Conversions & Swaps LSX Engines in Non-LSX Vehicles
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Old 01-17-2019, 11:01 PM
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Originally Posted by Vetteman61
1978 Caprice with 2004 Avalanche 5.3 and 4l60e. The most I'll ever has is maybe at some point 400 crank hp. Right now it's stock. This is a daily driver. I would like to get a new bolt in unit that would have Limited Slip, disk brakes and a gear ratio of choice.

. I like to do a burnout, donut or get sideways when it's raining sometimes, but that's about it.
Honestly, a junkyard 8.8 is perfect for what you're describing - if you've got the skills to fab it...
Old 01-17-2019, 11:37 PM
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No fabbing necessary, already has a gm 8.5. Turbo buick guys run single digits on that same axle. Pick out what gears and diff you want.
Old 01-18-2019, 08:22 AM
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On a related note, can you fit an 8.625" carrier in an 8.5" housing? Are they like some other rear ends I've seen where the housing is different depending on final drive ratio? I seem to remember some rears were made with like 2.xx ratios and some with 3.xx ration and you couldn't swap a 3.xx ratio carrier into a 2.xx housing. But I could be wrong.

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Old 01-18-2019, 10:59 AM
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Originally Posted by Vetteman61
So if I understand correctly I can basically order new guts for the diff housing, new axles and bearings and I'll be good to go. I suspect I'll order new axles as well as this car's body, and so rear end, probably has near 200K miles on it now. I realize this question may be like asking if "Ford or Chevy is better," but what type or brand of differential should I consider. Are there any generally agreed upon types that I definitely wouldn't want on daily driver? For example, I know enough to know I wouldn't want to buy a locker. Do some have better longevity than others? For the 400 crank hp max level, do 28-32 splines make a difference?.
Yes you can replace the guts of the rearend and you have a lot of options. The stock carrier is probably an "open" differential, meaning it will spin one tire if you floor it. Depending on your goals, you might want to replace it with either a limited slip "posi" or a gear-type such as a tru-trac. I would stick to Eaton personally. The carrier itself must be replaced if you plan to increase spline count, but in your case I would stick to the stock spline count since you really don't have enough power to warrant an upgrade. If you want to upgrade the axles, you can get aftermarket axles that use a stronger material and heat treat. Strange, Moser, and others offer these. C-clips are fine for this application. I used custom Strange axles on my Nova and I was very happy with their customer service and quality of the product, but I have also heard good things about other companies. For what it's worth, mine are Strange 30spline street/strip axles. I eliminated c-clips on mine and upgraded to Ford bearings, but I autocross my car and I have more power than you're planning on. I also changed to disc brakes in the rear I did not want to worry about pad knockback which can be an issue if you are autocross or tracking the car with c-clips and discs.

For bearings and seals, you will want new carrier and pinion bearings, new pinion seal, new axle seals, and diff cover gasket. When you buy new gears you can get an installation kit that will usually come with all the pinion and carrier related bearings and seals, but it will not come with axle bearings and seals. Use Timkin bearings - don't skimp in this area. Find a good differential shop and they can advise you on how to build for this power level - you don't need much.

Consider upgrading to a cast aluminum diff cover - they are more reliable at sealing and some offer carrier support. Also think about whether you want to upgrade to 1350 u-joints - if so you would likely need a new yoke and corresponding bits for the driveshaft. I don't think this is necessary at your power level. If the car has 1310 or 1330 u-joints those are probably fine. For what it's worth I am running 1310s on my Nova.

Last edited by -TheBandit-; 01-22-2019 at 12:17 PM.
Old 01-18-2019, 01:24 PM
  #25  
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Originally Posted by JayinMI
On a related note, can you fit an 8.625" carrier in an 8.5" housing? Are they like some other rear ends I've seen where the housing is different depending on final drive ratio? I seem to remember some rears were made with like 2.xx ratios and some with 3.xx ration and you couldn't swap a 3.xx ratio carrier into a 2.xx housing. But I could be wrong.

Jay
There are definitely carrier bearings to do the opposite - 8.5 carrier in 8.625 housing.

The 8.5 10 bolts have a 3 series carrier on 2.73 and higher numerical carriers, if memory serves.




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