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Rear end for 79 malibu

15K views 21 replies 14 participants last post by  Slant3 
#1 ·
i have a 79 malibu with a built 327 and 350 turbo trans but my rear end is the question it is the factory 7.5 10 bolt i wanna swith the factory gears to a 4.10 posi trac by using a spool, would you guys build this rear end or swap it with another and if so what rear ends would fit with little or no work?
 
#2 ·
Is this a street driven car? If it is, rebuild the stock rearend with a good POSI unit and a good set of gears. You will not like driving a spooled rear on the street... Don't do it.
Mark
 
#4 ·
Just about everyone who knows anything about axles will tell you what the previous posts have.
A spool is only practical for racing purposes where you want all the power to both wheels and won't be doing much turning.
A spool on the street will tear up a new set of rear tires pretty quick, and the 7.5 inch in your car won't last long with that spool and 327 giving it what it wasn't designed to handle.
Posi, limited slip, or whatever the manufacturers want to call it is the most sensible choice for the price and benefits of the unit.
If you plan on racing that car you might want to look for a 8.5 inch g-body rear (getting pretty scarce), of an A-body rear with the changeover bars, this one is around 2 inches wider at the axle flanges- so a different offset wheel will be the only change necessary.
 
#5 ·
If your looking to get a limited slip unit on the cheap, here`s what I did. I have a 86 olds cutlass supreme, it has the same 7.5 inch rear, I got a rear out of a 83 Firebird T/A with posi and 3.23 gears, all I did was swap the guts to my cars rear, added a bottle of GM limited slip anti chatter lube and have been running it ever since. I later did this same thing to a friends 82 cutlass, however, we looked in 4 junkyards and 32 different F-body`s before we found one, we would jack up the passengers side rear and use sand paper and WD40 to sand off the rust on the front passenger side axle tube to expose the code and compared it to our notes, I`ll leave the codes here, 82 - 87 camaro Z28 and firebird T/A`s, after 87 they used a aussie rear, which won`t interchange.
Year Code Ratio
1982 2JR 3.42:1
1982 2JY 3.08:1
1982 2JZ 3.23:1
1982 2PZ 3.23:1
1982 2PY 3.08:1
1983 4JQ/5JQ 3.73:1
1983 4JR/5JR 3.42:1
1983 4JY/5JY 3.08:1
1983 4JZ/5JZ 3.23:1
1983 4PQ/5PQ 3.73:1
1983 4PY/5PY 3.08:1
1983 4PZ/5PZ 3.23:1
1984 6EF 3.42:1
1984 6EP 3.42:1
1984 6JQ 3.73:1
1984 6JR 3.42:1
1984 6JY 3.08:1
1984 6JZ 3.23:1
1984 6PQ 3.73:1
1984 6PY 3.08:1
1984 6PZ 3.23:1
1985 8JP 3.08:1
1985 8JQ 3.23:1
1985 8PP 3.08:1
1985 8PQ 3.23:1
1985 8PR 3.42:1
1985 8PS 3.73:1
1986 2H5 3.73:1
1986 2HT 2.73:1
1986 2HV 2.73:1
1986 2HY 3.23:1
1987 2HQ 3.23:1
1987 4HF 3.08:1
1987 4HY 3.23:1
 
#7 ·
thanks for all the help guys, and yes this car will see limited street use, also i have a 9 inch ford how hard and how much would it cost to narrow it to fit, because one of my friends has a 68 firedbird with a chevy 454 and 400 turbo he has a 9 inch ford with 3.89 gears and he has a spool in it and drives it on the street quite a bit
 
#8 ·
79 Malibu327 said:
thanks for all the help guys, and yes this car will see limited street use, also i have a 9 inch ford how hard and how much would it cost to narrow it to fit, because one of my friends has a 68 firedbird with a chevy 454 and 400 turbo he has a 9 inch ford with 3.89 gears and he has a spool in it and drives it on the street quite a bit
Or he has a posi, or locker and is lying to you. More likely the case.
 
#9 ·
79 Malibu327 said:
thanks for all the help guys, and yes this car will see limited street use, also i have a 9 inch ford how hard and how much would it cost to narrow it to fit, because one of my friends has a 68 firedbird with a chevy 454 and 400 turbo he has a 9 inch ford with 3.89 gears and he has a spool in it and drives it on the street quite a bit
Malibu...
Does your buddies car squeal the rear tires when doing a slow tight turn in a parking lot? If it does he is running a spool. If not, the car has a limited slip posi unit. If there is a spool present watch the inside rear tire during a turn and you will actually see the tire spinning trying to keep up with the outside tire... Even if he has a spool don't follow him over the cliff just because he jumped... Spools are not intended to turn corners. They put the rear axle and tires in a bind EVERY time you turn because the outside tire wants to turn faster then the inside tire. This puts a massive REVERSE twisting motion on the axles and spool and is very hard on them. It's also very dangerous when going around corners in the rain as the car can go sideways at a moments notice... I really don't think you want that to happen...
As far as doing the 9"? You really won't hurt the stock rearend if you put a good posi and gears into it. It's plenty stout for your 327.... and it's much cheaper to rebuild then replace.
Mark
 
#10 ·
The guys here gave you very good advice.

If it is an 7.5" rear end it will not live long with a spool.

Spools have NO place on the street. As mentioned above corners will cause a bind that usually ends up breaking an axle or the spool. It might not happen on the first corner but sooner or later it is going to break something. The problem is even worse if you have sticky tires.

