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Discussion Starter · #21 ·
With a TH- 350 the 36 element sprag upgrade requires a different drum also.....it's not just a drop in on the stock drum and it is well north of $100. You must be thinking of the TH-400, which does have a $100 sprag upgrade to 34 element sprag.
They are not the same piece.
The relatively inexpensive 34 element sprag for the TH-400 will not fit a TH-350.

The good TH-350 sprag only comes assembled on the drum, since the inner stock race has to be modified to take a 36 element....and it is a $300-400 piece. $550 if you want a steel drum rather than cast iron.

TH350 Drum 36 Element Sprag 350-327900 TSR Racing Products (tsr-racing.com)
BTE Racing: BTE TH350 Heavy Duty Drum w/ Sprag
Transmission Specialties | Transmission Specialties (tsirace.com)
TH350 Iron Drum/HD Sprag Assembly (tciauto.com)

It was not included in this level of trans from TCI, you have to buy a transbrake equipped model from TCI to get the good high power drum and sprag.

All TCI puts in this level of trans is a new roller clutch package with HD springs and a hardened sprag race....not really all that much stronger than stock really. Still only 8 or 10 contact rollers in that stock style roller clutch/sprag.
Just the hardened race is $100 bill...
TH350 Intermediate Sprag Race‚ Hardened 350-35732HD TSR Racing Products (tsr-racing.com)
And the roller clutch, $70
All Products (tsirace.com)

I had a 450 hp 383 SBC break 3 straight so-called "hardened " stock style sprag races in a fresh manual valvebody TH-350, 6 to 7 1/4 mile passes each before I got smart and bought the good drum/sprag package....never touched the trans again.
And this was just a low 12 second pump gas 3600 lb street car with soft compound 8" wide dirt track tires on it("cheater slicks').

You've already got the trans....but TCI would not have been my choice at all for a trans builder.

You'll have to find another stock drum if you are going to try the new stock style roller sprag with a new hardened race and put it back together(I don't recommend it, you are paying more than 1/2 the cost of just getting the good drum )....blowing up a stock type ruins the drum for re-use.
thanks for the info going to start looking into this in few days.
 

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Discussion Starter · #22 ·
Swapping hard parts from one TH350 to another TH350 is a common repair route, the thing that must be paid attention to is that you are keeping clearances within specification. TH350's are not that difficult to work on but again if you do not have or have access to some of the specialty tools that you will need to disassemble it and reassemble it correctly - you're setting yourself up for a possible failure.
If I'm reading this correctly, you purchased the trans through Summit Racing? I would get them on the phone tomorrow morning and see what they can work out for you. A major failure in that short of a time period is something that they should provide you some help on.
thanks for this info.
 

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I have a very good VHS tape on rebuilding, repair and testing TH350's. I was planning to learn how but then I watched the video several times and decided it's a bit more voodoo than I wanted to get into. That and my uncle is a tranmission specialist so I just take stuff over to him and leave it on the patio and pick it up in a few days. He's never failed me. If you want the video tape, PM me and address.
 

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Discussion Starter · #24 ·
I have a very good VHS tape on rebuilding, repair and testing TH350's. I was planning to learn how but then I watched the video several times and decided it's a bit more voodoo than I wanted to get into. That and my uncle is a tranmission specialist so I just take stuff over to him and leave it on the patio and pick it up in a few days. He's never failed me. If you want the video tape, PM me and address.

Yes i will take it if you still have it. thanks so much.
 

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Discussion Starter · #25 ·
I have the tci trans apart now sorry it took so long, Sprag and ring gear crack. Have any 1 tried this or no any 1 drag race with it.
Man TCI sucks 30 day warranty and no help.

Heavy Duty Intermediate Overrun Clutch Outer Race
Part No. 35723HD-02
 

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Oh wow - that looks like a stock intermediate sprag setup. I thought you had a bum hardened piece and figured TCI should cover it. The stock stuff is okay for going up and down the road but certainly not for any high performance work. The downside is that the better pieces are getting more and more expensive. Just looking around, ATI has the steel based drum for $309 Part # 355682. Little hard to tell in their online catalog but I assume that includes the 36 element sprag and race with it. Out of everything in a TH350, it's probably the one piece that you really want to have in it. They do carry the HD piece which if I remember correctly is just a stock sprag with a hardened outer race part - $55, but again you can't go leaning on it real hard.
 

