1968 Dart sudden rear end noise.

[1968 Dart 270]

Just replaced the fuel pump.yesterday abd decided to take the dart out. After driving for about 15 minutes the car felt like it was pulling a trailer and I heard a sound like a marble clattering around in the rear end or possibly a brake drum. I was driving it home and I'd hear a scraping,clicking sound when the car would go into 3rd (torqueflite) and every once in a while there would be a sound like a marble bouncing or rattling around. I just got it home and haven't pulled off the drum to.see if a brake spring broke. Anyone here have any ideas? I'm really depressed as I've done a lot of things and wanted to make this a daily driver since my past darts were super reliable. This one is fighting me. Lol

 

[AJ/FormS]

I'm really depressed

If yur depressed now, you haven't been;
> 500 miles from home, with an engine that is overheating for no apparent reason.
> 300 miles from home, with your A833 is stuck in Fourth gear,
> 200 miles from home, when at 60mph, the engine just quit running,
> 100 miles from home, on a Sunday afternoon, with a derailed fanbelt
> 70 miles from home, you hit a dear, at night, and yur headlights are smashed.
> in your driveway, you wife askes you a question, that you cannot answer with any degree of honesty; you know, one of those questions like;
- does this dress make me look fat? or
- how long have you been poking the neighbors daughter, or
- you love this car more than me, don't you.
> or my favorite; you think I'm stupid!?

Did you leave the parking brake on?

 

[1968 Dart 270]

If yur depressed now, you haven't been;
> 500 miles from home, with an engine that is overheating for no apparent reason.
> 300 miles from home, with your A833 is stuck in Fourth gear,
> 200 miles from home, when at 60mph, the engine just quit running,
> 100 miles from home, on a Sunday afternoon, with a derailed fanbelt
> 70 miles from home, you hit a dear, at night, and yur headlights are smashed.
> in your driveway, you wife askes you a question, that you cannot answer with any degree of honesty; you know, one of those questions like;
- does this dress make me look fat? or
- how long have you been poking the neighbors daughter, or
- you love this car more than me, don't you.
> or my favorite; you think I'm stupid!?

Did you leave the parking brake on?

Sounds like you've been the route. Lol. Oh yeah,I've had similar things happen like walking for a week decades ago because a u-joint went bad on a 59 custom royal only to have a girlfriend ask. "Why would you buy a car they don't make parts for" when nobody had the u joint and it took a week to get one from Andy Bernbaum. I've driven home with no lights when the headlight switch failed on another 68 dart. I've driven late 50's mopars home on the parking brake drum on the torqueflite when a master failed (single pot) And I also got the question about why I love the cars so much. Lol.
No,the parking brake isn't on. I'm not that stupid. It's in the rear end. It's making a sound like grinding gears and a couple times on the way home there was a loud bang and it felt like something getting ground in gears

 

[BrianT]

Jack it up and pull the drums. You might get lucky and there's a spring in the drum that bounced around in there and locked the drum? You gotta start somewhere.

 

[69conv]

I would start with the brake drums. Open up and look. I had some retractor springs that weakened and allowed the drums to jam. If that doesn't reveal a result, look into the gears. How many miles on the rear end?

 

[1968 Dart 270]

Jack it up and pull the drums. You might get lucky and there's a spring in the drum that bounced around in there and locked the drum? You gotta start somewhere.

I'll have to do it tomorrow had to go to work. I'm hoping you're right. I had a brake return spring break on a 70 dart once but it just made the shoe drag and I never had this issue. It's making a gear sounding noise. Push the brakes and it goes away but then comes back in a few seconds even if you're still braking. When driving it would be grumbling and then make a sound like a marble bounching around and the make a pop or bang like it was getting caught in something. I ordered some springs just in case. Nobody had them in stock

 

[AJ/FormS]

I'm not that stupid.

That thought was never on my mind. My apologies if it sounded that way.
I was only trying to inject some levity into your situation.

 

[George Jets]

If it's a 7 1/4 rear end, then the pin that holds the spider gears came loose in the differential housing and is working it's way out rubbing on the case.

Soon to grenade.


☆☆☆☆☆

 

[1968 Dart 270]

That thought was never on my mind. My apologies if it sounded that way.
I was only trying to inject some levity into your situation.

Oh no,I know. I didn't take it that way I was meaning it in a joking way too,I know there are really folks that stupid out there.lol.
In fact the emergency brake doesn't even work on the car. I pulled the handle last week for the first time to test it and nothing happened other than the light coming on. I think most people with automatics never used that feature...unless you have a push button torqueflite in which case you used it all the time.
I stopped by the parts store on the way to work and picked up a brake hardware kit with springs,etc. I'm truly hoping it's just a spring jammed up in the drum making that awful racket and grinding sound. I just wish I had the time to get to it today. I hate the unknown and like to get things fixed asap. Thankfully I have other old cars to drive. I'm hoping it's not rear end. I NEVER abuse my cars or beat on them. Never tried peeling out in them. I want them to last and I enjoy driving them.

