I was wondering if i could put 3.55 in my 7 1/4? how long will it take?
thanks

I thought you had an ASE certified tech friend...part of his 'rudimentary' training should've been a 10 week class on rebuilding rear-ends...

You should be looking around for that 8 1/4 or 8 3/4 rear-end....

-D.Idiot

Yes my good friend dave is Ase certified he is also married certified kids certified and two jobs certified Besides i want to ask some of my fellow slant lovers every, time i ask him a question about my car he says get a 2 door with a v-8

If your buddy can't help you swap gears and run patterns for a Saturday, then you'll need to take it to a shop. If you are to the point of putting 3.55's into a 7 1/4" it might become more prudent to find one of the larger rears, since they can take more abuse, and it's easier to get a sure-grip unit for them (you'll want to have one during 'speed tests')...

You won't be able to do it on your own without his knowledge and tools....

-D.Idiot

What car can i get a 8 1/4 rear D.I?

You're looking for a 1973-1976 Dodge Dart,Dart Sport, Plymouth Valiant, Duster that the rear has 10 bolts in a roundish cover.... all the cars I've seen with 8 1/4" had Front Disc Brakes, but some cars during those years had front discs and a 7 1/4" rear with 10" drums too.... The 8 1/4" usually got used in HD applications all 340/360 cars had them, but some 318 AC cars and some slant cars have them too...

-D.Idiot

Look towards the bottom....
http://www.moparts.com/Tech/Archive/axle/6.html

Several years ago I replaced the 7 1/4 rearend in my 68 Valiant that had a 2.76 gear in it with a 7 1/4 rearend with a 3.23 gear in it. Many that sure helped the way the car started from a stop. I bought the whole rearend with springs, (springs were even the 5 leaf HD units) backing plates, drums mounts brake lines, emergency brake cables and all for $50.00. When I pulled the cover and axles I found that the rearend had been serviced recently and even had new seals in it. It sure helps if you keep your local junk yard on retainer. Later on I put a 904 in it with a lock up converter in it and that helped keep the crusing rpms down some and helped with mileage.

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Former bent 6 owner
Mark

I heard that 3.23's came stock on manual trans cars even in the 7 1/4"rear. is that true?

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A non- definitive list that I've seen on why chrysler put X rear ratio in to X car...

I have noticed that all the 3 speed manual cars I've owned, or looked at have the 3.23/3.21 rear ratio (Sure makes for a 'Peppy car'). Oddly the 4 speed cars get 'what they were designed for'...so 'muscle cars' with a 4 speed get the 3.23-4.11 rears, some years the OD 4 speed cars got the 2.94's and automatics depending on engine options/year could have 2.24,2.45,2.76, or 2.94's..with the 'performance' versions getting the 'hot ratio's like 3.21-4.11.... I have even noticed on part swapping lists that the 1964-1966 Barracuda could even come stock with a 3.55-3.91 7 1/4 rear, but I haven't seen one so equipped yet....

-D.Idiot




since we are into the 'next generation' many cars I find in yards aren't the 1st/2nd owner wrecked it and still has 'stock' items under it. 90% have had the rear swapped (blew up the original 7 1/4, so they bought a $50 2.76 and ran it until the Dart died...etc...), so crawling under the car and rolling the pinion around and counting revolutions will be your guide when you can't find the tag or stamp on the cover or casing for the ratio.

If the cover is already off, you can look at the edge of the ring gear, usually there is a marking. Otherwise, you can count the number of teeth on the ring gear and divide by the number of teeth on the pinion to get a precision ratio.

The 3.23 that I had gotten came out of an automatic car that appeared to have never been touched.

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Former bent 6 owner
Mark

You're absolutely right on target-- that was pretty much the rule, for other than a handful of V8-3spd cars. According to my collection of dealership literature for Plymouth Valiants: both the 1964 and 65 booklets indicate all cars got 3.23 ratio unless ordered otherwise, no matter whether standard or automatic transmission. The 66 booklet is slightly more interesting: the 3.23 was the choice for all 225 engines with manual transmissions, and the 273-2bbl with 4spd, and all 273-4bbl with either manual or automatic. The only remainders from that were: with the 225-auto, or the 273-2bbl-auto or 273-2Bbl-3spd, the ratio was 2.93 (again, unless ordered otherwise.)

The above matches my experience of about a dozen cars. And you're right, darn near everything I've seen has been 3.23, except my 66 Fish 273-2Bbl 3-spd.

- Erik

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Lots of early Valiants and Barracudas have crossed my path.
Also a handful of other toys for variety now and then.

Just for what it's worth. The lowest ratio gear, the factory installed in the 7 1/4 rear, was a 3.91. The old Direct Conection parts program, had 4.11, 4.56, 4,88, and 5.13 ratios for the 7 1/4 rear. These came out for "stock eliminator" racing back in the 70's. At that time, the rules required retaining the original rear housing. You were not allowed to upgrade to a stronger rear or one that had a larger selection of ratio's.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Note that the pattern shown here for the 8 1/4 is rotated 90 degrees from the way you will find it under the car, so don't let that throw you. The easiest way to spot an 8 1/4 rear is it is the only one that has a bolt at the top of the cover that is centered.