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Looks like some replaced the pinion seal and botched it up. Can't wait to hear from Gary. Jerry
I actually already addressed this on FB. But since some may be interested, here is what I see with a 10 second eyeball on it.
Looking at the pictures, clearly the pinion crashed back into the case, looking at the case, those little ears tell me it is a 65-66 posi, so combined with the gouging and year the posi should be replaced. The spiders in it should be 10-18's which are ok but not the best. 10-17 are better. Eaton posi's were first used in 1965 in corvettes and the 65-68 were not good, it doesn't matter if they were BB or SB cars. If the posi was shot peened or not, they were a bad design that were destined to fail, and many have. Same for the 63-4 Dana posi's.
The gears appear to have been setup wrong from day one, look at the ring gear pattern- the pattern is longer in the root of the tooth. The pinion was too deep.
Next look at the housing, it is a narrow one, so it is a 63-66 since those were all narrow. It is mostly likely original to the car and correct for the period. Today try and find a vendor master kit with the correct case shims and pinion shims, not happening. Yet the customer isn't told about it. I have stock or machine my own.
Other signs it was a base build- the caps have the original hex bolts. The ring gear bolts appear to be stock or kit replacements. They worked but not the best option to use.
When one is looking at a build such as this one, and this is nothing against the owner by any means, but I don't see anything beyond a common rebuild shown. If you have a vette that rolls on and off a trailer or is rarely driven, base builds are ok. I personally would never use one, but they will work.
For those with power and even the old stock 300-375 cars, given enough abuse parts will break posi's. The term bulletproof is overused and really nothing is bulletproof. My son blew apart a blueprinted 10 bolt in under 5k miles of hard use. Power was under 375hp.
Today power levels are easily into the 600-800hp range. Many will drop $15k on an engine and put it in a stock drivetrain lightly designed for under 450hp and that is pushing it. Since 1963 guys have been breaking stock diff's and outer axles all the time at the track on the street.
The problem with the common advertised, low-ball differential builds today is they are all just a master kit, paint job, and maybe clutches. Some are still using new snowflake clutches, some tried to offer polished and tuned posi's but it helps if you know what you're doing since it involves a lot more than leaving out the spring pack. Some have used Tom's parts but don't know how to set them up. Some have copied Tom's parts and did a bad job of it, yet still sold them to inexperienced and unsuspecting customers.
I am not saying that is what is shown here, but it sure looks like a base level build. I am not going to get into who is doing what in the business, that is up to the buyer to do their homework, and they better do it well since costs have double or tripled over the past few years. Many places have sold out, many have lost the old timers who built these cars 50 years ago, and many places don't rebuild them - they buy them wholesale. When price is the first choice, quality suffers, and chances are they won't last with some abuse.
For decades now, I have repaired the work of a LOT of places- car owners, local garages, vette shops, hot run shops, specialty shops, etc. I used to cover all these at my seminars at Carlisle. Possibly some here have attended them, but I stopped going after 2016. Bad work, cheap work, is not new but it's more prevalent today than ever before. One common question I got 25 years ago and even today is " who would I use, if I retired today".
If that was my car I would first decide how I am going to use the car, then build a diff to that application.
Looks like some replaced the pinion seal and botched it up. Can't wait to hear from Gary. Jerry
I actually already addressed this on FB. But since some may be interested, here is what I see with a 10 second eyeball on it.
Looking at the pictures, clearly the pinion crashed back into the case, looking at the case, those little ears tell me it is a 65-66 posi, so combined with the gouging and year the posi should be replaced. The spiders in it should be 10-18's which are ok but not the best. 10-17 are better. Eaton posi's were first used in 1965 in corvettes and the 65-68 were not good, it doesn't matter if they were BB or SB cars. If the posi was shot peened or not, they were a bad design that were destined to fail, and many have. Same for the 63-4 Dana posi's.
The gears appear to have been setup wrong from day one, look at the ring gear pattern- the pattern is longer in the root of the tooth. The pinion was too deep.
Next look at the housing, it is a narrow one, so it is a 63-66 since those were all narrow. It is mostly likely original to the car and correct for the period. Today try and find a vendor master kit with the correct case shims and pinion shims, not happening. Yet the customer isn't told about it. I have stock or machine my own.
