FAQ Regarding Cobra Drivetrain Setups - Page 3

blykins · #41 (**permalink**) 11-06-2010, 04:27 PM

There are modifications that can be done to give between 10-15% more torque on a TKO 600. That would put you somewhere between at 660-690 lb-ft capacity.

If you are truly putting down 650 lb-ft of torque at the wheels (I'd like to see that dyno sheet and engine build sheet), then even with those modifications, you're not adequately covered. Even the Magnum T-56 would not be rated enough to cover that much power.

It all boils down to this: if you're just playing around on the street with street tires, I'd probably leave it the way it is. Tires give up WAY before a lot of stress is placed on a driveline. If you're running a lot on the strip with drag radials or slicks, then you need to swap trannies altogether. You really need a Jerico 4-speed or an automatic at those requirements.

With either one, you need to be running a twin disc clutch setup.

Excaliber · #42 (**permalink**) 11-06-2010, 04:51 PM

Whats stronger than a TKO600, a top loader maybe?

...just curious what the options might be.

blykins · #43 (**permalink**) 11-06-2010, 04:52 PM

Big input Toploader could be if it's built right.

Otherwise you're looking at a Jerico, G-Force 5-speed, Lenco, etc. Or any C4/C6 can be built to handle that.

Excaliber · #44 (**permalink**) 11-06-2010, 05:48 PM

A Cobra is fairly light, I would think a TKO600 would actually work for this application, due to traction issues as much as anything else. Even with awesome slick's it would be doubtful all that power could be put down at one time without substantial chassis mod's.

I'd sure be interested in what might have failed on the one "stuck in gear", it may not be related to big horse power at all.

My choice would be a Top Loader or a Jerico model that is very much the same as a Top Loader (many different Jerico models are available).

I think we can rule out a Lenco.

Some models don't even have neutral, you gotta keep the clutch in at all times. Not to mention the EXTREME cost!

blykins · #45 (**permalink**) 11-06-2010, 06:01 PM

Quote:

Originally Posted by Excaliber

I think we can rule out a Lenco. [/IMG]

I think that a TKO 600 would work fine too unless there were a lot of hard launches on slicks.

I'd like to see the build sheet on that engine...

Mac VABCH · #46 (**permalink**) 11-06-2010, 08:09 PM

Brent,

What are your thoughts on dog ring verses synchronized? Helical or straight cut gears? My car is road course only track car so the noise of straight cut isn't an issue for me. With cost being the same aren't straight cut gears stronger? The motor is making 500 rwhp, I have been lucky not to break the stock t-5 behind it now but I don't do launches or power shifts... Great thread though, lots of info.... Mac

Excaliber · #47 (**permalink**) 11-06-2010, 08:47 PM

BigE, what kind of tires are you running? I'm having a hard time finding a set that won't break loose and I'm not running anywhere near that level of Rear Wheel Horse Power (I think).

scottj · #48 (**permalink**) 11-07-2010, 04:19 AM

Quote:

Originally Posted by Mac VABCH

Brent,

What are your thoughts on dog ring verses synchronized? Helical or straight cut gears? My car is road course only track car so the noise of straight cut isn't an issue for me. With cost being the same aren't straight cut gears stronger? The motor is making 500 rwhp, I have been lucky not to break the stock t-5 behind it now but I don't do launches or power shifts... Great thread though, lots of info.... Mac

If you are placing a high importance on lap times (competition) I would run a dog ring box. Matched with a low MOI button clutch it's about as good as it gets, short of a sequential box. With a standard weight clutch and an aluminum flywheel, downshifting is done with consecutive movements, i.e., blip the throttle, wait for the revs to come up, downshift. With the button clutch downshifting is done with simultaneous movements, i.e., blip the throttle and downshift at the same time. For a hamfist like myself, I found the latter much easier to accomplish and not snatch the tires loose under threshold braking. That allowed me to focus more on going fast and staying on the track. The combined benefit was about a 3 second reduction in lap time.

blykins · #49 (**permalink**) 11-07-2010, 04:20 AM

Quote:

Originally Posted by Mac VABCH

Brent,

What are your thoughts on dog ring verses synchronized? Helical or straight cut gears? My car is road course only track car so the noise of straight cut isn't an issue for me. With cost being the same aren't straight cut gears stronger? The motor is making 500 rwhp, I have been lucky not to break the stock t-5 behind it now but I don't do launches or power shifts... Great thread though, lots of info.... Mac

Straight cut dog ring boxes boxes are the preferred type for racing. But as you say, they're also the noisiest and they are harder to shift on the street (you have to heel toe to downshift). But since you're running a track car, I'd go for it.

And yes, you're very lucky with that T5....they usually shatter in a million pieces with that much power and sticky tires.

Mac VABCH · #50 (**permalink**) 11-07-2010, 04:50 AM

Scott,

Thanks for the input. I'm running the Quarter Master 7.25 clutch w/ a button flywheel. Clutch, flywheel and flex plate weigh less than 13 lbs all together, so a dog ring gear box it is.

