3.45 Differential install

Drivetrain discussion including Transmission, Differential, Driveshaft, and related items.
s/c'd cav
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Re: 3.45 Differential install

Post by s/c'd cav »

not sure whats so hard to find on the caprice bolts , they are in the diagram with the driveshaft

the driveshaft to coupler bolts are sold in a kit - 92267162

coupler to trans - bolt #92139225 , nut #92228333

coupler to diff - 92139104
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kevink
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Re: 3.45 Differential install

Post by kevink »

s/c'd cav wrote: Wed Sep 25, 2019 2:41 pm not sure whats so hard to find on the caprice bolts , they are in the diagram with the driveshaft
the driveshaft to coupler bolts are sold in a kit - 92267162
That is the exact problem! Show me where you can buy JUST the nuts and bolts. They are only available as a kit that comes with the coupler. There is no number for just the prop shaft to coupler bolts and nuts which is what I have been saying the whole time. To get those bolts, you have to look up the Camaro numbers.
s/c'd cav wrote: Wed Sep 25, 2019 2:41 pm coupler to trans - bolt #92139225 , nut #92228333
Yes, they are shown in the photo on pg 7.
2011 9C3: 11.48 @118.
Capeasy
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Re: 3.45 Differential install

Post by Capeasy »

Did any of you guys experience the loss of the traction control feature after the diff swaps ? I did and it has me puzzled. :|
Walt (AKA:Capeasy) So. Cal.
2013 Caprice 9C1,Huron white, Blackbear tune, DOD Delete, Texas Speed stage 2 cam with all the goodies, Circle D 258 mm converter, 3200 stall. Spectra CAI, 3.45 Diff, deep trans pan. BlackWidow Venom exhaust,Granatelli oval cutouts, Doug Thorley tri-Y headers, Pedders coilovers,Tower brace, Widend OE. rear wheels to 10" wide with 295 Nitto's
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kevink
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Re: 3.45 Differential install

Post by kevink »

kevink wrote: Fri Sep 06, 2019 11:10 am I'm not Maurice, but I used the Caprice coupler when I installed my Camaro diff. It mated to the Camaro diff exactly like it mated to the Caprice diff. There was no difference. I don't remember having to support the LCA with a jack. Actually, I had to force it down. This is really an easy bolt in swap. Just tear into it and you'll have no problems. Make sure you upgrade the diff bushings before you put it in. I also put steel clutches in mine, got rid of the Belleville washers, and added a Ford S-spring. I hammer it repeatedly every time I take it out and it's been great so far with drag radials on the street.
Alright, so a thousand miles later and my factory diff with steel clutches is shot. At the track, only one wheel would spin from time to time during the burnout. I recommend not wasting time on the steel clutches and going straight to an Eaton Truetrac. I'm taking advantage of the situation and swapping my 3.45s for 3.91s while I have it apart. Should have done that right away, too.
2011 9C3: 11.48 @118.
bstoner
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Re: 3.45 Differential install

Post by bstoner »

I just completed a 3.45 diff install on my 14. These cars should have come with 3.27 or 3.45 from the factory. 3.45 feels like a perfect ratio. It is definitely not too much gear. With the weight of these cars the 3.45 really helps the car get up and go effortlessly. It is hands down the best mod so far!

First off to those who knocked this out in a couple hours; you guys are amazing! It took me several hours just to drop the exhaust. Every exhaust bolt was lube, heat, and then snap with the air ratchet. Very rusted. Ended up grinding them flat and drilling them all out. Fun times. Car manufacturers really need to install grade 2 bolts and nuts for exhaust. Then we can just snap them out and replace them easily. No flange threads! I ended up buying 5/16x1.5 stainless bolts, washers, and nuts to replace all 8. Rear gaskets to mufflers were trashed. Had to knock them off then grind the flanges smooth again. Picked up two 31512 gaskets in stock from O’Reillys to fit. No RTV needed. Front ball/sockets had to pound apart but they went back together no problem after they were cleaned up. I also took a bunch of measurements for my next mod; 3" exhaust.

Also I know some of you left the driver axle in and angled it into the diff as you installed. Impressive. I spent an hour trying that approach. I eventually gave up and just pulled the driver side as well. An 18mm air ratchet and 18mm wrench make quick work of the suspension bolts. Its very well designed and comes apart quick and easy. With both axles out I could install the diff no problem then get the axles back in. If your due for brakes soon might as well replace since you have it apart already.

It took me about 8 hours on my back in the driveway with air tools. Doing it again I could probably get it down to 6, maybe 5 if I hussle and the exhaust comes apart easy. I also ran into one other small snafu; the rear diff cover I bought hit the mount. I had to drop the diff back out and grind it a little on the top rib of the diff cover to clear the car mount.

