Can anyone tell me if the standard axle for my February built 1968 GT350, 4 speed, non A/C car would be a 28 spline or a 32 spline? I know the 3rd member ratio is suppose to be 3.89:1 but sometime over the past 50 years it was changed out to a 3.50:1 (correct for automatic trans. car). Would this make a difference for the axle spline count?
All 1968 Shelbys used 5e larger 31 spline axle.
A GT350 with a 4 spd and no AC would have been built with a 3.89:1 open rear axle.
The axle ratio is determined by the ring gear , not the spline count of the axles
I know, I am just looking at a new rear that is 3.89:1 but the gentleman asked me if I had 28 or 31 spline axle. The rear he is selling has a 31 spline. So that sounds like it is correct.
What does open rear axle mean?
Open= peg leg, look at your axel in the center of lug nuts there should be 3 small circles, that would be 31 spline.
Open is the same as conventional; or not a locking (traction lok)
Thank you Pete and PR for your help.
Here are some pictures of what I am looking to buy.
Quote from: Corey Bowcutt on February 14, 2018, 07:58:59 PM
Here are some pictures of what I am looking to buy.
If it matters the case is not the N type webbed case .
I do not know what that means but if I am suppose to have a N type webbed case then this one would not be correct. Should a February 1968 car have an N type webbed case? Do you have any pictures?
The car should have a N case, but the N is not present on early cases. The ribs are in the same places and it appears the same in every other way
This case has a January 68 date on it which seems OK for my February car so is it a correct case for me? I believe you are saying it is but I want to be as sure as I can before pulling the trigger.
No. Look at the ribbing on the case. The case you posted does not look correct.
(http://www.kevinstang.com/nc1.jpg)
Looks like this w/o the "N". Note the ribbing is different. It has two vertical ribs, not one. The no "N" case is about $1500-2000 if you can find one. It is a hard part to find.
Again thank you so much for the help!
Actually a 3.89 car could have SPEC case. Might be easier to find than a no N nodular
So now I need to know what an SPEC case is? Is the one I pictured in previous reply an SPEC case?
Corey,
The case you are looking for 'might" have a 7M xx date code on it. the casting number on the inside MUST say C4AW 4025B or simply C4AWB . This is the ONLY casting number that is original for your car. It would NOT have an N on the front as that was added in late '68 for '69 productiom. The pinion retainer is as Pete ( Coralsnake's photo shows. The C5AW letters are below the surface , NOT raised . If you are only concerned with function, the one you are being sold will "function" but again is not the "as produced" version. I believe the guys here are concerned about spending potential big bucks on an incorrect assembly. IF the M 3.50 diff has the proper case and bearing retainer you would be money ahead by simply having the gear set changed. 7M cases are out there. Your car is a bit too late for a SPEC ( where the date code is normally) case but it "is" possible as TLea suggested. The Axle tag would say C8ZX-? Check the Coralsnake site for the specific suffix. You can't go wrong with the information on his site.
Randy
Thank you Randy. I go on The Coral Snake web site all the time but it is amazing even with that how much I miss and do not know. This is all great information. This weekend I am going to check and see what case I currently have in my car and I will go from there.
Until this discussion I knew I had a 3.50:1 gear but I had no idea there were so many nuances with the case.
Hopefully the 3.50 was put in your original diff and you will only need a gear replacement .
Quote from: gt350hr on February 15, 2018, 06:03:03 PM
Hopefully the 3.50 was put in your original diff and you will only need a gear replacement .
Ever see any N type web cases (no "N") with a late 1968 date ? I was told about a Dec 1968 dated casting but thought they were all "N" marked by then.
you can make a "N" with some jb weld, I know people that have. phred
I could not stand the suspense of waiting for the weekend to find out if the 3rd member in my car was correct or not. So last night on my way home I stopped in and looked at my car. I was very relieved to find the gear casing and pinion retainer are correct for my car. It even has the tag on it which is hard to read because it has all been painted black. Returning it to the correct color and possible gear ratio will be a job for another day.
Once again this Forum really helped me out! Thank you all.
Corey ,
Looks like response #18 was "spot on" LOL. As with many situations there are patterns for parts in certain ranges and yours fit into one I was familiar with. Nice that you still have the original tag on your original diff. Every picture shows the correct parts , original to your car. Before "I" pulled it, I would verify that the ratio is 3.5 not 3.89 unless you are certain for some reason. Mark "a" tire and the driveshaft. Turn the drive shaft , not the tire to determine how many turns are needed for one revolution of the tire. If you turn the tire instead ( on an open diff) the spider gears might turn and throw the count off.
Glad your curiosity got to you and you found "all the right stuff".
Randy
Randy,
That is very interesting. When I did the check for gear ratio I was turning the tire and counting the shaft. I will do it the other way and see what happens. It would be crazy if all along I had exactly what I was suppose to have gear wise. It would not all be for nothing since I did learn a whole bunch about 3rd members in 68 Shelby's.
