Toploader trans wr or cr?
 

If you have a Fe Motor and a top loader trans, are you using a wide ratio or closed ratio and what rear gear?
Jon

Wide-ratio, 3.31 rear gears.

I was running a CR top loader with the classic 3.31 Jag rear gear. What I liked about that setup.
Better wheel spin control due to the high 1st gear ratio. It was great going through the gears at higher mph speeds. The close ratio has a really nice feeling in the top three gears. Shifting into 4th at speeds ABOVE a 100 mph is pretty cool.

Things I didn't like. The high first gear while good at controlling wheel spin can be pretty hard on a clutch. Several people have noticed/mentioned that their best 1/4 mile ET was achieved using SECOND gear (with a WR, TKO or whatever other trans) but that better ET came with damage to the clutch. One of the basic problems almost ALL Cobras have is to low a 1st gear. Makes for a great tire smoke, difficult to control traction, can be downright dangerous. A "tall" first gear can save the tires and save the car from a potential spin and will certainly provide a better ET. All that at the possible expense of a new clutch if your not careful in how you use it.

Eventually I decided I wanted an overdrive to reduce the noise and rpm's of the engine at cruising speed, so I am running a TKO600 these days. I DO NOT like the MUCH lower 1st gear ratio!!! It's all but worthless trying to get off the line without major wheel spin. My 1/4 mile ET is actually SLOWER with the TKO because wheel spin is much harder to control. The car is certainly more prone to an unexpected spin out because the tires break loose SO easily! I like the lower gear ratio's (1st, 2nd) for around town, parades and slow speed driving though, but have to be much more careful than before.

With the CR I would NEVER do a parade and was always concerned about getting stuck in slow moving traffic. That 1st gear was just to high to creeping traffic.

If I had to pick between the two top loaders today, I think I would go with the WR. A taller 1st gear than the TKO's or T5's, shorter than the CR. Best overall gearing does not seem to be available. Which would be, a WR top loader gear ratio WITH a .8 overdrive.

...guess I'll have to design my own trans! :)

3:31 rear end and a WR Toploader here.

My understanding of transmission gears in general is that wide ratios were more commonly used for street use and close ratios were for road racing use. Close ratio transmissions typically have a big jump in gear ratio between 1st and 2nd, allowing 2nd, 3rd and 4th ratios to be closer together. On a road track where you only start from a stop once and seldom slow enough to use anything below 2nd, it allows the driver to more easily keep the engine RPM in the peak torque range.

Simple:

Track car = CR
Street car = WR
Street car with some track time - WR

FIA Mike

I use a David Kee unit that has:
an aluminum case
wide-ratio gearing
big input shaft (normally found on just the close-ratio unit)

I run a 3.70 rear end.

David

First FE powered Cobra - 3.08 axle / Close Ratio TL, with stock 3-3/8ths input shaft. In a light weight Cobra, the FE had plenty of torque where it was usable, and the final drive in 4th was decent on the freeway. I keep thinking 3.25 ratio would be nice. Car was fast off the line too since it was able to roll off the line without completely blowing the tires off. With a larger cam over 282S it would have too tall of gearing though. It worked okay as long as idling along in traffic for long periods was not required.

Second FE powered Cobra - 3.31 axle / Wide Ratio TL, with custom big input 3-3/8ths input shaft. Works great on the street, taking off from lights is good, like the gear spacing for street better, and can still cruise on the freeway a bit, but not like I could with the former 3.08 setup; 3.31 works on the highway (somewhat okay) IF you have a larger cam that does not mind spinning up the motor a bit more for stretches here and there.... Sometimes I think a .82 5th gear would be nice, but I'm still stuck on the diehard FE-Toploader combo scene; the Toploader is butter so it stays in the ERA!. An in between custom rear 3.25 rear axle ratio with a WR trans might be the sweet spot for me with my motor/cam setup.

After trying different setups, I still believe a well built FE has plenty of torque to pull right through a taller 1st gear / taller rear axle ratio, which I prefer over low gearing or transmissions with a low first gear and just blowing the "street" tires off, thus having a completely useless 1st gear.

I agree Duane -

All my Cobras had WR toploaders....

Put a 3.54 gear in my ERA (454 cubic inch, 282R, 750 Holley) then soon switched to a 3.31. The 3.54 was just too much aggro on the highway. 3.31was about perfect.

Next car was a Kirkham - about 300 pounds lighter and the motor was 30 more cubes so I figured it would easily pull a 3.08 - I was right.

I'm happy with my ERA 428 FE with 3:31's. I originally thought my T/L was a WR, but it was in fact a CR. Absolutely great to drive, but I know the clutch won't last.

