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toploader vs t5 powertrain drag

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The Iron Icon
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toploader vs t5 powertrain drag

Post by The Iron Icon » Fri Jun 12, 2020 1:17 pm

Hi all, was wondering if someone might know anything about drag and hp loss thru a toploader (3 or 4) and a t5. my thought would be less mass moving in the toploader so it would be better from a loss standpoint. looking at getting a t5 built up for one of the cars but figure I can gear the car to work well with the toploader (3 Speed for now) in the 1/4. any thoughts guys?

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Re: toploader vs t5 powertrain drag

Post by SupStk » Fri Jun 12, 2020 2:14 pm

Due to the high helix angle of the T-5 gears and the extra drag of the 5th gear, I think the T-5 would absorb more power.

If using for 1/4 mile racing only, the top loader would be likely to give better service due to its strength.
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Re: toploader vs t5 powertrain drag

Post by The Iron Icon » Fri Jun 12, 2020 5:40 pm

Wonder what changing gears would do to the t5

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Re: toploader vs t5 powertrain drag

Post by SupStk » Fri Jun 12, 2020 6:23 pm

G-Force and Astro have stronger T-5 gear sets with 26 spline inputs (weak link on small toploaders). G-Force has straight cut sets and face teeth for racing and there are those that have less helix with synchros.

Ratios are a strong advantage of T-5s. The 4 & 6 cylinder boxes, on the most part can be ruled out. It seems the 2.95 ratio is the most popular for performance use.
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Re: toploader vs t5 powertrain drag

Post by BCjohnny » Mon Jun 15, 2020 5:47 pm

...... but figure I can gear the car to work well with the toploader (3 Speed for now) in the 1/4. any thoughts guys?
If you're going to use a '3 speed Toploader' there are good, and not so, ways to do it

The only one worth using is the 'nine bolt' top cover '3.03' type, and there are (at least) two fundamentally distinct versions of that, strength wise ...... it's certainly not as simple as '6 cylinder' vs '8 cylinder' 'boxes
"If an honest man is wrong, after demonstrating that he is wrong, he either stops being wrong or he stops being honest." Anon

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Re: toploader vs t5 powertrain drag

Post by The Iron Icon » Sat Jun 20, 2020 7:01 pm

BCjohnny wrote:
Mon Jun 15, 2020 5:47 pm
...... but figure I can gear the car to work well with the toploader (3 Speed for now) in the 1/4. any thoughts guys?
If you're going to use a '3 speed Toploader' there are good, and not so, ways to do it

The only one worth using is the 'nine bolt' top cover '3.03' type, and there are (at least) two fundamentally distinct versions of that, strength wise ...... it's certainly not as simple as '6 cylinder' vs '8 cylinder' 'boxes

I have 2 of the old 9 bolt covered ones both from small blocks, I imagine your talking about avoiding the 3 speed overdrive that people keep mistaking for a 3.03. what advise would you have for how to properly run one?

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Re: toploader vs t5 powertrain drag

Post by BCjohnny » Sun Jun 21, 2020 11:04 am

Nope, not talking about the 3 spd overdrive, that's a toploader 4 spd with the flipped 3/4 selector arm, and has a ten bolt cover

There are two different '3.03 3 speed nine bolt cover' transmissions, that are almost identical appearing, apart from length

The shorter one is the one most people know about, that backed the six & eight cylinder mustangs, lower capacity trucks, etc

The longer one, with wider gears and larger bearings went on to morph into the Pontiac 'Dearborn 3 speed', considered to be the strongest of all the 3/4 spds

If you have a choice, this is the one you want
"If an honest man is wrong, after demonstrating that he is wrong, he either stops being wrong or he stops being honest." Anon

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