i have a 1972 plymouth scamp was a slant 6 car paid someone to put a 318 in it. but now i have cash again and i wanna upgrade the rear end as its still the slant one what should i go with and what all do i need ( like will i need a bigger or stronger drive shaft
needing a new rear end and advice
- Thread starter ohnogerm
- Start date
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Locomotion
Well-Known Member
An 8 1/4 rear would probably be the easiest to find. (I think.) You don't need the extra strength of an 8 3/4" with a mild combo, but it wouldn't be bad to get if you find a deal. Anything out of a '72 or older a-body would be an easy swap and same width.
You will need the proper length driveshaft with the proper slip yoke for your trans and correct size u-joint (probably the small 7260) for the rear end pinion yoke. Different rears will need different length driveshafts. Not sure if there are 2 that may be the same.)
Best bet would be to find a junkyard V-8 Scamp, Valiant or Swinger with the same trans as yours and get the rear and driveshaft together. I believe all 3 have a 111" wheelbase.
Dusters, Dart Sports and Demons have a shorter 108" wheelbase so the driveshaft length is different.
http://www.rasoenterprises.com/index.php/mopar/69-general/128-bodies?start=1
Chart shows •1967-1973 Plymouth Valiant as having a 108" wheelbase, which surprised me. Can anybody confirm that or is it a typo? (I'll do a search.)
In 1973, front disc brake cars had the bigger 4.5" bolt patterns, so you'd need different rear wheels. But many drum brake cars still retained the 4" bolt pattern.
Did I miss anything??? :scratch:
You will need the proper length driveshaft with the proper slip yoke for your trans and correct size u-joint (probably the small 7260) for the rear end pinion yoke. Different rears will need different length driveshafts. Not sure if there are 2 that may be the same.)
Best bet would be to find a junkyard V-8 Scamp, Valiant or Swinger with the same trans as yours and get the rear and driveshaft together. I believe all 3 have a 111" wheelbase.
Dusters, Dart Sports and Demons have a shorter 108" wheelbase so the driveshaft length is different.
http://www.rasoenterprises.com/index.php/mopar/69-general/128-bodies?start=1
Chart shows •1967-1973 Plymouth Valiant as having a 108" wheelbase, which surprised me. Can anybody confirm that or is it a typo? (I'll do a search.)
In 1973, front disc brake cars had the bigger 4.5" bolt patterns, so you'd need different rear wheels. But many drum brake cars still retained the 4" bolt pattern.
Did I miss anything??? :scratch:
no not at all you nailed it and i believe the scamp has the 111 wheel base at least thats what auto zone told me . I'm looking at a et of rally rims for my scamp would they fit the bigger rear end
mguner
How many is too many?
If you can find an 8 3/4 rear fromn a 65-66 Fury or similar or 67-70 B body you can move the spring feet in just a little and it will work well with properly backspaced wheels.
Chrysler built a lot of 318 2 barrel a-bodeis with the 7-1/4. A stick shift would typically get you an upgrade to the 8-3/4. An automatic is easier on the driveline because there is less chance of shock loading the drivetrain. Stick shifts tend to transmit more abrupt loads. Neutral drops, burnouts, stickier rear tires would kill the 7-1/4 eventually---if not immediately.
If you want to keep the same Small Bolt Pattern you have now then the logical choice is a 65-72 a-body 8-3/4". Direct bolt-in.
Swapping a bolt-in 73-76 a-body 8-1/4 is an option but then you have the Big bolt Pattern in the rear but the SBP in the front. The 73 340 and 74 and later 360 4 speed cars used this rear.
In my opinion it depends on what you are going to do with the car and how you are going to drive it. The 7-1/4 will live for the present time if you don't abuse it.
If you want to keep the same Small Bolt Pattern you have now then the logical choice is a 65-72 a-body 8-3/4". Direct bolt-in.
Swapping a bolt-in 73-76 a-body 8-1/4 is an option but then you have the Big bolt Pattern in the rear but the SBP in the front. The 73 340 and 74 and later 360 4 speed cars used this rear.
In my opinion it depends on what you are going to do with the car and how you are going to drive it. The 7-1/4 will live for the present time if you don't abuse it.
