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Discussion Starter · #1 ·
Was finally gonna get some track time Friday, first of the year. What'ya know, Thursday night about 11:00 pm, second gear goes bye-bye.

On Wednesday night I experienced a weird 1-2 shift, kinda felt like a two stage process. It was under semi aggressive acceleration, but hardly a fully commited launch. Other than the funky shift, everything seemed normal the last mile, or so, home. Probably because I left it in drive after that.

Then, after work Thursday, I have to run over to my mom's. The speed limit is 25mph for the first couple of blocks, so I again don't notice anything. Once on a regular street, I notice the 1-2 shift really sucked. For a few miles I try different things, eventually discovering that manual second had gone away. Pull into a gas station, fluid level looks good to go, however, a couple of air bubbles on the dipstick have me a little concerned. Decide to get it back to the homestead, intending to evaluate its behavior in various gears along the way. At the first light, a cop gets behind me and stays there for all but the last two blocks. Best I could tell, everything was normal except acceleration in manual second.

Yesterday I put it on jackstands and drain the fluid. A little darker than new, not bad though. Drop the pan, no shrapnal, in fact, very little friction material, alot less than I expected, although it did get all new stuff just three weeks ago. Button up the pan, yank it, onto the bench and in pieces within an hour. Right away I discover that the sprag will spin both ways. Mixed emotions, glad the intermediate lugs are intact, disappointed that the sprag is shot.

I know that the 36 element "Super Sprag" uses a specially machined direct drum and oversized intermediate clutches, as well as, there's no chance in Hades that one could be found locally. Still wanting to race, I figured that a 34 element would be good enough for the time being, so I'd swap all the necessary parts from one of the TH400's left lying around after last months case/lug fiasco. First I check the one already disassembled (donor of the case currently being used), damn, only a 16 element. Next, I tear into the original perspective donor (bellhousing anomalies), after all, it was supposedly built by the local tranny guru for a 505 cid monster 4X4. Surely it would have atleast a 34 element sprag. No such luck, another 16. Thwarted again.

I'll call Art at COAN Monday. Really don't expect much more than selling me another. COAN warranteed the failed unit 50 miles into service (cost me $200 freight each way), but I've had to pay for everything else since ($400+ to COAN, $200+ to Hughes). Yes, warranty has passed, but what the hey, when you shell out nearly $3K for a tranny and converter, and short of catastrophic damage during racing type conditions, you don't really to expect to have to pull it in and out every month for the rest of your life. Don't get me wrong, Art has provided very good customer service in the technical department, I just feel that I need it way more than I should. Admittedly, I don't see many negative experiences (if any), however, I can't help but feel like I got a lemon.

Every website that I've visitied, COAN, Rossler, Etc... has the 36 element offered in a direct drum, intermediate clutch package ONLY, pretty damn pricey too($600-$900).
I emailed CK Performance and actually got an almost immediate reply, on a Saturday even. They'll sell me the 36 element sprag seperately for $89.99. I'd say that there's a good chance that this is where I'll be ordering from.

O.K. RANT OVER

I think that I already feel better...

OR

Maybe I just have to pee really bad.
 

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Ahhh, The joy of having too much power :D


Rowdy, I know it has to be getting aggravating!! Seems like everytime you get going and have a little fun something else happens. I wish you the best of luck and I know you'll get it figured out. :beers:
 

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Rowdy,

Transmission is where I don't tread too deeply, so correct me if I am incorrect in that you can't use the factory drum with the 36 element sprag?

Tom
 

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Discussion Starter · #4 ·
Rowdy,

Transmission is where I don't tread too deeply, so correct me if I am incorrect in that you can't use the factory drum with the 36 element sprag?

Tom
That is correct. The sprag that failed was a 36 element, so I already have the special drum. It came that way from COAN.

It wasn't a catastrophic type failure. The drum, which uses an adapter of sorts, and the outer race/intermediate hub appear undamaged.

I'll post a picture shortly.
 

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hey Rowdy its been a while since I been inside a trans I have all the books. but I forgot how to get the clutch packs apart with out the special tools what did you use. I got a power glide offerd to me and I wanna assemble it and see what I need. he told me stuff was missing but I have never done a glide so dont know anything about them. the two books I have are very good but one covers th400 exclusively and the other th350's only. the gilde already has the th400 style input shaft so I can use my current converter. I am just thinking about all this plus in all honesty I was gonna tear apart my th350 thats in the car and check it out cause there was alot of meterial in the pan when I took it off to change filters.
Jeff
 

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Was finally gonna get some track time Friday, first of the year. What'ya know, Thursday night about 11:00 pm, second gear goes bye-bye.

On Wednesday night I experienced a weird 1-2 shift, kinda felt like a two stage process. It was under semi aggressive acceleration, but hardly a fully commited launch. Other than the funky shift, everything seemed normal the last mile, or so, home. Probably because I left it in drive after that.

