Hi there.
I'm on my 2nd TH-350 in 3 weeks & just had the same problem happen again.

Broke the sprag (2nd gear doesnt work) It is a full reverse manual in a full interio 81 Z-28 and i havent even put a set of slicks on it. They said they upgraded the sprag to a heavy duty until but obviously something is wrong.

Its behind a mild 383, 11:1, Sportsman II's, CompXE284, RPM intake, 770 Street Avenger, 3500 stall, 4:10 rear end with 295-50-15 street rubber.

I just need some opinions on whether the shop is screwing me around or i need to by some type of FORGED SPRAG KIT that retails for $700CAN. This is after i already spent $2200CAN on the tranny. I think this is a little ridiculous.

Have many friends that run $800 tranny's & have no problems. What could be causing this same problem to surface again now. I only did 1 full throttle pass with this 2nd one & it blew when i tried to do the 2nd.

Any help/suggestions is appreciated.

 

Also if it matters, the tranny has a manual reverse valvebody.

 

The sprag has to stop the direct drum when shifting from first to second. The factory sprag (intermediate roller clutch) is very weak.

You have 2 options if you wish to stay with a TH350.

Rebuild it with factory parts again. Chances are you're blowing it up while doing a burnout. If the tires hit dry pavemnet and stop spinning suddenly while in second gear it will blow up the sprag. Do a burnout and make sure you're in third gear before letting off on the throttle.

Invest in an aftermarket, B&M etc, 36 element roller clutch and direct drum.

Your other option is to install a TH400 tranny.

 

When you're doing your burnout, while burnin' them in 2nd, instead of just stopping let go of linelock button and burn it out of box while letting off throttle. Also, at end of run don't just cross the stripe and toss it into neutral instantly as this can hurt the sprags too. The T350 and its little cousin the T200 can take some decent power levels but you must upgrade the internals accordingly.

 

A hardened roller race is an option but I suspect the real problem is that the Tranny has no accumulation for 2nd gear and possibly no wave plate on 2nd. Both, IMO, are essential. The Roller OR Sprag MUST lock BEFORE the clutches do. This is true of a stock 350 or a full race unit. The laws of Physics don't change.

 

OK thanks for the help so far....

How much does this B&M Sprag upgrade go for. My tranny shop says they want upwards of $700(CAN) to put in some super drum & sprag kit.

This is a little out of the price-range and frankly i went though 4 700R4's and now 2 th-350's with these guys & its getting ridiculous.

TSo is this $700 CAn really necessary. This isnt a crazy strip car or anything, nice & strong 383 motor here on street tires @ the moment, have a set of slicks for the track IF I EVER GET THERE!!!!

 

That price is about right including labor. The TH400's 34 element sprag goes for $100. The TH350 also needs a special direct drum so it costs a lot more.

The "newer" TH400's, after 1970 or so, also use the weak sprag similar to the TH350. By using a 16 element drum from a late 60's TH400 it becomes cheaper to rebuild a TH400 than it is a TH350.

That's what I did last winter. I only blew up one TH350 at the track but when I wanted to go with a manual valve body and transbrake I decided it was cheaper to build a TH400 than sink more money into a TH350. The only thing I didn't put in the tranny was a case saver.

When you see a race ready TH400 or TH350 for over $1500 Canadian it's usually a good deal.

I suggest contacting transfixleo and let him decide how to save your tranny.

 

Heres the deal.....that $700 is WITHOUT labour.

The labour is free because its "under warranty" type of thing....i just have to pay for the upgraded part supposedly.

So how can i find this part for a good deal. Do i really need it in my application or is something else making this thing screw up?

I mean the motor prob makes just barely over 400HP, and many ppl here dont pay anywhere near 2K for a th-350 & have 10X the longivity that i have.

So my moron builder must be screwing something up, at least thats my thought.

 

TCI sprag and drum kit from Jegs. Part #890-327900
http://www.jegs.com/cgi-bin/ncommerc...94&prmenbr=361
$295 USD

The current exchange rate puts that at $465 CAD. Add on shipping and brockerage fees and it should be close to $550. Add PST and GST and you're the final cost to get it in your hands would be between $600 and $650. $700 is very close with a bit of a markup.

 

Well looks like your right.

And this si something i absolutely need in my application in your opinion?

 

It's up to you. I ran a TH350 for 2 years. First race out I blew the sprag to pieces. I swapped in some new hard parts from a junkyard tranny and ran it for the 2 years with no problems after that. You could just use factory parts again but you'll have to learn the limits of the tranny and what not to do to keep from blowing the sprag again.

That's why after 2 years of using the TH350 I wanted to go to a stronger tranny and a transbrake. I felt it was cheaper to beef up a TH400 than the TH350.

 

When you are in 1st gear and go to about 4,000 rpm & let off, does the engine have braking? do you slow down quickly? or is it in a false neutral? (no braking effect). Let me know?

 

Hioly **** your good!!!!

Its in false neutrel.

UPDATE

Car goes in again tommorrow, he said he talked to some tech racer & they told him he has to do some modifications to "lower the pressures" and change a whole bunch of other **** of course.....

Anyways i am not paying for this just so everyone knows, nor have ipaid for anything other than the intial cost. I told him this would be the last time, and any more probs i want my money back. LOL he told me not to threaten him like that, i told him its not a threat, thats how its gonna be.
[/b]

I will keep you updated....

Pro-Built, what did you have in mind. And i wonder if i could get him to call you. I know you dont need to deal with idiots but either him or me.....or u tell me what to tell him.

THX for the help everyone!

 

ttt please