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FFCobra Craftsman
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Discussion Starter · #1 ·
I have become aware of a company that is looking at making a heavy duty, close-ratio gearset for the T-5 transmission.

The proposed gears would be:
2.51
1.75
1.30
1.00
0.79

These would be hardened gears that should be able to take somewhere around 500 ft/lbs of torque.

This would be nearly perfect ratios for a Cobra. See this thread for more info on optimum ratios:

http://www.ffcars.com/ubb/ultimatebb.php/ubb/get_topic/f/1/t/088274.html#000000

The company is Astro Performance: http://www.astroperformance.com/

Tony, the owner, is trying to see if there is enough interest to justify making these.
If you have an interest, let him know. Call him at: 866-253-0019 or e-mail him at: [email protected]

If he gets enough positive feedback, we should have a very good alternative available for gearing.

Kevin

Edit: I am updating this because they are at the decision stage concerning making these. See the bottom of this thread for the new information.

[ July 27, 2007, 11:39 AM: Message edited by: KevinM ]
 

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Senior Charter Member
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1,168 Posts
Make it a true close ratio box. I vote for a 0.82 5th. Great for road racing. I like the ratios better than the close ratio TKO600 (2.87 1.89 1.28 1.00 0.82).
Once you get proper gearing for the track (4.10 rear or so), first gear runs out pretty quick so the 2.51 first looks good.

Pete
 

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1,889 Posts
Looks good for track use with .82 OD but I think it's a bit "tall" for the street. May limit usage/sales.
 

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FFCobra Craftsman
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1,441 Posts
Discussion Starter · #4 ·
The standard Wide-Ratio GM trans in the 60's was a 2.52 first. The Close-Ratio box was a 2.20 first. They worked well for general street use with much heavier and lower powered cars than Cobras.

The Close-Ratio Toploader was a 2.32 first, and was the only trans available on 427 and 428 powered Fords. It worked fine on the street also.

Kevin
 

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Vendor
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8,399 Posts
I would like a trans with
2.51
1.75
1.30
1.00
.68

matched up with 3.27 rear gears and 408 stroker. That would give you 0-60 in first with a 25.8" rear tire and 150mph in 4th. 150 is plenty fast in these cars so why would you need 5th to be close too?

[ May 31, 2007, 10:34 PM: Message edited by: Wayne Presley ]
 

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just another builder
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8,238 Posts
Originally posted by Steve Powell:
Looks good for track use with .82 OD but I think it's a bit "tall" for the street. May limit usage/sales.
for first thru forth i'd have to agree...but with 3:73 gears it could work out...but then again i'm working w/ less power than wayne
 

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SNAFU
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438 Posts
You can get a g-force with
2:46
1:54
1:22
1
.90 and there are other options for the overdrive
 

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To Steve Powel's question is a .82 fifth too tall for the street?
Common rear ends RPM at 70 MPH with a .82 fifth:
Diff___RPM at 70MPH
3.27___2459
3.55___2669
3.73___2804

If anything a .82 fifth is too low or "short" [high numerically].

For street, you'd go with a taller gear like a .64 or .68 fifth like Wayne suggests. Then highway cruzing is pretty relaxed. For example with a .68 fifth, highway rpms are in a better range.
Diff___RPM at 70MPH
3.27___2039
3.55___2213
3.73___2326

Regards,
Pete
 

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584 Posts
I just rebuilt my gearbox with G FORCE Helical Synchronized. Cost was just a tick over 2k, gears shafts and bearings shipping. Also had to purchase a new clutch disk, input shaft goes to 26 spline. Total cost 2,125.00 for better than new gearbox.
The .73 od puts me at 65 mph at 2500 rpms -- 3.27 rear gear. I have put the first 200 miles on it in the past 6 days. It is nice not having the car bog in 5th like it did with the standard od gear. I did build this myself but I would not recomend building it (buy it built)
unless you have done a gear box befor and have a diverse selection of tools. Here are your options

G-Force T-5 Ratio Charts
Please note there are three different gearsets: Spur Dog Ring, Helical Dog Ring and Helical Synchronized.

