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Discussion Starter · #1 ·
Ok, I am catching so much grief for NOT using a larger rear end than my GM 7.5. So, if anyone can help me with this situation, I am more than happy to jump up to a larger rear end.

I will use a any larger size rear end as long as the pumpkin housing portion edge from side to side is no wider than 16". I will have to narrow the axle tubes it down of course. Right now the inside edges of my leaf springs are 16" plus 3/8" U-Bolts. So as it is right now, I am already 3/4" too wide for my springs but I can spread them slightly and make it work. I have been looking but I cannot find any online info about any rear ends that come close to this dimension. All help is appreciated.

Project Specs:
1989 S10
Narrowed stock frame rails (21" out to out)
33x 21.5x 15 Mickey Thompson Sportsman PRO
15x15 wheels
Product Triangle Slope Rectangle Line
Tire Wheel Automotive tire Tread Locking hubs
Tire Wheel Automotive tire Locking hubs Tread
 

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Don't know what housing you have pictured, but looks like a quick change. Whatever it is you are not going to be able to get it narrow enough if that drawing is anywhere close to scale. You are going to need very short axles, and its going to be somewhat difficult to get the ends of the housing square if you don't know how to do it , or have the tools to do it.

I would set the rear end on a steel table and level it from end to end. Then tack weld it so it can't move. Make some plates that bolt to the end s of the housing and they should be parallel to each other . Measure front and back and get the same reading on the plates. Then measure top and bottom and get the same reading. If everything is correct, then cut one end off and reweld it back in place. Just tac it. When the plates are reading the same dimension in all four locations, it should be good to go. Weld slowly and move from place to place to prevent warping. Then cut the other end and weld it back parallel to the first one. Then find someone who can cut the axles and spline them as well as drill them for your wheels. You are probably better off getting someone who knows how to do it, but get your rearend first rather than have them get one. That will save some money. If you can find it online, Hot Rod Garage has a video where they narrow a rear end. Might be worth watching.
 

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1941 Chevy Special Deluxe Coupe
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leafs at 19" on center doesn't seem stable if going around a turn at more than parking lot speed. Consider ladder bars, coil overs and a roll bar.

It will be as stable as is can be with a careful driving habit. I am going to use a heavy sway bar in the front and not sure about the rear yet. These leaf's with some coil spring shocks would make it pretty stable. Again, this is a pro street truck with skinnies on the front. I will not be taking runs at high speeds or running an slalom courses with it. The truck will only be used for street cruising around town some and to my local car cruise in. If i were going to drag race, street race or beat on it, I would be using a ladder bar and coil-overs but there is simply no need for that with my intended purposes for the truck. Thanks for the input.

I measured today, the distance of wheel mounting surface to wheel mounting surface will be 34-1/2". That leaves 1/2" between the tire and the frame. going to be a very narrow rear end.
 

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If you install a rear sway bar, you can get shafts with splined ends (Nascar/Ebay) that are different lengths. Then they have arms that are splined and slip onto the splined shaft. I did that on the front of a 49 pickup with Corvette front suspension. Given the leverage of the wide tires on the narrow suspension, its good to have one if you can find room for it.

There is a road on the way to my son's house that has a slight downhill curve............that is off camber. I hate that curve (and I used to race motorcycles). You never know what lies ahead on a road, even when you attempt to be a safe driver. The curve I was talking about has no guardrail and then continues downhill into an open field.
 

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If you install a rear sway bar, you can get shafts with splined ends (Nascar/Ebay) that are different lengths. Then they have arms that are splined and slip onto the splined shaft. I did that on the front of a 49 pickup with Corvette front suspension. Given the leverage of the wide tires on the narrow suspension, its good to have one if you can find room for it.

There is a road on the way to my son's house that has a slight downhill curve............that is off camber. I hate that curve (and I used to race motorcycles). You never know what lies ahead on a road, even when you attempt to be a safe driver. The curve I was talking about has no guardrail and then continues downhill into an open field.


Click on above. I used one of these on my Street Rod. Worked great.
 

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With that width your running a parallel 4 link and a wattz link off the diff. You might even be able to get away with running quarter elliptical leafs with a watts link and some good coil over shocks doing most of the work.

For what your describing I would cut down some small diamiter rear outers and slide them inside a large diamiter inner housing(with several inches of overlap and smart welding). Its a old trick that works requiring basic tools. Then your left with some custom length axleshafts and leaving the 3rd open.
$500 to $1500 depending on what deals you find.
 

