Some have mentioned that the first gear of a 5 speed is not really usable. (they were speaking specifically of my engine.) Do you find your first gear as very short and not very functional when accelerating hard? I was also wondering what kind of hp engine you were using, if you don't mind me asking? Thanks for your time.
Drbb, everyone will have a little different setup to suit there use. For my car I have a 289 HiPo engine that will most likely (I haven’t ran it yet, but it’s the same engine I had in my Mustang) be very high RPM with not a lot of low end torque. I have a 4.27 rear axle ratio and a 5 speed with a 2.95 first and .63 overdrive. by using the link I posted earlier I have come up with this info. 1st gear at 1500 rpm is about 10 mph, 7000 in 1st is about 45 mph, 3500 rpm in 4th is 65mph, 2500 rpm in 5th is 75 mph, 4000 rpm in 5th is 120 mph, top speed (on paper) at 7000 rpm is 210 mph. I think for my engine this is going to work fine, and most likely will use 1st gear even with the very low rear axle ratio. I’ll find out for sure when I finally get on the road.
Rod
Roseville, Ca.
289 FIA #9152 "The Flintstone Cobra"
+1 to Rod's post.
With low rear end gearing, you will run out of 1st. gear pretty quick. With all that stroker torque you're gonna have, your likely best bet in a 5-spd would be the TKO-600's as they have a taller first gear than the TKO-500's (2.87 vs. 3.27). Richmond 5-spds are also an option, and they do appear to have some selection in how you set up the gear spread. Of course it goes without saying you will pay for this selectability.
The 3.27 first with a 3.31 or 3.25 type rear ratio won't be useless at all, and might even be much more comfortable than the 2.87 (i.e., smoother easier startups). I believe the standard T-5's have 2.95 firsts, but might not be quite enough trans for a big inch stroker - but the World Class models might be OK......check with D&D Performance (http://www.ddperformance.com/index.php) before you go for one of these. Before I start hearing all the shouts about T-5's and how they break, remember these are 2500 lb. Cobras, not 3600 lb. Mustangs - and most of us just don't regularly do holeshots with 10" wide slicks under the car. Stuff like that does make a difference.
As regards the overdrive.....with 482" either the standard 0.64 or the road race 0.82 will be fine, especially with 3.31's or lower in the rear. You will, no doubt, have enough torque to pull the 0.64 high gear and not want for performance. The 0.82 would allow the engine to cruise with a bit more rpm, which may or may not be desirable to you. Your call.
-Roger
Yeehah
The cam that I am using is a Crower blower specific cam. That's why the good response with the Paxtons. Advertised duration is 288/288 with 228/288 at .050. The cam worked good prior to the blowers but really came alive their addition. From the first planning session with my machinist my ultimate goal was to create an engine that was very streetable. While the crazy power is always on tap she makes for a real fine street cruiser and can be lugged around all day without protest.
65 MPH is at 2700 RPM.
-Geary
My cam specs are lift .594 in. & ex.
In. duration@.050 .242 ex. duration@.050 .246 solid lift
I am running about the same horsepower and torque as you.
I do not get any clunking or jerking from the rear in turns. The car is too light. One tire will turn faster then the other but then again with this little car and the narrow rear I don't feel that it is a major factor.
What I do get is predictability in handling. I have autoX and open tracked my car and the posi-lock has not been an issue with me.
I feel that the car will do the same thing every time.
A posi-trac changes the power from side to side as each wheel needs it and makes the car squirrely. This is good for easy driving on slippery roads under normal driving conditions but not for spirited driving in such a light car.
An open rear and you lose the extra power to the street.
You could go with an Auburn posi set up. Which I believe Rick has(Eliminator) as far as I know the more power you put to it the harder it locks up and puts power to both wheels then with easy cruising it act like and open rear, so I fell that would be
a very good choice. Rick could let you know more about how he feels about it.
I hear guys talk about how easy it is to spin out in their Cobras but I don't seem to have that problem.
Tony
Unique 427 #4279480 Precision Engine Machine Company 427 s/o 483.47 stroker close ratio toploader 3.31 jag rear
The "clunking" that you have heard about is more of a problem with certain types of carriers than others. Some units transfer power to the wheel that has the most traction, some have a mechanical method of locking up, and some simply have clutch packs inside that lock both wheels to a point and then allow them to "slip" as nessasary. The clutch pack type is probably the most common and needs to have a friction additive included in the gear lube to keep the plates from sticking and creating the clunking noise.
Rod
Roseville, Ca.
289 FIA #9152 "The Flintstone Cobra"
I have heard lots of different names for these "posi" rear-ends... Detroit Locker, Power Lock (Auburn??), limited slip, Auburn, etc.
I recall hearing about the differences in bench-racing conversation, but I am not able to recall all the nuances at will.
Could someone with some expertise/knowledge post here about the differences so that we could have a reference point for future, and old, users? It might be a help for those looking to make this decision.
EDIT:
I guess this info would be better placed in this thread...
http://www.uniquecobra.com/forums/showthread.php?t=7967
Thanks!
END EDIT
Last edited by Slither; May 31st, 2009 at 09:56 PM.
Paul
289 USRRC
1964 289 5-bolt block
Toploader and 3.31 rear
Those are all brand names. In fact, Positraction is a GM name. I know some Ford guys that would pounce on anyone that used the word Posi in relation to a Ford.
There are open, limited slip, locking, and spool setups.
Open is the old peg leg setup. One wheel spins and the other does nothin' as said in one of my favorite movies.