In my completed Cobra I have a mildly warmed 351C, WR with 3.70's. With 3.05x15's and a Detroit Locker it hooks hard, BUT, I hate driving it ant distance at 65-70 mph. Now, in my Cobra that I am building it is a very stout FE with a Crower cam 252 degrees at .050. CR Top Loader with 3.50's. I think it will be perfect. 3000 rpms at 70 is not bad at all to me. I am using a Hurst Street Super Shifter and the rear end is from Currie. You can look in my gallery for both cars. Yes, I am blessed. Merry Christmas to all !!

Byron

You won't be turning 3000 at 70 mph with 3:50's. That's about what I run at 70 with 3:31's, give or take. Make sure you do your homework before spending your hard-earned $$.

Hi,
Gear ratios are all math. When you factor a nominal 26" tire diameter. The magic number for driveability is 8.2:1 1st gear overall. That said you have the CR 2.32:1 and the WR 2.78:1.
With a 2.32:1 and a 3.54 rearend ratio you have a 8.2:1 overall ratio.
1st gear 3000 RPM = 29.3 MPH/ 6000 RPM = 58.6 mph
4th gear 3000 RPM = 65.5 MPH/ 6000 RPM = 131 MPH
With a 2.78 and a 2.94 rearend ratio you still have a 8.2:1 ratio
1st gear 3000 RPM = 28.4 MPH/ 6000 RPM = 56.8
4th gear 3000 RPM = 78.92 / 6000 RPM = 157.8

Again the 8.2:1 minimum ratio for street drivability is not good for drag racing and road racing can get use with as low as 7:1 1st gear ratio.
Call me with any questions.

BTW, My old Z-28 had a nice dry sump smallblock and a 2.20:1 Muncie and 3.50 rearend gears so a 7.7:1 1st gear overall. It was a bit to get it rolling, but once rolling the gears were awsome. For every 1000 RPM it was 10 MPH. That was 75 MPH in 1st!!! It still had 2nd, 3rd & 4th.... That 154.7 MPH at 7000 RPM not figuring any tire growth... I like that!!

275/60-15=28 in diameter

So if you are running 28 in tall tire, you need to multiply Mike's results by 28/26=1.077

Something else to think about is being able to drive your car into a trailer. For my old car 427 FE, cam with lots of over lap, 3.31, CR, aluminum flywheel, and a 28 in tire, it is very difficult to load into the trailer, with out smoking the clutch. So I drive fairly fast into the trailer. I really should use a winch.

My other car, 302 healthy cam, alum flywheel, CR TKO 600, 3.54, 26.6 in tire is easy to drive into the trailer.

Question …

A lot of guys run the TKO 600 with the 2.87 first gear and either the 3.54, 3.31 or 3.07 rear axle ratio.

That works out to:

2.87 x 3.54 = 10.16

2.87 x 3.31 = 9.5

2.87 x 3.07 = 8.81


If 8.2:1 is the minimum ratio recommend for street driving and the low end for road racing is at 7:1 … In general terms ...


- Is there a maximum recommended street driving ratio ?

- What would be considered an ideal street driving ratio ?

Good point about the trailer Tom. I'm pretty sure that is exactly how I damaged my last clutch which I recently replaced (again,,,). Moving the car from Hawaii to California then Oregon it was on and off trailers a number of times and that was always a "slipping the clutch" episode. Top Loader C.R. with a 3.31, not good for hill climbs, ramps or steep driveways. :)

Tom,
if you don't mind me asking, what have you determined is the advantage of an ultra light weight aluminum flywheel vs. say a 32lb stainless on a warmed up FE?

I think the "minimum/maximum" stuff Mike provided is really intended for guidance. And it's good information based on math. Your personal tolerance for of and definition of "acceptable" will determine how far from that guidance you can go and still be happy with the result. Some guys wnat their car to behave like a new BMW, while others want a top fueler...

That .82 number will get the car away from a traffic light without drama, keep the clutch intact, and make it pleasant to drive around town. The .71 number and close ratio will keep the car in a useful range on a road course where all the gears can be utilized without abrupt RPM changes that would unsettle things.

There have been many debates on the aluminum vs steel flywheels on Club Cobra. But to quickly answer your question and not hijack this thread, the advantage is the engine accelerates faster. This obviously helps in accelerating the car... but it also helps in shifting gears. The lighter flywheel helps the engine speed match quicker to the transmission speed. This is most apparent when heal and towing.

I am also running an aluminum flywheel for all the reasons Tom mentions above. Although, Tom's other reason may be that his real goal is to build everything out of aluminum! :D Just holiday kidding.....