I would like to know if any one has used new r/p gears from LMC? How did they work, did they make noise. I have been told that some aftermarket gears cannot be made to not make noise. Does anyone have any experience with this subject that can shed some light on. Thanks for any help.

 

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Haven't had any reply about lmc gears, need help here.

 

Speaking for sure about myself, and possibly also speaking accurately for many others that post here (based on years of reading this board), most of us do not buy separate gears, whether from LMC or anyone else. Some do, I know, but for specific reasons.
May I offer some thoughts?

Ford made it easy to change gear ratios in the 9" axle without having to go through the trouble of changing the ring and pinion. If you already have a Ford with a 9", rear third members are still easily available in many different ratios, and can be changed to the ratio you want in less than an hour. For your '66, you will need one that accepts 28 spline axles.
Do you have a Ford 9" rear, or a Dana 44?

If you have an F-100 with a Dana 44, you will have to change the actual gears, and go through the trouble that involves.
However, depending on what you want to do with your truck, it might be a lot easier and cheaper to change out the Dana 44 rear axle with a Ford 9". The axles from at least 1960 all the way up to '72 are direct bolt ins.
By the way, the Dana 44 was the locking rear axle offered in '66. If you are wanting to keep that feature, then you will have to change out the ring and pinion.

(Note that '67 and earlier axles use narrower rear brakes than the '68-'72 axles. if you obtain a later axle, '68-'72, be sure to get the entire setup, with the half shafts and brake backing plates.)

Finally, although LMC is a good company, I would not buy gears from them. They are simply resellers, and I wouldn't want to trust a secondary warranty. I would prefer to buy from gear specialists.

Just my opinions, but I hope they help.

 

LMC doesn't make these gears, buys them from an auto parts store. Eliminate the middle-man (LMC) and save a few bucks.

You failed to mention what rear axle your truck has. Standard equipment is the Ford 9 inch.

Optional: Spicer/Dana 44 with Limited Slip, Spicer/Dana 60.2 & 60.3 with Limited Slip.

Dana's have an inspection cover, the 9" does not.

 

Thanks for the replys, I have the 9" with 3.89 gears. My truck has a 302 with a mild cam and a 5spd od std. I would like to put 3.25 in it for mileage. I have heard that some aftermarket gears will wine even if set up correct.

 

Ring&pinion gears need to be setup and installed by someone who knows what they are doing. Not really a job for a novice....I won't attempt it.
They should not whine if set up properly.

 

It can sound daunting I suppose, but it really isn't that hard as long as you have a dial indicator - especially on a removable carrier axle like a 9 inch.

 

3.25s are only going to help mileage in 5th gear. How often are you using 5th gear?


At $2 a gallon, you would have to put a bunch of miles on your truck to break even on buying new gears.


Most Pick-N-Pulls will sell the gears or entire rear end for under $100. That's the way to go.

 

any gears whether aftermarket or factory will whine if the tooth contact area and backlash are not correct . I have done many gear changes in differentials and never had any of them whine . Many people just set the backlash of the gears and stop there without using dye and looking to see if the contact area of the teeth are correct , pinion depth MUST be set correctly for this to be right and have a quiet differential .

 

A 302 with an overdrive gear is a nice combination!
The 3.89 rear end ratio might be a bit high, but as Shadowrider points out, you would have to drive thousands of miles to get your money back on a gear change.
Now, performance is a different story.
What RPMs are you running at 30-35 and at 70?
By the way, you should be able to find a complete third member for $100 - $150. Easy to swap out with simple hand tools and can be done in an hour, especially if it has been done before.
Regarding performance, your 302 will have better performance, response and mileage at somewhat higher RPMs than motors with longer strokes, such as the 460. When contemplating gear ratios, one must look at all the factors, not just the CID of the engine.
(For example, the difference between the 300-6 and the 302 V-8 is only 2 CID, less than 1%, but their performance curves are greatly different, because the 302 is a short stroke motor, and the 300 is a long stroke motor.)
If I may recommend, I would suggest you look for a 3.50 for your rear axle. You will have to be doing 70 MPH or higher quite regularly to take advantage of the overdrive with anything else (lower, like a 3.25). Performance will really suffer on the lower end too. 1st gear with a 3.25 rear ratio will feel almost like starting out in second, which is not pleasant, and reduces the ability to use the truck as a truck.

Ford and the other manufacturers since the '30s have done and continue to do a lot of testing and research to identify the ideal ratios with different engine, transmission and rear end combinations. For our Slicks, they put a 3.50 behind the 352 V8 with an overdrive transmission (the T-85N). I had one like that, tried changing the rear ratios and found that the factory 3.50 was the best compromise. To this day, the 3.50 is a popular combination for trucks. I had a 3.5x in my F-250 Diesel with an overdrive, so that ought to tell us something.
Even though you would think it will save gas to lower the rear end ratio, too low a ratio hurts performance enough that you end up wasting gas, unless you are running at 70 or higher most of the time. Since most of us drive in town some, you want a good compromise between mileage and performance.

Now, I have a 460 with a C6 automatic, and have a 3.25 in the rear. With the power of the 460 I could use even a 2.50, but it would be a dog. (I tried it. It was a dog, and actually hurt mileage.) I also intend to use my Slick for towing, so anything lower will hurt performance. An ideal combination (if I could have it) would be a 3.50 rear ratio with a 0.75 OD factor, which is what most overdrive units have. In other words, I would want the 3.50 for town and towing, but still have the 3.25 for highway mileage.

I concur.
In short, I think the 3.89 is probably a bit low, but I would want to check out the RPMs at different speeds first - especially in overdrive at 70 MPH. It appears to me that a 3.50 will probably be your best compromise for performance, mileage and how much money it takes to do it.

I hope this helps. I know it has been a bit rambling, and covered several factors. Just my opinions though.
I wish you best of luck!

PS: As for the whining, the Ford 9" is so though that at 100K miles, the gears often look like they are just getting broken in.

 

Lots of other factors as well.


Have you compared your speedo against a gps to see if it is accurate?


What size tires are you running?


What are your engine specs, exhaust, carb size, and what dizzy are you using?


All these things affect mileage and performance, maybe you can pick up a few mpg without changing gears.

 

To banjopicker and shadowrider, Thanks for your help. Don