ID'ing the REAR DIFF..?
- Thread starter bobpo
- Start date
Aerocraft
Well-known member
I assume that you have a flat driveway where you can push the car. To check the ratio, put a chalk mark on the driveway and a matching mark on the sidewall of a tire. Remove the spark plugs and put the car in third gear. Open the right side of the hood and make a mark on the fan belt pulley. Have someone push the car one full revolution of the marked tire. At the same time, very carefully watch and count the revolutions of the pulley.
If the pulley revolves slightly more than four turns, you have a 4.11 ratio. If it revolves slightly more than 3 3/4 turns, the ratio is 3.78. If it revolves just under 3 3/4 turns it is a 3.70. It follows that if it turns about 3 1/2 turns it is a 3.54 ratio.
Gar Williams
If the pulley revolves slightly more than four turns, you have a 4.11 ratio. If it revolves slightly more than 3 3/4 turns, the ratio is 3.78. If it revolves just under 3 3/4 turns it is a 3.70. It follows that if it turns about 3 1/2 turns it is a 3.54 ratio.
Gar Williams
pooch
Well-known member
If you mean ID the ratio.
Jack only one rear wheel up.
Move crank handle to a convenient starting point, say 9 o'clock.
Take up any backwards slack in drive train, mark bottom of tyre with chalk.
Put car in top gear (direct only no OD if you have one).
Have someone gently hold tyre to keep any back slack at bay.
Wind engine over until tyre has turned one exact revolution.
Count how many times crank handle went around.
(I always forget this part, I can't remember if you halve or double the turns of crank, because of the spider gears running around.)
Someone else will chime in on that.
You will see when you do it, I think it is half crank revs, means if one wheel is on the ground the other moves twice the revs.
So, I "think" you wind the tyre around twice.
If you cannot get it accurate, just wind several revs of wheel, and divide it out.
Jack only one rear wheel up.
Move crank handle to a convenient starting point, say 9 o'clock.
Take up any backwards slack in drive train, mark bottom of tyre with chalk.
Put car in top gear (direct only no OD if you have one).
Have someone gently hold tyre to keep any back slack at bay.
Wind engine over until tyre has turned one exact revolution.
Count how many times crank handle went around.
(I always forget this part, I can't remember if you halve or double the turns of crank, because of the spider gears running around.)
Someone else will chime in on that.
You will see when you do it, I think it is half crank revs, means if one wheel is on the ground the other moves twice the revs.
So, I "think" you wind the tyre around twice.
If you cannot get it accurate, just wind several revs of wheel, and divide it out.