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JonnyAngle | The old 3.73 vs 3.53 debate | ||
Senior Guru
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My car:
86 auto stock 3.07s stock tranny and stall LTs and true dual exhaust are the only mods. I cannot decide between 3.73s and 3.53 for my rear end D36. What I need to know: When I change my gear ratio, how much more power will the 3.73s provide over the 3.53s, and how much more fuel efficient are the 3.53s over the 3.73s? Obviously everyone's results will vary, but I need a starting point. Thanks, Jack I should add that it is a daily driver, but not my only means of transportation. If I cant drive it in the rain I'll survive. I do some highway driving, but mostly in the city. |
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Posted on: 2009/4/18 22:53
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When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car. |
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Danspeed1 | Re: The old 3.73 vs 3.53 debate | ||
Elite Guru
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There is really very little difference between 3.73's and 3.54's. I wouldn't worry about driving in the rain as long as you stay out of the throttle.
DG |
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Posted on: 2009/4/19 1:52
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1971 Chevelle SS (The Original) 1972 Chevelle SS 454 1995 Corvette Convertible 1996 Ford Explorer 2009 Cadillac CTS-v |
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bogus | Re: The old 3.73 vs 3.53 debate | ||
Grand Imperial Pooh-Bah
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You are going to be winding up a rather slow revving engine.
A few thoughts about that in general... you will be hitting the wall quicker... and that may not agree with an older L98. Also, 3.73 is as much as a D36 will support... I would go with the 3.54 or, find a D44 with 3.42 gears. |
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Posted on: 2009/4/19 3:06
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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vetteoz | Re: The old 3.73 vs 3.53 debate | ||
Senior Guru
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Quote:
bogus wrote: If you do a search you will find that 3.07 is the recommended allround gear for a stock(ish) L98 unless you are going to specialize in stoplight to stoplight racing OR have done some mods to increase engine rev range. |
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Posted on: 2009/4/19 5:44
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85L98-84L83 | Re: The old 3.73 vs 3.53 debate | ||
Guru Newb
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Don't be a sheep and do what everyone else does, the 3.07 rear is boring, it is good for the 1/4 mile if your don't have any power adders. 3.07 rear keeps the L98 in its power range when traveling a 1/4 mile. But in your case, driving around town, you need that extra gearing to impress chicks when you light em up. You will have a blast with the 3.54 gears or the 3.73 gears. Doing 65 mph with 3.73 depending on tire size you will be at 2300 rpm and with 3.54 you will be at 2200 rpm. If it were me I would probably get the 3.54 gears, I live in the country so it is mostly 60+ mph but for you I would go with 3.73 in the city unless you hit the drag strip, but most vette owners don't even live near a drag strip or even go to one on a regular basis. You will think you added 100 hp with the new gears and wondered why you didn't do it sooner. Remember the old muscle cars and vettes of the 60's had 4.11 gearing in some and they produced the same power as the L98 vettes so go for it, they didn't complain about a few extra rpm back then why complain now.
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Posted on: 2009/4/19 18:09
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85 vette - 3.54 gears,pulleys,160 stat,hypertech chip,K&N,no cat,B&B cat back,cut air lid,TB bypass,air pump elim pulley,air foil,Torque thrust II wheels,maaco paint job 84 vette - K&N,renegade,2 inch TB's,adustable fuel pressure to 15 psi,air pump e... |
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vetteoz | Re: The old 3.73 vs 3.53 debate | ||
Senior Guru
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Quote:
They also had engines that made power past 4500 rpm |
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Posted on: 2009/4/19 23:25
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bogus | Re: The old 3.73 vs 3.53 debate | ||
Grand Imperial Pooh-Bah
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I am just concerned about how quickly he will hit the wall... if he had more revs to work with, 3.73 wouldn't be an issue.
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Posted on: 2009/4/20 2:59
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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85L98-84L83 | Re: The old 3.73 vs 3.53 debate | ||
Guru Newb
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I currently have 2.73's in my 85 vette and I can still turn over the tires from a stop but I think I could use a little more gear. I still think the 3.54 gears would be good.