Other signs it was a base build- the caps have the original hex bolts. The ring gear bolts appear to be stock or kit replacements. They worked but not the best option to use.
When one is looking at a build such as this one, and this is nothing against the owner by any means, but I don't see anything beyond a common rebuild shown. If you have a vette that rolls on and off a trailer or is rarely driven, base builds are ok. I personally would never use one, but they will work.
For those with power and even the old stock 300-375 cars, given enough abuse parts will break posi's. The term bulletproof is overused and really nothing is bulletproof. My son blew apart a blueprinted 10 bolt in under 5k miles of hard use. Power was under 375hp.
Today power levels are easily into the 600-800hp range. Many will drop $15k on an engine and put it in a stock drivetrain lightly designed for under 450hp and that is pushing it. Since 1963 guys have been breaking stock diff's and outer axles all the time at the track on the street.
The problem with the common advertised, low-ball differential builds today is they are all just a master kit, paint job, and maybe clutches. Some are still using new snowflake clutches, some tried to offer polished and tuned posi's but it helps if you know what you're doing since it involves a lot more than leaving out the spring pack. Some have used Tom's parts but don't know how to set them up. Some have copied Tom's parts and did a bad job of it, yet still sold them to inexperienced and unsuspecting customers.
I am not saying that is what is shown here, but it sure looks like a base level build. I am not going to get into who is doing what in the business, that is up to the buyer to do their homework, and they better do it well since costs have double or tripled over the past few years. Many places have sold out, many have lost the old timers who built these cars 50 years ago, and many places don't rebuild them - they buy them wholesale. When price is the first choice, quality suffers, and chances are they won't last with some abuse.
For decades now, I have repaired the work of a LOT of places- car owners, local garages, vette shops, hot run shops, specialty shops, etc. I used to cover all these at my seminars at Carlisle. Possibly some here have attended them, but I stopped going after 2016. Bad work, cheap work, is not new but it's more prevalent today than ever before. One common question I got 25 years ago and even today is " who would I use, if I retired today".
If that was my car I would first decide how I am going to use the car, then build a diff to that application.
Gary, to my uninformed eye it looks like the pattern that is long in the root is not the gear tooth pattern the setup was running for most of the 20 years, but instead is the wear/machining after the pinion lost it’s spacing and crashed back. It matches the wear in the case. I’m surprised it was doing a lot more than whining.
Gary, to my uninformed eye it looks like the pattern that is long in the root is not the gear tooth pattern the setup was running for most of the 20 years, but instead is the wear/machining after the pinion lost it’s spacing and crashed back. It matches the wear in the case. I’m surprised it was doing a lot more than whining.
I dont disagree with anything in this thread. I had a friend build it but had a high speed vibration from day one. Im working with Gary on an option that will last the next 20 years under my right foot. Im pretty hard on stuff.
Gary, to my uninformed eye it looks like the pattern that is long in the root is not the gear tooth pattern the setup was running for most of the 20 years, but instead is the wear/machining after the pinion lost it’s spacing and crashed back. It matches the wear in the case. I’m surprised it was doing a lot more than whining.
That is very possible but that would be a lot of wear for a short run once the pinion crashed into the case. I would think the car was shut down at that point of impact. Regardless, the posi and gears are no good now. It would have been interesting to see the diff before it was taken apart to see where the issue began.
That is very possible but that would be a lot of wear for a short run once the pinion crashed into the case. I would think the car was shut down at that point of impact. Regardless, the posi and gears are no good now. It would have been interesting to see the diff before it was taken apart to see where the issue began.
The major damage occurred when I thought I could be John Force and did a big smokey burnout last month.
I can relate. I had a very subtle vibration coming from the rear, but I was having a hard time locating the cause. One day, my heavy right foot found the problem.
in fairness, the rear was rebuilt, 50,000 miles ago, and endured a fair amount of abuse over the years. i’m getting up in years, and I’m to starting to mellow out. my new rear should last me at least another 50,000, or maybe outlive me.
Well my spare is back in the car until Gary can get to rebuilding my broke diff. Then again now I have a new project. Broke a wheel stud in the process today
But the pink is 'different.'