just wanted a simple way to find the gear out oldjeep, starting at the front and working my way back. I'll pull the cover off soon though. I wanted to say this to ms_michelle. I look at your truck, and you have one of the best looking trucks that I have seen on the web. I like the way it sits, and to me the wheels set it off. Hated to read about the wreck but you have done a very good job on it. If I was you I would be very proud to drive that truck around.

 

I'll have to try your math problem. Not real good at it but I'll figure it out. Hated to see your truck on it's side in your pic. I'm sure it looks good now though. I know I would be proud to drive that 56 around. Hope I can get my 48 to sit like yours does. Hope to see your 56 at the next ford nationals at Tenn. Me and my family are planning to go this time around. I would like to gat a closer look at your awsome truck.

 

I agree, there is probably simpler ways of doing it. Of course if you know your RPM at a given speed, it is a lot cleaner than crawling under your truck and only takes a couple of minutes to figure.

I will use a 70 MPH at 3,000 RPM with a tire that has a 25.5 inch diameter.

RPM X tire diameter
MPH X 336

3,000 (RPM) X 25.5 (tire diameter) = 76,500
70 MPH X 336 = 23520
76,500 Divided by 23520 = 3.252551 This indicates a 3.25 rear.

You can change this around to figure your MPH or your RPM.
Say for instance you wanted to how fast you were going at 3,000 RPM, you would figure it this way.

RPM X tire diameter
Gear ratio X 336

3,000 (RPM) X 25.5 (tire diameter) = 76,500
3.25 (ratio) X 336 =1092
76,500 divided by 1092 = 70.05 MPH

You can use any combination of speeds or RPMs or gear ratios, your constant is 336. If you don't have a tach and want to know your RPM, you can do it this way. This is also a good way to figure what your RPM would be at any given speed if you wanted to change rear end ratio. Just subtitute the 3.25 with the desired ratio.

MPH X gear ratio X 336
tire diameter

70 MPH X 3.25 X 336 = 76440 divided by 25.5 tire diameter = 2997.6 For all pratical purposes your doing 3,000 RPM.

Michelle
Chelle's 56 Hauler

 

Whatever you're ratio turns out to be you probably won't like it with the Spicer/Dana 41. Don't bother trying to find a different ring and pinion either. As much as I wanted to keep the rear original I ended up putting in the 9". If you get one from the right year F-100 you only need to reposition the spring perches and change the driveshaft length (Look at the Sticky). I was lucky enough to find one with the 3.25 ratio I wanted. Of course the downside is the truck will be doggier. With a stock flathead and 3 speed like mine I wouldn't recommend going any lower than a 3.25.

 

Thanks alot ms_michelle. That helps me alot by seeing it worked out. I've always been like that I quess thats why I like old cars, and trucks. I can see the problem in front of me and fix it. I hope you have some more answers for me when I need help.

 

Thanks for the info JDMick. I looked at your truck pics. If you don't mind I will have alot of questions about your truck. That truck looks awsome!! I would love to see more pics. if you have them. Where did you get you dash gages from. The way yours is set up, that what I want mine to look like. My dad is trying to get me to change my set out,but I'm going to have the original one redone. I saved the pics. of your truck on my computer so I can show my wife what I'm shouting for.

 

Your very welcome, I hope you can get some good from the formulas.

Michelle
Chelle's 56 Hauler

 

Thanks for the compliments. The guages are original from the truck. They were in pretty good condition except for the speedometer. My sister touched that up for me. I think Jon's F Funhundreds or somewhere may even sell redone guage faces. As for pictures those are the only digital ones I have. Questions are what we're all here for! Good luck with the wife. Keeping the wife agreeable during a job like this can be the toughest part of the job.

 

Now wait a minute, I never complaned when my husband wanted to build street rods. I was always in there with him. I was his number one supporter.

Michelle
Chelle's 56 Hauler

 

HOLD ON!!! Don't want to get a argument going here. I just ment I wanted my wife to see what I want my truck to look like when it's done. The oldest car she has ever road in until she met me was a 93 mustang. It's hard for her to picture my truck like JDmicks. Or looking like Chelle's 56 hauler. My 48 is a complete truck, but it needs some tlc. Matter of fact we got married last March and I sold my 66 fairlane GT so we could have a nice wedding and in return she seen a ad for a 1948 ford truck 1/2 ton in the round-up mag. that was close to home and she said if you want it, then go get it. And the rest is history. So she is supportive. But she does laugh at it alot when she comes out to the garage though. My toughest project yet will be getting her to ride in it. She says that will never happen b/c of how old it is. I think when the truck is done and I spend alot of time driving it and not so much time at home she will change her mind. I just hope that flathead does pretty good on gas b/c this might be a expensive lesson for me.

 

Another qestion for you JDMick. I've never rebuilt a flathead 8 before, just worked on them some with dad. So I guess you redone your motor so where did you get your rebuild kit from and was you satisfied with it. I've read alot in the books I have and some look better than others to me. And what model is your alternater. I'm going to convert mine to 12 volt to.

 

On the subject of getting the ladies into driving the old iron, you just have to get 'em started young! Love them driving shoes...


ROB

 

Boy you don't want to mess with the ladies around here! If you're into this sort of thing you don't count. You must be some kind of different species or something from the kind of woman most of us have to deal with in regards to this old truck stuff. Just kidding!
Anyway, Restoringmy46, or shouldn't it be 48, I have a cousin who owns a machine shop up here who redid my engine. I don't know what brand of kit he used but one thing I'll say is don't go with the adjustable valves. They use some kind of newfangled offset screw that didn't hold at all so I ended up taking the engine out again to have him put some different ones in. After all that we agreed the best way to do it would be the old fashioned way and grind the valves into adjustment. As for an alternator you might want to try this guy http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7938135039&catego ry=33573 . If that link doesn't work just go to ebay and search under "flathead alternator". Good Luck!

 

I can see a future old iron driver there. Looks like she can't wait for those legs to get long enough to push those pedals. The history and the pictures you have of the truck would make it priceless to me. Your lucky to have all of that.

 

No you don't want to mess with the ladies here. She's different though you can tell that by her truck. Not alot of ladies like to do what she does. That's why I think her and her truck is really cool! Yes I quess it should be 48 but my dad is working on a 46 truck and I was in the 47 and older section trying to find out all I could about that truck. Anyway thats where 46 come from. Thanks for the tip on the valves. I quess if something works don't change it. I went to a show in Oct. and a man had a 50 model there. I asked him what was the difference between the 48-50 models. He told me the doors on a 48 was about 3/16 to 1/4 inch shorter than a 49 or 50 was. So I come home and looked at my 48 and he was right adout the doors not even with the bottom of my cab. And my doors are original doors to. So I was wondering on your truck. Does your doors come even with the bottom of your cab on your truck. He said 49 and 50 are even. Have you heard this before?