Looking for 9s all motor what auto trans?

1317 Views 34 Replies 17 Participants Last post by coupe1993, 2 mo ago

HIVOLTJ

Discussion Starter · 3 mo ago

Automotive parking light Car Wheel Land vehicle Tire

1991 GT AOD car I'm going to build a drag and drive unit out of. Looking for 9s all motor SBF bolt pattern auto trans.

Looking for something to hold up to 750hp or so reliably on a budget. I would like to do drag week, rocky mtn race week etc. Car we see minimal use outside of that but does need to be able to cruise 65-70 on the highway.

Car currently has 3.73 geared 8.8. Would be in "street car" classes requiring full interior etc. Some require 3200lb with driver.

Built AOD? Built C4? 4R70?

What would you run? Leaning towards a stout C4.

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q6543

· #2 · 3 mo ago

I would go straight to a Th400 or glide, this is coming from a mid 9 second C4 owner.

seems like the trans needs to come out waaay too often.. every one I’ve talked to tells me the same Th400 and be done.

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massacre

· #3 · 3 mo ago

q6543 said:
I would go straight to a Th400 or glide, this is coming from a mid 9 second C4 owner.

seems like the trans needs to come out waaay too often.. every one I’ve talked to tells me the same Th400 and be done.

Agreed.

HIVOLTJ

Discussion Starter · #4 · 3 mo ago

Ugh, I made a face at that. I may consider it, just much more beefy? What C4 issues have you had? A 400 will fit in a fox trans tunnel?

strokeme

· #5 · 3 mo ago

HIVOLTJ said:
Ugh, I made a face at that. I may consider it, just much more beefy? What C4 issues have you had? A 400 will fit in a fox trans tunnel?

The c4 simply doesnt have the real estate in the case. The 400 is superior in every way to a c4, its not even close.

Reactions: 1

AL P

· #6 · 3 mo ago

The problem with the 400 is the area of real estate in your wallet. They get really pricey really quickly. You mentioned not using a C4, doing it on a budget and reliability. To me that means one word..... powerglide.

92stroker331

· #7 · 3 mo ago

Went with a coan TH400 setup for my supercharged 331 9 second street car and never looked back. Zero issues with it and it’s been in the car since 2017.

Reactions: 1

96pushrod

· #8 · 3 mo ago

How much money are you looking to spend?

Stock case Th400 with a sbf bellhousing would be the best somewhat budget oriented option. One could be bought that would meet your goal in around the $3500 range including converter. Plenty of shifter options with a 400 as well.

HIVOLTJ

Discussion Starter · #9 · 3 mo ago

Yeah around $3500 would be acceptable. But I don't want to cut up the trans tunnel. If one was to go th400 then why not c6 at that point? Parts availability?

I forgot to add I don't need a trans brake... in fact I'm not sure some of the street classes allow it.

I have also considered power glide but is it good for a high revving NA combo? Is there a lot of RPM drop on the one gear change slowing it down?

KEVIN$

· #10 · 3 mo ago

What does a Gear Vendors OD unit cost? I know a buddy of mine uses one on his cars.

ks

96pushrod

· #11 · 3 mo ago

HIVOLTJ said:
Yeah around $3500 would be acceptable. But I don't want to cut up the trans tunnel. If one was to go th400 then why not c6 at that point? Parts availability?

I forgot to add I don't need a trans brake... in fact I'm not sure some of the street classes allow it.

I have also considered power glide but is it good for a high revving NA combo? Is there a lot of RPM drop on the one gear change slowing it down?

Even if you don’t need a trans brake now, better to get one that has it already in case you decide on one in the future. I’d really just go with a th400 over the glide. Glide has worked great for a lot of people, it wouldn’t be a bad option. Both will fit a stock trans tunnel.

A c6 doesn’t have 5% of the aftermarket parts availability of a pg or th400. Plus finding a small block case can prove challenging. They’re good transmissions, but I wouldn’t bother.

KEVIN$ said:
What does a Gear Vendors OD unit cost? I know a buddy of mine uses one on his cars.

ks

They’re like $4000 for just the od unit.

HIVOLTJ

Discussion Starter · #12 · 3 mo ago

KEVIN$ said:
What does a Gear Vendors OD unit cost? I know a buddy of mine uses one on his cars.

ks

Yeah a couple grand.... or you can just Rev higher on the highway or drive a bit slower lol.

