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EFV-8 Club Forum / General Ford Discussion / changing ring and pinion in our 46

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Posted By Discussion Topic: changing ring and pinion in our 46     oldford2 12-16-2009 @ 5:17 AM reply profile send p.m. Member Posts: 275 Joined: Oct 2009 We plan to do some long tours next summer and studying how to change the 3:78 to 3:54. Are there any good step by step manuals out there. I know that once I get into the job the forum folks can help me when I get stuck. Thanks John supereal 12-16-2009 @ 8:19 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 John: Probably the best step-by-step instructions is in the 39-48 shop manual. It is a reprint of the Canadian book, as Ford didn't actually furnish a comprehensive shop manual, preferring "service bulletins", instead. I believe the manual is available from C&G (800/266-0470). It contains about 475 pages. Be forewarned that changing rear end gearing is a big job, not recommended for those with limited experience. The change to 3-54 will help some, but at the expense of low speed power. I kept the 3-78 in my '47, and added an overdrive unit. Mitch*ll has a good one. The OD allows you to keep up out on the highways, but retain good "in town" driveability. tudorbilll 12-16-2009 @ 11:23 AM reply profile send p.m. New Member Posts: 108 Joined: Oct 2009 I beleave super is right I have two 35,s one with 354 & one has the 378, A lot of the touring we do is on country roads perfect for the 378 and you can still run 60-65 tudorbilll 12-16-2009 @ 11:24 AM reply profile send p.m. New Member Posts: 108 Joined: Oct 2009 I beleave super is right I have two 35,s one with 354 & one has the 378, A lot of the touring we do is on country roads perfect for the 378 and you can still run 60-65 ford38v8 12-16-2009 @ 9:19 PM reply profile send p.m. Senior Posts: 2758 Joined: Oct 2009 John, I changed my ratio from 4.44 to 3.78 and am very happy with the results. There are two ways of doing the job, the easiest is to change out the entire assembly, which can be done on any Saturday, providing you have a refrigerator full of beer to speed things along. The more time consuming method is to go through your existing rear end, replacing seals and bearings as well as the gears themselves. This method will require the help of a good buddy, and someone to keep that refrigerator full of beer. I suggest a couple of racks of ribs on the Barbee also, as you want to do the job right. As a side note, I do agree with the others that 3.54 is too low for street use, but I don't agree that 3.78 is too low for highway use. My '38 has been cross country several times with the 3.78, and my motor purrs like a kitten at 70 mph. I guess my points must start to float at 82 mph though, as that's about all I can get on flat ground. Alan oldford2 12-17-2009 @ 4:35 AM reply profile send p.m. Member Posts: 275 Joined: Oct 2009 Alan, Thanks to you and others for your advice. I am beginning to think this project may not be worth a try. I think I will stay with the 3.78. With 6:00-16 tires what is the rpm at 60 mph and for a good engine is it OK to run for hours? Maybe change the tires to lower the rpm's? Thanks John oldford2@verizon.net Stroker 12-17-2009 @ 4:58 AM reply profile send p.m. Senior Posts: 1460 Joined: Oct 2009 You'll be turning about 2800 rpm, which a stock flathead will handle for hours on end. 39 Ken 12-17-2009 @ 5:33 AM reply profile send p.m. Member Posts: 380 Joined: Oct 2009 A 3.78 to 1 rear with 6.00x16 tires will give you approx. 2600 RPMs at 55 MPH. Your best bet would be a Columbia rear or a Mitch*ll O/D. The Columbia will give you approx. 1900 RPM's at 55 MPH. The Mitch*ll will also lower the cruise RPM's, but how much depends on which ratio you choose. Mitch*ll advertisment is in the EFV8 club magazine. Ken 37RAGTOPMAN 12-19-2009 @ 6:54 AM reply profile send p.m. Senior Posts: 1958 Joined: Oct 2009 hi I changed my 37 over to 3.54 and it is the best thing I EVER did, I swear it gets better gas milage , and seems to run smoother at higher speeds, with less noise,and has plenty of power for me , I did this about 4 years ago,after owning the car since 1975, if you can get help and study the instructions,you will be able to do it, Be BE CAREFUL,with the rear spring, you will need some special tools,some you might be able to borrow or make, the big thing is the rear spring spreader,be carefull using it, take your time, Remember You have a lot of People Behind you here on the V8 FORD CLUB Web Site to help you,just incase you need it, a lot of memebers will put there knowledge and put their 2 cents in, HOPE THIS HELPS,, MERRY CHRISTMAS to All My Fellow V8 FORD MEMEBERS, 37 RAGTOPAMAN in GOD WE TRUST,,,,,!!!!!

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