direct drive th350

Transmission to Rear-end

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phantomfab
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direct drive th350

Post by phantomfab » Mon Feb 13, 2017 4:12 am

Anybody made a at home build for a direct drive 350, either by using external valve or by drilling the passages in the valve body. I've heard of a few guys drilling and tapping the valve body to accept holley jet to allow a bleed off in the transmission to allow the transmission to be put in gear without an external valve. If anybody knows how to do this could they share some of the knowledge. Thanks in advance.

barnym17
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Re: direct drive th350

Post by barnym17 » Tue Feb 14, 2017 6:06 am

externally drill and tap the pump inlet and outlet for 1/4 pipe install fittings needed for your hose set(1/2 or3/8 hyd hose works well).grind the fittings flush with the pump cover on the inside so as not to restrict flow.Reassemble pump install in tranny and your done.

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Re: direct drive th350

Post by ZIGGY » Tue Feb 14, 2017 11:15 am

Re this and your earlier post on pg vs. 3spd - if you're going to run direct drive auto,
don't bother with the 350. Use a 'glide.

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Re: direct drive th350

Post by phantomfab » Wed Feb 15, 2017 2:21 am

ZIGGY wrote:Re this and your earlier post on pg vs. 3spd - if you're going to run direct drive auto,
don't bother with the 350. Use a 'glide.
well id love to. The problem is i have a working three speed and working 350. The glide needs rebuilt and i need the internal part of the shift linkage where the detent rides. I'd be glad to run the glide. Anybody have detent for the glide? Or does anyone have a glide core they would be willing to let go of fairly cheap. Being on a tight budget kinda sucks.

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Re: direct drive th350

Post by phantomfab » Wed Feb 15, 2017 2:50 am

barnym17 wrote:externally drill and tap the pump inlet and outlet for 1/4 pipe install fittings needed for your hose set(1/2 or3/8 hyd hose works well).grind the fittings flush with the pump cover on the inside so as not to restrict flow.Reassemble pump install in tranny and your done.
Could you take a picture of where exactly to drill the pump?

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Re: direct drive th350

Post by ZIGGY » Wed Feb 15, 2017 5:39 am

phantomfab wrote:internal part of the shift linkage where the detent rides
Called the "rooster comb" and it's readily available for cheap.
http://www.atiracing.com/products/trans ... ansacc.htm
The rebuild parts for circle track use are relatively cheap. DO GET an aftermarket hardened
input shaft. You don't need a cooler. There are several ways to achieve direct drive.
Cheapest quick & dirty is front pump drill. Location is at about 5 & 7 o-clock bottom where
pressure & return fluid channels are. IME 3/8" holes are better. You need someone familiar
with the pg as you must keep pump halves aligned, etc. Get a rebuild book.
Carl Munroe's is considered one of the best although it's drag race oriented.
P.S. - Whoever does the work must be a careful, clean, detail focused person.
A half-ass, of which there are many, will cause nothing but grief and expense.

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Re: direct drive th350

Post by phantomfab » Wed Feb 15, 2017 6:47 am

ZIGGY wrote:
phantomfab wrote:internal part of the shift linkage where the detent rides
Called the "rooster comb" and it's readily available for cheap.
http://www.atiracing.com/products/trans ... ansacc.htm
The rebuild parts for circle track use are relatively cheap. DO GET an aftermarket hardened
input shaft. You don't need a cooler. There are several ways to achieve direct drive.
Cheapest quick & dirty is front pump drill. Location is at about 5 & 7 o-clock bottom where
pressure & return fluid channels are. IME 3/8" holes are better. You need someone familiar
with the pg as you must keep pump halves aligned, etc. Get a rebuild book.
Carl Munroe's is considered one of the best although it's drag race oriented.
P.S. - Whoever does the work must be a careful, clean, detail focused person.
A half-ass, of which there are many, will cause nothing but grief and expense.
I knew the name of the part just couldnt recall it at the time. i appreciate the link, and i am really good friends with a transmission builder that builds a ton of glides for the drag guys in my area. I've personally seen his trannys hold 1400hp at the tire and a ton of them in the 5-800 range. Im from the neo-nwa area and there are some fast "street" cars around here and most of his trannys get drove and raced. But why do you say i don't need the cooler? Also, do you know of anywhere to get the shaft the rooster comb bolts to? and the s clip the attaches it to the main shift valve? And thanks again for the reply.