 

[1968 Dart 270]

Pulled the drums today and no broken springs or loose components inside. Looks like it's inside the rear end.

 

[1968 Dart 270]

If it's a 7 1/4 rear end, then the pin that holds the spider gears came loose in the differential housing and is working it's way out rubbing on the case.

Soon to grenade.


☆☆☆☆☆

Yes,7 1/4" rear with 273 v8. Would the pin be the piece that was making a sound like a marble bouncing around in the rear end? Thankfully I got it to the garage before it did grenade. Can you tell me how to fix it? What causes the pin to come loose? I have never abused this car at all since I've owned it. When it started doing this I was driving about 35 mph on a city street. I hope it can be fixed easily and nothing was damaged yet.

 

[AJ/FormS]

I NEVER abuse my cars or beat on them. Never tried peeling out in them. I want them to last and I enjoy driving them.

Ok gotcha.
I'm a Mechanic by trade.
I build my own stuff and I do beat the chit out of it, then fix it when it breaks then beat the chit out of it some more, until something else breaks. I did that for five years and then finally got everything strong enough, that nothing after that broke any more, lol, Then I drove it for over 100,000 miles with no more breakage. Well except for clutch discs, and tires, lol
Oh yeah and mychit peals out in three gears to 85 mph and more.
If you want my recipe, just PM me, lol.
If you want a ride, come with an empty stomach.

 

[George Jets]

Yes,7 1/4" rear with 273 v8. Would the pin be the piece that was making a sound like a marble bouncing around in the rear end? Thankfully I got it to the garage before it did grenade. Can you tell me how to fix it? What causes the pin to come loose? I have never abused this car at all since I've owned it. When it started doing this I was driving about 35 mph on a city street. I hope it can be fixed easily and nothing was damaged yet.

First off a 7 1/4" rear end is a very light duty rear end.

As the small 2 spider gears start to wear, it wrenches on the cross pin in the case. So much so that it eggs out the case that the cross pin sits in.
Eventually it sheers the the 3/16" bolt pin on the end and the cross pin starts to work out.

They used to sell diff rebuild kits on rock auto for the later year a bodies. New pin, spider gears, side gears, shim washers and anchor pin/bolt.

In reality not much fixing them when the diff case wears out from the cross pin moving.

Last ditch hillbilly effort > weld the cross pin into the case and start looking for an 8 3/4 as a replacement.

☆☆☆☆☆

 

[1968 Dart 270]

First off a 7 1/4" rear end is a very light duty rear end.

As the small 2 spider gears start to wear, it wrenches on the cross pin in the case. So much so that it eggs out the case that the cross pin sits in.
Eventually it sheers the the 3/16" bolt pin on the end and the cross pin starts to work out.

They used to sell diff rebuild kits on rock auto for the later year a bodies. New pin, spider gears, side gears, shim washers and anchor pin/bolt.

In reality not much fixing them when the diff case wears out from the cross pin moving.

Last ditch hillbilly effort > weld the cross pin into the case and start looking for an 8 3/4 as a replacement.

☆☆☆☆☆

Wow. I didn't think these rear ends were absolute trash that coukdnt be rebuilt when they fail. Most things from the 50's and 60's can always be rebuilt. Chrysler put tons of them in these in A bodies and I've seen people state they lasted a couple hundred thousand miles. If they were such junk why did Chrysler put these behind 273's and 318's knowing they wouldn't hold up? Youd think their pride and reputation for being "the engineering company" would be on the line. B bodies never used this rear end I take it. My next question is if it's all doom and gloom and the rear end can't be properly rebuilt to last,how hard to find is an 8 3/4" rear end that will drop on with no modification?.

 

[missing linc]

Wow. I didn't think these rear ends were absolute trash that coukdnt be rebuilt when they fail. Chrysler put tons of these in A bodies and I've seen people state they lasted a couple hundred thousand miles. If they were such junk why did Chrysler put these behind 273's and 318's knowing they wouldn't hold up? B bodies never used this rear end I take it. My next question is if it's all doom and gloom and the rear end can't be properly rebuilt to last,how hard to find is an 8 3/4" rear end that will drop on with no modification?.

