rear end question

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38 Dodge

38 Dodge

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OK I picked up a parts car 67 Barracuda the other day and today I pulled the rear end out. it looks like to be a 8 3/4 on the casing it has the following numbers 2070741 6V29 24. So can anyone tell me what I have or how can I tell with out breaking the unit open?
Thanks for any help
 
It's a 741 center section. Sounds like 8 3/4 to me. No idea on gear ratio or sure grip or not.

Turn one axle if the opposite axle turns the same way sure grip, if it turns the opposite way open.

Turn one axle one complete rotation and count how many turns the yoke turns, this will give you an idea of ratio.
 
It is the third one down, and I did turn the axles on one side and the other one turn in the same direction, I also tried to hold one axle while turning the other and I could not keep it from turning. Is the 741 a good rear end?
I will try to find out what the ratio is tomorrow and post what I find out.
 
A 741 has the smallest pinion diameter of the 8 3/4 but they are durable. I flog the snot out of mine with a 400 horse 340 and a 4 speed. It been great for the last 7 years.
 
OK so with my street / strip build on my 67 cuda I should have no issues?
 
I must doing something right I pick up this parts car for 100 bucks and it turns out to be a 8 3/4 sure grip rear end, a V8 K frame with a sway bar, plus lots of extra parts. Then I go to the local pick and pull yard and find an roller 318 out of a 86 Dodge truck, and the motor is almost spotless.
Knock on wood; turn around threee times anything to keep this going.
 
38 Dodge said:
OK so with my street / strip build on my 67 cuda I should have no issues?
Click to expand...


I don't believe there is much for ratios out there for the 741 case. Factory did offer 3.91's but most aftermarket only go 3.73 for their steepest gears.
 
Thanks,
can you explain the ratio thing to me I get alittle confused on on the ratio. What would be a good ratio to run, higher ratio means _____ and a lower ratio means _______
 
crumpuscreature,
Are you stating I should not have an issue or are you saying I will have issues with this rear end?
 
The problem with the 741 case is gear selection. I would pull the 3rd member to see if it's a sure grip. It might have a spool in it or even a lincoln locker.
 
38 Dodge said:
Thanks,
can you explain the ratio thing to me I get alittle confused on on the ratio. What would be a good ratio to run, higher ratio means _____ and a lower ratio means _______
Click to expand...

Well a steeper gear set for example drag racing would be like a 4.56 and a highway set would be like a 3.23. If you pull the 3rd member it will tell you the ratio on the outside edge of the ring gear.
 
So if I understaaand this correctly the lower the gear the better for street use and the higher the gear is more for racing?
Also you stated a spool or a lincolin locker what would I look for to determine which one is which? Also what is the differance between the two?
 
38 Dodge said:
So if I understand this correctly the lower the gear the better for street use and the higher the gear is more for racing?

Yes, numerically.

Also you stated a spool or a lincolin locker what would I look for to determine which one is which? Also what is the differance between the two?

Spool would be a solid piece in the center where the ring gear attaches, effectively making it a solid shaft across the diff.

Lincoln Locker is where the spider gears are welded together.
Click to expand...
..
 
38 Dodge said:
crumpuscreature,
Are you stating I should not have an issue or are you saying I will have issues with this rear end?
Click to expand...



If in fact it's a sure grip and the gears are decent it should live a long and happy life in a moderately driven street car.
 
First off Congrats:thumblef:, you made out like a bandit on this deal. And as Badart said, just pull it and make sure what you have. Hey, it's gotta be done anyway. You don't want to use 40 yr old gear oil in your new build.:D
 
That is true, I have never messed with a rear end before, so Ill tear in to it tomorrow and see what I have, I will try and post pictures to make.
Thanks for all the help and information
 
Dont get too into the rear, pull the axles with your hands after the 5 nuts are removed, pull them all the way out so you dont rest them in the inner seals. Flip the rear so the pinion points up and remove the nuts. The pig should lift right out barring any RTV used as a gasket. Careful it is heavy and clunky, if you grab it by the gear it will roll right out of your hands. Look at the edge of the gear, the ratio should be on there somewhere stamped clear as day. 741 is adequate for most A builds as they are pretty light. You should have no problems with it. If its going into that antique, there is no weight back there, good to go.
 
Thanks pista,
I will pull everything like you suggest and this rear end is going into my 67 Barracuda, I have been told that I should get a rear end from a B body that it will bolt right up in my 38 truck.
 
There might be a tab held on by one of the center section bolts that will give you the gear ratio. Sometimes they are on backward.
 
Well I pulled the rear end apart today and here is what I have found on the outer ring gear 2070611-323-1 M6 277 10 7 66 J86. Also when I was rolling the gear aaround to find the numbers these two parts fell out (see Pictures ). So the question I have is what do I need to do / know and where do they go?
 

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Well sir what you have there appears to be 3.23 gears on a clutch type suregrip. Nice score.


The pieces that fell out are the thrust buttons, no worries you can order a new pin and pop them right back in. They act as a center section of the axles so you can set your axle end play.

If you decide to go any further there are some steps you should take before you tear it apart.
 
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