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| 8 1/4 chunk https://slantsix.org/forum/viewtopic.php?t=30396 |
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| Author: | RossKinder [ Tue Aug 05, 2008 11:37 am ] |
| Post subject: | 8 1/4 chunk |
How might one start looking for an 8 1/4 inch chunk of a given ratio. With a 2.94 ratio and big tires I think I need to fix something. Thanks |
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| Author: | Joshie225 [ Tue Aug 05, 2008 12:19 pm ] |
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8 1/4 axles are carrier-tube type like the 7 1/4 and do not have a removable carrier/third member/'chunk'. 2.94 is not a bad ratio for most street cars. Do you have a need to run large tires? How large exactly are the tires? |
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| Author: | RossKinder [ Tue Aug 05, 2008 4:55 pm ] |
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Quote: 8 1/4 axles are carrier-tube type like the 7 1/4 and do not have a removable carrier/third member/'chunk'. 2.94 is not a bad ratio for most street cars. Do you have a need to run large tires? How large exactly are the tires?
Note: I'll refer to either a step in gear ratio or a step in tire size generally as a "step."We're talking about a '65 Valiant. To get better brakes and get beyond nearly impossible to buy (around here) 13 inch tires I put Duster running gear under it. The upshot is that I ended up with 15 inch wheels. Original tires were about 24 inches. The _smallest_ 15 inch tires I have found are 25 inches. That's one step in the wrong direction, at least under my circumstances - at take-off. I believe the 2.94 rear end ratio is another step in the same direction from the original 7 1/4 inch rear that was in it (3.55?). I think these and my steep driveway are what finally ate the first gear in my 3 speed trans. With a 4 speed OD I'd get one step back on take off, compared to the original 3 speed. An ordinary 4 speed would not give me that step, so I'd still be 2 steps to the bad in first gear, altho it should really fly at cruise. A 4 speed OD would give me back one step on take off and another step (3 steps total) at cruise. According to my "calculations" I'd still be one step "in the red" at take off. Therefore the notion of a different rear end ratio. Altho that is starting to look like it's "over the horizon." Make any sense at all? Thanks. |
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| Author: | Joshie225 [ Tue Aug 05, 2008 8:16 pm ] |
| Post subject: | |
It's true that most V8 4-speeds have a pretty high 1st gear (2.66 or worse), but slant 6 and 318 4-speeds should have the same 3.09 1st gear as the A833OD. 3.55 rear gears were usually only in 170 engined cars. 225s typically had 3.23s. You can buy 24" OD 15" rim tires. I ran 225/50R15 tires on 15x7" cop car wheels and they are 23.9" OD, but if you only have 5.5" or 6" wide wheels 225/50R15 is too wide. 195/60R15 are only 24.2" OD and fit a 5.5"-6" wide wheel. |
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| Author: | RossKinder [ Tue Aug 05, 2008 10:29 pm ] |
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Quote: It's true that most V8 4-speeds have a pretty high 1st gear (2.66 or worse), but slant 6 and 318 4-speeds should have the same 3.09 1st gear as the A833OD.
Hm. Interesting. What I had read was 2.44. Hard to find good info. If I ever come across one I'll have to remember that. (Too much to remember when I come across prospects so rarely.)Quote: 3.55 rear gears were usually only in 170 engined cars. 225s typically had 3.23s.
Thanks. But don't I still need to be taking steps in the other direction?Quote: You can buy 24" OD 15" rim tires. I ran 225/50R15 tires on 15x7" cop car wheels and they are 23.9" OD, but if you only have 5.5" or 6" wide wheels 225/50R15 is too wide. 195/60R15 are only 24.2" OD and fit a 5.5"-6" wide wheel.
These wheels are 6 inches. And when I got these new tires 196/65 was all I could find in this town. If they ever wear out (I don't drive much) I'll have to go find something else.Thanks |
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| Author: | Joshie225 [ Tue Aug 05, 2008 10:54 pm ] |
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My point on the axle ratios was that you're not as far off from the original ratio as you think. 195/65R15 is only 25" tall and only 4.2% taller than original. Not a big step there either, but it does add up. Here are the A833 ratios:  I had the 2.66:1 first gear trans in my race car with 3.55s and it was great for road racing. I have two A833s and one is supposed to have the 3.09 1st gear, but I haven't verified that. It's for my Valiant in any case. |
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| Author: | RossKinder [ Wed Aug 06, 2008 8:51 am ] |
| Post subject: | |
Quote: My point on the axle ratios was that you're not as far off from the original ratio as you think.
I may have to fritz these two 3 speeds together temporarily.Quote: 195/65R15 is only 25" tall and only 4.2% taller than original. Not a big step there either, but it does add up.
Yes. This steep (and bumpy) driveway enters into it a lot. Quote: Here are the A833 ratios: Awww...I had the 2.66:1 first gear trans in my race car with 3.55s and it was great for road racing. I have two A833s and one is supposed to have the 3.09 1st gear, but I haven't verified that. It's for my Valiant in any case. Saved and printed. Thanks a lot. |
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| Author: | RossKinder [ Thu Aug 07, 2008 5:24 pm ] |
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Quote: My point on the axle ratios was that you're not as far off from the original ratio as you think. 195/65R15 is only 25" tall and only 4.2% taller than original. Not a big step there either, but it does add up.
Do you have one of these for the A-903?Here are the A833 ratios: I had the 2.66:1 first gear trans in my race car with 3.55s and it was great for road racing. I have two A833s and one is supposed to have the 3.09 1st gear, but I haven't verified that. It's for my Valiant in any case. Thanks |
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