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Differential


old rat 49

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One thing I have noticed is that back in the day these cars were using 8 and 9 leaf narrow spring. Now we use wider with fewer leafs. Buying/fabbing new brackets is easy. Also noticed that on a Ford Ranger site I ended up on they are quite frequently reversing hangers for lowering swapping out different length springs with relocated mounts with apparently no ill effects. The Ranger springs seem to be quite a bit flatter also so lowering a bit may not require too much work.

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Thanks Robert that eases my mind a bit. My thought is to use the entire rear end as an assembly; driveshaft (modified to fit P15 trans)-diff-springs by just adding new mounts to frame. Spring location on axel would more than likely have to be moved. The Ranger does not appear to have the arch of the P15 springs therefore providing a little lowering. During install rear mounts can be reversed to use for more lowering if desired by changing length of hangers. It would seem to me that the truck springs are wider with fewer leafs than back in the day so weight carrying ability should not suffer. Any obvious flaws with my conjecture. Will try the Aerostar coils in front.

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I am running 3.55/1 gearing in my car. I do have a 251 CI Desoto flathead engine and an overdrive transmission. I have no problem pulling all but the steepest of hills without shifting out of overdrive. At 70 MPH I am spinning the engine around 2200 RPM's with the overdrive engaged.

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Did you do the math using a 3.55/1 differential and 27 inch tires? There is a calculator on the web site of forum member Tod Fitch that will give you engine RPM's at any given speed. I think your 218 engine would do well with a 3.55/1 rear gear and no overdrive transmission.

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Don; your engine has a bit more pep than my stock 218 and I would like to keep the 3 speed for right now. PS: Love that engine work you did.

I think for pulling power a 5 speed, (Ranger trans) would be a big improvement for you.

My 38 has a stock 218, 5 speed Ranger trans, 3.73 rear, very good pulling power, and very

driveable on the highway in 5th gear. I usually start out in 2nd gear, if on a level surface.

I used a driveshaft from a Ford Explorer 2wd, short wheelbase, (2door Sport).....

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 I'm not sure if my 46 3/4 ton pickup had a 218 or 230,  but I installed a 3.55 mid 60's 8 3/4 rear and drove it everyday for about 3 years, including hauling my kids racing go kart all over the northeast. No speedometer, but I passed as many cars on the highways as passed me, so I figured I must be doing the speed limit or more. Had the 4 speed truck tranny with granny gear, but I usually started out in 2nd gear with no problems. Engine was stock, but after about 40/50 thousand miles, I wore the poor girl out.

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