Seems slightly dumb for me to remove the AOD instead of build it but I worry about the fragility of even a built AOD

CDW6212R

· #13 · 3 mo ago

What is the value of the 9 second SBF, how much is in that? Given that, a nice high budget for the engine and chassis, why not give plenty of love to the trans? I suggest a more modern trans, although I do have a rebuilt(not upgraded) C6 you could talk me out of.

I'd suggest thinking about a 6R80, the 1st gear is 4.17:1, and 6th gear is still 0.70:1, so plenty of strong gears. With no bands, it's stronger that almost all older stuff.

The hardest part is the cost, and the control system. It can be done without a $700+ adapter kit. The TC should cost about the same as a nice 4R70W unit or others. But the trans rebuild cost is a bit higher, you have to add at least the $600+ upgraded clutches, and a $600+ intermediate shaft. The 6R costs a good $300+ more just for the regular rebuild parts and solenoids. So the 6R can end up being easily $3500 plus the needed ring and pinion gear change and new driveshaft.

I'm plotting on a 6R swapped into my 98 Explorer, using a 2014 F150 PCM to run it and the SBF. I've just been browsing for drive by wire TB's, it will have to have that and the matching pedal, and some rewiring for the CC at the least. But the PCM control I have a plan that should work, for the cost of harnesses for the PCM, tuning, and work to the cross member etc. Without an adapter plate kit between the block and trans, it makes it a little shorter than other examples. You have to be willing to do without one bell housing bolt.

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tjm73

· #14 · 3 mo ago

At this point it's probably easier to find a C6 SBF pattern than a C4 around my parts. I've both in my barn, but they are both my brothers. He'd give me the C6 if I asked for it probably. I've been looking for a C4 to add to add to my "stock". Have a future project in mind it might be good for. But I have an AOD that woudl suffice for it as well. If I come across one I'll secure it. But I digress.

The C6 can be made to be plenty strong. Fully rollerized. But it'd be a you build it yourself deal. The real old school way. Research and hand fit hard parts. Not as efficient as a TH400 they say, but you'd never break it. Many a C6 lived behind serious BBF's.

There used to be a guy on one of the 460 forums with a serious 3 part build for a C6 the needs minimal maintenance. I wonder if I can find it/it still exists.

Reactions: 1

tjm73

· #15 · 3 mo ago

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64Cometkid

· #16 · 3 mo ago

Why not a built 4R70..? Can’t they handle around 500-550hp in stock form? I would think a 4R could be built to be reliable at 750whp. Then you get to keep an overdrive and don’t need an adapter to run it.
Nice hatch, btw.

CDW6212R

· #17 · 3 mo ago (Edited)

64Cometkid said:
Why not a built 4R70..? Can’t they handle around 500-550hp in stock form? I would think a 4R could be built to be reliable at 750whp. Then you get to keep an overdrive and don’t need an adapter to run it.
Nice hatch, btw.

The 4R is a nice strong trans, and can be upgraded a good amount now given the Sonnax hard parts. But when the 1/4 mile speed gets higher and higher, you might have to put in a higher R&P gear, to not run out of 3rd gear. You might have enough rpm to run through just 3rd gear in the 1/4 mile, but the 4th gear is useless except for cruising. That's why I'm moving to the 6R from the 4R, I think I may make use of the 5th gear by the end of the 1/4 mile.

98yellowstangGT

· #18 · 3 mo ago

750 rear wheel to run 9s? I am running 9s with 500 rear wheel. Maybe your talking low 9s?

Reactions: 1

LilRed86

· #19 · 3 mo ago

Freddy Brown builds the strongest AOD's on the planet! Got a friend with a twin 67mm 363 making 1200rwhp with one of these AOD's going on 5yrs now. Runs 8.80'[email protected] in a full weight 3200lb 91 coupe. He puts 2-3k miles a year on it plus about 100 passes. Went 3yrs before it needed freshend up and that was only the overdrive band flaring up.

high performance, 4r70w, transmission, AOD, racing, Freddy Brown

Reactions: 3

HIVOLTJ

Discussion Starter · #20 · 3 mo ago

No I know it doesn't take 750hp to run high 9's the point is to have it a little overbuilt.

It would be kick ass to keep the AOD but I dunno. I've already built a C6 for my BBF project and as far as 6r80 I don't want electronics on a drag week type car... well as few as possible. Electrics will let you down.

I've been looking into Might Mite C4 sounds good, maybe a built AOD with 4r70 guts?

I'd be OK with a freshen up every couple years so long as it doesn't eat up hard parts.

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