Rear End Ratio Woes...

1st Official Post

    Hey kiddies...


    Well, I've been testing a motor I built for my '66 Sunbeam Tiger currently installed in my '65 Mustang HiPo Covertible this year, and I've finally had enough. The origial HiPo motor is being detailed during my "test."


    My HiPo stang is transmission and engine "numbers matching," and is all (restored) original. My problem is my rear end ratio.


    I've owned this car since around 1991, and it's always been a bear to drive. It has 4:11 gears in it (correct, per the door tag), and unlike the Beach Boys song, it drives like a friggin' school bus.


    Since I have no desire to pull tree stumps out, or be shifting into forth gear around 40 MPH, I've had enough, and need to put some "longer legs" into this 'Stang before I get disgusted and sell it.


    I also own a 1966 Shelby (note my user name) which has 3:89 gears in it. I kinda like this set, since it has plenty of punch, yet seems better suited to highway driving.


    My '65 has stock styled steel wheels, and dual redlines. Any feedback on rear end ratios you guys like?


    Thanx.

    I've had 4:11, 3:89, and 3:50 gears in my HiPo cars over the years. The difference is not subtle, and with the close ratio 4 speed, I find the 3:50 gears make the most sense considering the way I like to drive.

    My Kar has 3:50 gears and I like all aspects! Plenty of go power yet you can drive on the highway without buzzing the motor. Acceleration at on ramps is perfect, never do you need to downshift and fourth gear in town is just right. I think it is the perfect gear for our motors.

    • Official Post

    I have 3.00 gears in my Kar and I like it because I do a lot of freeway driving here in Los Angeles. This Kar has been like this since at least 1984. I have had 3.50 gears in most of the other Kars that I have had over the years and although they are great around town, I prefer highway gears for my use. I had a 64 K Fairlane with 3.89 and it was not that great on the freeway. I had a 65 K Fairlane that had 2.75 gears and it worked well for me. My Boss 429 has 3.91 and it too would be more useful to me with a taller gear but then I rarely get it out on any long trips. The taller gears make the Kars a little lazier getting away from a light but make all of the speed gears much longer winded. Keep in mind that all of this comes from a guy that had 4.88 gears in his new 67 Camaro that he put a 427 in just after he bought it new. I thought nothing of revving my engines at over 4K consistantly on my trips to Las Vegas and San Francisco at the time. I even ran 5.38 gears in my street 427 Vega panel truck. My 66 427 Corvette had 4.88 gears in it when I first bought it 29 years ago and it was useless for my canyon driving as I ended up in 4th gear most of the time. I now have 3.36 gears and it is far more useful. All that said, the 3.50 gears that Ford used as a standard ratio in K Mustangs works well around town but where I live I have a lot of freeway driving so a taller gear is my preference.

    -Fred-

    65 Koupe early San Jose Phoenician Yellow 4 speed
    66 GT Koupe Dearborn Blue 4 speed
    66 KGT San Jose fastback pony interior Silver Frost 4 speed
    64 Falcon sedan delivery 289 4 speed
    65 Ranchero 289 4 speed
    66 Corvette roadster 427/425 4 speed

    I am running 3.89 gears, C4 trans and 3200 rpm stall converter. I don't take it on long trips, but is fine for the country rips and town cruises. If I had to make longer 400 mile trips etc. I would install a Gear Vendors unit before switching to an AOD or T5. I run a 4.30 gear in my street/strip 1993 5.0 coupe and no problem there thanks to the T5 overdrive. This car sees 8000 rpm on a pretty regular basis though.<img src=images/icon_smile_tongue.gif border=0 align=middle>

    I have been living with 4.56 gears for 32 years. When I was young, single, and had $ to spend on a toy, I thought those gears were cool and damn, the car was fast, so I left them in. Now, when $ is tight, I am looking for some 3.50 to swap in....

    I love this board. It's the perfect place to ask these kinds of questions. You guys are great.


    Based on this input, I think I'll try out the 3.50 set on this car. Do you guys have any good third member suppliers, as I plan on swapping out the whole chunk? Does anyone know what speedo gear to use with 3.50 and stock styled steel wheels and dual redlines? (I can get more wheel/tire info if needed).


    I see that David Kee sells these units, but I'm guessing his prices are high.


    Also: Do I need to be concerned with the number of splines? Obviously, I would prefer to get the new third member here before ripping the rear end apart. My car is bone STOCK, so I would assume that there is one set of spines for it. Then again, I know what can happen with ASSuming, so I'd better ask here first. I'll take it out and count before I order if I have to.


    You can see some of my cars on You Tube at:


    http://www.youtube.com/user/TheREALroadtripguy


    Just weed through the iguana videos, and you'll find them.