Corey
7M21. The same date housing that was in my brothers April 25th Mustang with 4.30s and my May 11th Torino GT with 3.91s.
Quote from: Corey Bowcutt on February 16, 2018, 01:12:32 PM
Randy,
That is very interesting. When I did the check for gear ratio I was turning the tire and counting the shaft. I will do it the other way and see what happens. It would be crazy if all along I had exactly what I was suppose to have gear wise. It would not all be for nothing since I did learn a whole bunch about 3rd members in 68 Shelby's.
Corey
FYI a 3.50 gear is much more street friendly then the 3.89. If it turns out that is a 3.50 I would be torn with going to the trouble to change just for the reason of it not being original . It is not like anyone could tell looking at the car. Is everything else visually on the car 100% correct? If not then shouldn't be a big deal. If you find it is a 3.89 then all good. Ether way I think you are in very good shape. Just my opinion ,others may think differently. ;D
Quote from: 68stangcjfb on February 16, 2018, 01:16:03 PM
7M21. The same date housing that was in my brothers April 25th Mustang with 4.30s and my May 11th Torino GT with 3.91s.
Drum to drum axle assemblies were built at the axle plant per requisitions that could be for a hundred or more , the same went for component parts used on them. As you have noted there can be some large "ranges" in dates of parts used. The casting plant "req" may have been for a thousand (or more) castings and it took a week to macing the "run" . They ship to the assembly plant and get built as third members ( more time) and then into complete drum to drum assemblies , get palletized , and finally shipped to the car assembly plant. This is one of the reasons there is a "manufacturing date" on the axle tag as well. Your case has a wide range while another could have a real close one. I-we have seen both cases on original unmolested applications.
Randy
Quote from: 68stangcjfb on February 16, 2018, 01:16:03 PM
7M21. The same date housing that was in my brothers April 25th Mustang with 4.30s and my May 11th Torino GT with 3.91s.
never seen nodular casting between 7M and 8D. I've seen original 7M cases in June cars
fyi my car has 3.89 and spec case but it is nov build
http://www.kevinstang.com/Ninecase.htm
Paul Bartus , as quoted on Kevin's site page is wrong about the "magnesium" being added to grey iron to make it "nodular. The material added was/is manganese. Big difference.
Also ALL 9" equalocks were 28 spline . Never 31 that was a traction lock only. Pre '68 31 spline "locking axle" cars were Detroit lockers.
Randy
Quote from: gt350hr on February 19, 2018, 01:18:10 PM
Paul Bartus , as quoted on Kevin's site page is wrong about the "magnesium" being added to grey iron to make it "nodular. The material added was/is manganese. Big difference.
Also ALL 9" equalocks were 28 spline . Never 31 that was a traction lock only. Pre '68 31 spline "locking axle" cars were Detroit lockers.
Randy
Randy's page is more accurate then Kevin's page 8) .
I did get a chance to Check out my axles and gear ratios this past weekend and I do in fact have 31 spline axles noted by the 3 counter bored holes in the end of the axle. I also rotated my drive shaft and counted the # of turns for 1 rotation of the tire and it is in fact a 3.50:1 ratio. I also noticed that I appear to have posi traction. I say this because when rotating the drive shaft both tires rotate in the same direction. Also when I rotated one tire the other rotated as well in the same direction. Does this indicate posi traction? If so did they come with posi traction?
Corey ,
Ford called it "Traction Loc" and it was an option. If your tag says 3L89 , then you r diff was originally equipped with one. It would also show on the Marti report. If not , they are often added to improve traction. It is also interesting that GT350s got 3.89 gears not 3.91s which were "new for '68".
Randy
There was also something about a three disc and a five disc limited slip.
I don't remember the details but it might have been equal-lok vs. traction-lok?
Doug ,
That applied to Equalocks only which as I said were all 28 spline. The clutches were not "torque sensitive" like the later traction locks are. initially they had four steels and three frictions with 2 "Bellville" springs ( conical ) for clutch pressure. later units had 5 steels and four frictions with one Bellville spring. Traction locks have 4-1/2 "friction discs" and steel plates as one steel plate has friction material on one side. The traction lock design uses the "wedge action" of the spider gears to increase the load placed on the clutch pack , hence the name.
Quote from: gt350hr on February 22, 2018, 10:40:54 AM
Doug ,
That applied to Equalocks only which as I said were all 28 spline. The clutches were not "torque sensitive" like the later traction locks are. initially they had four steels and three frictions with 2 "Bellville" springs ( conical ) for clutch pressure. later units had 5 steels and four frictions with one Bellville spring. Traction locks have 4-1/2 "friction discs" and steel plates as one steel plate has friction material on one side. The traction lock design uses the "wedge action" of the spider gears to increase the load placed on the clutch pack , hence the name.