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I get things like that all the time concerning AMCs. AMC made a 7-9/16" ring gear axle (AMC15, Dana 35 is the same) and an 8-7/8" (AMC 20). The smaller one was used with sixes, the larger with V-8s and in there big cars with a six. The prevailing "wisdom" is that you need the larger axle with a V-8, period. The smaller axle, however, will easily take 300-400 hp... depending on other factors. The main thing is how do you expect to DRIVE/USE the vehicle. You're narrowing the frame and installing big tires. If you have a big engine and plan on doing burn-outs often, you will need a larger axle for longevity. If only on rare occasion you should be fine. It's not like the axle will BREAK the first time you get on it, but it will wear a lot faster. If you just plan on cruising around and driving it normally/easily, save yourself the weight of a bigger axle. Occasional burn-outs and such should be fine with street tires, but then those are some pretty big meats you plan on running on the back. I'd lay off the burn-outs since the tires have a good bit of grip. Then again, it's a truck with not much weight in the rear, so you really should be okay, at least in the short term. Normally I'd say run the 7.5 while you look for an axle, but you have to narrow that thing. Probably not worth the expense to narrow the 7.5 just to run it temporarily. A Ford 8.8" from an Explorer is a good alternative (and easier to find) than a 9", and close to the same strength (factory Ford 9" -- some of the aftermarket units have much stronger cases and tubes).
 
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Discussion Starter · #13 · (Edited)
I get things like that all the time concerning AMCs. AMC made a 7-9/16" ring gear axle (AMC15, Dana 35 is the same) and an 8-7/8" (AMC 20). The smaller one was used with sixes, the larger with V-8s and in there big cars with a six. The prevailing "wisdom" is that you need the larger axle with a V-8, period. The smaller axle, however, will easily take 300-400 hp... depending on other factors. The main thing is how do you expect to DRIVE/USE the vehicle. You're narrowing the frame and installing big tires. If you have a big engine and plan on doing burn-outs often, you will need a larger axle for longevity. If only on rare occasion you should be fine. It's not like the axle will BREAK the first time you get on it, but it will wear a lot faster. If you just plan on cruising around and driving it normally/easily, save yourself the weight of a bigger axle. Occasional burn-outs and such should be fine with street tires, but then those are some pretty big meats you plan on running on the back. I'd lay off the burn-outs since the tires have a good bit of grip. Then again, it's a truck with not much weight in the rear, so you really should be okay, at least in the short term. Normally I'd say run the 7.5 while you look for an axle, but you have to narrow that thing. Probably not worth the expense to narrow the 7.5 just to run it temporarily. A Ford 8.8" from an Explorer is a good alternative (and easier to find) than a 9", and close to the same strength (factory Ford 9" -- some of the aftermarket units have much stronger cases and tubes).

Thanks Farna.
Yes, your perspective is much appreciated and more inline with mine as far as the utilization of a my 7.5 rear end. So, my truck will be used STRICTLY for cruising around town, hitting the local car cruise in and back in the garage. It will NEVER see a drag strip, street race, burnouts or just stomping it. I CANNOT afford to replace these tires at roughly $600 a piece every time I turn around. The tires I have now are new and I plan to save the treads as long as possible. Aside from that, I am a former Police Officer who will never be caught acting foolish on the streets. Otherwise, I bought a pretty healthy SBC recently that has most all the goodies and probably somewhere around 350-400HP. The reason I bought this engine is because a friend who builds racing engines put it all together so I know it is done right. Secondly, it has the cam, heads, intake, carb, internals and all those things that will help bring out the sound I am looking for.

I recently read an article about the 7.5 / 7.625. Many people have come up with ways of improving these rear ends to last a bit longer under heavier loads. Of course, these 7.5's are what they are and no matter how much one improves it, it will still always be weaker than most other rear end choices. However, like you mentioned, just cruising around town this rear end will last me a very long time. I will more than likely follow some of the suggestions in the article for improving the strength of the housing.

Beefing Up the 7.625 10 Bolt - ThirdGen.Org

My other issue is; I have 16” to inside edge of the leaf's. Even the 8.8 center housing is 16.5” plus the U-bolt thickness (x2). That would put me having to spread the leaf's out some 1-1/4”+/- and I think that might be too much. That would eat the rubber bushings in the end of leaf's up pretty quick I would think.

I know there are too many who just don't understand my way of thinking on this rear end setup and that's fine. When any one of these individuals feels like cutting me a $2-3K check, I will gladly install a 4-link, frame rails, coilovers, 9 inch, posi lok, slicks and on and on and on. However, for right now and for my budget, the way I am doing it is the best option and will still give me the same look I'm after whether I have a Jerry Bickel built back half OR doing it my way. No, I am not dirt poor by any stretch of the imagination. I make an above average income but regardless, I have to get the most bang for my dollar as I can. Recovering from Kidney cancer and Kidney removal surgeries (august of this year) , I am pushing well over $200K in medical bills. Even with my owed portion, I will be feeling those effects for many years. So, I do not have the money that some on here do when it comes to spending thousands on a "hobby". This truck build on my priority list is now towards the bottom. When you get told you have cancer, lots of things on your priority list WILL change in a matter if seconds! I am NOT whining or complaining, I am happy for those who can drop $30-40K or more into a build with all the good stuff, I can't. Like millions of other people, I still get up and go to work every day. Like millions of other people, I still have a house payment, 2 car payments, insurance, bills and so on. Not trying to get personal with my life but some on here need to understand why my purposes for this build are NOT intended for building a drag or high HP truck. My drag racing days, high HP builds, etc. are long gone. Today and for ever how many more years I have left on this Earth, I'm just trying to enjoy this hobby as much as I can from the most affordable standpoint I can. I'm just looking to build a street cruiser that simply put; looks and sounds bad ass. Nothing more, nothing less.
 

