Best axle swap

[64nailhead]

What is that 10 bolt out of ?? As Driven said if you plan on upgrading, what is your expections and find out what you need to achieve them.

^^^this and Driven's comment are spot on. If you never intend to put much more than 500HP to the wheels with street tires, then the 7.5 with an axle upgrade will work for longer than the motor will stick together.
Drag radials, slicks or more HP is an entirely different story.

 

[JohnnyUtah1]

^^^this and Driven's comment are spot on. If you never intend to put much more than 500HP to the wheels with street tires, then the 7.5 with an axle upgrade will work for longer than the motor will stick together.
Drag radials, slicks or more HP is an entirely different story.

Really I just want to have a mean street machine

I am still driving this on the road regularly and I want it to be as badass as it can be while still being decent on the highway handling wise (I don’t care about fuel economy)

I understand that a 10 bolt with a 7.5 will be fine for a 350. But who knows 10 years from now i might want to park this thing and put a BBC in it so wouldn’t the 9” be the best choice?

And what are my options if the calipers do run the frame ?

 

[86LK]

johnnyutah,

what was mentioned by the previous posters is all correct. you won't go wrong in using their thoughts. however, because I am familiar with your point of view from 5 years ago (ie, "Lack of knowledge"), there are a few missing pieces of information that will also help you. Things they didn't mention perhaps because it was assumed to be so obvious. One of the best things about the Gbody is all the interchangeability of parts. Read my bullet list below and any followup clarifications made by more knowledgeable forum members.

Suspension parts:
For the most part the rear axle is, IMHO, the fly in the vaseline. There are several ways to fix it as previous posters pointed out. A "great" fix will not be cheap. Depending on whether you plan to hotrod it, dragrace it, just drive it, that will dictate your rearend choice at what horsepower levels.

dragrace : don't even think about it, replace the 7.5" 10bolt, preferably with a Ford 8.8 or 9"
hotrod it : if you can afford to upgrade it ($$$), do it, either by replacing the rear axle or at least the rear gears
just drive it : it'll be fine but replace the rear gears if you can, the butt-dyno can tell the difference

Here's where the really cool part comes in; each Gbody came with it's own selection of suspension performance parts that were partially shared with other Gbodys. You can either get those parts at a junkyard or get them from one of the forum members who sells them. Each one of these parts will absolutely improve the handling of your GMC Caballero (aka El Camino). Since the Caballero came with practically nothing (like the El Camino), it wouldn't hurt to acquire them all.

I may have missed one or two but these are the parts that come on Gbodys alone.
Jounce bars
Monte Carlo bar
Radiator crossbars
Firewall to fender bars
Fender to radiator support bars
F41 front and rear anti-sway bar
quick-ratio Monte Carlo SS steering box

There are some other things you will want to do, or have done
-unless you buy aftermarket replacements or change your rear axle, modify the rear control arms by welding on plates to prevent them from flexing
-install a replacement steering shaft from a Jeep
-install a true dual exhaust but this will require modifying/replacing the transmission cross-member

Now, due to beauty of interchangeability from OTHER GM parts, you can do the following:
-replace the whole front spindle/rotor and disc brake calipers with those from a junkyard 1998-2005 4dr 2WD Blazer
-you can also replace the rear drums with the rear discs from the same Blazer. alternatively, leave the drums and simply upgrade the brake cylinder to that of an S10 pickup truck; it's a larger bore and applies more pressure for braking
-swap out the 7.5" differential gears from that of another 7.5/7.625" rear, like say, that from a Camaro. however, be forewarned this is not as straight-forward as it looks as most Gbodys had 2.4 or less gears and there is what is called a Series 2 and what is called a Series 3. this upgrade is best left done by a professional.


As you can see there are lot of mechanical upgrades that can be done and fairly cheaply at that. Just to blow your mind, there are also a number of body parts (front fenders, doors) that you can swap out, but that's a different thread/subject for another day.


All corrections to this post by more qualified forum members are welcome!

 

[454GrandPrix]

I, too, am gonna add something to this thread: think about the end from the beginning.

I agree with what a few other members have already said: re-gearing your car will definitely wake it up and help it get off the line faster even if you don't add more power to the engine. To that end, you may consider re-gearing the stock axle. However, I would advise against this. If you will ever swap in a different axle in the future, then do not spend one penny modifying your current axle--this is money you'll just need to spend again when you install a better axle down the road. Spending money twice on the same thing is (obviously) unwise, and if you're on a tight budget it can be downright painful.

Just a thought.

 

[64nailhead]

Really I just want to have a mean street machine

I am still driving this on the road regularly and I want it to be as badass as it can be while still being decent on the highway handling wise (I don’t care about fuel economy)

I understand that a 10 bolt with a 7.5 will be fine for a 350. But who knows 10 years from now i might want to park this thing and put a BBC in it so wouldn’t the 9” be the best choice?

