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Author Topic: Rear end swap  (Read 1537 times)

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Offline Crazy Lacy

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Rear end swap
« on: February 26, 2018, 10:59:19 PM »
I have a 2.0  4 speed pinto, Rear end is howling a little, I was looking to get an 8" one out of a wagon, IS IT better to get another rear end from a pinto wagon that had an Auto Trans or Stick Trans. I WAS wondering if one has a lower gear set up than the other.??  This is my new whip 1972
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Offline pinto_one

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Re: Rear end swap
« Reply #1 on: February 27, 2018, 11:17:06 AM »
That depends , One you have to see what ratio rear you have now , (tag on rear cover should tell you)  if it is howling you may have lost oil and burned up the gears , look for oil leak , last you my just have a bad pinnon bearing going bad , most stock 4 speed early 2.0,s had a 3.55 or 3.40 ,  later 3.18 .  if you swap in a 8" rear you my be lucky to find a 3.55 or 3.40 gear , but you will almost pick up almost 75 to 100lbs in weight , next is do you just stay around town or on the hwy , low gears get up and go and engine screaming on hwy ,  high ratio gear good gas milage and quite on hwy ,  standard rear ends were lower gears ,   auto I have found 3.4 up to 3.00 to one , had one that was 2.79 in a MPG pinto and was a slug , but good MPG , 
76 Pinto sedan V6 , 79 pinto cruiser wagon V6 soon to be diesel or 4.0

Offline pinto_one

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Re: Rear end swap
« Reply #2 on: February 27, 2018, 11:20:39 AM »
forgot to add that I do have a brand new set of 4.11 gears in the box for the 6 3/4 rear end , you have to have a shop install it and use new bearings and seals,
76 Pinto sedan V6 , 79 pinto cruiser wagon V6 soon to be diesel or 4.0

Offline Wittsend

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Re: Rear end swap
« Reply #3 on: February 27, 2018, 12:28:58 PM »
Rearends from Pinto's OR Mustang II's will work. I Highly recommend you buy the WHOLE thing "Drum to Drum." The 6-3/4" brakes drums do not fit the center of the 8" axle. In the 8" you will find 3.00, 3.40 and 3.55 as OEM ratios from Ford in the Pinto and Mustang II. Unless it has been removed there is a bolt on tag that tells what gears are inside.


  If mileage or significant highway driving is important avoid the 3.55.  Ideally you probably want something between the available 3.00 and 3.40 but you need to go to aftermarket gears to do that. If I was using 13" tires and mileage was somewhat of a factor I'd think the 6-3/4" rear, 3.18 gears would be best.  As a second choice for zipping around town 3.40 and for highway 3.00.

Remember that tire circumfrence does exactly what gears do. They alter the number of engine revolutions per give distance travelled. I really, Really, REALLY wish the industry would adopt some standard like 'engine revolutions per 100 feet' that factored tire circumfrence with the gear ratio. Then people could have a true value of the overall effect of the tires AND gears.  But, if I've lost you in my explanation basically the potential for a shorter tire and 3.40 gears or a taller tire and 3.55 gears to produce the exact same results exists.

So, what tire size will you run? What is the intended purpose (highway or zipping around town)? Is the price of gas and mileage a factor?  All these things go into deciding what ratio to use.

Offline dick1172762

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Re: Rear end swap
« Reply #4 on: February 27, 2018, 04:12:19 PM »
You know there seems to be a lot of people on our web site that want better mileage out of their Pinto and I ask why. Very few of us use our Pintos as daily drivers so what does better mileage get you? Almost always better mileage gets you less low end power and we all know that with less than 100hp, we need more low end power. I've used 3:00 to 4:11 in street driven Pintos and the most fun I ever had with any of my Pintos was with a 4:11. This was an around town car and the mileage was ok at around 15mpg' Why would I ever have needed better mileage? Car was a hoot from a stop lite and perfect on an autocross track. Pintos are too valuable now days to use as a daily driver so put a 3:40 / 3:55 in it and have some fun with your treasure. Be there / done that.
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Offline Wittsend

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Re: Rear end swap
« Reply #5 on: February 27, 2018, 05:02:20 PM »
Yikes, 4.11's with 13" tires?

