[Dragncar]

So the last pass at the end of the season when I hit 2nd gear the engine went to the rev limiter. Hit 3rd and drove it back to the pits and it went up on the trailer OK.
Engine was fine. I built the trans years ago. Just a T400 with stock drums, extra clutches and all the Trans Go tricks. Its worked perfectly for years. Has a J&W aluminum brake valve body.
But it might be hurt now. Never rolled a sprag before. What can I expect to find ?
Can I just clean it up, put in a new 34 element sprag and go ? I bet the clutches will look very good.
I want to race a few races next year, not a full season though. I bought a new house on a acre and I am putting up a 1800 sq foot shop.
I will not have the time to race a lot.
I would like to just get this trans up and running. I have a bunch of aftermarket drums ect but if I am going to do all that it will take time.

So, is repairing a rolled sprag all that bad ?

[Half-Inch Stud]

Yea, open it up, and go thru it. Find the rolled dogbone sprag.
I might have a Spare nice smooth Dir drum. Or Spring Roller version.

Not a low fluid deal. HIS

[Bill Eveland]

When mine broke it tore up the front snout of the center support, so really would do a teardown and a full inspection of everything while its apart. I got a quality 34 element from Coan, wasnt going to trust some cheap chinese knock off. Install a case saver if you dont have one already

[chuckies76ta]

Can I just clean it up, put in a new 34 element sprag and go ?

This is my understanding on this. The 34 element sprag is installed on the back of the direct drum as you know. The locating race on the direct drum measures in at 3.1590 on a good drum. If you measure comes in at 3.1585 it's no longer advised to use the drum. Get yourself a good used 4L80E drum. I've used the Borgwarner 34 element sprag without any issues. You can also get yourself a billet aluminum drum with 36 element sprag and not have to worry about a cast drum letting go if something goes south.

https://www.tcsproducts.com/product/...drum-xl-sprag/

[65 Lamnas]

If the sprag has rolled, you're gonna need a different drum and outer race, in addition to a new sprag. You can buy a good drum that comes complete with a sprag and outer race from Global Transmission for about $100-130. Or you can contact Richard Goemaat in IA as he deals in used TH400 hard parts.

If you're "lucky", you didn't send any shrapnel through the rear carriers (planetaries, sun gear, etc) and they can be reused. But you'll have to visually inspect to determine that.

https://globaltransmissionparts.com/...urbo-400-3l80/

Richard Goemaat 641-891-8235

But Chuckies76ta is right....you're better off with converting to a 36 element sprag, which is significantly stronger. It's not "IF" you're gonna roll the 34 element sprag when racing...it's "when"

[Dragncar]

I have a aluminum drum with 36 element sprag, high gear aluminum drum and 10% larger center support. Its Speedmaster stuff but if I find much damage I will put the stuff in, check clearances and let her rock.
I have a new pump half too.

[Neil Scott]

How many runs are on the trans? What did the fluid look like? Depending on the rest of the parts look like. Are you rebuilding it or having someone do it ? I would at a minimum replace the clutches if they're not relatively new. I've rolled the sprag on 2 - TH400s. My fault for starting my burn outs in 1st I guess. One of the trans ended up with a cracked case from it.

[Dragncar]

Trans fluid looks perfect. I do the work myself. Clutches can be re used if they check out.

[Dragncar]

I got the trans out today. I will pull the pump out sometime this week and see what I have. Fluid looked and smelled new. I will run what I have through a shop towel in a funnel and reuse it. Top it off with new, That ATI Synthetic Type F is not cheap.
Looked at my Speedmaster aluminum forward and direct drums today. The forward drum has 8 steels, .060. The direct has 9 also .060.
I will buy new steels and clutches. Probably go with Borg Warner green solids. Or Red Alto red solids. Not a fan of the waffle ones.
I wish the aftermarket made radial ones like GM used.
The forward drum has a 36 element Super Sprag copy deal. Have the 300M input and intermediate shafts too.
Not sure if I will pull some bushings out and rollerize them.
Also have a new larger center support, 10% more area.
Now, I know people pull out lip seals in a few places modifying OEM stuff for more area/pressure. But I do not think I am going to take apart either of these drums and do that. Run them like they are.

[Bill Eveland]

The Allison 540/545 clutches are a nice clutch that will fit , still a waffle but way more aggressive material for the direct drum. They will actually eat up the steels. Towards the end of this video. I dont have part numbers .

https://www.facebook.com/share/v/1ATFmRwq92/

[Half-Inch Stud]

@Bill, i would prefer the original BW material over the Allison, just to keep the steel grit on the down-low. Such opinions as this strike a balance near the optimal.