    Thanks again for all the help, guys!

    Gerry, You might try some of the self-serve type wrecking yards. I don't know if they have many back east, but they are plentiful around here on the west coast. Find a 60's or 70's vintage station wagon or full size Ford, they typically ran a 9" with anywhere from a 2.75-3.50 ratio, most common units are the 3.25's which is a good all around setup. Fairly inexpensive as long as you don't mind doing alittle wrenching to get them out, and can check the spline count. Also, the full sized Fords rear gear sets rarely got abused and are usually in pretty good shape.

    I have the same dilema in my 65 KFB, with 3.89 gears using first gear seems like a waste of time unless you are drag racing. Thought about the gear set change, but I think I'm going to go the 5 spd. route, so i can cruise it on the freeways.


    Edited by - 66tiger on 04/23/2008 16:06:44

    My 66 originally had 3.89 gears but I repalced them with 4.11's in the late 80's because both the ring and pinion had chips. For some reason 3.89's were on a big backorder back then. Anyway the difference between 3.89 and 4.11 really isn't that much IMO, about 200RPM @ 60 mph. Either one is winding pretty good at freeway speeds.

    Dave
    6S1757

    Per my axle spline question earlier, I just happened across this:


    http://www.metropartsmarket.com/rearend/measure.html


    I definitely have the 28 spline axles. Unfortunately, good bone yards don't exist around where I live anymore. There used to be a bunch of them when I was cutting my teeth on these cars as a kid that I visited quite regularly.


    As an added bonus, I'm old and lazy now, and don't feel like finding a junkyard and getting all dirty pulling apart a rear end.


    I found this dude on Ebay. What do you guys think of the price?


    http://cgi.ebay.com/ebaymotors/9-F…emZ220226124232


    This might work for me, and he has good feedback and reasonable freight.

    • Official Post

    That unit that you linked with is a Trac-Lock if that is what you really need. Unless you are driving this Kar in slippery conditions, like snow, an open rear end is all that you will need. There is really no need to pay a premium for the locking rear end. Ford did not even offer a locking rear end for a 65 Hipo Kar. My only concern would be that your Kar will need a very specific and hard to find pinion yoke which the seller may not have. If you are not concerned with date codes on your castings, this may be right for you as all of the internal parts are new.

    -Fred-

    65 Koupe early San Jose Phoenician Yellow 4 speed
    66 GT Koupe Dearborn Blue 4 speed
    66 KGT San Jose fastback pony interior Silver Frost 4 speed
    64 Falcon sedan delivery 289 4 speed
    65 Ranchero 289 4 speed
    66 Corvette roadster 427/425 4 speed

    • Official Post

    The first auction is for a mini spool rear end only. This would not be suitable for street driving.

    -Fred-

    65 Koupe early San Jose Phoenician Yellow 4 speed
    66 GT Koupe Dearborn Blue 4 speed
    66 KGT San Jose fastback pony interior Silver Frost 4 speed
    64 Falcon sedan delivery 289 4 speed
    65 Ranchero 289 4 speed
    66 Corvette roadster 427/425 4 speed

    <BLOCKQUOTE id=quote><font size=1 face="Verdana" id=quote>quote:<hr height=1 noshade id=quote>

    My only concern would be that your Kar will need a very specific and hard to find pinion yoke which the seller may not have. If you are not concerned with date codes on your castings, this may be right for you as all of the internal parts are new.

    -Fred-

    <hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana" size=2 id=quote>


    Hi Fred.


    I'm not concerned with date codes, as I plan to keep the original 4.11 third member on the shelf, since it's proper for the car. Is there something "special" about the pinion yoke as well? I wasn't aware of this.

    • Official Post

    Most of the rear ends offered these days use later model pinion yokes which are not the same as your original. Make sure that you give the seller your application and dimensions from your original yoke so that a replacement rear end will fit without any driveshaft modifications.

    -Fred-

    65 Koupe early San Jose Phoenician Yellow 4 speed
    66 GT Koupe Dearborn Blue 4 speed
    66 KGT San Jose fastback pony interior Silver Frost 4 speed
    64 Falcon sedan delivery 289 4 speed
    65 Ranchero 289 4 speed
    66 Corvette roadster 427/425 4 speed

    • Official Post

    Gerry, Here is another link that may be good for you.

    -Fred-


    http://cgi.ebay.com/ebaymotors/For…1QQcmdZViewItem

    65 Koupe early San Jose Phoenician Yellow 4 speed
    66 GT Koupe Dearborn Blue 4 speed
    66 KGT San Jose fastback pony interior Silver Frost 4 speed
    64 Falcon sedan delivery 289 4 speed
    65 Ranchero 289 4 speed
    66 Corvette roadster 427/425 4 speed

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