Toploader or Tremec 600???

DP935 · #1 (**permalink**) 11-01-2004, 07:53 PM

Putting in an order for a CSX Cobra and plan to power it with a 550 HP 427 sideoiler engine. I think, all in all, the Tremec would be the better all around transmission but I am struggling with the idea of keeping it somewhat original and going with the Toploader. If resale is taken into consideration, would the Toploader be the better transmission? Are they unbearable at highway speed? What would be the best rear end gearing?
And which one shifts the best? Thank you.

jdog · #2 (**permalink**) 11-01-2004, 09:01 PM

I have a CSX car on order and I am putting a Tremec 600 in it! I believe that the 5 speed will give my Cobra some 'legs' and run a little quieter at cruising speed.
As for resale? My heirs can worry about that! I don't plan on ever selling CSX4795, she will 'always' be mine.
Good luck with your car. What color?

jdog

decooney · #3 (**permalink**) 11-02-2004, 08:32 AM

Choice also depends on other factors too. What gear ratio will you have in your differential?

DP935 · #4 (**permalink**) 11-02-2004, 09:48 AM

Probably a 3:31 rear end. The engine is built for power in the upper rpm band with the high riser heads and intake. I wonder if the 5th gear would lower the rpm at cruise to much compared to a wide ratio toploader. In 4th gear with the toploader, at 60 mph, is the engine turning around 3000rpm? How bad is that from a noise standpoint? It looks like the gearing is pretty close between the two for the 1st 4 gears. Not considering the 5th gear with the Tremec, and using a 3:31 rear, is the performance about the same 1st through 4th? Thanks.....

Ford of France · #5 (**permalink**) 11-02-2004, 10:16 AM

For originality and strength, the Toploader is a great transmission. Bullet proof, too. David Kee is now making them in aluminum, which is a great weight savings.

The big question is this: if you have trouble with your Tremac where are you going to go to have it worked on? I see a lot of guys selling them, but I don't see too much happening when there is a service issue.

I had trouble with one of mine a few years ago, and when talking to the guy who sold it was like talking to someone who really wasn't interested in me after the sale.

Just food for thought.

priobe · #6 (**permalink**) 11-02-2004, 10:59 AM

Dp935,

Correct me if I am wrong. I have the same set up that
I am currently building in a EM.427 SO with a Toploader.
I received a gear calculating formula on CC from someone and I worked the #s

Running a 3000 Rpm
305/40/15 tires
3.36

= 65 mph

I would like to use 3.36

3000 rpm
305/35/17
67 mph

Clois Harlan · #7 (**permalink**) 11-02-2004, 12:43 PM

Where did you find 305-40 15 tires? What brand?

305-40 15 tire diameter 24.6"

3000 RPM = 64.5 mph

6500 RPM = 138 mph

http:/www.smokemup.com

(go to auto math)

bobt427 · #8 (**permalink**) 11-02-2004, 06:06 PM

I have a wide ratio top loader 3.27 to 1 rear end Goodyear 295/50/R15's . She runs 3100 at 70 miles perhour.

decooney · #9 (**permalink**) 11-02-2004, 07:32 PM

DP935,
I asked because I'm running the 3.31 too, with a w/r Toploader. Also, runing a bigger rpm cam comes into play as well if your engine runs well at say 3200rpms with no strain. It works well from 1-4, and every once in a while, when wanting to cruise above 70mph for sustained periods of time, the extra 5th would be nice but not an absolute requirement.

I believe if you are planning to drive your car more than 50% of the time on the freeway, then you will probably like the new TKO 600 better. If you drive less on the freeway, like 20% of the time, the Toploader is a great choice. I'm considering trying a TKO 600, but have not done it yet because I realized that I don't actually drive that much on the freeway except for a few times a year... What I like so much about the TL is the gear spacing and the butter shifting vs. the ratchet shifting feel of a TKO.

Decisions Decisions.

Anthony · #10 (**permalink**) 11-03-2004, 07:16 AM

If you are going with 3.31 rear, I'd get the close ratio toploader.

If you go with the wide ratio toploader, go at the most with 3.07 rear, and maybe be better with the 2.88 rear.

If you want a five speed, the TKO600 has wider spaced gears than the wide ratio toploader, so I think you may be better with the wide ratio toploader and 2.88/3.07 rears, and you won't need an overdrive. If you want a close ratio 5 speed, either get the richmond with the 3.04 first gear instead of the 3.27, and use 3.07/2.88 rear gears, or get a custom made jerico/G-force with similar ratio's as the richmond.

