Ok, this one's for the gearing gurus. Time to start filling my empty Ford 9" housing with some guts. This will be a street car, with occasional trips to the track, for fun. Here's the current setup: 34 cabriolet ford bronco 9", 28 spline 4-71 blown 390 cadillac T5 camaro, 2.95 1.94 1.34 1.00 0.63 OD 700-18's in the rear (32" tall) I'd plan to run 29 x 9 cheater slicks at the track. First impulse is to use a stock case, with a TrueTrack, 3.90s-4.11s and a daytona pinion support. Am I on the wrong track? Any suggestions? More info needed? Thanks!
4.56's will give you a 2.87 for a nice cruser and killer light to light if your that kind of guy. 4.11's are around 2.55's both are your best choices. Don't even think about something around 3.00 which your trans can work with in 1st gear but IMO sluggish with 32's in the rear on the street. No OD with 3.00's ever it's a 2.09.
If you ever get it to hook up, that T5 will probably explode.... And for a street car, I think a 3.7 or 3.5 would be a better choice. Blower motors make low-end power and will easily pull a taller gear, making low-speed cruising much more pleasant with very little loss of performance.
Crazy Steve. You're right about the T5. Although some mustang/camaro guys are running pretty quick with them. I'll use it as an excuse to upgrade to a TKO if it happens! As for your gear recommendation, the caddy made gobs of torque stock, so you're probably right that I could pull the taller gear, which was why I was really questioning this selection. More food for thought, I suppose. a 3.50 gives me 1618 RPM at 70 MPH 3.70 is 1720 3.90 is 1800
I have a Chevy II with a blown 427, automatic with GV overdrive, and the same size slicks (and same height street tires). I've run lots of gears in the car, and finally settled on 3.89. The rpm going through the traps is right where I want it, close to 6000. So, if you are serious about racing, maybe see what rear end ratio it takes to get it to be near red line rpm as you cross the finish line, in 4th gear. The cam might affect your choice, you didn't mention what you are running...my guess would be you have it set up to make power from around 2000-5000 rpm, or maybe a bit higher?
Jim, Thanks for weighing in. Cam is a 270/280 mega from Isky. It's .496 INT .517 EXH with 112 LC. Duration at .050 is 221/232. I'm guessing on the rpm range but I'd think you're right. Plan is to start with around 5 lbs of boost and see how she goes. I don't want to rev this thing too far on stock rods, though.
the cam probably works to 5500? I don't know enough about those engines to know how high it will rev, but the stock bottom end is probably stronger than you think. you did put good rod bolts in it, right?
Still ***embling, but yes. that's the plan. The pistons are still being made...should be here soon...
I do hear they are rumored to be fairly stout rods though. Cadillac apparently used great materials back then!
Speedway has a good deal on Ford chinks with posi. Can't hardly build one for what they sell one for. I think a 3.89 gear would be real close for what you want to do.
From what I've read here, many people swear by the TrueTrac limited slips for mostly street use. I think that's what I'll end up with. I'll look to see if Speedway offers it in a complete third member. Anyone here on the HAMB build them? Love to support a HAMBer if there was a reputable source.
There are many 1/4 mile calculators on the web that take into consideration gear ratios, rpm, weight, and rear end. Squirrel is right. If you run the 1/4 pick a gear just under red line at the lights. I don't run at a strip but do light to light on the street. I will only go up to 60mph. Enough to get in trouble but not locked up. I only want to shift once. Using a calculator I found out that at 200 rpm under red line I'm at 60mph in second gear, with my tires and gears. Therefore I run a 3.8 and am very happy with it.
I have a locker in mine, I've been driving with one for 20 years, lots of miles, and it works well. I've also heard good things about the tru trac, but they're kind of quiet I throw mine together myself, it's not rocket surgery.
Thanks Jim. I'm sure I'm plenty capable of doing it, so I'll weigh out the options. By the way, what do you run for boost on your 427? Are the pulley/OD %/boost calculators accurate at all? I've seen some conflicting charts, so I'm gonna start on the conservative side.
There's a guy in Gr*** Valley Ca, that sells setup 9inch dropins, for the life of me I can't recall who it is, but the price is good for sure and I never heard of anything bad about him.
I run around 6-8 psi, the boost charts are kind of flaky...and each blower is different, each engine is different.
I run one in everything I have. I run the mechanical equivalent in all of my German stuff (except the motorcycle!) My LTL hauler uses them in his tow rigs, too. I ran them in the front of all of my 4x4 stuff, when I still had some.
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