buy XR's or upgrade B1's?
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03-05-2003, 10:42 PM
#33
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Hey, great.
What's your timeframe?
I'm bad about starting things late, and I don't want to hold you up. I work well to deadlines, though, so don't be shy, just let me know on the time..
Price? Dunno. B1's/1.36:1. 390 hp is all they've seen, and they act fine, no shavings in the oil, etc. Showers on them their entire life (they are both replacement drives - I learned my lessons on the originals). One not-bad chip on one skeg from the forklift truck (I can fix it if you want). I can surely get you some pix. What sounds fair to you?
email me if you want: [email protected]
What's your timeframe?
I'm bad about starting things late, and I don't want to hold you up. I work well to deadlines, though, so don't be shy, just let me know on the time..
Price? Dunno. B1's/1.36:1. 390 hp is all they've seen, and they act fine, no shavings in the oil, etc. Showers on them their entire life (they are both replacement drives - I learned my lessons on the originals). One not-bad chip on one skeg from the forklift truck (I can fix it if you want). I can surely get you some pix. What sounds fair to you?
email me if you want: [email protected]
03-05-2003, 10:56 PM
#34
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%&^$#*( Of course they have to be 1.36 That means new props or change the gears. Man I wish they were 1.50. This is the pile I am rebuilding now. Would be nice just to bolt on and go. Let me way out the options.
03-06-2003, 08:29 AM
#36
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Russ: I got a set of 23 Mirages on them now. I reckon they could stay with them. What props do you have to trade right now?
These Mirage 23's/1.36:1 drives run 72-73 with a light load on a 1991 F311SR1 with 502 Mag carb motors (415/390pshp).
For "whatever" reason, the boat was always a mile-an-hour faster than an identical 1990 311/502 boat with 1.5:1/25p. Goes against conventional logic, but was also a dead-heat with a 1991 292SR1/502Mag boat with 1.5:1/25's as well. Boats in question were owned by friends and we even switched drivers on occasion and ran them. Same result.
Let me know.
These Mirage 23's/1.36:1 drives run 72-73 with a light load on a 1991 F311SR1 with 502 Mag carb motors (415/390pshp).
For "whatever" reason, the boat was always a mile-an-hour faster than an identical 1990 311/502 boat with 1.5:1/25p. Goes against conventional logic, but was also a dead-heat with a 1991 292SR1/502Mag boat with 1.5:1/25's as well. Boats in question were owned by friends and we even switched drivers on occasion and ran them. Same result.
Let me know.
03-06-2003, 08:34 AM
#37
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Kaama
Of course the top cap is the best bang. The rear cap with its extra holes to the top cap probably won't do that much for drive integrity or top cap stability, but it definitely won't hurt.
Any time you have a large access hole in a casting, it can be a flex point. The stouter the cover and the more secure the fasteners, the better chance you have of reinforcing that opening. The top cap fits the bore which acts as a filler to reinforce the case since the bore will try to eggshape as the case distorts. The rear cap is a flat mount, which does not work as well to prevent distortion, BUT if it secures via two studs to the top cap, then it can offer some measure of additional reinforcement.
I do agree that the amount of reinforcement is not very significant given the geometry of the case and the expected thrust loading.
Of course the top cap is the best bang. The rear cap with its extra holes to the top cap probably won't do that much for drive integrity or top cap stability, but it definitely won't hurt.
Any time you have a large access hole in a casting, it can be a flex point. The stouter the cover and the more secure the fasteners, the better chance you have of reinforcing that opening. The top cap fits the bore which acts as a filler to reinforce the case since the bore will try to eggshape as the case distorts. The rear cap is a flat mount, which does not work as well to prevent distortion, BUT if it secures via two studs to the top cap, then it can offer some measure of additional reinforcement.
I do agree that the amount of reinforcement is not very significant given the geometry of the case and the expected thrust loading.
03-06-2003, 10:14 AM
#39
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Platinum MemberThread Starter
Nordic
Yes and No.
The billet or steel bearing tower is a much stronger anchor for the gear and shaft bearings in regards to the top gear (LH rotation drive). With a stock cast cap, the thrust load on the cast bearing tower can approach the failure strength of the top cap. This is indeed the most critical weak point on a LH drive.
BUT, the aftermarket caps offer more than a secure bearing anchor for the top gear. They typically offer a thicker structure to provide more stability to the Bravo case itself in reducing case distortions. They usually offer fins or water passages to dramatically increase surface area for heat transfer to cooling water when used with showers. Thye are also thick enough that high strength studs can be used to secure them without worry of cracking the cap from the extreme hold-down force of the studs and fine-thread nuts and hardened washers.
Teague and Imco are now recommending the cap upgrades for both sides.
But YES, the need is FAR greater for the LH drive for the upgrade.
Yes and No.
The billet or steel bearing tower is a much stronger anchor for the gear and shaft bearings in regards to the top gear (LH rotation drive). With a stock cast cap, the thrust load on the cast bearing tower can approach the failure strength of the top cap. This is indeed the most critical weak point on a LH drive.
BUT, the aftermarket caps offer more than a secure bearing anchor for the top gear. They typically offer a thicker structure to provide more stability to the Bravo case itself in reducing case distortions. They usually offer fins or water passages to dramatically increase surface area for heat transfer to cooling water when used with showers. Thye are also thick enough that high strength studs can be used to secure them without worry of cracking the cap from the extreme hold-down force of the studs and fine-thread nuts and hardened washers.
Teague and Imco are now recommending the cap upgrades for both sides.
But YES, the need is FAR greater for the LH drive for the upgrade.
