New Guy in Town

[bobinyelm]

Thanks, guys!

Sounds like a pretty well-represented group of folks and cars! Next Saturday sounds like a winner, and I look forward to making it up there to meet some of the group. That might dovetail well since I am supposed to go to a car race in Ft Worth with a very old friend later in the day. Heck, until he proposed it, I didn't even realize there was a track over there! I've got a lot to learn and catch up on!

As far as expertise, it will be I who will likely be learning from you all, since I've never done the "kit car" experience (though in reality I wimped out by buying a 98% turn-key deal with the 'lazy-man's' example I chose). Heck, I don't even know how the register the car here in Texas when I get it done!

Having had buddies in the very early 70's with "real" CSX cars (they were well under $10k back then, of course), I have for a long time intended to actually build a car from a basic kit when they became available (and I finally became able to afford one), but never got around to it (a case of the shoemaker's kids having no shoes), but then another good friend in Olympia, WA near where I lived got me hot on the Cobra idea again when he became first a Hurricane and then Backdraft dealer. Thankfully, he finally "twisted my arm" until I bought one from him. It must have been a very easy twist, because I didn't even have any decent bruises to show my wife, though I told her how insistent he was, giving me literally no choice in the matter.

While I have the engine work done, I've yet to pick out the transmission I will install. After driving my friend's car (3.46 differential) in which he has a T-5, I was unhappy driving around town given the big gap between 4th and 5th/O.D., especially for driving at intermediate speeds 38-58mph). He has since switched to a 3.91 differential, which he likes far more, but I haven't driven it to see for myself. Five gears ought to be plenty with the light weight of the car and the adequate torque of the engine, though I am not sure whether to go with something like a T-56 with two overdrive gears (one a lot closer to 4th, then one like the T-5), or just get a T-5 or TKO-500/600 and have O.D. regeared to something like .75-.82. I'll be relying a lot on the opinions you all have formed based on your cars to make up my mind, I suspect.

I am really looking forward to meeting some like-minded gearheads because so far in my travels down here, I haven't seen much sporting iron on the roads. As you correctly point out, it's about the people, and not just about the cars, but the cars are a marvelous way to find common ground from which to forge associations that can maybe take root and grow.

Bob

[Francis]

I presume by Kit - you mean a cobra kit. You did not mention anything about wheelbase (wb). The Tremec 6 speed (t-56), you will find, is way too long dimensionally. If your W/B is 90", the T-56 will not work. I tried it. The T-5 with the 0.62 OD as you noted is not very easy to drive as you noted. It has a tendency to "buck" - and you are correct about the 3.42 gearing, a 3.73 or 3.91 would work much better. 3rd time a charm, I put the TKO-6 with the 0.82 OD with the stock 3.42 dana R/E. Runs beautifully with 500+HP 351/408W. The 0.82 can handle more torque.

If you're gonna do a lot of highway cruising, 65-80mph, then go with the 0.62. With 3.42 RE, 70mph, 1700 RPM - a lot quieter

If you intend to race it or a club "drive fast laps" around a track for fun, I would definitely go with the 0.82. Stay away from the 0.62, you will lose too much momentum on the straights, and you will be past in the straights - the dynamics of acceleration.

My 0.82 works better - at 70mph, in 5th, 2300 RPM. I can still accelerate quickly to over 100+.

Back to the W/B, there are several kits with WB variation from 90.5 to 94", that might accept the T-56 and give you the best of both worlds. This seems logical from a mathematical perspective (longer wb for a longer tranny), but the real world - I couldn't tell you.

[Madmiles442]

Bob, we are also blessed to have one of the best Tremec dealers in the country in Standard Transmission in Fort Worth. Lots of the Dallas gang has had theirs worked on there and they are awesome.
http://www.standardtransmission.com/

Jimi Guthrie from Standard posts here under the Transmission Talk forum.
Tell Jimi I sent you and maybe, just maybe, he'll add on your "Miles hassle-factor" pricing for you! jimig@standardtransmission.com

Here's a good discussion of transmission/rear end gear combo's. Check out the rpm calculator that's linked.
Rear Gear Ratio??

I agree with Francis - I have the 3.73 with the .62 and there is a big drop in rpm from 4th to 5th, but that's kinda the point. A close-ratio 4 speed that will get you through 120 mph with a big overdrive. There's an unhappy zone around 60 mph or so where the rpm's are too low for 5th but I got 20.43 mpg on a 3 hour drive to Austin at 75 mph!