Limited slip is what most people get. It used cluch material and is great on the street and track. This is what people often call a Posi. The Ford variation is the Trak-Lock.
Locking units (aka Detroit Locker) is popular with the drag race croud that still wants something that can be used on the street. They tend to make a clunk sound around corners. They handle a lot more power than the limited slip solutions.
Spool setups are solid axles are are best kept on the drag strip. I do know of people that use them on the street. There is tire scrubbing and axle binding on sharp corners. Probably best kept out of the mall parking lot.
Patrick Brown
Forum Administrator
Last edited by Naumoff; June 1st, 2009 at 04:17 PM.
Tony
Unique 427 #4279480 Precision Engine Machine Company 427 s/o 483.47 stroker close ratio toploader 3.31 jag rear
And within the "locking units" category, you have three types.
Lowest end of the scale and easiest to install is the "lunchbox locker." This is a basic unit that uses the factory carrier, but replaces the spider gears & cross shafts. Very popular in front differential applications in 4wd.
Next is the full locker, which completely replaces the factory gear carrier. Stronger than the lunchbox style, it also (generally speaking) has manners that take more getting used to. Some of the clunking, clicking, etc. that Patrick mentions.
Last is the manually-selectable locker. These are operated either by onboard compressed air (ARB locker) or a cable linkage (OX locker). When unlocked, you have a completely open differential. Throw the switch or move the lever, and you essentially have a solid spool. Another, fairly new, variation on this is the selectable locker offered in some Jeeps, like the Rubicon. It is electrically actuated, acting like a limited slip when disengaged, and becoming a solid spool when engaged.
The Power-Lock is noted amongst Jeepers as being about the best limited-slip ever offered from the factory.
Zach Butterworth
289 FIA #9367
I don't have nearly the hp that most of the guys do around here. I've only got about 360 or 370 at the crank, with roughly the same torque numbers. My first gear goes by quick, but it's definitely usable (probably thanks to my 3.31 rear).
My car hooks up very well, even with the crappy Goodyear Eagle GT II tires, and I often wonder if that is due to the fact that I actually have a less powerful engine than most Cobras. In 100% street trim, I can cut 1.7 second 60' times at the drag strip, which normally is in the range for cars that are more powerful than I am, or are on slicks. Once I hit third gear though, my lack of power become noticeable. But out of the hole my little car gets with it.
Obviously, the biggest deciding factor is the one that everybody else has mentioned, but that I failed to: how and where are you going to be driving your car? If you don't plan on doing a lot of highway cruising, then the 5- or 6-speed may be unnessecary. For me, I'd say highway cruising accounts for probably at least 50 or 60% of my driving time; so I kinda like the fact that 70mph is at 2000 rpm in 5th.
Unique 289FIA - Chassis #9229 - Viking Blue
Thanks for the good info Patrick.
I was lucky enough to have had lunch with Butch Capps and Ralph Scott last Monday, up in Knoxville, TN, as I was traveling to a conference. I very much enjoyed seeing Butch again, as well as meeting Ralph. They are both first-class individuals. It was a treat! Thanks for coming on such short notice Ralph.
Butch explained the "posi" stuff well, though we did not go into the obscure stuff. Interestingly, he mentioned that the Auburn Power Lock unit, the limited-slip with clutch packs found in the Jag center sections, has not been made for about 25years... Auburn now makes the cone-style clutch setup that Rick has.
Butch mentioned that he has a Detroit Locker in his 289 car, and the Power Lock in his 427 car.
Paul
289 USRRC
1964 289 5-bolt block
Toploader and 3.31 rear
DRBB I currently have an edelbrock Performer RPM #7106 in Lil Cobra the specs:
Ford FE 390-428
Operating Range 1500-6500 RPM
Duration Advertised 296° Intake/296° Exhaust
Duration @ .050'' 236° Intake/236° Exhaust
Lift @ Valve .572'' Intake/.572'' Exhaust
Lift @ Cam .325'' Intake/.325'' Exhaust
Lobe Separation Angle 108°
Intake Centerline 103°
Intake Timing @ .050" Open 15° BTDC
Close 41° ABDC
Exhaust Timing @ .050" Open 51° BBDC
Close 5° ATDC
I plan on going to a Comp Cam Dual Pattern CCA AL33-207-3
It's specs are:
Basic Operating RPM Range: 1,500-5,750
Intake Duration at 050 inch Lift: 211
Exhaust Duration at 050 inch Lift: 223
Duration at 050 inch Lift: 211 int./223 exh.
Advertised Intake Duration: 265
Advertised Exhaust Duration: 275
Advertised Duration: 265 int./275 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.484 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.510 in.
Valve Lift with Factory Rocker Arm Ratio: 0.484 int./0.510 exh. lift
Lobe Separation (degrees): 110
I have also changed out my carb from a 780 to a 650 I have much better thottle response from a stop and go situation.
Had a great time meeting Paul. We ate at a Mexican restaurant and Butch brought one of the twins, Will. Great meeting you Paul.
Ralph
Has anyone used a tremec t56? and if so what gearing ratios? If so anything you would change?
Lee Dahmer of Sterling Replicars is running a t56 in his car.
Maybe he will chime in.
Tony
Unique 427 #4279480 Precision Engine Machine Company 427 s/o 483.47 stroker close ratio toploader 3.31 jag rear
You can call Lee at Sterling Replicars. He seems like a great guy. He has a nifty quick-release steering wheel hub, too.
703-404-0663
Paul
289 USRRC
1964 289 5-bolt block
Toploader and 3.31 rear