I bought a used 3.45 Camaro carrier and had it shipped to me via Greyhound. Greyhound was the cheapest. Probably wouldn't use them again. Had a few issues and took a month to get to me. It just randomly showed up one day at my local station. Nobody ever called me to let me know. It also took a tour all over the US with 12 different stops/buses to get to me even through there was a direct bus from the pickup/drop-off locations.

I replace the diff with Detroit Truetrac 912A686 from Jegs. Reused carrier shims. Installed new carrier bearings/races 92230402, seals 291338, and 10 ring gear bolts 11610549 from Rockauto. Bought JRE caps and had them milled at a local machine shop for $60. Installed Speedmaster diff cover PCE515.1009 from Jegs. The cover I had to grind a little on the rib on the top of the mount in order to fit. Pushed the old rubber bushings out with my press and used a saw to cut a notch to get the metal out. Replaced bushings with BMR BK029. Old gears had .005 backlash initial and .007 after Trutrac install and reused shims. Perfect! Gear pattern looked ok as well (but I am a rookie at rear ends). I build the rear end to handle 700+ FI eventually. Changed gears in HP Tuners and took it for a spin today.
2014 Caprice PPV, 6.0L, BTR Stage 2 Cam, 3.45, 3" exhaust, Rotofab intake, Chris Henry tuned, future LSA....
Pursuit
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Re: 3.45 Differential install

Post by Pursuit »

You could say that I had it easy... I voided the warranty at 2,500 miles... Exhaust had never seen any elements other than rain. I took it off all in one piece from the manifolds. ;-) And, I love the 3.45 in this car. I hope that you do, also!
Next thing to do is the DoD delete and a cam. With the 3.45, the DoD will never engage above 70 mph. To many RPM and Throttle position percentage. :D

Maurice
Maurice Sheil

mhsheil@gmail.com

2011 Caprice Phantom Black 9C3
2012 Impala 9C1
1995 9C1 Caprice
1996 GMC Sierra C1500
1996 Chevrolet K2500 Extended Cab, long box, 454, 91,000 rust free miles
1974 SJ Grand Prix 455 well optioned with factory moon roof
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elc32955
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Re: 3.45 Differential install

Post by elc32955 »

I'll say it again, 3.45 is the recommended flavor of gearing by far for L77 cars! I was one of the first that upgraded to that ratio in my 2011. Only lost a few MPH off the top end - my old install thread and a performance post is still active if anyone cares to look it up.

And, yes these cars were originally slotted to have better gearing - I believe the V8 cars were supposed to receive 3.45's out the gate going from memory. You can thank CAFE standards and GM bean counters for making the design revise to 2.92's for all. Bleh.

Eric
System Manager and your tour guide for the day. 2015 Caprice w/LFX, former NC DPS staff car. Partial hybrid G8/SS/Camaro SS interior mods, SS MyLink radio upgrade, 2016 Camaro V6 rims, GMPP Malibu chrome exhaust tips, otherwise bone stock for now.
bstoner
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Joined: Wed May 05, 2021 2:12 pm

Re: 3.45 Differential install

Post by bstoner »

Eric, you were the inspiration for me to go to 3.45 gears! Ha. It wouldn't surprise me the 2.92 gears were for CAFE.
2014 Caprice PPV, 6.0L, BTR Stage 2 Cam, 3.45, 3" exhaust, Rotofab intake, Chris Henry tuned, future LSA....
GammaFlat
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Location: NW Indiana

Re: 3.45 Differential install

Post by GammaFlat »

bstoner wrote: Wed Jul 28, 2021 5:02 pm First off to those who knocked this out in a couple hours; you guys are amazing!
Also I know some of you left the driver axle in and angled it into the diff as you installed. Impressive. I spent an hour trying that approach. I eventually gave up and just pulled the driver side as well.
I agree with the above. I think my "end to end" time was a little less but I had a lift, assist from a good friend who's a good wrench and less rust on my bolts. If I had my acetylene torch, it would have gone better. I wound up hammering a 6 point socket onto some metric bolts. Now I have to take the 'zaust back down again if I install an O2 sensor....
Current: 2013 9C3, deeper trans pan, 12VoltSolutions Remote, Class III hitch, Android Auto capable radio
bstoner
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Joined: Wed May 05, 2021 2:12 pm

Re: 3.45 Differential install

Post by bstoner »

Here is where I had to grind the cover to get clearance to fit inside the mount.
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2014 Caprice PPV, 6.0L, BTR Stage 2 Cam, 3.45, 3" exhaust, Rotofab intake, Chris Henry tuned, future LSA....
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