Then, after work Thursday, I have to run over to my mom's. The speed limit is 25mph for the first couple of blocks, so I again don't notice anything. Once on a regular street, I notice the 1-2 shift really sucked. For a few miles I try different things, eventually discovering that manual second had gone away. Pull into a gas station, fluid level looks good to go, however, a couple of air bubbles on the dipstick have me a little concerned. Decide to get it back to the homestead, intending to evaluate its behavior in various gears along the way. At the first light, a cop gets behind me and stays there for all but the last two blocks. Best I could tell, everything was normal except acceleration in manual second.

Yesterday I put it on jackstands and drain the fluid. A little darker than new, not bad though. Drop the pan, no shrapnal, in fact, very little friction material, alot less than I expected, although it did get all new stuff just three weeks ago. Button up the pan, yank it, onto the bench and in pieces within an hour. Right away I discover that the sprag will spin both ways. Mixed emotions, glad the intermediate lugs are intact, disappointed that the sprag is shot.

I know that the 36 element "Super Sprag" uses a specially machined direct drum and oversized intermediate clutches, as well as, there's no chance in Hades that one could be found locally. Still wanting to race, I figured that a 34 element would be good enough for the time being, so I'd swap all the necessary parts from one of the TH400's left lying around after last months case/lug fiasco. First I check the one already disassembled (donor of the case currently being used), damn, only a 16 element. Next, I tear into the original perspective donor (bellhousing anomalies), after all, it was supposedly built by the local tranny guru for a 505 cid monster 4X4. Surely it would have atleast a 34 element sprag. No such luck, another 16. Thwarted again.

I'll call Art at COAN Monday. Really don't expect much more than selling me another. COAN warranteed the failed unit 50 miles into service (cost me $200 freight each way), but I've had to pay for everything else since ($400+ to COAN, $200+ to Hughes). Yes, warranty has passed, but what the hey, when you shell out nearly $3K for a tranny and converter, and short of catastrophic damage during racing type conditions, you don't really to expect to have to pull it in and out every month for the rest of your life. Don't get me wrong, Art has provided very good customer service in the technical department, I just feel that I need it way more than I should. Admittedly, I don't see many negative experiences (if any), however, I can't help but feel like I got a lemon.

Every website that I've visitied, COAN, Rossler, Etc... has the 36 element offered in a direct drum, intermediate clutch package ONLY, pretty damn pricey too($600-$900).
I emailed CK Performance and actually got an almost immediate reply, on a Saturday even. They'll sell me the 36 element sprag seperately for $89.99. I'd say that there's a good chance that this is where I'll be ordering from.

O.K. RANT OVER

I think that I already feel better...

OR

Maybe I just have to pee really bad.
After reading all that now I have to pee, J/K. :D I know nothing about auto trans, hope you get it fixed and better luck in the future.:thumbsup:
 

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Rowdy,

I hear you...Got my new 496/TH400 together, NO REVERSE!! Got to pull it, install the spare, get her fixed. I hope my journey to a good tranny is not as long as yours. Hang in there....
 

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Was the sprag a 34 element sprag or stock?

The lightweight drum is a good idea on a TH-400 with the 36 element sprag but not needed in most applications. Look at it this way ::

The Direct drum spins at 2x engine speed in low gear, stops in second gear and goes to engine RPM in high gear. The lighter drum is for sure better, but do you need it? If your putting out over 650tq i would say do it, The ATI direct drum is good but pricey
 

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Tom, the factory drum (while strong in it's own right) is a weak link. I just had my T400 done over by Trans-Specialties. Ditched the stock drum and went to a 34 element /drum assembly. My tranny was hanging in 2nd gear at WOT. Culprit was most likely the stock drum.
Yes, I agree. What I thought he was going to do was try to install the 36 in a stock drum. But I must have misread and didn't realize that Rowdy already had the 36 drum in the Coan Tranny and just needed the sprag.

I have a 36 in my Monte 400 Tranny with the Correct Drum ($650 for both) (Dynamic Trans in CT). Trans Specialties Converter.

I have a 34 element with the stock drum in my Chevelle TH400. (Dynamic Trans in CT.) Coan Converter
 

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Discussion Starter · #11 ·
Like stated, my TH400 already utilizes the 36 element sprag. To run a 34, I would have to also purchase the appropriate drum, as well as, smaller I.D. intermediate frictions.

For the record, COAN offers packages/kits for both sprags with aluminum drums. The 34 is $620, the 36 is $996. The original steel direct drum with a Super Sprag (36) is $695 racer, $825 list. They'd have to be outta their minds if they think that I'm giving them that kinda money. I would start over from scratch first. This thing is cursed, I know it. Chris at CK perf has the steel direct drum, 36 element sprag for $399.

On that note, I will see if Art over at COAN will make me a deal on a replacement 36 sprag only first. I've talked to him many, many times concerning this trans and spent a pretty penny besides the initial cost. Customer service has never been an issue, downtime has and now, expense is starting to surpass my patience threshold.

