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New Transmission For My 66 GTO

  
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New Transmission For My 66 GTO

 
chrisaustria chrisaustria
User | Posts: 187 | Joined: 01/13
Posted: 12/29/13
06:10 PM

Hi!

I'm thinking of a new transmisson for my 66 GTO. At the moment I use a Muncie M20 (wide ratio) and it works nice. But since the engine is making about 500ftlbs of torque I may need to upgrade it at some time. With the street tires it wasn't a problem until now, but next year I'll start to use semi-slicks for the track days.

Also I would like to have an overdrive. Now with my 3.55 rear end it's not fun to drive longer distances. I don't want to build a drag car but I would like to find the best compromise between performance and the ability to cruise along with 70-80mph without very high rpm's.

I think the options are an overdrive automatic like the 200r4 or 700r4, a Tremec TKO500 or TKO600 and a gear vendors kit.

Which swap would be best? I like my manual shifter, so an automatic isn't my first choice. Also the gear vendors seems to be pretty expensive compared to a TKO.

Does anyone know how much work is involved to put in a Tremec 5 speed manual? And what gear ratios would fit best?

TKO 500: 3.27 / 1.98 / 1.34 / 1.00 / .68
TKO 600: 2.87 / 1.89 / 1.28 / 1.00 / .82
GM200r4: 2.74 / 1.57 / 1.00 / 0.67
GM700r4: 3.06 / 1.62 / 1.00 / 0.70

The engine starts to build power at 1800rpm and has it's peak at about 4000rpm.

What do you think?

Chris  

dond1965 dond1965
User | Posts: 116 | Joined: 12/13
Posted: 12/29/13
06:36 PM

how about a super T-10, [4] speed? an easy change over, deep first gear, wide ratios. use it with a 2.75 or so rear gear [maybe even 2.50 ish]. you have a VERY strong engine! it has MASSIVE low end torque, you can pull that gear with ease. the super T-10 is VERY strong, and available used if you're pinching pennies. also the taller ring and pinion set is stronger than what you are using. p.s. i found a bunch of them on ebay, even a 77 corvette unit with 47,000 miles on it, 2.64 first gear, for $300.00 u.s. a rebuild kit for $135.00 u.s., food for thought.  

shyrgfuh70 shyrgfuh70
User | Posts: 93 | Joined: 12/13
Posted: 12/29/13
06:49 PM

Hello Chris;


Muncie M20's had 2 different ratios depending on year.

1963 - 1965   2.56   1.91   1.48   1.00  

1966 - 1974   2.52   1.88   1.46   1.00


M21 and M22 ratios.

1963 - 1974   2.20   1.64   1.28   1.00  


Manual trans gear spacing


600 .98 .51 .28

M20 .64 .42 .46

M21 .56 .34 .28



Out of the manual trannies you listed, I would run the 600, but first is fairly lower than what you currently have which is a bit low imo, BUT more importantly, it is a L O N G way from 1st to 2nd so you need to drive your car and determine if thgis is an improvement for you or not.

3rd and 4th on the 600 are also a little closer together so check this out too.

Out of the autos, I would run the GM200 and around a 2600 rpm stall in your case.  

chrisaustria chrisaustria
User | Posts: 187 | Joined: 01/13
Posted: 12/29/13
07:15 PM

I would still miss the overdrive so I don't think it's a good choice for me.
Is a Super T10 much stronger than a Muncie? Gearing is about the same as my M20.

Do I want a longer or shorter first gear for my application? Car is pretty heavy.. and I read something about final ratio of about 10 is good (2.56 x 3.55 at the moment). The Super T10 with 2.75 rear gears would be 2.43 x 2.75. I don't think I want to move into this direction.

Is there any kind of manual transmission with overdrive that will fit into my 66 GTO without big modifications?  

chrisaustria chrisaustria
User | Posts: 187 | Joined: 01/13
Posted: 12/29/13
07:21 PM

Do you think the 200r4 is strong enough? And will it fit right in without big changes? The only reason to use a automatic is if a manual (with overdrive) is too much trouble and money. But it would be good to know either way if the 200r4 is a good option or not. I also read that the 700r4 is much heavier and "consumes" about 70hp instead of only 35hp the 200r4 consumes.

My M20 has a case from 65, so if the case fits the rest it is the 2.56 version.
I just changed the fluid and it shifts well, I now have a little better Feeling when shifting.. maybe it's just imagination, but it feels a little "harder".(80w90 gl4)  

dond1965 dond1965
User | Posts: 116 | Joined: 12/13
Posted: 12/29/13
07:22 PM

yes the richmond street 5-speed. it is based on the super T-10, and has an additional, overdriven fifth gear set. the nascar racers use the super T-10. those engines make about 800 horse power, and those cars can do about 200 mph., art carr is a man famous for improving automatic transmissions in america. he has parts to make the th_200 4r pretty strong, and yes those transmissions have bell housings that bolt to the pontiac engine.  

shyrgfuh70 shyrgfuh70
User | Posts: 93 | Joined: 12/13
Posted: 12/29/13
07:33 PM

"Do I want a longer or shorter first gear for my application?"