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Posted on: 2009/4/20 5:50
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85 vette - 3.54 gears,pulleys,160 stat,hypertech chip,K&N,no cat,B&B cat back,cut air lid,TB bypass,air pump elim pulley,air foil,Torque thrust II wheels,maaco paint job 84 vette - K&N,renegade,2 inch TB's,adustable fuel pressure to 15 psi,air pump e... |
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JonnyAngle | Re: The old 3.73 vs 3.53 debate | ||
Senior Guru
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I would love to put a cam and some new heads in the '86, but realistically I most likely never will. So as far as the higher revs it doesn't sound like theres that much difference between the 3.53s and 3.73s.
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Posted on: 2009/4/20 12:42
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When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car. |
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CentralCoaster | Re: The old 3.73 vs 3.53 debate | ||
Senior Guru
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I've looked at the other options, and this one wins out every time for your setup. Even with a 6-speed and double-overdrive, I couldn't find any situation where a gear taller than 3.45 was beneficial. Again, with a stock motor. 3.73s on your setup will hurt economy, and 1/4 mile acceleration. Sure they'll feel quick when you stomp the throttle at the stoplight, but it'll make up for it on the other end and then some. I think a looser converter would get you what you're looking for without giving up anything. |
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Posted on: 2009/4/20 16:29
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1985 Z51, ZF6 |
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JonnyAngle | Re: The old 3.73 vs 3.53 debate | ||
Senior Guru
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CC: So If I'm on the freeway and I hit the gas with 3.73s, is it going to feel like I'm driving a golf cart? How much better would the 3.53s be in that same scenario?
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Posted on: 2009/4/20 21:31
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When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car. |
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dan0617 | Re: The old 3.73 vs 3.53 debate | ||
Senior Guru
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Take CC's advice! Get yourself a 2000 or 2200 stall if it is a daily driver, or a 2200 or 2400 stall if it is weekend only. Make sure it is a lock-up converter. Talk to PeteK, he can get you one at a great price, or make sure you buy a good one. There is much more to be had here than in the gears with your setup. The car will feel like it has more gear in it because the converter will put you in your powerband when you take off. Trust me, you will be blazing the tires when you want. Another great mod for you would be a B+M shift improver kit. They can be had for less than $50 and can be installed yourself in an afternoon if you are careful and follow the directions to a T. OR you could have the same shop that installs the converter put in the shift improver kit. It has like 3 different shift settings, use the all out performance one since the higher stall converter will soften the shifts some. If you had the 2.59 rears then I'd tell you to go to 3.07's, or 3.54's at most. Since you already have the 3.07's keep them and call it money ahead. |
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Posted on: 2009/4/21 13:34
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´89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's. On spray, 10.55 @ 132.78, 1.55 60 ft. On motor, 12.08 @ 113.15, 1.66 60 ft. |
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dan0617 | Re: The old 3.73 vs 3.53 debate | ||
Senior Guru
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Oops, double post, sorry!
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Posted on: 2009/4/21 13:37
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´89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's. On spray, 10.55 @ 132.78, 1.55 60 ft. On motor, 12.08 @ 113.15, 1.66 60 ft. |
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Josh | Re: The old 3.73 vs 3.53 debate | ||
Guru
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I put 4.09 gears in my L98 car and loved it. Everyone will tell you that the steep gear and L98 combo won't work, but mine did. I went high 12's at 106 pretty regular with the stock heads, cam, and intake on my 91.
Theoretically, it would have been faster with less gear, but it was faster with the 4.09 gear than it ever was with the stock 3.45's. Beyond that, it was fun as Hell to drive around town. 360 RWTQ at 2000 RPM's and a steep gear like that make the car fun to drive on the street, and easy to drive around town. I have a 6 speed, so overall fuel economy didn't really suffer, and it still only turns about 2200 at 70-75 MPH. Since you have an auto, I don't think 4.09 will work as well for you, but the 3.73 is what I would recommend. Good luck! |
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Posted on: 2009/4/21 14:02
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"Have ya paid your dues, Jack?" "Yessir, the check is in the mail." - Jack Burton |
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anesthes | Re: The old 3.73 vs 3.53 debate | ||
Master Guru
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Gears should match the tire size + camshaft. There is no debate.