Smallest rear axle in a b body was 8.25 to the best of my knowledge. The 7.25 was a very light duty piece that would last forever behind a slant 6, but it doesn't live as long with a V8, even a bone stock 273 or 318 has enough torque to wear it out. Lots of a bodies had 8.25 differentials, but I am pretty sure they were all big bolt pattern, which of course presents a new problem in that your 68 is likely small bolt pattern axles.

 

[missing linc]

An a body 8.75 differential is typically a fairly expensive piece when you find them. I sold a bare housing last year for $500.00. I've seen them for sale here on FABO for anywhere between $750.00 to $2500.00, depending on the condition.

 

[1968 Dart 270]

An a body 8.75 differential is typically a fairly expensive piece when you find them. I sold a bare housing last year for $500.00. I've seen them for sale here on FABO for anywhere between $750.00 to $2500.00, depending on the condition.

Wow. So what is my best option here? Is the 8.25 much sturdier? I just don't understand why Chrysler wouldn't just put a more robust rear end behind all the a bodies.
I like the B body cars like.the Satellite and Coronet a lot too. So all 8.25 dart rear ends had larger bolt pattern wheels? What would I expect to pay for a 8.25 rear?
P.S. My dog makes that same face all the time and rests her chin on me like that.

 

[missing linc]

If your existing differential is not repairable, or too costly to fix, a b body 8.75 or 8.25, or a Ford 8.8 from a Ranger pickup, or an Explorer are also options, with varying costs involved. The Ranger will have 28 spline axles and drum brakes, and the Explorer will have disc brakes, 31 spline axles, a Trac lok differential and either 3.73 or 4.10 gears. Both Ford differentials will also have 5 on 4.5 bolt circles.
Best suggestion I can make is to first find out if you can repair what you have, then do a whole lot of research on the subject. There are threads on the subject here on the forum.

 

[1968 Dart 270]

If your existing differential is not repairable, or too costly to fix, a b body 8.75 or 8.25, or a Ford 8.8 from a Ranger pickup, or an Explorer are also options, with varying costs involved. The Ranger will have 28 spline axles and drum brakes, and the Explorer will have disc brakes, 31 spline axles, a Trac lok differential and either 3.73 or 4.10 gears. Both Ford differentials will also have 5 on 4.5 bolt circles.
Best suggestion I can make is to first find out if you can repair what you have, then do a whole lot of research on the subject. There are threads on the subject here on the forum.

Thanks,I'd like to repair what I have like you said and drive it for as long as it lasts and look for an 8.75 or 8.25 in the meantime

 

[George Jets]

There are differential rebuild kits for '68 > 7 1/4 rear ends on rock auto.

May have to send out the diff housing to a machine shop to weld and redrill the center pin holes if they are egged out.

Here you go:

May be other parts on their site for 7 1/4 too besides these....


☆☆☆☆☆

 

[1968 Dart 270]

Thanks,any chance you have photos of what happens to the housing? I'm curious to see it. I'm hoping I caught mine in time before it got damaged. I've never had a rear end ever go bad before,but I've always had the big cars and my only two other darts never had this issue. I had just about licked the other problems this car had except the fuel sender and then this happens.

 

[George Jets]

Possibly looks like this but the pin wears out in the case.

Sometimes you have to pull the diff housing and ring gear, then remove the ring gear to get it out of the way so you can get the cross pin out for the spiders.

Another hillbilly trick is to grind off the one corner of the ring gear tooth so you can slide the pin out.

You may have just cracked off one or two teeth off the spider and or side gears. Putting the diff rebuild kit in could get you back on the road.

Have to take the rear cover off and see what is bad.

Take multiple pictures and put them up here on this post.

☆☆☆☆☆

 

[1968 Dart 270]

Thanks for the photos. I won't be able to get to it until the weekend. I know when I bought the car it appeared the pinion seal was bad because the outer housing was covered in grime. It's interesting thar the axle bearing kit costs nearly as much as the gears. Are the sure grip 7 1/4" rears more robust?

 

[Washington Dart]

Thanks,any chance you have photos of what happens to the housing? I'm curious to see it. I'm hoping I caught mine in time before it got damaged. I've never had a rear end ever go bad before,but I've always had the big cars and my only two other darts never had this issue. I had just about licked the other problems this car had except the fuel sender and then this happens.

Where do you live? I have a 7.25 complete. Come and take it, free. They are everywhere cheap, if you don't beat your car just swap one out. Same bolt pattern straight swap. Good luck.

 

[missing linc]

Where do you live? I have a 7.25 complete. Come and take it, free. They are everywhere cheap, if you don't beat your car just swap one out. Same bolt pattern straight swap. Good luck.

Best plan right there.^^^^^^^^
If nothing else you'd have a lot of spare parts for future use.