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And there you are, cruising down the boulevard looking and feeling cool, and grandma pulls out of her driveway in her Prius right smack dab in front of you and with your hard left evasive maneuver over you go in a double barrel roll.
Your first thought is holy crap, your second is why didn’t I do it right! Shoulda turfed those springs and done some bars and coil overs.
just sayin‘!
 

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Discussion Starter · #15 ·
And there you are, cruising down the boulevard looking and feeling cool, and grandma pulls out of her driveway in her Prius right smack dab in front of you and with your hard left evasive maneuver over you go in a double barrel roll.
Your first thought is holy crap, your second is why didn’t I do it right! Shoulda turfed those springs and done some bars and coil overs.
just sayin‘!
And a bolt of lightning could strike me down too! just sayin'.

Again, the highest speed limit in my town where I will be cruising is 45-50. If I can't stop or evade someone as in your scenario, then I need to forget the whole project right now. I have worked too many wrecks to count over the years at every speed imaginable. I am very well educated on the cause and effect of car wrecks at varying speeds. If I go outside of my town, I will trailer it.
 

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Race it, Don't rice it!
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I wanna see go it go down the road and the smile on your face when the heads turn. Damned what others think.
You always have the option of redoing it a different way if you didn't like it.
Thanks for all you do as well, LEO's have been put into a tough spot and I at least appreciate it the level the BS that has to get dealt with these days.
 

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Discussion Starter · #17 ·
I wanna see go it go down the road and the smile on your face when the heads turn. Damned what others think.
You always have the option of redoing it a different way if you didn't like it.
Thanks for all you do as well, LEO's have been put into a tough spot and I at least appreciate it the level the BS that has to get dealt with these days.
Thank you. I appreciate your understanding and comment as to my intentions with this build. I am sure one day if things change for me, I will go back and redo the back half. I just cannot justify it at this time.

Thanks. Being a LEO was the best work experience I ever had. It was tough at time but through every situation, I always learned something new. Just helping one person in a positive way was worth dealing with 100 negative people. I left LE in 2006 and it was bad then but today, it is insane crazy more than ever. (y)
 

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Well, being an '89 S-10 it will at least have 28 spline axles and not the earlier small 26 spline.
As long as your fine with the cost of the custom axles it should be fine as a cruiser. Since they will be custom length, I'd expect $300-350/pair for those. Maybe more with the way prides are rising lately.
If you did have some worry about breaking an axle and losing the wheel out from under the truck in motion you could put C-clip eliminators on it....another $150 expense though.

Have you considered the new tire diameter and the rear gear ratio??
Happen to know what the stock ratio is??
if it is something like 3.42, or even 3.73 it may be too low for the planned engine and end up with poor driveability, blubbering, stumbles, etc.
Gearing for those 33" tires to match a typical 26" tire and 3.42 rear gear would be 4.33 as the new gearset needed.
 

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See picture of rolling chassis and profile picture. When I first built the the car I used a Posi Lock or also called Governor Lock rear end from a '97 S-10 Blazer because I owned the Blazer from new. The triangulated 4 link and coil overs worked great. The rear end worked fine for cruising around like a 90 year old driving 10 MPH under the speed limit. In my case I'm running an LS1 making over 400 HP with a Tremec 5 Speed manual with 3.27 1st gear and .67 5th gear. The s-10 Rear was a terrible choice with my engine and trans combo. The rear acts like an open diff until you get on the throttle and one wheel starts spinning then the diff locks and both wheels start to hook. This all sends the car into a very violent uncontrollable fishtail action. Forcing you to back out of the throttle. I nearly rolled my freshly built street rod. Very, very dangerous. The S-10 rear was designed to get you out of a stuck situation in mud or snow not a performance rear end at all. I drove the car 500 miles and changed the rear to a '97 Ford Explorer Rear with 3.73 gears, disc brakes, 31 spline axles, and a real positraction design with friction clutches etc. like in a Ford 9 inch or a GM 12 Bolt. I shortened the left axel 2 7/8" by using another right side axle. This also centers the pumpkin to align the driveshaft in the tunnel. I did a complete rebuild of the Explorer rear. By far a much better rear over the S-10 unit. Much, much safer. No more insane fishtail from unpredictable posi lock. Nice positive, safe experience and by far better brakes. DON'T waste your time, money, and energy on the S-10 Rear. I did and learned the hard way. You say you're only going to gently cruise with your car. Come on it's a Hot Rod. You're gonna "See what this thing can do". We all do and believe me, you don't want to find out like I did.
 

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Coil overs are cheap from a local oval tracker---you don't need fancy shocks. Springs are cheap. A ladder bars bracket with rear coil overs mount is narrow and more likely to fit than a leaf. Need a panhard bar or a track locator too. And a crossmember above the axle to mount the coil over.
 
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