For a street car that means keeping it in the power band for passing and acceleration, for a track car that means crossing the finish line in your 1:1 gear right below redline. http://members.cisdi.com/~anesthes/gear.html A 3.07, with 26" tires crossing the finish line in your 1:1 gear at 4500rpm (redline) would be going 113mph.. No stock L98 does 113mph at the track, so saying 3.07 is a perfect ratio for 1/4 mile in a stock L98 doesn't make any sense. The math doesn't lie. Most L98s run somewhere between 95-98 mph, so a 3.45/3.54 gear ratio should have you cross the finish right about where it needs to be, and it should provide the best 60' and ET. The 3.73, I think may run out of steam up top with a stock cam, I think you'll see around 93mph at redline which tells me it's too steep. A 3.73 would be PERFECT with a short duration (6,000 RPM shift) camshaft and a good intake like a miniram. That's an instant 125mph car, mid 11s. -- Joe |
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Posted on: 2009/4/21 16:43
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'79 Z28. 412 CID, NP 833 transmission, 3.73 10.5" rear end. |
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JonnyAngle | Re: The old 3.73 vs 3.53 debate | ||
Senior Guru
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Quote:
FWIW I've got 275/40/17s which are about 24.75" |
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Posted on: 2009/4/21 17:16
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When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car. |
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CentralCoaster | Re: The old 3.73 vs 3.53 debate | ||
Senior Guru
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Actually its closer to 25.5", which is a very common diameter for C4s. I think a decent driver can pull 98 mph traps in a stock L98. My tired '85 can do that.
So I should clarify, I believe 3.33 is actually ideal for the strip in your case. I went with 3.45s which a bit short but I have a tall overdrive, you don't. So I think the 3.07 are a good compromise for you if you're not a track whore. Here's some more numbers at 98 mph with a 25.5" tire in the 1:1 gear: 3.07 - 3970 rpm 3.33 - 4300 rpm 3.55 - 4590 rpm 3.73 - 4820 rpm I shift at 4200rpm. If I go beyond that I'm losing power vs what the next gear could make. I believe this also applies in the top gear, you don't want to run the engine too far out to where it starts causing your average hp on the run to decrease. You simply can't have both on the 700R, a good drag gear is going to hurt your fuel mileage in the crapper on the highway. at 80 mph in overdrive: 3.07 = 2270 rpm 3.33 = 2460 rpm 3.55 = 2620 rpm 3.73 = 2750 rpm My '85 lugs along at 1800 rpm in 6th gear at 80 mph. I love it, and I can manage about 26 mpg. At 2500 rpm, I bet I'd be down to 22mpg or worse. |
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Posted on: 2009/4/21 18:01
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1985 Z51, ZF6 |
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dan0617 | Re: The old 3.73 vs 3.53 debate | ||
Senior Guru
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Quote:
WOW, I need a new car then. If I could start over with an L98 car bone stock, throw in a set of 3.73's, a short duration cam (224/230 maybe??) and a miniram and run mid 11's then that is what I should do. I'll even throw in a converter and a good exhaust if I can pull mid 11's at 125 mph with just those mods. I think I'd need those mods AND your blower setup to run mid 11's at 125. |
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Posted on: 2009/4/21 18:03
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´89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's. On spray, 10.55 @ 132.78, 1.55 60 ft. On motor, 12.08 @ 113.15, 1.66 60 ft. |
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Josh | Re: The old 3.73 vs 3.53 debate | ||
Guru
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The optimum gear, IMO, is what makes the car the most fun for the owner/driver. If ET is what you are after, then math should be able to dictate what gear is optimum. I had more fun with the 4.09 gear than I would have with the optimum gear for drag racing, so that was probably the optimum gear for me. Your results may vary.
