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v6 conversion tranny question

DanR

Diamond Level Sponsor
I believe you have the 3:89 from what is posted above: USA/Canada standard trans non O/D from B395010313 returned to 3.89:1
 

260Alpine

Donation Time
Lower profile tires maybe. Taller tires would be closer to 70 at 3000RPM. You have to determine what transmission you have. Could be T5, Ranger or T9. T5 can change OD gears, don't know about the others. You have to verify if your rear axle is stock or Ford 8". A picture of the back of rear axle and both sides of transmission will help identify.
 
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husky drvr

Platinum Level Sponsor
vin reads 12051

Stratman101,

At this point I'm a bit curious about your Alpine. With more info, someone may see something that will help you better than we've accomplished so far.

Is that five digit number your complete VIN? Or is it just a partial number?

Are your tachometer and speedometer the original equipment or aftermarket units? Have you checked the calibration of those units against a known reference?

What size are your tires and wheels? Any chance you could measure the rolling radius of the rear wheel/tire combo (center of wheel to ground)?

Is their any chance the previous owner said the the trans was from a turbo T-bird or Mustang? That would be about the worst unit to choose for your Alpine. (1352-018 Ford 1983-84 T-Bird/Mustang 2.3 L4 Turbo C R=3.76 1st=4.03 2nd=2.37 3rd=1.49 4th=1.00 5th=0.86)

In your rear axle picture looking at the drain plug, drive flange, and the way the parking brake is operated, I'd say your axle is original Rootes. More pictures of your Alpine can only help.

The bad is after trying some off the wall numbers, I think there is a good possibility you do have a 4.22:1. I think the only way to know for sure is to do some counting, if you are are willing.

Be aware this only works for an open differential. One rear wheel on the ground so it can't move and two wheel rotations due to the effects of the spider gears.

Safety first! Block the fronts wheels so no movement - might need readjustment.

Jack up one rear wheel enough to see the driveshaft from outside the car. Support the car in this position so it can't move or fall.

Transmission in neutral.

Mark the driveshaft by a stationary point so you can count rotations from outside the wheel (masking tape or light colored marker).

Mark the tire and ground so you can count wheel rotations.

Rotate the wheel/tire exactly two rotations while counting the driveshaft rotations. Try more than once.

If just under four rotations, then it's 3.89:1.

If about four and a quarter turns, then it's 4.22:1

Sorry for the length but I hope this helps,
 

Stratman101

Silver Level Sponsor
Many thx for the info.
Im runing 155/80/13 tires on oem steel wheels
Only marking i can find on the tranny is “87” embedded in a round snowflake stamp
Vin number B395012051
I will try the tire rotation once more following your instructions.
the PO has passed with no information from family member who sold me the car.
If i can confirm a 3.89 then what is my fix? Another tranny with taller gearing or ?? If its a 4.22, then would a 3.89 solve freeway driving rpm issue?
 

husky drvr

Platinum Level Sponsor
Is there any chance the letters "OD" are also stamped on the VIN tag in addition to the LRX? If so, your Alpine was originally equipped with the 4.22:1 gears. Considering the almost sixty years since your car was built and rear diffs can be problematic due to loosening of ring gear bolts, it's definitely possible the rear gears aren't original to the car.

155/80/13 tires should give about 887 revs/mile - or looked at as 887 revs/min at 60 MPH. (1 mile per minute X 60 minutes gives 60 MPH)

At 60 MPH in 4th gear (1:1 ratio), a 3.89:1 should show about 3500 RPM. - a 0.80 OD ratio would drop RPM's to about 28oo RPM's.
..........................................................a 4.22:1 should show about 3800 RPM. - a 0.80 OD ratio would drop RPM's to about 3000 RPM's.

Even with 4.22:1 gears, a 0.70 OD ratio would drop the 60 MPH RPM's to about 2700 RPM.

As you can see, just changing from 4.22 to 3.89 is only good for about 200 RPM improvement at 60 MPH. That would be a start, but not as big of an improvement as I believe you seek. If your Alpine has a T5 - the most likely possibility - a different unit would probably be the biggest improvement.You might also have to combine that with a taller wheel/tire package to achieve the results you desire.

Time to identify your transmission. The V6 folks can probably help with that task the best.

Hope this helps,
 
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260Alpine

Donation Time
T5 transmission looks like this. I like the version that has the 2.95 first and .72 OD fifth. It was only available in the 83-84 Mustang V8 or aftermarket. GM and aftermarket had an .63 OD fifth. Later Mustang V8 had 3.35 first and .68 fifth. Some V6 had .72 fifth. Pre 94 had a shorter input shaft than 94 and later. Dan R has a spacer for that. Late 80's and newer are World Class and older are non-World Class. For the little V6 that doesn't matter. lrs-7003a_5988_t5+transmission.jpg

T5 Transmission Identification - What the Tags and Markings Mean - Lugnutz65ChevyStepside (weebly.com)
 
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PROCRAFT

Donation Time
"www speed.com identifying a T5 transmission"
I have a world class T5 bolted to a Crate Ford .72 over didn't like the RPMs with a 3.73 rear gear just went to a 3.27 solved my problem !
The rear gear will determine the RPM at road speed veris MPH ?
By the way it's a 4-cylinder T5 which the naysayers say you cannot run against a SBF I prove them wrong every day
 

Paul A

Alpine Registry Curator
Platinum Level Sponsor
Hmm. So i have a later S5 vin 12o51. I understand my gearing s/b 3.89 not 4.11 due to my vin being after 10000??
I jacked up the car and marked the flange, rotated left wheel 2 revolutions and i get just under 2 turns on the flange. Does that confirm a 2.89??

My Series V is later than yours with VIN 14649 Stock 4.11 rear end
 

Bill Blue

Platinum Level Sponsor
Cannot emphasize Husky Drvr question about dashboard gauges enough. Not that they are junk gauges, but that nobody considered they would still be in use 60 years after manufacture. There are components, especially in the tach, that simply do not age well.
Bill
 

DanR

Diamond Level Sponsor
Our Sunbeam Tach's can and often get out of calibration as such the RPM's that we expect at certain speeds will be off also..

Tom H, a fellowmember of our club has rebuilt/repaired several for me. Sure helps to know the Tach is accurate when discussing transmission, tires, rear axle ratios.
 
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