Aren't those clutch plates sourced from the C4 automatic transmissions as well?
I bought my first one over the counter in 1972 from my Ford Parts guy.
I had taken in an 9"-3.50 with an Equal lock, a "N" housing and 31 spline axles from, a 69 casting date, from of all people, a Ford Factory rep. I think he's the guy that wanted the 4.44 Detroit locker? I think I made about $150 on the deal?
That Equa lok started some discussion, not necessarily an argument. I remember the issue was it was 3 disc's. Maybe it was 28 splines? Huh?
I was a 23 year old Architect and I'm not supposed to be getting greasy crawling around under these things so it wasn't a matter of what is supposed to exist, it was a matter of what was in front of me.
The Equa-lok got sold off for $50 just by itself. No one really wanted it. The Traction-lok's are nice units. Nice and quiet.
Not like the Detroit lockers. Gee-se. That one almost got me arrested and I was only going 10 miles an hour IF EVEN THAT!
No traction lock clutches are all by themselves despite being close in size to a C4.
Quote from: shelbydoug on February 22, 2018, 01:52:35 PM
Not like the Detroit lockers. Gee-se. That one almost got me arrested and I was only going 10 miles an hour IF EVEN THAT!
Now you're scaring me Doug. My car originally had a 3.00. Someone changed it to a 3.50 with a Detroit Locker. Tim sent me some info stating that my car had been in for warranty work on 7/6/68. Rear end rebuild including a new ring an pinion. I'm wondering if that is when they changed the gear out. Not to derail the thread, but does anyone know why the build sheet shows two digits for the axle? My build sheet shows 76 but the axle code on the door tag is 6.
Quote from: Corey Bowcutt on February 19, 2018, 04:40:44 PM
I did get a chance to Check out my axles and gear ratios this past weekend and I do in fact have 31 spline axles noted by the 3 counter bored holes in the end of the axle. I also rotated my drive shaft and counted the # of turns for 1 rotation of the tire and it is in fact a 3.50:1 ratio. I also noticed that I appear to have posi traction. I say this because when rotating the drive shaft both tires rotate in the same direction. Also when I rotated one tire the other rotated as well in the same direction. Does this indicate posi traction? If so did they come with posi traction?
Do the 3 counter bored holes always mean it's 31 spline axle? Had a 77 Granada with axle of that type.
Quote from: TXShelbyman on February 22, 2018, 08:58:44 PM
Quote from: shelbydoug on February 22, 2018, 01:52:35 PM
Not like the Detroit lockers. Gee-se. That one almost got me arrested and I was only going 10 miles an hour IF EVEN THAT!
Now you're scaring me Doug. My car originally had a 3.00. Someone changed it to a 3.50 with a Detroit Locker. Tim sent me some info stating that my car had been in for warranty work on 7/6/68. Rear end rebuild including a new ring an pinion. I'm wondering if that is when they changed the gear out. Not to derail the thread, but does anyone know why the build sheet shows two digits for the axle? My build sheet shows 76 but the axle code on the door tag is 6.
The problem with the "law" with MY Detroit Locker was that on a left hand turn, it would lock the inside tire.
There was just a simple situation where there was a traffic light that crapped out and we had two "motorcycle" cops directing traffic.
At my turn at the light, the cop signaled to me to turn left. The car was idling at 800, I let the clutch out easy, just feathered the throttle as one normally would, and here goes the locker. It locks the tires and as I turn spins the tires and leaves rubber.
OK, I'm not going to call anyone names. Let's just project a scenario where I need to explain to the "motorcycle contingent in 'Dirty Harry'", exactly WTF "my problem is"? Not a comfortable scenario.
The Traction-lok was in the car by the next weekend.
Quote from: jguyer on February 22, 2018, 11:26:20 PM
Quote from: Corey Bowcutt on February 19, 2018, 04:40:44 PM
I did get a chance to Check out my axles and gear ratios this past weekend and I do in fact have 31 spline axles noted by the 3 counter bored holes in the end of the axle. I also rotated my drive shaft and counted the # of turns for 1 rotation of the tire and it is in fact a 3.50:1 ratio. I also noticed that I appear to have posi traction. I say this because when rotating the drive shaft both tires rotate in the same direction. Also when I rotated one tire the other rotated as well in the same direction. Does this indicate posi traction? If so did they come with posi traction?
Do the 3 counter bored holes always mean it's 31 spline axle? Had a 77 Granada with axle of that type.
The three holes are there for machining operations. The "center" is a lathe center and the outer two are holes for a "driver" for the spline operation and some turning. While this "precision method" was used for 31 spline axles , it is not unique to them. '60s axles had the three holes and were 28 spline. ALL 31 spline "performance axles" did have the three holes through '73. The process was also used on 28 spline axles from '72 forward on some vehicles.
gt350hr, thank you for the explanation.