Funny forray with kolene steels showed me that the plain stock steels are optimal, then is good to match the wet-clutch material to such stock steels. I was a happy sucker for Raybestos frictions in the 90's. Buuut the waffle crap came out to obfuscate proper purchase ability. Not a waffle pattern fan.

[Bill Eveland]

Well the video that wouldn't post was for a 1400hp deal. So totally differant deal i think than a 6-700 engine.

[Dragncar]

The clutches in the trans I am working on are Borg Warner solid green. Our local transmission guy told me he takes a hacksaw blade and makes some radial cuts in the so the fluid can get out. I made 8 cuts on each side of my forward and direct clutches. I will see what they look like tomorrow.
Might do the same thing if they look fine. I just do not like the waffles in any way. They give up a lot of surface area. The first trans I built used them. And I noticed a few hot spots when inspected after a few seasons.
These BW solids have been in the car for a long time and the trans was working great. 1.35 60 foots so I know forward was getting it done. Trans is pretty basic. The Trans go tricks, stiff springs in the direct drum and all that. Drilled a few holes where they said too. Big spring in the pump. There is a place on E Bay that sells new pump halves, gear side for 180 $ so I bought one in case the pump has any issues but I doubt it.
I stood the trans up on its tail getting all the fluid out today before work. Did not spill a drop either for the first time. I will pull the pump and the forward and direct drums and see whats going on tomorrow.

[Half-Inch Stud]

Originally Posted by Dragncar

The clutches in the trans I am working on are Borg Warner solid green. Our local transmission guy told me he takes a hacksaw blade and makes some radial cuts in the so the fluid can get out. I made 8 cuts on each side of my forward and direct clutches. I will see what they look like tomorrow........

Imagined trying to make radial grooves, but never did it. That Hacksaw (24 tooth) approach sounds clever. A fixture with a dremel wheel ( or thin stone) might do as-well. Result is likely waay better than new waffle patterns.

["QUICK-SILVER"]

Had 2nd gear go MIA when a plastic accumulator valve broke

Clay

[Dragncar]

Pulled the pump, forward and direct. Everything looked perfect.. Sprag was in good condition, clean inside, fluid smelled new. I pulled a couple clutches and steel out of high gear. The top cover plate still had the Scotch Bright marks and no burn marks. Clutches measured .0815 and steels measured .088.
Now, have to try and figure out why when I hit 2nd the engine went to rev limiter (7000)
Have not had it happen before. I have stayed in the same gear before due to shifter adjustment issues.
Might just put it back together after I put a case saver in. New seals front and back ect.
Or I can get the thin clutches and steels and put the after market drums and center support in.
But this thing look really good.
Maybe I took it apart out of a abundance or caution ? Over thinking it like I always do.

[Dragncar]

So I ordered the thin 8 clutch, 8 steel packs from ATI for forward and direct. Got ATIs thin intermediate plate and the 5 clutch/steel pack for 2nd too. Might as well rollerize the tail shaft bushing while I am in there.
Trans worked great as is but preventing a cast iron drum from blowing through the case is a good thing. Lighter weight drums and oversized center support should not hurt anything either. Think I will run the pump as is too. It has the Trans Go spring in there and I believe I drilled a bigger hole in it too as per instructions. Clutches look really good so pressure is not a issue. I do have a new pump, they can be hard to find. 180 $ not too bad.https://www.ebay.com/itm/187500091092 Its a 6 bolt but you can drill the other 2 bolt holes yourself, I have done it before.


Still, anyone have a idea why the trans would go into neutral on the 1/2 shift ? I have had in not shift due to cable adjustment issues.
Funning thing is the tech guy at ATI had his T400 not shift on his 1/2 shift his last race and thought he rolled his sprag too. He has not had it apart yet.

[Half-Inch Stud]

Open up the DIR and INT drums to check the Lip-seals, but really thinking the Center-Support bushing/Sun shaft clearance needs to be verifies as a slip-fit, not a hotdog in the holland tunnel.

[Dragncar]

I can remember having a hard time finding a Clevite or FM center support bushing. when I built the tans. A local builder had one in stock. The kits I had all the bushings except for the center support were FM s or Clevite.

[Half-Inch Stud]

C-Support bushings are Delco i think. Not seen Clevite or Fed Mog. Any ways the goal of a good press-fit is key to avoiding pinching, which will bind the Sun Shaft.

A sticking Sun Shaft might reflow the babbit (not always good result).