Does an M-body use the same leaf spring as an F-body wagon?

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They're all the same, but came with 4 or 5 leaves. Trailer towing package also had a helper leaf (at least mine has!) See this list at dippy.org.
Olaf

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Aspenized

Thank you, that chart is great!

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Rear springs for my 77 Aspen from springsnthings, only $215 a pair. Just state your wanted ride height.
Olaf


Correction, email said leaf springs $215/pr.
Olaf

Correction2: clarified by email: /pr. = pair, which makes those springs quite cheap!
Olaf again.

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Aspenized

I have a question about F-body leaf springs too.

What are the dimensions of the stock U Bolts? Aspen '76 w/ 7 1/4" rearend.

The dimension between the holes in iso-clamp plates, which U bolts go through, is 3". But the diameter of the 7 1/4" axle tube is only about 2.5". Is it acceptable to use U bolts with 3" inside diameter?

There were 2.5" inside diameter U bolts used in my application. The U bolts were stretched so that they fit into the iso clamp holes, which is suspicious. All 4 U bolts snapped during the removal, thanks to rust. Thankfully they didn't snap on the freeway...

Thanks for the answers! I apologize my bad English. Hope you understand what I mean.

Hi, 1967 Dart. You probably have an original version (see text below) 7.25" rear axle in a a car that was factory fitted with a 8.25 rear axle. The 8.25" rear axle has 3" axle tubes, and the iso-clamp plates in your car also have the bolt pattern for 3" U-bolts, that is why they don't fit properly with 2.5" U-bolts. The iso-clamps can also have different measures depending upon how many leaves (4 or 5) you have in your rear suspenion, and the U-bolts will also be of different length. Maybe the best solution for you would be to try to find an F/J/M-body 8.25" rear axle in reasonable condition.

With permission, the material below is copied from Farley's Page at http://www.dippy.org, here are the links to the pages about 7.25" rear axle and 8.25" rear axle.

There were at least three versions of the 7.25" rear used in cars:

Original Version:
Introduced in 1960, these units had 9-bolt covers with 2.5" diameter axle tubes from the axle flanges to the differential housing. These were originally small bolt pattern (5 X 4" bolt circle) axles used in A-bodies (Dodge Lancers, Darts and Plymouth valiants). From 1973 through 1976, they were also offered with a large bolt pattern (5 X 4.5" bolt circle) on cars with front disc brakes. Large bolt pattern versions were even used in some Slant 6 E-body Barracudas and Challengers. The small bolt pattern was discontinued around 1975 or 1976. They continued to be produced with the large bolt pattern as late as 1980, showing up in F/J/M platform cars. 1980 appears to have been a transition year. Per Randy's Ring & Pinion website, the 9 bolt rear uses a different case and spider assembly which is not compatible with later units.

Intermediate Version:
These units had 10-bolt covers with 2.5" diameter axle tubes from the axle flanges to the differential housing. As far as it is known, these were all large bolt pattern axles. This was likely an intermediate version of the 10-bolt rear before the all Chrysler axle tube ends were standardized to 3" at the axle flanges. The change to this version seems to have taken place around 1980, with both 9-bolt and 10-bolt versions appearing that year. A 10-bolt 7.25" rear with a 2.5" diameter axle has been verified in a 1980 Mirada.

Late Version:
These units had 10-bolt hexagon (stop sign) shaped covers with 3" diameter tubes at the axle flanges that stepped down to 2.5" at the differential housing. This appears to have been a bean counter change to standardize the size of the spring fastening and shock plate hardware between the 7.25" and 8.25" axle, which has 3" diameter axle tubes. As far as it is known, these were all large bolt pattern. These units appeared in all light duty (civilian duty - not police or taxi) M-body cars (Diplomats, Caravelles, Gran Furys and Fifth Avenues) from the early 1980s through the end of the production run in 1989.

Many people mistake the 10-bolt 7.25" rear for the beefier 8.25" rear due to the bolt count being the same. There are two ways to tell the two units apart:

* The diameter of the 10-bolt 7.25" axle tubes will either be 2.5" entirely, or they will reduce to 2.5" as they get closer to the differential housing. 8.25" units will have 3" diameter axle tubes all the way from the axle flanges to the differential housing.
* The 10-bolt 7.25" axle rear access cover will look more like a stop sign. The 8.25" unit will have a cover that appears to be rounded or oval.

Even later versions of the 7.25" axle were also used in 80s and 90s Dakotas. The axle tube diameter has not been verified, but it is likely that they had 3" diameter tubes at the axle flanges that stepped down to 2.5" at the differential housing like the ones used in 80s M-bodies.

Factory axle dimensions (7.25" and 8.25") for all F/J/M cars:
* Axle flange to flange: 54.34"
* Perch center to perch center: 44.46"

I hope this was helpful.
Olaf.

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Aspenized

Thanks for the info, Olaf!

That was something I expected. I was told about different iso-clamp plates, but I have never seen the ones with 2.5" pattern. I have gone through several parts cars, all with 5 leaf + 7 1/4, bul all had plates with 3". Never seen the U bolts, because they were cut as usual.

The car is US federal model sedan, originally with 4 leaf springs. I changed the springs and iso-clamps to 5 leaf version. I have identified my 7 1/4 as an early F-body version, which is correct for the car.

Almost all export model F-body cars, which came here as new, were equpped with HD suspension. 4 leaf springs are rare. 8 1/4" F-body axles are also quite common, since most STW:s had one.

I'm quite satisfied with 7 1/4", since it's working and I have several of them at reserve.

I found the production broadcast inside the seat and it confirms that the car was factory fitted with 7 1/4". Then there's possibility that someone has changed the iso clamp plates to bigger models.

I solved the U bolt problem. I bought Motormite 35602 bolts for 2.5" tubes, stretched them to fit 3" holes and cut to proper length. Works fine. FYI that there's just enough threads in these bolts for proper tightening.

Thanks for your help.

http://chucker54.stores.yahoo.net/extraheavyduty.html

What about these leaf springs for my 63? I want the rear higher, and since I am putting new shocks in, I might as well replace the leafs.

I will also replace the torsion bars in the future and wouldn't mind something stiffer as well. would the 1" ones from Just Suspension be a good bet?

I am also waiting on a quote on ESPO springs too.

63Dart170,

I suggest you start a new thread about your car's needs. It will make it easier for people to find it and respond, and find it later using "search." I will be happy to respond.

Thanks,

Lou

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