  I had 3.90 gears with 215-50-13" tires on my Datsun 510 and I absolutely hated it. I was literally shifting into 3rd gear before I crossed a 4 lane intersection and was at 4,000 RPM going 60 MPH on the freeway.  I got a 3.36 rear from a 240Z and the car was far more drivable. I could maximize the torque to pull the car along nicely.

 Before it was like having a 10 speed bike in very low gear and starting off down a steep hill. The engine just rev'ed out of its (roughly stock) torque curve with no perception of acceleration.

As I've noted before my Turbo Pinto with T-5 trans acutally pulled decently with 3.00 gear (215-60-14" tires). I loved to do the rolling start (35 MPH, 3rd gear), slowly plant the gas and watch the passengers eyes widen. Whether faster or not the perceived experience was a l-o-n-g, enjoyable pull of the boost rising.  The down side was for everyday driving I could never find the right gear for posted speed limits. I went to 3.40 gears and now every day driving is pleasurable at the expense of the enjoyable "long pull" of the 3.00 gears.

Different cars, different experiences, different expectations.

Offline Srt

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Re: Rear end swap
« Reply #6 on: March 02, 2018, 09:59:44 AM »

You know there seems to be a lot of people on our web site that want better mileage out of their Pinto and I ask why. Very few of us use our Pintos as daily drivers so what does better mileage get you? Almost always better mileage gets you less low end power and we all know that with less than 100hp, we need more low end power. I've used 3:00 to 4:11 in street driven Pintos and the most fun I ever had with any of my Pintos was with a 4:11. This was an around town car and the mileage was ok at around 15mpg' Why would I ever have needed better mileage? Car was a hoot from a stop lite and perfect on an autocross track. Pintos are too valuable now days to use as a daily driver so put a 3:40 / 3:55 in it and have some fun with your treasure. Be there / done that.


what he said
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Offline dick1172762

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Re: Rear end swap
« Reply #7 on: March 02, 2018, 10:42:02 AM »
Yes its what I said! Having owned 16 Pintos, I've tried lots of different mods on some of my Pintos. Having raced cars for most of my 83 years, I had a far different need than most people for some of my Pintos. In the 80's it was very easy to build a Pinto for SCCA racing that could also be driven on the street back and forth to and from the track. My Pinto with the 4:11 gears was such a car. Driving the car 20 miles in Denver to the track was very easy and really fun. So yes, I did have a 4:11 with 205/60/13 tires on the street and track. Won lots of races with that car! Just goes to show you there could be more than one use for that Pinto in your garage.
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Offline Crazy Lacy

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Re: Rear end swap
« Reply #8 on: March 02, 2018, 10:39:56 PM »
I drive it around town mostly, So the 8" adds like 80lbs, Yikes :P I got 13" tires, I'll have to ckeck the size. I could pick this basic rear end up for $50
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Offline Crazy Lacy

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Re: Rear end swap
« Reply #9 on: March 02, 2018, 10:41:04 PM »
r end
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Offline Billnparts

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Re: Rear end swap
« Reply #10 on: March 03, 2018, 02:36:17 AM »
The ratio is stamped by the bolt head on that tag. Lower left corner. Clean it off, you can read it. Surprised itís still there.


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Offline Wittsend

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Re: Rear end swap
« Reply #11 on: March 03, 2018, 11:12:49 AM »
Yea, that is a 6-3/4" rear end.  The first digit is still blocked by gunk but since the other two digits are .18 I'm 99.9% sure it is a 3.18.  My personal two choices (a non-racer position) with 13" tires is 3.18 if it sees a lot of highway use and 3.40 for more in town sprinting around. I'll still stand by my (negative) experience with my Datsun 510 and 3.90 gears/215-50-13" tires. 4,000 RPM @60 MPH and shifting to 3rd gear before crossing an intersection was not enjoyable.


Below are the tire size (205-60-13) gears (4.11) that were mentioned in another post. Below are the calculations.  While I get that the purpose of the car was racing and it was feasible to drive it to the race..., for everyday driving I thing the near 4,000 RPM's on the highway would get wearisome after a while. I'd say to test drive the highway with your current ratio in 3rd gear 3,954 RPM (to stay within the speed limit) and see how long you like it.