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I've not had a chance to use the -02 Sonnax race, it wasn't in existence the last time I fooled with a TH-350, all you could get was an aftermarket fully hardened race(the -01), and just like the chart at Sonnax shows it wasn't much of an improvement over a stock race....but that new Sonnax race could just be your ticket to avoiding the expensive drum and sprag solution.

Your broken race looks like a hardened aftermarket piece....is it black finish(remnant of heat treat) on the spline section??
Looks like it broke right where they always do, right at a lube hole.

Make sure to also replace the sprag element when you add the Sonnax race to your used drum from the spare transmission, and make sure to also put new lip seals in that spare drum and clutch piston.

Make sure yu get "HD-02" and not HD-01...the -01 is just the hardened old version.

Sonnax Heavy Duty Intermediate Overrun Clutch Outer Race - 35723HD-02

616048
 

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Discussion Starter · #28 ·
Here's few more pictures, TCI's and the 1 on my old Trans all so side by side pictures of the drums.
TCI is the cracked 1, and the drum that has the groves in it is TCI as well. Do it looks like I need to replace the drum to.

I can't tell if it's heat treated the outer race. On my old 1 the finish don't look like TCI outer race.

My old trans if i remember was built in 2009 or 2010 with a lot tree light racing. never had a problem with it until the mounting base cracked.

When I sent pictures to TCI of the shavings in the oil pan TCI said it was from my stall - only 30 day warranty race transmission, They did not even off to send back to check it.
We kinda went back and forth about this. The shaving pictures are the beginning of this post.
 

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I installed about 6 TCI hardened races about 20 years ago. Everyone came back broken! I was not impressed,and I never bought another product from them. Spend the money for the drum with the 36 element sprag from ATI. It is priced right. Make sure the wavy plate is installed in the intermediate clutch pack. Without it, it will shock the sprag on the shift,and lead to early failure. The sonnax race is a good alternative if funds are an issue.
 

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Yes, you'll need to replace the drum....once the roller clutch and race have exploded, it ruins the inner notched race on the drum....which is not a removable and replaceable piece.

You'll need to use your old spare drum, and new roller clutch assembly(rollers, springs, cage) and the new Sonnax race if you aren't going to step up to the HD drum with the 36 element "dogbone" sprag on it.

Looks like the Sonnax race, the new roller clutch package is going to cost you somehwere close to 1/2 to 2/3 the cost of the full race HD drum with the 36 element sprag.....so your choice is going to be if you feel the Sonnax race and stock roller clutch are going to be able to handle the job??....or if you should just step right up to the piece that will never break.
 

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Little known in the transmission world... these "hardened" races. If they have the usual thru holes for lube, what they are is an OEM race that has been annealed and re-heat treated to a different rockwell hardness. The OEM race is actually too hard , near brittle before they are processed to a lower rockwell number. These re-treated races are often coated with a dry lube coating or black oxide coating like is used on guns. I know one company was re-heat treating the OEM races , then running the races thru a cryogenic treatment process. That was years ago when it came out that Nascar teams were cryo treating parts.

I have not seen the Sonnax new T-350 race for OEM roller clutch. It was explained to me the lube holes have been moved to avoid the break thru that is common on the OEM T-350 race.

The purpose of the lube holes in the race is obvious. Many folks do not know there is a pressure feed hole on the back side of the pump cover that sprays oil directly into the intermediate race. That is why the race retainer is designed as it is from GM.
 
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Discussion Starter · #32 ·
Yes, you'll need to replace the drum....once the roller clutch and race have exploded, it ruins the inner notched race on the drum....which is not a removable and replaceable piece.

You'll need to use your old spare drum, and new roller clutch assembly(rollers, springs, cage) and the new Sonnax race if you aren't going to step up to the HD drum with the 36 element "dogbone" sprag on it.

