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Rear Gear Help!!(long)

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Last week I posted that I had a knocking noise coming from the rear of my 65 V-8 Fastback. I had some free time today so I did some checks and this is what I found.I jacked the car rear up and spun the right rear wheel and there was a clacking coming from the pinion shaft area. Ah-ha I thought U-Joint problems. I took out the drive shaft and the u-jounts were good as new. I reached up and turned the pinion shaft and it said clang,clank as it turned and it has play from say 12'o clock to 3'o clock. Sounds like a metal to metal sound and the sound travels down right axle . Is my rear toast should I be looking for a replacement? I have a spare rear from a 66 C code with 3 speed trans. originally. My fastback has a 3:00-1 original A code 4 speed. Would this 66 be a 3:00-1 also being a factory std. shift car? Any help greatly appreciated.
This is the only major problem I have had in 13 years of ownership of my car .
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It is simple to check the ratio.
1. be sure BOTH wheels turn in the same direction. Have someone turn them to start the process.
2. count how many times you have to turn the pinion yoke to make both wheels do ten complete turns.
3. write down the number.
4. 28 turns is a 2.80 35 turns is a 3.50 ect ect.
5. have you kids do the turning,
you do the counting

M.C.A.# 50000
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Yes thats the easy way, but its 30 miles to where its at and its under a pile of parts. I was taking a shortcut picking brains to avoid a trip tonight.I think all std shift A and C code were 300:1 minimal ratio to avoid being sluggish in 1st gear acceleration.There is a tag on it,I think. Been a while since I have looked at it. gtsteve/gt_350_clone
gt_350_clone /gtsteve
65 Shelby Replica 13 year owner
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Sounds like your spider gears are history. When they get lunched the loose metal particles wipe out the ring and pinion gears and all the bearings in a relatively short time. I'll leave it to the sharper troops, but I thought the lowest gear for standards was 3.25. A 3.00 or lower would be tough on the clutch. My PO had put a 3.00 in mine and resulted in clutch chatter. I since put in 3.55 and have a better performer with no chatter. If you want to rebuild your pumpkin (new gears, bearings and seals) figure on $300 from Summit for parts. Not that big a deal to rebuild if you are not in a hurry.

Mustang Lovers ---- A Box-O-Choclates !!!
One thing at a time Steve....

Pop the axles out and isolate the differential....tell us what you hear when you turn the pinion now...

Since most likely the problem area would end up being in the differential carrier, you can just swap that item from your other 8"....when the other unit is out of the housing, just count ring and pinion teeth to determine gear ratio....

Keep us posted....

My 65 2bbl 289 4spd.factory came with 2.80 gears. somehow it managed for 100K.

M.C.A.# 50000
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