Spur Dog Ring Ratios
3.22 2.94 2.46
2.05 1.94 1.54
1.34 1.34 1.22
1.00 1.00 1.00
.59* .59* .59*
.73* .73* .73*
.90 .90 .90
*Synchronized only

Helical Dog Ring Ratios
2.92
1.99
1.34
1.00
.90, .73* or .59*
*Synchronized only

Helical Synchronized Ratios
2.94
1.94
1.34
1.00
.59 or .73
 

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Senior Charter Member
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540 Posts
From out in left field.............

If you're going looking to make a bunch of HP, then wouldn't a taller 1st gear work better? So, as to not run the hides off the tires. Besides, if you're going for track duty how many times would you use 1st gear?

If it were me, I'd keep the a taller 1st gear, (3.15-3.35) to get the thing going then work it out where 5th gear is 1.00. That way, 2-5 can be closer together. Get your Grand Turismo 4 out and try it.....there's a 427 Cobra to play with.

Now for the street, yea....the 0.68-.70 would certainly be the gear of choice for 5th. About 2k is about all that's necessary in 5th gear.

But, that's just me.
 

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just another builder
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8,238 Posts
part of the problem with a tall 5th and lower gears like 3:27 is keeping the revs high enough when cruising so the car doesn't buck...if your cam doesn't wake up until 1800-2000 rpms you may have to run 65 mph in 4th for it to behave ....once again, the cam is a big picture type item
 

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1,648 Posts
Grego,

No problem with mine I'd still be runnin 4.30 gears :D 2500 in 5th = 65mph with a .68 overdrive. Cam dosen't like anything below 2200.
 

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FFCobra Craftsman
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1,441 Posts
Discussion Starter · #14 ·
They are at the decision point for making these. i am attaching a copy of an e-mail I received from Tony. Anyone who is interested, now is the time to contact him.

_____________________________________________


Kevin,

I was able to get the Gear Manufacture to agree to 50 Kits. In order for me to proceed I want to get at least 25-30 people "locked in". If that can be done I will proceed in manufacturing the Gear Kit. We will be reusing our .79 Ratio 5th Gear Kit with the Upgraded 1st-4th (2.51 Close Ratio Gear Kit).

If you have anyone asking about the Close Ratio "Synchronized" Gear Kit, here is a few more things you could add that may help jump-start manufacturing:

A-5 Close Ratio Gear Kit Components:

-2.51 Close Ratio "A-5" Gear Kit $1,250.00

Includes Cluster, 26 Spline Input Shaft, 1st M/S Gear, 2nd M/S Gear, & 3rd M/S Gear.

As with our A-5 Gear Kits available now (2.95 Ratio), we will offer customers Reman. Or New T-5’s with the Upgraded Components. However, in order to purchase a Reman. T-5 with Upgraded Components the customer will be required to send/exchange in a T-5 “World Class” 5 Speed Core for the one built. New T-5’s with Upgraded Components will not require any type of Core Exchange.

I am also seeing a lot of the Cobra Kit Car Customer’s are using the Chevy S-10 Mechanical Style Tailshaft Housing. Of course we will have a Upgraded Mainshaft Available for use with this version Tailshaft Housing. However, if our .79 5th Gear is used, Modification to Tailshaft Housing will be needed. We are thinking about manufacturing a Tailshaft Housing similar to the S-10 Mechanical Design, but it is not going to happen to quickly. We have dozen’s of other projects in front of it.

Hopefully this information is useful to you. I was thinking about putting together a “Group Purchase”. What do you think?

Thanks,

Anthony (Tony) Sarvis

(866) 253-0019 Ext.101

President

www.astroperformance.com
 

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5,559 Posts
Kevin, keep us posted on this because I've already started pricing gears and components made by Astro for a winter overhaul of my midshift t-5. I'd be very interested in the close ratio A-5 gearset with the optional .79 5th gear. Since I already have the S10 tailshaft, I'd be interested in learning more about the mods needed for the .79 5th also, so if you talk to Tony again, please inquire about that...

Brian
 

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FFCobra Craftsman
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1,441 Posts
Discussion Starter · #17 ·
Brian,

Please call or e-mail Tony and let him know your interest. He has to lay out a lot of money up front to do these, and if he doesn't feel there is enough interest, he won't take the chance on getting stuck with a lot of expensive gear sets he can't sell

Thanks,

Kevin
 

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5,559 Posts
I'll give him a call sometime this week to see where things are at with this project.

Brian
 
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