I'll assume you have the small bolt pattern? What front brakes are you running? Do you have Rallyes all around now?
grumpuscreature
Resident Curmudgeon
Valiants and derivatives (Duster, Demon, Dart Sport) were 108" wheelbase. Darts and Scamps were 111" wheelbase. Whichever rear end you go with, all you have to do is take your current drive shaft to a competent drive line shop and have it shortened to suit. All they will need to know is which rear you are replacing and which rear you are replacing it with. If you haven't replaced the front and rear U-joints yet I would have the shop do that as well. If you have replaced the U-joints, no worries, your rear joint will bolt up to the new rear end. The U-joints didn't get bigger until big blocks came out to play...
74DartSwinger360
The Brat Pack
You are wrong how can you say the valiant was 108 inch and a scamp is 111 inch?????
THEY ARE THE SAME CAR!!!!!!! One is a four door and other is a 2 door.......
Duster, Demon, and Dart Sport = 108 inch wheelbase
Dart Swinger, Dart 4 Door, Valiant 4 Door, and Scamp = 111 inch wheelbase
im using the car as my daily driver noting to crazy just something fun to drive .i would like to keep all small bolt pattern and make it a easy swap in as i plan to do it my self
yes i believe i have small bolt there drum brakes and no rallys just 14" slotted mags i believe there called
If you go can big bolt pattern, you could also use a 70's maverick/comet 8" rear and it is a direct bolt in and has a drop out pumpkin like an 8.75...and they can take a serious beating. Just a thought
I'd go big bolt pattern it opens you up to a whole bunch of different wheels etc....but that's just me
I'd go big bolt pattern it opens you up to a whole bunch of different wheels etc....but that's just me
buckshotbishop
Old Soul
the valiant two door and barracuda is 108 the four might be 111
scamps and valiants are totally different cars
abodyjoe
Well-Known Member
is it a stock 318? planning on putting sticky tires on it and heading to the track? if not i'd leave the 7 1/4 in it.
gniknayrb18
Well-Known Member
i have an 8 1/4 im replacing with a dana 60 but it has the big bolt pattern
I have to agree that the 7 1/4 rear should hold up to a mild 318. We have one in my Son's "73" 4 door Dart and I'm not concerned it will break anytime soon. There are two good ways to upgrade in my opinion. The easiest is to get a 8 3/4, either complete or piece it together. The 8 3/4 is strong, has the good adjustable rear bearings that will last a lifetime, has the small bolt pattern, and has a removable carrier that makes a gear change 1/2 hour away. Next, if you do not have 10 in front drum brakes, swap the Kelsey Hayes small pattern disc brakes on the front. I've done this on two of my cars and am very pleased with the results. The other way to go, since you have front drum brakes (9 in?), is to swap the big bolt pattern disc brakes on the front. Then an 8 1/4 rear. Obviously this can be done in any order. The main point is to think ahead to what you want to end up with, and work toward that goal. I'm assuming Chrysler parts, the same bolt pattern front and rear, and the simplest in the long run.
plymouthgerm
Member
sorry guys lost my password but its a 318 with 360 heads and a mild cam what the guy told me and no its not a track car just my driver but i do like to squeal my tires and take off at red lights
tekslk
Well-Known Member
That will soon kill the 7 1/4.
plymouthgerm
Member
i never plan on going any crazier with the motor i like the 318 an d don't want to sink a whole lot of money in to it how much do these rear ends go for
abodyjoe
Well-Known Member
i think the 7 1/4 will live a long time in that car. down the road if you have any issues stick a 8 1/4 in the thing.
plymouthgerm
Member
thanks so if i run it till it breaks that won't mess my motor up any right ?
If I were to do it again, I would have gone with a B Body 8 3/4 instead of an A Body as it closer matches the offset for the front when it comes to wheels. However, since you don't seem to want to go too crazy with your car, I'd suggest an 8 1/4.
So far my Dart with a 273/904/7.25 has held up fine. Granted, my 273 is tired and probably makes as much power as a rebuilt slant.
So far my Dart with a 273/904/7.25 has held up fine. Granted, my 273 is tired and probably makes as much power as a rebuilt slant.
abodyjoe
Well-Known Member
if it does begin to go i would think your hear signs of it before hand.
plymouthgerm
Member
ok cool
plymouth73
Well-Known Member
If you mean totally different cars because one has 2 doors and the other has 4 doors then you are correct. otherwise they are the same car.
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