No matter what, get your CSX with provision's made for the 5 speed (partially cut out crossmember), so even if you do go with the toploader, your frame will already be modified for the 5 speed if you ever wish to change, and it will be an easier swap.

DonC · #11 (**permalink**) 11-03-2004, 12:59 PM

TKO 600 (0.82 fifth)
3.07 rear end
315/35/17 rear tires (25.68" dia.)
2300RPM @ 70MPH
I hear more wind noise than exhaust noise at this speed.
DonC

Cracker · #12 (**permalink**) 11-03-2004, 03:46 PM

TKO - Seven days a week. There is no comparison between how effortlessly and fast you can shift the TKO unit to that of a Toploader. Have fun!

mdross1 · #13 (**permalink**) 11-10-2004, 05:38 AM

I just converted my big block cobra from a toploader with a 3:54 gear to a TKO and a 3:73 gear.At road speed the screaming engine will wear on you. With the new setup,getting out of the hole just about takes my breath away,and out on the turnpike clicking into 5th is a true pleasure,1000rpm drop.Not to mention that if a little horse play is in order,and mind blowing acceleration is only a short positive throw of the stick.Honestly, it is very hard to contain the excitement.

Big-Foot · #14 (**permalink**) 11-10-2004, 06:09 AM

I'm with the others when it comes to the level of racket you can tolerate out on the highway - also when it comes to wear and tear on the engine.

Another factor to consider when ordering your Tremec is at what RPM does your cam start to make power. If you order the tranny with the .68 5th gear - will the engine be loping and stumbling in 5th gear at highway speeds given the rear end ratio you have?

Here is a little bit of little known trivia about Top Loaders and Tremec 3550's and their variants;
When the Top Loader was first being developed back in the early 60's, there was a young engineer by the name of Julio who was on the project team. Today, Tremec transmissions are built by Dana Spicer / Tremec and the Chief engineer who brought the TR3550 to the table was none other than Julio!.
I had a considerable amount of conversation with Tremec over this transmission as I was an advisor to the SCCA's American Sedan committee and we were considering the Tremec for a legal "Alternate" transmission to the weak T5 (Also manufactured by DSA's Tremec division). When I last spoke with Julio about the TR3550, he told me about this and went on to tell me that the TR3550 is, essentially, the Top-Loader 4 speed transmission with a 5th gear hung off the output / main shaft.

So - In a sense - If you hang a Tremec off the back of your bellhousing, you are still using the Top Loader 4 speed!

Cal Metal · #15 (**permalink**) 11-13-2004, 03:10 PM

Big Foot:

Except for the fact that the 3550 has two forward gears that are, for all intents, of little value. First is a stump puller and the .68 doesn't worlk too well in engines that have a high power band.

The synchro, blocker rings on a 3550 use a material on the inside of the ring that is prone to wear. I have never understood that design, although they seem to hold up well on the TKO.

While the 3550 may resemble a TL externally to some degree, the TL is a much tougher transmission and can take considerably more abuse than a 3550. I have used both and wouldn't go back to the 3550. I evidently had trouble with shifting from first to second in the 3550--not so with the TL.

Big-Foot · #16 (**permalink**) 11-14-2004, 07:07 AM

Hi there Cal. You live in one of my favorite towns as we raced at Red Cedar Speedway for a LONG long time!

Certainly the gearing is different between the two boxes.

I have seen only a few cars that could make "good use" of the .68 5th gear - my own included. The .82 5th gear makes much more sense and is available for the same price.

The really nice part about the 3.27 first gear in some of the Tremec's is that you can gear the differential more for higher speeds while generating less heat and HP loss through friction/heat. It's all about proper design and implementation of all the components in the driveline.

According to my notes from my conversations with Julio, the basis of the TR3550 (and the TKO derivatives) is the main shaft, countershaft spacing, design and implementation of the sliders, synchronizers (blockers) and finally the design / pitch of the gears themselves. They were in the process of creating the TKO at the time of our discussion. At that time they were concentrating their efforts on the heat treating of the gears and beefing up the diameter of the output / main shaft to reduce flex and torsional stress.
The material on the inside of the blocker rings you are talking about is probably the same carbon fiber traction ring that BW had pioneered in the World Class T5.

In my own car, the transmission (TR3550) shifts smoothly and very precisely. The only issue I have had is a slight grind on up-shift to 3rd when the transmission is really hot (20+ laps). This will probably go away when I change the lube before the next race. There is absolutely no grinding on down-shifting - I could not ask for a more precise shifting transmission and my customers tend to agree.