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Re: direct drive th350

Post by phantomfab » Wed Feb 15, 2017 6:53 am

ZIGGY will this work with that rooster comb for a stock powerglide? And my glide has already been used, the pump is already drilled.

http://www.atiracing.com/products/shift/shift.htm

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Re: direct drive th350

Post by ZIGGY » Wed Feb 15, 2017 9:08 am

With no converter, the trans doesn't build enough heat to need a cooler. Just use a loop to bypass it.
Very, very common practice in circle track pg's. IME does not affect trans reliability or life, so get rid of the weight and
complexity. Check your builder buddy first for the other pieces rather than buy new.
Initially I just skimmed this thread before my other replies, but now I see you were asking about internal mods for direct
drive. If and when I get time to dig out some notes to refresh my memory of hole sizes, etc., I will post alternative mods.
Or if you win some purse money, go buy an aftermarket valve body. :)

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Re: direct drive th350

Post by ZIGGY » Wed Feb 15, 2017 6:19 pm

First while I'm thinking about it, if you decide to run without a cooler, you can eliminate the loop as well and plug the external cooler line holes by removing the cooler bypass inside the trans.
Okay, no wonder I couldn't remember the hole sizes - there's argument and maybe confusion about it. I think the mod you were asking about consists of drilling a hole (many say .100 or 7/64 (.109375) OR .125 OR .147) in the bottom of the low gear servo pipe, and a .100 OR 7/64 OR .125 OR .168 hole in the reverse clutch piston (in bottom of case).
My guru said DON'T because it causes low gear to slip all the time if low is used and since the fluid pressure passes through this circuit, it can cause high gear and low gear band damage. I never have used this method. Another builder I knew used, according to my notes, ".125 in low and three .087 holes in the three dimples on the reverse piston. Adjust band to suit (3 & 3/4 to 4 turns)."
Like most everything else in racing, there are even more ways to skin this particular cat (some will make you puke and the cat doesn't like any of them) and various ways to lighten and strengthen the pg. If you're using a rear crossmember, use a rubber mount. Use long dowels from block regardless and make sure
your yoke travel is more than adequate. I used the same pg for years in dirt stocks and mods and briefly in a late model as a loaner. Never hurt it. Sold to a street
stock moron who managed to break it his first test & tune day because of his shit drive train and chassis setup.

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Re: direct drive th350

Post by phantomfab » Thu Feb 16, 2017 7:06 pm

ZIGGY wrote:First while I'm thinking about it, if you decide to run without a cooler, you can eliminate the loop as well and plug the external cooler line holes by removing the cooler bypass inside the trans.
Okay, no wonder I couldn't remember the hole sizes - there's argument and maybe confusion about it. I think the mod you were asking about consists of drilling a hole (many say .100 or 7/64 (.109375) OR .125 OR .147) in the bottom of the low gear servo pipe, and a .100 OR 7/64 OR .125 OR .168 hole in the reverse clutch piston (in bottom of case).
My guru said DON'T because it causes low gear to slip all the time if low is used and since the fluid pressure passes through this circuit, it can cause high gear and low gear band damage. I never have used this method. Another builder I knew used, according to my notes, ".125 in low and three .087 holes in the three dimples on the reverse piston. Adjust band to suit (3 & 3/4 to 4 turns)."
Like most everything else in racing, there are even more ways to skin this particular cat (some will make you puke and the cat doesn't like any of them) and various ways to lighten and strengthen the pg. If you're using a rear crossmember, use a rubber mount. Use long dowels from block regardless and make sure
your yoke travel is more than adequate. I used the same pg for years in dirt stocks and mods and briefly in a late model as a loaner. Never hurt it. Sold to a street
stock moron who managed to break it his first test & tune day because of his shit drive train and chassis setup.
No offense meant to your guru but has he put a tranny brake in? theres a .125 hole that is put in to one of the circuits that is always leaking, my tranny guy couldnt believe it would overcome that big of a leak so he called tci(thats who supplied the brake) and they said it isnt a problem. This is in a truck that is driven daily. That transmission was a th350 behind a 5.3 in a 4500 lbs truck with a 3800 stall. Hasn't had a problem yet, and another friend of mine drives it everyday to work.

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Re: direct drive th350

Post by phantomfab » Thu Feb 16, 2017 7:09 pm

I have a really good transmission guy but he just hasn't messed with the direct drives any other than ones that are brought to him to be fixed or he puts in a different valve body, the only valve bodies he messes with are making full manual 4l60e valve bodies. Other than that he doesn't mess with them. And i had heard of guys drilling the valve bodies and tapping them for holley jets so it was adjustable if the hole was to big.

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Re: direct drive th350

Post by ZIGGY » Thu Feb 16, 2017 8:24 pm

phantomfab wrote:That transmission was a th350
We (or at least me) are talking 'glide here, not TH350's. I don't think it relates
to what your builder is doing.

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Re: direct drive th350

Post by phantomfab » Fri Feb 17, 2017 4:25 am

ZIGGY wrote:
phantomfab wrote:That transmission was a th350
We (or at least me) are talking 'glide here, not TH350's. I don't think it relates
to what your builder is doing.
This is true. and yes i was talking glides as well. But when i was refering to the valve bodies, I've heard of guys drilling the th350 valve body for the direct drives so a external valve wasnt needed, which made the example i was giving relevant IMO. The thread began for the 350 but has became for powerglides lol I'm not complaining though cause info on either one is fine by me, I'll take knowledge on any subject.

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Re: direct drive th350

Post by pdq67 » Fri Feb 24, 2017 10:41 am

I have a stupid question and I think that the Pontiac guys did it at one time say like in the '63 or '64 Tempest rear tranny cars??

Can we hook two PG's together to make a 4-speed automatic?

I mean, heck, the PG is one stout tranny.. IMHO, it just doesn't have enough gears is all........

pdq67

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