I'm also starting to think that the ripped outer piston seals in one or both, int and direct clutches, happened during the original installation. When I replaced them three weeks back, there was a considerable shift improvement from that of anytime prior.

Still not rippin' COAN, mostly disappointed in the particular unit that I received. When I returned the defective unit that failed 2 years ago within 50 miles, I really thought that they should send me a entirely different unit. If not as a general practice, then to reduce turn around time. Now I think that I should have insisted, not that it would have made any difference.

I knew that I was fortunate with the performance of my previous Fairbanks TH400 , although I realize that my 439 only put out 550hp max. Considering that I bought it right off the display booth at the 1980 SEMA for $220, add $150 for an 11" 2800 stall converter, then ran it with out incident (welded monting ears several times) until it was stolen 7/31/05. Twenty five years of very abusive driving without as much as part needing replaced. Filter and seals of course, but nothing inside EVER failed. Yellow and black tiger striped too. Fashion and function. Sure wish Fairbanks still existed. I mean more than being the performance label for Superior Trans Products, which bought the company/name in the late 90's.
 

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Discussion Starter · #12 ·
Here's some pictures. Keep in mind that the sprag was intact when removed. Some "rollers" (dog bone/hour glass shaped) were stuck, some floated loose, one was rotated between the inner and outer cage. When I tried to reposition it, as well as, bend the inner race back into the proper shape/position, rollers started falling out. Most were not spring loaded inward or outward, as I would have expected them to be. There is a spring/wire thingy that goes all the way around each side of the rollers, a retainer of sorts. They are still intact. Whenever I try to replace the rollers, the spring interferes a bit, then it pops all the way through. I think that because of the bent inner cage, the holes aren't exactly aligned properly, as for to allow the spring to retain them correctly.

The sprags inner race/adapter has a square center opening that fits over a square base on the back/hub of the direct drum. Different manufacturers detail the need to machine the drums for the larger sprag. I sure didn't picture it being done like this. Is this the same method used by other companies? This is the only one that I have seen. Makes me wonder if the parts are interchangeable, although, the sprags themselves are likely identical, possibly produced by the same manufacturers, only the means of incorporating them into the drums could differ.
 

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Was the sprag a 34 element sprag or stock?

The lightweight drum is a good idea on a TH-400 with the 36 element sprag but not needed in most applications. Look at it this way ::

The Direct drum spins at 2x engine speed in low gear, stops in second gear and goes to engine RPM in high gear. The lighter drum is for sure better, but do you need it? If your putting out over 650tq i would say do it, The ATI direct drum is good but pricey
The direct drum doesn't spin 2x engine speed in low gear, it's about 85% of engine speed in the opposite direction. It's the sudden stop going into 2nd gear that kills the sprag. A lighter drum and more robust sprag element is always a good idea just beyond the budget of many enthusiasts.

Rowdy,
Check the inner race and outer race closely for scoring, and if possible get the proper diameters from COAN or CK. I have the diameters in my notes and on drums at the shop but don't have access to the info right now.
 
G

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CK's drum is machined a bit differently and the inner race is pressed on the drum, or at least the last one I used was made that way.

I'm working on prototyping an aluminum drum using the 36 sprag and trying to determine the best method of attachment.
 

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Good luck on that one Rowdy. My son has broken the 400 Turbo with the 36 element sprag and the super lightweight drum, twice. The 'glide hasn't even whimpered, no matter the power it's subjected to. Here's the kicker the 350 Turbo has never broken and was run in the car down into the low nines, go figure. I'd think the 400 should last at your power level, good luck after the next fix. It seems in our case, the sprag rolled the first time and it took out all the clutches the next. I think Rossler has the fix but it's a real expensive crap shoot.
 

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I second the idea of measuring and checking over all associated parts carefully. The sprag may have been assassinated. If this is the case you will just be feeding the transmission parts until the real problem is resolved.
 

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Discussion Starter · #18 ·
Rowdy,
Check the inner race and outer race closely for scoring, and if possible get the proper diameters from COAN or CK. I have the diameters in my notes and on drums at the shop but don't have access to the info right now.
The outer looks perfect, polished even. The inner has some discoloration and very minor scoring. I will attempt to polish it out. The inner surface of the rollers were noticeably worn and discolored. I honestly think that there will be minimal size difference after clean up. I will measure and possibly take it to a friends machine shop to do it right and verify measurements.

The inner race is split. Meaning that it looks like the square actually expands it somewhat.

I'll get a better picture
 
G

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If the inner race is split, it is ruined. It should not be split, it will cause the sprag to fail, as you now know.

Get a new drum assembly.

If the inner race is even a thousandths too small, it will cause premature failure.
 

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Discussion Starter · #20 ·
I'm pretty sure that the split is intentional, as in purposely engineered and machined into it.
 

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