And what are my options if the calipers do run the frame ?

Sounds like you're in the 'classic' quandary between budget and lofty goals/expectations. Some guys can hold off on getting their car on the road and waiting until the entire build is funded, versus those of us that prefer enjoying it while they save some money to make future upgrades. You have to decide which way you want to go and what you have budget for.

For myself, I prefer to get it on the road and enjoy. If I were in your shoes, then I'd be spending less than $500 to upgrade the 26 spline 7.5 and axles to a 28 spline 7.625 with either aftermarket or S-10 axles. And down the road when the big power hits upgrade to a heavier rear (that you can be shopping for in the meantime). That was the path we chose and we were able to find an stock 8.5" for $600 that we sold the dif, axles and gears for $300 or $350. From there we built the 8.5" to take all we are putting to it. There are other options - 9", 12 bolt, etc, but these all are expensive options if you have to buy everything right now as opposed to picking up used parts.

 

[DRIVEN]

One of these days I'm going to sit down and write down all the things that I wish my present self could tell my new Gbody owner self 10 years ago.

To the OP; If instant gratification is a factor, I'd probably suggest picking up another 7.5 with either 3.42s or 3.73s. Then I'd swap it in and hang on to the original for a just-in-case spare. There are a few reasons I am suggesting this. First, it's a 100% direct swap. Second, it's probably going to be cheaper than regearing your current rearend. Third, it's the least expensive way to audition a ratio. If you find you don't like it, sell it and try a different one. Fourth, going from 2.4Xs to 3.42s feels like you added 100hp under the hood. And fifth, it'll make it more fun while you're deciding what you really want to do with the project. And when you're done, you should be able to sell that 7.5 for what you paid for it when you install your 8.5/8.8/12bolt/9".
7.5s will last a good long time if you don't mercilessly beat on them. They will not tolerate a gravel to asphalt burnout.

 

[pontiacgp]

figure out what you want to do with your car and don't let others influence you into do what they want. My GP needed work so it didn't bother me from modifying the car but if my GP was in the great condition like your GMC I don't think I would have touched it. As for upgrading I had the advantage of building and crewing on a G body circle track car. I got to test what works and what doesn't and the circle track world has lots of parts made for the G body or Mertic as it is known in racing.

 

[lilbowtie]

Really I just want to have a mean street machine

I am still driving this on the road regularly and I want it to be as badass as it can be while still being decent on the highway handling wise (I don’t care about fuel economy)

I understand that a 10 bolt with a 7.5 will be fine for a 350. But who knows 10 years from now i might want to park this thing and put a BBC in it so wouldn’t the 9” be the best choice?

And what are my options if the calipers do run the frame ?

So you want one of these -

That does this -

Get your check book out !!!

 

[JohnnyUtah1]

I, too, am gonna add something to this thread: think about the end from the beginning.

I agree with what a few other members have already said: re-gearing your car will definitely wake it up and help it get off the line faster even if you don't add more power to the engine. To that end, you may consider re-gearing the stock axle. However, I would advise against this. If you will ever swap in a different axle in the future, then do not spend one penny modifying your current axle--this is money you'll just need to spend again when you install a better axle down the road. Spending money twice on the same thing is (obviously) unwise, and if you're on a tight budget it can be downright painful.

Just a thought.

Just because l

So you want one of these -View attachment 94257

That does this -

View attachment 94259

Get your check book out !!!

Best option and cheapest option is something to consider. The G-body 8.5 is a rare bird these days. Came in some of the later 442's and the Grand National. They can usually be found in the $1000 range, depending on how long you search for one.

The stock 7.5" will last for a while if you avoid drag slicks and traction.

The GM 10 and 12 bolts from the A-Body (68-72 Chevelle GTO Monte Carlo Cutlass an so on) fit with a conversion kit. Those rears can be found between $300-$1000, depending on how long you search for one.

https://southsidemachineperformance...olt-swap-double-adjustable-upper-control-arms

The Ford Explorer uses an 8.8" ring gear (basically a GM 12 bolt clone) and can be found for around $100 or less, again depending on how long you search for one. This also requires a kit.

https://southsidemachineperformance.com/products/explorer-88-swap-kit

Another common solution is to have a Ford 9" built and delivered for around $1800-$2200 if you don't have a tight budget.

Another thing to consider is the poor geometry these cars came with and weak trailing arms. All of our kits are focused around these weaknesses.

All of the above solutions can offer multiple gearing choices and a positraction as well.

What year Ford Explorer should I be looking for?

Trying to explore all my options

Sorry for the late reply Will be getting on my computer soon to reply to everyone and ask some more questions

This forums really messy on my phone

 

[JohnnyUtah1]

find a monte with a 7.5 3.73 posi if its just a low power stock 305, if your gonna do work with this find a culass/regal/gn 8.5 with a locker

Why year Monte should I look for?