Brent,

I am looking at a used box right now but I'm not sure, the guy that has it has been running it on the street. From what I've heard thats not good for them.
Any thoughts on that?..Mac

blykins · #51 (**permalink**) 11-07-2010, 05:01 AM

As long as he knows what he's doing, I don't see an issue with it. But it's really easy to not match the revs and do a little grinding on the gears...

BigE · #52 (**permalink**) 11-07-2010, 05:09 AM

So I post in a tranny thread and get called out on the engine build

.

I'll see if i can dig it up and post it. It was built by Southern Automotive with the orders to give the most NA HP on pump gas (in this case for 93 octane as it was originally built for use in areas where 93 is available). I can understand the skepticism but I can assure you it's a beast and on the outer edges of streetability.

I do appreciate the advice. A little more on the tranny problem. The motor was built to run to 6,500 but I currently have it set to 6k and running a bit rich to be on the safe side. It has never shifted well at higher rpms, especially on the 2-3 shift. One the day it stuck in gear, I warmed it up and took it out for a spin. I got on in at about 3k rpms in 2nd, easy shift I into 3rd then up to about 5,500 and went to grab 4th and it made a grinding sound and would not go into gear. I pushed in the clutch and came to a stop. Shifted throughout the gears when I was stopped and idling and everything was fine. I pulled away easy and shifted up through the gears at low rpms easing my way up to 5th. Pulled up to a red light and started to downshift and could not get it out of 5th. I had a friend with me so we tried a few things including rocking it back and forth while pushing on the lever and a few other tricks but nothing worked. I got it home in 5th (lots of tq, remember

) and started my research on how to a) fix the problem and b) keep from happening again.

BigE · #53 (**permalink**) 11-07-2010, 05:14 AM

Quote:

Originally Posted by Excaliber

BigE, what kind of tires are you running? I'm having a hard time finding a set that won't break loose and I'm not running anywhere near that level of Rear Wheel Horse Power (I think).

Nitto drag radials on the back and traction is constantly an issue.

blykins · #54 (**permalink**) 11-07-2010, 05:19 AM

It wasn't really scepticism, but in order to make a recommendation for clutches or transmission parts, I often ask for verification on engine horsepower. A lot of people are "told" they have so much, and others can produce a dyno sheet. Usually, the ones that are "told" don't have what they are "told".

Being an engine builder, I know how hard it would be to get over 700hp out of a 505ci FE while still making a lot more torque than horsepower without forced induction.

As for the transmission, TKO's just don't shift well at 6500 rpm. That's just a given. They'll fight to the end at that kind of RPMs. I think what's happened is that you may have bent a shifter fork at some point trying to get it into gear at a higher rpm.

There are ways to fix this, especially if a service center needs to go into the transmission anyway.

If you have a mechanic looking at it, then I will wait for verification of the diagnosis before I prescribe a remedy. If you would want to send it to me, I'd be happy to go through it.

So what clutch are you running?

BigE · #55 (**permalink**) 11-07-2010, 05:20 AM

Brent, I realize that In it's current state of tune, it probably making less than what i previously stated (probably not much less though) but I want to set it up so I can run it at max power if I want.

blykins · #56 (**permalink**) 11-07-2010, 05:22 AM

Do you have a dyno sheet or at least a build sheet?

If it's making that much power, you need to have the TKO modified (if you want to keep it) to 1. hold more power and 2. shift better at higher rpms.

You'll also need more clutch. If you're running any single disc clutch (unless it's something like a McLeod Soft-Lok or an equivilent drag race only clutch), it will start slipping with 700hp. You can bet on it.

BigE · #57 (**permalink**) 11-07-2010, 05:37 AM

Brent, thank you again. I'll dig up the info you requested and get it to you. Most of that is in a file in the trunk of the car which is currently at the mechanic's shop. Again, I really appreciate your help, info and advice.

blykins · #58 (**permalink**) 11-07-2010, 05:40 AM

You're very welcome. Let me know if I can do anything else for you. I'm easily reached here, email, or by phone: 502.759.1431.

Stentor · #59 (**permalink**) 11-07-2010, 05:49 AM

Quote:

Originally Posted by BigE

I am running a 427 FE stroker in a SPF Cobra with 600rwhp and 650rwtq.

What kind of HP and TQ did that bad boy make at the flywheel?

scottj · #60 (**permalink**) 11-07-2010, 06:00 AM

Quote:

Originally Posted by Mac VABCH

Scott,

Thanks for the input. I'm running the Quarter Master 7.25 clutch w/ a button flywheel. Clutch, flywheel and flex plate weigh less than 13 lbs all together, so a dog ring gear box it is.

Brent,

I am looking at a used box right now but I'm not sure, the guy that has it has been running it on the street. From what I've heard thats not good for them.
Any thoughts on that?..Mac

That's the clutch I have... V-Drive 3-disc w/reverse mount starter.

The only issue I had on the street was that these boxes like to have a load on them, accel or decel, doesn't matter. At a low speed, steady throttle cruise, they can get to rattling like crazy. Didn't hurt mine, but I didn't do much street driving either. With a street camshaft and a stock-type clutch it may not rattle.