Looks like the Sonnax race, the new roller clutch package is going to cost you somehwere close to 1/2 to 2/3 the cost of the full race HD drum with the 36 element sprag.....so your choice is going to be if you feel the Sonnax race and stock roller clutch are going to be able to handle the job??....or if you should just step right up to the piece that will never break.
Thanks for the info
 

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Discussion Starter · #33 ·
Little known in the transmission world... these "hardened" races. If they have the usual thru holes for lube, what they are is an OEM race that has been annealed and re-heat treated to a different rockwell hardness. The OEM race is actually too hard , near brittle before they are processed to a lower rockwell number. These re-treated races are often coated with a dry lube coating or black oxide coating like is used on guns. I know one company was re-heat treating the OEM races , then running the races thru a cryogenic treatment process. That was years ago when it came out that Nascar teams were cryo treating parts.

I have not seen the Sonnax new T-350 race for OEM roller clutch. It was explained to me the lube holes have been moved to avoid the break thru that is common on the OEM T-350 race.

The purpose of the lube holes in the race is obvious. Many folks do not know there is a pressure feed hole on the back side of the pump cover that sprays oil directly into the intermediate race. That is why the race retainer is designed as it is from GM.
Little known in the transmission world... these "hardened" races. If they have the usual thru holes for lube, what they are is an OEM race that has been annealed and re-heat treated to a different rockwell hardness. The OEM race is actually too hard , near brittle before they are processed to a lower rockwell number. These re-treated races are often coated with a dry lube coating or black oxide coating like is used on guns. I know one company was re-heat treating the OEM races , then running the races thru a cryogenic treatment process. That was years ago when it came out that Nascar teams were cryo treating parts.

I have not seen the Sonnax new T-350 race for OEM roller clutch. It was explained to me the lube holes have been moved to avoid the break thru that is common on the OEM T-350 race.

The purpose of the lube holes in the race is obvious. Many folks do not know there is a pressure feed hole on the back side of the pump cover that sprays oil directly into the intermediate race. That is why the race retainer is designed as it is from GM.
thinks for the info yes this do have the 3 holes. My old th350 that was drag racing never had a problem like this. What makes different levels hp specs for the th350 and parts needed. This is my 1st time pulling a trans apart.
 

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Discussion Starter · #34 ·
Man TCI will not do anything or help at all only 160 miles easy riding, I just notice this on the th350 TCI could this be a problem having this chip like this as well. Also there was no ball bearing in this TCI trans
This trans is a forward manual. So how come TCI would give this a specs 750hp.

There's a chip on the bottom,
 

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That chipped edge could be a leak path, if that section of the valvebody is used for something, if it is dead area, or an area now blocked off by some other modification I don't know....I'm not good enough of the fluid routing to be able to tell you...sorry.

The no check balls thing bothers me too, I'd expect at least 1....but I have no idea what TCI did to that valvebody, or if the balls are missing by mistake?

Did it work just fine prior to losing 2nd gear? If so fix the race/roller clutch problem and stick it back together the way TCI had it valvebody-wise.
 

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Discussion Starter · #36 ·
That chipped edge could be a leak path, if that section of the valvebody is used for something, if it is dead area, or an area now blocked off by some other modification I don't know....I'm not good enough of the fluid routing to be able to tell you...sorry.

The no check balls thing bothers me too, I'd expect at least 1....but I have no idea what TCI did to that valvebody, or if the balls are missing by mistake?

Did it work just fine prior to losing 2nd gear? If so fix the race/roller clutch problem and stick it back together the way TCI had it valvebody-wise.
Yes shift ok
 

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Discussion Starter · #38 ·
I have a very good VHS tape on rebuilding, repair and testing TH350's. I was planning to learn how but then I watched the video several times and decided it's a bit more voodoo than I wanted to get into. That and my uncle is a tranmission specialist so I just take stuff over to him and leave it on the patio and pick it up in a few days. He's never failed me. If you want the video tape, PM me and address.

wow thanks so much man. I "O" you. I have dvd convert player that can copy vhs brand new never use it 4 years old. I will have fun trying it out.
 

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notch in the TCI drum was just a balancing cut, it has no other function. You don't need to worry about it or duplicate it when you substitute a different drum..
I've seen them both with and without, and sometimes 2 notches like that of different sizes.
 
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