Good luck man, let us know what you decide to do. |
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Posted on: 2009/4/21 19:45
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_________________
"Have ya paid your dues, Jack?" "Yessir, the check is in the mail." - Jack Burton |
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dan0617 | Re: The old 3.73 vs 3.53 debate | ||
Senior Guru
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I'll bet the 4.09's and a TPI and a stick = MAJOR fun factor. I would have liked to have gone for a ride with you touting that setup. |
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Posted on: 2009/4/21 20:28
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´89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's. On spray, 10.55 @ 132.78, 1.55 60 ft. On motor, 12.08 @ 113.15, 1.66 60 ft. |
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JonnyAngle | Re: The old 3.73 vs 3.53 debate | ||
Senior Guru
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Quote:
I'll let you know. I am looking for the fun factor, but my car is an auto, so it's not pure apples to apples. I'm leaning towards the 3.73s. I'd say I'm a little more hillbilly than I am an engineer. |
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Posted on: 2009/4/22 1:02
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When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car. |
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anesthes | Re: The old 3.73 vs 3.53 debate | ||
Master Guru
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Quote:
I think you missed my point a little bit in regards to gearing for expected MPH at the finish line. Though, while we're on the topic, the kid I sold my miniram to has it in an fbody. With 195cc heads, a cam, and the miniram the car is running low 11s.. Pretty fast for naturally aspirated 350.. -- Joe |
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Posted on: 2009/4/22 1:06
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anesthes | Re: The old 3.73 vs 3.53 debate | ||
Master Guru
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Depends on manufacturer I guess. BFG TA 25.7" , Kumho 25.7", yours 25.5".. Quote:
I'd think 4200rpm is a bit early even for a L98. -- Joe |
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Posted on: 2009/4/22 1:12
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dan0617 | Re: The old 3.73 vs 3.53 debate | ||
Senior Guru
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Joe, yes, that is very fast for a N/A 350. It can be done but usually takes a big converter to do it. I do see your point and agree with optimizing the gearing, but for the OP I just feel he would get more bang for the buck with a higher stall converter than he would with changing up the gears in an L98.
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Posted on: 2009/4/22 2:01
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´89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's. On spray, 10.55 @ 132.78, 1.55 60 ft. On motor, 12.08 @ 113.15, 1.66 60 ft. |
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anesthes | Re: The old 3.73 vs 3.53 debate | ||
Master Guru
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Quote:
Oh, of course. But I was answering his question. -- Joe |
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Posted on: 2009/4/22 2:08
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CentralCoaster | Re: The old 3.73 vs 3.53 debate | ||
Senior Guru
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Quote:
Yes but you have to shave off a few % from the tire diameter to calculate speed accurately. Chevy does this when determining speedo gears, and the revolutions per mile published by the tire manufacturers do the same. So your tire might measure 25.7" on the lift, but on the ground, it's less. Especially after some burnouts. Care to split any more hairs? |
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Posted on: 2009/4/22 2:11
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1985 Z51, ZF6 |
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BeachBum | Re: The old 3.73 vs 3.53 debate | ||
Master Guru
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I personally do not like to gear a 700R4 transmission with the traditional 1-1 gear vs rpm as being done here.... I don't think it works, in part due to the rpm limit on the TPI motor coupled with the steep 1st gear.... I think you instead look at speed vs gear..... too much gear in a TPI motor and you're hitting 2nd gear so early in the speed the car loses inertia. Its just hard to lug 3200 lbs in 2nd gear at 30 mph. I switched from a 3.07 to 3.45 gear and unfortunately, was rewarded with no et improvement. The 3.45 gears were theortical the better gear that was supposed to improve my et based upon it being closer to my peak HP rpm in the 1-1 gear.... my results were similar to a few others back a few years that did the same. There are other things involved with this as well, but I won't go into right now.
I do think more gear would help a TPI motor if it was running a th350 or a manual transmission dependant on the gear ratio. I think for the OP in this thread...... as somebody else had said, I think you'll get the biggest bang for the buck with a good torque converter. They are always good for a 2-4 tenths et gain it seems..... but I will say, if you have the original 85 torque converter, it was a little loose from the factory and I believe rated at somewhere around 2100 rpm..... thus its not bad, but you could still improve with a jump up to a 2500-2600 converter. good luck with whatever you decide ! |
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Posted on: 2009/4/22 4:26
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lavalumfress | Re: The old 3.73 vs 3.53 debate | ||
Guru Newb
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i have an 85 with a stock rear end, but theres something wrong with it...were going to be running the car in the big bend open road race and my mechaning/co-driver wants to put a 3.73 in the car.....BUT having hell finding the parts to do it...any suggestions?? please e-mail me at laval_umfress@hotmail.com
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Posted on: 2010/9/14 20:31
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