Please reread my previous post again. YOU, need to determine this for yourself, however if your tires a spinningly wildly away as you said before AND you already have traction bars, they will spin even more off the line with a lower first gear than you already have which is NOT what it seems to me you want but maybe you do.  

chrisaustria chrisaustria
User | Posts: 187 | Joined: 01/13
Posted: 12/29/13
07:34 PM

Sounds nice, the Richmond 5 speed fits without big trouble?
I checked the ratios and they have a 1.00 5th gear. So I would need to change the rear end to benefit from this transmission. But it would be an option if the TKO will be much harder to fit in. (450ftlbs vs the 500 or 600 from the TKO.. so the TKO would give me the option to increase engine power in the future).

That's something I will have to think about. Do you have experience with a TKO or Richmond in a 66 GTO installation?  

chrisaustria chrisaustria
User | Posts: 187 | Joined: 01/13
Posted: 12/29/13
07:38 PM

I posted while you gave me the information about what I want (longer or shorter 1st). I will determine it. On the track with street tires I had problems in 1st with traction but with the drag tires it may be better and a shorter gear could be possible, I'll check this as soon as it gets warmer outside Smile
I was told the closer ratio is better for performance cars and the longer 1st of the TKO600 (even shorter as the M20) sounds like a better match, but I'll have to test it like you said.

The Richmond 3.28 2.13 1.57 1.24 1.00 would surly work better with a longer rear end gear. This is something I would think about if the TKO is much harder to install. (advantage of the TKO600 is better gearing with overdrive and my 3.55 rear plus more strenght, at least on the paper.. 450vs600)  

shyrgfuh70 shyrgfuh70
User | Posts: 93 | Joined: 12/13
Posted: 12/29/13
07:42 PM

They make richmonds with overdrive for high hp apps dso there is no need to change your gear ratios. They are only 3500 - 3800.00 us dollars. see ratios in link below.

http://www.jegs.com/p/Richmond-Gear/Richmond-Super-Street-5-Speed-Transmissions-with-Overdrive/773418/10002/-1  

shyrgfuh70 shyrgfuh70
User | Posts: 93 | Joined: 12/13
Posted: 12/29/13
07:46 PM

Your traction with semi slicks will be improved but not by a huge margin. Keep in mind, 1 - 2 gear on the 600 is a lot farther apart then what you currently have so your rpm's will drop more than they currently do when you shift between those two gears. I would HATE that.

Why don't you buy a 6 speed manual?

You can also buy a 3 speed auto like a turbo 400 with an aftermarket overdrive that turns it into a 4, 6 or 8 speed with the push of a button.

As you see there is no end to the options.  

dond1965 dond1965
User | Posts: 116 | Joined: 12/13
Posted: 12/29/13
07:51 PM

may i ask a question? what would happen if you revved your engine to 3,000 rpms, and released the clutch very quickly? instant tire smoke? with your engines power/rpm band i would think you do not need and can not use 10 to 1 primary reduction EXCEPT with minimal throttle opening.  

dond1965 dond1965
User | Posts: 116 | Joined: 12/13
Posted: 12/29/13
08:02 PM

the th-200 4r is an easy swap. if you understand WHY i asked the question about dumping the clutch, you can then maybe understand my recommending a taller rear gear set and a little wider ratio 4-speed trans. with the taller ring and pinion, in effect it acts like an over drive. richmond makes TWO 5-speed transmissions. one with a low first gear and direct drive fifth speed, and another unit with a taller first gear, and over driven fifth speed.  

dond1965 dond1965
User | Posts: 116 | Joined: 12/13
Posted: 12/29/13
08:09 PM

Icon Quotechrisaustria:
I would still miss the overdrive so I don't think it's a good choice for me.
Is a Super T10 much stronger than a Muncie? Gearing is about the same as my M20.

Do I want a longer or shorter first gear for my application? Car is pretty heavy.. and I read something about final ratio of about 10 is good (2.56 x 3.55 at the moment). The Super T10 with 2.75 rear gears would be 2.43 x 2.75. I don't think I want to move into this direction.

Is there any kind of manual transmission with overdrive that will fit into my 66 GTO without big modifications?


2.56 x 3.55 is NOT your final reduction, that is your PRIMARY reduction. your final reduction is 3.55 x 1 to 1, for 3.55 final sir.  

chrisaustria chrisaustria
User | Posts: 187 | Joined: 01/13
Posted: 12/29/13
08:16 PM

I didn't see the Super Street 5speed before, that one looks nice and has an overdrive. Will it fit as well as the street 5speed?

A 6 speed may be even harder to fit in I guess? Didn't think a lot about this option..
Are you talking about the TH400 with gear vendors? The TH400 is very nice, a friend of mine uses one and is very happy even with "only" 3 gears. But his car is race only and he don't need an overdrive.

I like the idea of a 5 speed manual with overdrive the most at this time!

@dond
At 3000rpms and a quick clutch release the tires will smoke badly. Don't know how the drag tires will react but I guess even with the 275/50/15 it will not make much sense.. but I'm not sure at the moment.
So probably I should not change much from where I'm at now you think?

@shyrgfuh70
What do you think about the Richmond gearing? 2.89, 1.85, 1.31, 1.00, .77
It looks like it has a big drop as well from 1st to 2nd.
The 6 speed I found has: 2.97 2.10 1.46 1.00 0.74 0.50 which is also a rather big drop from 1st to 2nd... it looks like all of them are bigger than my M20 now. I'll have to check if the drop isn't to big. I ran a better time when I shifted from 1st to 2nd a little bit earlier on the track is all I can tell now.  

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