Spools are meant for drag racing or dirt circle track racing.

A 9" is a great rear end, but if you can hop up your 7.5" it should live. You may also want to look for an 8.5"GM 10 bolt. They are very strong and cheap. I don't know what donor cars will have them to bolt into your car.
 
#12 ·
Unless all my researching was wrong, along with many websites, and automotive parts stores and their parts books too, the 78-87 G-bodies came from the factory with a 7.5-inch ring gear 10-bolt EXCEPT certain models with certain equipment.

The Buick Grand National came with the 8.5-inch 10-bolt.
Some (NOT ALL) Monte Carlo SS cars came with the 8.5.

More than 90 percent came with the 7.5 inch.
 
#14 ·
79 Malibu327 said:
would you guys build this rear end or swap it with another and if so what rear ends would fit with little or no work?

I suggest finding a Monte Carlo SS with a 3.73 and installing the complete rear end.......:)

With a 14 inch tire your would be close to your desired ratio and will NOT have spent a lot of money......plus it should bolt in....


.
 
#16 ·
rear end for 79 malibu

your car doesnt sound overly radical. we have a 12.5:1 400 sb in a 79 cutlass. we are running welded spider gears in that one. a spool is fine. use a mini spool from like speedway motors (about 80 bucks) we run these on asphalt cicrle track. paint a line across your axles and with one turn of twist replace the axles. 373 pozis are redily available in junk yards in 4wd early s-10s and blazers
 
#17 ·
8.5" rears from Buick GN's & Monte Carlo SS's & the occasional Hurst Olds will bolt in with maybe a driveshaft shortening, but those rear ends sell for ~$1000 if you can find one. Southside Machine used to make adapter control arms so you could use a 68-72 A-body rear end, but those aren't too easy to find these days either. They told me they were working on a set to adapt 73-77 rears to the G-bodys, but they went out of business shortly after I talked to them. You might get by using the 7.5 if you don't do anything violent (neutral drops, trans-brakes, etc.) & if it's built right.
 
#19 ·
8.5 diffs are very cheap and easy to find as they came in nearly all 70's and early eighties cars but as far as the spool goes i have a 7.5 diff in my s-10 with a mini spool and 3.73 and have had no problems what so ever sure it makes the tires squeak a bit around corners but big deal i know its not as bad as people make it out to be but yes the proper way to do it is to buy a posi or limited slip but then again like me not everyone can afford 500 bux for a posi
 
#20 ·
sb72elcamino350 said:
Hello,
Would a Impala or caprice 8.5 fit under a 79 malibu wagon?

thanks
NO, first reason is they are too wide and will need a very negative offset wheel to even come close, and will look like a hack job at best.
Second reason, the control arms will NOT line up properly to allow the suspension to work without binding, and no one makes a conversion kit for this swap on the market today.
Third reason, the spring pads on the axle will need to be relocated.


tirefryin_s10 said:
8.5 diffs are very cheap and easy to find as they came in nearly all 70's and early eighties cars but as far as the spool goes i have a 7.5 diff in my s-10 with a mini spool and 3.73 and have had no problems what so ever sure it makes the tires squeak a bit around corners but big deal i know its not as bad as people make it out to be but yes the proper way to do it is to buy a posi or limited slip but then again like me not everyone can afford 500 bux for a posi

UMMM, a powertrax locker, or lock-right locker is around $250-$300 for the 7.5.
Sure the 8.5 came in lots of GM cars and trucks too, but the width of the axle and related links to affix it to the car are the main issue.
The only 8.5 that will directly bolt in is one that would be found in another G-body, which I correct myself from previous statements in saying the Monte Carlos did not have the 8.5 even in the SS cars from the factory unless you knew somebody when you ordered it.
The G-bodies with the 8.5 include the 84 Hurst/Olds, 85-87 Olds 442, or 84-87 Turbo Regal, and of course the Buick Grand National.
 
#21 ·
rear

A 64 to 67 "A" body 10 bolt is the same width as the rear thats in the car. Everything bolts up except the top control arms. They are at the same angle but are about 1/2 " off center of the "G" body rear. I have seen several companys that make a upper arm to fix this. That 10 bolt with a spool and axels will be as strong as you need for your set-up.

If you are running the car mostly at the strip with only a few street miles a year a spool will be ok if you run a softer tire like a hoosier pro or m/t et strret. The soft side wall will help take up some of the shock the others are talking about. The biggest thing with a spool car on the street is common sense. You are not going to be able to auto cross in it. and turning around takes some getting used to. Like the others have stated driving in the rain is OUT. go get your trailer........ Think about it this way. I have been at tracks where you needed to make 3 rights and 2 lefts to get back to the pits after a run. Now if you make 10 passes that day thats 30 rights and 20 lefts. I can go out my drive way and make 1 left and 2 rights and be at the 7/11 thats only a total (round trip) of 6 turns..........I have a friend with a spool car thats been on the street for over 10 years. He only put one set of axels in it over that time. He maybe drives 150 miles a year on the street. Its all in what you want and your intended use....

Keith
 
#22 ·
Basicly The 7.5 will do fine...I had a stock rear with desert gears in it 2.06----Gutted the rear , bought an EATON LSD ,Set of 3.73 gears with the install kit and had my shop do the work...Like the guys said ,if its going to see more street use(main street crusing)than track go with an EATON or AUBURN .I had the same problem and the guys here helped me out with what direction I should take.Listen to them as thats why they are here (for some kickazz info):drool:
 
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