[Scott Stoneburg]

Originally Posted by chuckies76ta

Yes it is the smooth drum for the 34 element sprag. Get yourself a 4L80E drum and install an after market piston so you can add additional steels and frictions. Check the 34 element retainer plate on the drum and make sure the tabs are new looking. They sometimes are chewed up. I install the spiral snap ring on the drum to hole the retaining plate Cliff book page 77. I also set the drum up for dual feed.



Can I ask you Scott how you were doing your burn outs at the track?

I start my burn out in 1st. As soon as the tires turn I shift to 2nd. Then roll out of it letting the tires bite as I move forward. .

[Scott Stoneburg]

Originally Posted by chuckies76ta

Something else you could do before tearing your transmission apart is take a pressure reading on the Tranny see where it's at. The port is on driver side by shifter. Tells you what the pump is putting out.

At what rpm do I read the pressure? And will this port already be tapped?

[chuckies76ta]

FYI. My understanding is start burnout in second, do burnout in second and leave water box without squealing the slicks. I guess it can shock the sprag if it hooks quickly.

[chuckies76ta]

Originally Posted by Scott Stoneburg

At what rpm do I read the pressure? And will this port already be tapped?

You can read at idle and at 2000 and 3000 rpm see where it goes. The port I think is 1/8” NPT. It’s located right above the shifter linkage. You need a gauge that goes to at least 300 psi. Use a -3 or -4 an braided line. Pressure on my are around 160 to 180 right now. There saying for my valve body around 180-200 psi. I have a Hughes Revers Pattern Manual shift. I may shim my spring to increase pressure a bit.

[Scott Stoneburg]

Originally Posted by chuckies76ta

You can read at idle and at 2000 and 3000 rpm see where it goes. The port I think is 1/8” NPT. It’s located right above the shifter linkage. You need a gauge that goes to at least 300 psi. Use a -3 or -4 an braided line. Pressure on my are around 160 to 180 right now. There saying for my valve body around 180-200 psi. I have a Hughes Revers Pattern Manual shift. I may shim my spring to increase pressure a bit.

So read the pressure at those RPMs in neutral?
Thats how I pull out of my burn outs. I'll start in 2nd going forward though.

[Dragncar]

Start your burnouts in 2nd and keep the tires spinning hard as you roll out of the water box just to make sure you spin the water off and ease off the gas before the tires grab. Key to a long transmission life.
Hitting your 1-2 shift in your burnout is hard on the sprag.

[slowbird]

We've always done out burn outs in high. No issues and get good wheel speed.

[chuckies76ta]

I checked pressures on the transmission in park then neutral at Those rpms . Then I jacked rear end of ground and did first, second and third at each RPM

[chuckies76ta]

Here is a pic where the port for pressure off the pump

[chuckies76ta]

Good read. Get Cliffs book also.

https://www.yellowbullet.com/threads...urnout.120213/

[grandville455]

Never do burnouts in 1st and then hitting second! Either start in 2nd and then get into high gear asap or just start in high like brian said , the 1-2 raises hell on the sprag!

[Cliff R]

Experienced racers know how to effectively do a burn-out without shocking the piss out of the sprag, or at least they should.

LOTS of ways to skin that cat as we've seen, but for sure as you start to clean off the tires and they get ready to "grab" as you roll out of the water box I would be easing off the throttle vs hammering down on it........FWIW........

[AG]

I start in second gear and immediately hit third, no power out of the box at the end. This was a recommendation from JW.

[Scott Stoneburg]

I've been doing it this way for 25 years. In 1st gear As soon as the tires are turning I shift to 2nd. Then pull out of the burn out letting the tires catch. I've only broken the trans 2 times in all my years of racing. Of course both times the damage was the sprag rolled over. ( Could be from my burn out process ) Both times the trans has broke going down the track not in the burn out box. I will however learn from this thread and do my burn outs in 3rd going forward.
I hope to remove the trans this coming weekend. I built a fixture to mount to my engine stand to hole the transmission today.

[Scott Stoneburg]

Got my home made fixture done. It's ugly but functional.

[chuckies76ta]

Nothing wrong with that. I basically did the same thing with an engine stand.

[chuckies76ta]

Scott. I hope you have the time to keep posting when you tear into this Tranny. I’m really curious how it is setup and any mods that are done to it.
Sonnex makes a nice bearing and bushing for the rear of the Tranny. There is also a nice case saver if your removing the front band. Heavy duty snap ring for the intermediate clutch pack. There is also nice after market billet Aluminum pistons for the forward and direct drum. Have to pay attention to center support that use the fretting ring. Teflon sealing rings. Bushing clearances. There is lots of upgrades you can do.

[Scott Stoneburg]

I'll be happy to keep updates coming. Hopefully I can recognize when high performance parts were used. I am pretty sure it has a stock drum. I am thinking about upgrading to at least a 4L80 drum so I can add another clutch.

Chuckie....looks like you have a SFI bell housing, did it make it harder to get to the bellhousing bolts? I am thinking about adding one but the trans tunnel is so tight already.

[chuckies76ta]

Yes that’s the JW bell housing. You can tilt the engine back a bit which drops the Tranny down. Makes it a bit easier to access the bolts. Just have to watch distributor. I now have a Reid Transmission and bell housing and it still pretty easy to access. I remove exhaust and drivers side header to remove Tranny. The rules with NHRA I believe is bell housing shield and Tranny shield. Depending on 1/4 mile times. I had no room for a shield so new Tranny case.

[chuckies76ta]

There’s a guy on YouTube that does a lot of videos on Th400. Shawn at Mountain Garage. Check him out. TH400 are easy to build once you do one. Just lots of little tricks. The hardest part is trying to follow the fluid paths. But there fun to do.