drivetrains as I am, and with a typical soft launch, auto… they don’t break as easily as people think).

Actually, Rob, I’m thinking that that might be why you’re getting more life out of your posi. That 3.8 turbo + auto combination probably comes out of the hole fairly soft compared to a V8 + auto that is running the same times

TTA 1387

Mine was never rebuilt. When I bought it, all the fluid in the car(except oil) was original '89. Even the windshield washer fluid I changed the original gear oil to Mobil 1 and then changed it once a year like all the cars I've had.

I guess I'm not as hard on rears as you. I had 50K miles on the 10 bolt in the WS6 with a whole year of 1.7x short times and it was still as quiet as the day the gears were put in at 6K miles <shrug>

TTA 1387

I wouldn't think so. I was launching with about 10 psi, or as much as the Nitto's could hold. That should be close to 400lb/ft torque, maybe more. Good enough for a 1.61. With a stickier track, probably a high 1.5x.

The auto is definitely easier than a stick. But the V6 shouldn't be any easier on the rear than a V8.

83 Crossfire TA

iTrader: (2)

I’ve come to the conclusion that no one is as hard on rears as I am.

Yes, you have 400lb-ft (or whatever the actual value is, I wouldn’t be surprised if it’s more then that for the times you’re running), but a turbo + smaller displacement applies it on a different curve then a larger displacement NA. Without boost you’ll just have proportionately less torque then a larger engine (roughly 3.8/5.7 or 2/3 the torque of something like my 350 assuming the same VE, I’d bet that in real life it’s somewhere between ½-2/3). At the boost threshold your torque curve starts climbing steadily where I’m still making all the torque that I’m going to make. This is assuming that we both rolled into it.

A little more real world I’m sure that you leave with some boost. Lets say you leave at about 5psi, and lets assume your 3.8 and my 5.7 are both at 100% VE (neither will be, but the 5.7 will be closer because it doesn’t have the restriction of the turbine in the exhaust and is tuned for a lower rpm powerband).

At that VE the 5.7 will be making about 400lb-ft and the 3.8 will be making about 255lb-ft. Add that 5psi (figuring 70% adiabatic efficiency and 70% IC efficiency, it won’t be that high since you’ll be in a bad part of your compressor map, I wouldn’t be surprised if it was as low as 50%) and you’re at about 325lb-ft. Lets assume that we both have about a 2:1 converter ratio and I have a 3.06:1 first gear and you have a 2.74:1. At that point I’m putting 2448lb-ft into the axle and you’re putting 1781lb-ft.

Of course, I’ve blown my wad (I’ll never be putting down more torque then right there within a few feet of the line), where by 4-4500rpm in 1st you’re doing the full boogy thing, boost is up and you’ve passed me, but all that extra power is being applied gradually against an already loaded and moving drivetrain, where I’m hitting it all at once off the line.

cam-

I think you and I share that sentiment. At least with regards to lame third gen rears. I never broke a rear before I had a third gen now I have three under my belt. I would never hold off either... I don't build fast cars to go easy on them. I want to drive em like I stole em and if something breaks I will build something stronger https://www.thirdgen.org/techbb2/sho...hreadid=246969

TTA 1387

But, it isn't applied gradually on a stock Turbo TA. Here's a dyno of my car when I was still running stock everything(turbo, injectors, downpipe, cat back, etc). Now this is hitting the car at 63mph in 3rd gear. The turbo Buick is a low revver, about the same as a TPI car. If running from a stop and leaving at your 5psi, it would be at full boost by 2800 or sooner. Quicker/sooner than you would be coming into your torque peak.

But anyway, the dyno was back to back but the second run was with the converter locked.

89gta383

iTrader: (5)

Go to http://www.txdrivetrain.com/ he has 5 sets of 9-bolt 3.70 gears for $175 each.

My posi unit is shot after track use with nittos and et streets. I don't really want to shim it, so I'm just waiting until it gives up completely to move on to something else.

83 Crossfire TA

iTrader: (2)

Boost is proportionate to load, so your torque curve will be different in first gear then 2nd, 3rd and maybe even 4th, since you’ll be under a greater load at a lower rpm in higher gears (you’ll also likely make more power up top in 1st then you will in higher gears since with the smaller load the turbine will be less of a restriction).

Unless you’re able to hold full boost on the line, you will come off the line less power, even though a split second after you leave you will have more. FWIW, my L98 comes off the line at 2300rpm with the stock converter (I know but I have data logged it on multiple runs and I get between 2200-2400rpm when the VSS sees it’s first motion every time), and I’d be really surprised if my torque peak was over 3K (the car runs fastest shifting where the tach says 4400rpm, data logs show it shifting at about 4600rpm at that point).

Somehow I was under the impression that you were running a bigger turbo, but with boost coming in that low and the torque numbers that you’re posting I would expect that it’s actually smallish… BTW, nice power “curve,” you gotta love a car that puts within a few hp of it’s peak down through it’s whole power band…

TTA 1387

This was with the stock setup. It ran 12.1@111 on a 1.69. I have logs from Direct Scan showing my stock onverter stalling at 3000 before registering any movement. That's a pretty good load on the car Also stock torque peak was 2800.

After that, I upped the turbo, downpipe, exhaust, injectors and ran 11.6@115 on a 1.61 coming out at 3300. With the PIG rich at launch Thrasher, I ran a 11.8@121 on a 1.89. Couldn't go past 2600 as it wouldn't spool because of its richness. But I could gain 30mph in the last 1/8 with that chip. The revised chip in the car will probably gain the lost 3rd gear HP of the 11.6 run. That first chip just didn't get it in high gear.

As an aside, a car running the same mods as mine and running the same times dynoed 420/595 at the wheels. So I figure mine would be in that ballpark area. With better breathing, the car shifts at 5250 now. Still a nice low revver