5:55 Ratio?
Thread Starter
Melting Slicks
Joined: Apr 2004
Posts: 2,008
Likes: 38
From: Space Coast Gator Territory
5:55 Ratio?
Guys, I have had this rear for several years as it came with a lot of parts I bought. I haven't had a need for it as it is deep, but can it be a 5:55? It has 39 teeth on the ring gear and the pinion turns about 5:55 times for one turn of the axle. The pictured numbers are 3876476-N and D 5 5. Any help confirming the gear set ratio would be appreciated.
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Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Count the teeth on the ring gear and the teeth on the pinion then divide the pinion count into the 39 you got for the crown gear.
It will not be 5.55 for the ratio, not with only 39 on the crown.
Mark one pinion tooth and count the numer of teeth, do the math and it will tell the ratio.
39 divided by pinion teeth= ratio
It will not be 5.55 for the ratio, not with only 39 on the crown.
Mark one pinion tooth and count the numer of teeth, do the math and it will tell the ratio.
39 divided by pinion teeth= ratio
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
If your correct ........ I was trying to do some quick math. It can't be. Because it's math. Like if you have 39 ring and 13 pinion it would be 3.00. They don't make 7 tooth pinion gears (that I know off)which would be the math ratio for 5.55 or so
I have a 4.11 and when you pull the back off the space behind the ring gear is much larger (That would be to the left in your picture) The reason is because I have a small tooth pinion gear.
I have a 4.11 and when you pull the back off the space behind the ring gear is much larger (That would be to the left in your picture) The reason is because I have a small tooth pinion gear.
Last edited by gkull; Sep 1, 2004 at 09:47 AM.
Thread Starter
Melting Slicks
Joined: Apr 2004
Posts: 2,008
Likes: 38
From: Space Coast Gator Territory
I just returned home and after reading the replies decided to pull the cover and check again. Yep...39 teeth on the ring for sure. With one revolution of the pinion the axle turns 5 and 1/2. It didn't look like I could see well enough to count pinion teeth. I did a quick check years ago and dismissed it as a 5:13 as that was the lowest gear I had heard of, but it goes well past 1/4 turn in the 5th revolution.
Is there any chance the numbers help? I was thinking the D55 was the GM code for a 4:55 gear as the D was the 4th number, but it don't work for a 5:55 to 1 ratio. gkull is correct that the pinion would need to be a 7 tooth for the 39 ring gear to come out at 5:55. That must be what it is as every time I turn the pinion one revolution the axle turns 5 1/2 revolutions.
Any other thoughts on what this is?
Is there any chance the numbers help? I was thinking the D55 was the GM code for a 4:55 gear as the D was the 4th number, but it don't work for a 5:55 to 1 ratio. gkull is correct that the pinion would need to be a 7 tooth for the 39 ring gear to come out at 5:55. That must be what it is as every time I turn the pinion one revolution the axle turns 5 1/2 revolutions.
Any other thoughts on what this is?
Thread Starter
Melting Slicks
Joined: Apr 2004
Posts: 2,008
Likes: 38
From: Space Coast Gator Territory
Ok...after reading this thread I raised a suspicious eyebrow myself, so I went back in a third time. I took a harder look at the pinion gear from another angle and could see it. It does in fact have a 7 tooth pinion gear making it a 5:55 gear set. On the end of the pinion gear facing the ring there are some machinist numbers 188E over 2422. I went to the Richmond gear site and nothing is shown for a C-3 Corvette higher than 4:11. I never heard of a 5:55 but there it is 5:57-1. Anybody have a 9000 rpm drag motor to put it behind?
Last edited by Red 69; Aug 31, 2004 at 07:32 PM.
Race Director
Joined: Nov 2000
Posts: 11,872
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From: Waterloo ontario Canada
It can't be that hard to count the teeth on the pinion, use a flashlight, look for just one tooth of the pinion, turn the pinion slowly looking are any mark on a tooth. Start counting from there as the pinion is slowly turned and you can accurately count the teeth.
Do the math my actual tooth count.
I can't see a 5.55 gear with 39 teeth. Divide 5.55 into 39 and the tooth count on the pinion would be 7
Do the math my actual tooth count.
I can't see a 5.55 gear with 39 teeth. Divide 5.55 into 39 and the tooth count on the pinion would be 7
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Thread Starter
Melting Slicks
Joined: Apr 2004
Posts: 2,008
Likes: 38
From: Space Coast Gator Territory
Yes....I figured this gear was an odd duck and obviously made for some kind of racing in mind. The internals are in good condition, so I don't think it has seen much use. It rested under a work bench for a long time until I broke the cover on my 4:11 and it became useful. I had some thoughts of using the case to install a 3:55 gear set, but think a TKO 5 speed is in my future.
I agree, this gear would be killer for the 1/8 mile drags, but I am past that period of interest in my life. All I can visualize happening with the 32"x 14's" is a lot of broken parts, but it would be a lot of fun while it lasted.
Anyway, the other thread about the availability of 4:56 gears motivated me to pull the now cracked cover off and try to identify the exact gear set. I knew it was deep, only now the mystery of its exact ratio of 5:55 is known. It will continue to occupy the same space on my garage floor until parts are needed; curse the thought.
I agree, this gear would be killer for the 1/8 mile drags, but I am past that period of interest in my life. All I can visualize happening with the 32"x 14's" is a lot of broken parts, but it would be a lot of fun while it lasted.
Anyway, the other thread about the availability of 4:56 gears motivated me to pull the now cracked cover off and try to identify the exact gear set. I knew it was deep, only now the mystery of its exact ratio of 5:55 is known. It will continue to occupy the same space on my garage floor until parts are needed; curse the thought.
Melting Slicks
Joined: May 2002
Posts: 2,508
Likes: 0
From: Wisconsin
Originally Posted by gkull
They would be excellant gears for a ZF-6 speed with it's 50% OD
Tour overall ratio would be 2.775 Just take off in second most of the time.
Tour overall ratio would be 2.775 Just take off in second most of the time.