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Let's talk torque converters-Now a trans build thread without pics.

lectric80

lectric80

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Hey guys, finally getting my trans rebuilt, and I have no intention of using the old converter. So, based on a th350 behind a 350, what would be a normal(read:stock) stall converter for Krusty?

This is the final piece of the puzzle, the rebuild kit is at the house already and Krusty is parked in the garage. Unfortunately she is parked because of a brake issue I still haven't been able to fix, but I am also grabbing new calipers to finally solve that problem.
 
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Stock stall speed on the 350 converter will be about 1600 rpm which should be plenty for the 350 engine you are using. Using a TH-400 gas converter will get you some extra fluid capacity and a stall speed of about 1400 rpm. Your flywheel should have both bolt patterns to accept either converter but check to be sure.
 
lectric80 said:
Hey guys, finally getting my trans rebuilt, and I have no intention of using the old converter. So, based on a th350 behind a 350, what would be a normal(read:stock) stall converter for Krusty?

This is the final piece of the puzzle, the rebuild kit is at the house already and Krusty is parked in the garage. Unfortunately she is parked because of a brake issue I still haven't been able to fix, but I am also grabbing new calipers to finally solve that problem.
Click to expand...

what is your intended use for the truck...what rpm range will you spend most of your time in?
 
She is a trail cruiser, trailer hauler, freeway warrior. I put around 5k a year and most of that is winter time snow driving, as well as hauling our little camper. Typically she doesn't run above about 3k, cruising is about 2200 at freeway speeds.
 
i have a tci "saturday night special" in my 700r4 behind a built 383.....
 
If your doing ANY towing, I would use a RV/towing type convertor. You want to minimize slippage if your towing, and take advantage of torque production at lower rpm's.

If your only doing trails (not a lot of rpm, but may rev up from time to time) or doing sand or mud, I would say go up to 1400-1600 stall.
 
Well, not sure, went with a low stall converter that was recommended by a buddy of mine. We will see, but it can't be any worse than shifting from 1st to 3rd and needing to gun it up to about 2500 to get reverse to engage. Supposed to be in the 1400 RPM range and is the t400 version.

All told I am into this rebuild about $230 with the kit, converter, filter, and trans fluid. Now to see if I can tear it down and rebuild it without screwing it up worse.:doah:
 
Next question:

I have never taken a new dry trans and brought it online. For that matter I have never rebuilt a transmission before, which is why I have a Mitchells guide at the house. I know that I should put like 4 or 5 quarts of fluid into the torque converter before installation, but do I just overfill for the other 5-6 quarts that it calls for?

Any other tips for bringing this back online after I get it rebuilt? Are there any additives that should be used, or avoided? I want this to last for a while because it may be a while before I can afford to do the BTO 700r4 that I want, and I really don't want to have to rebuild this again.

I have dreaded doing this, and have put it off for longer than I probably should have. Right now I am getting it done so I have some time to break it in, so to speak, before a trip to Yellowstone in July. Ideally I want to have my truck on the road so I can take the trailer up camping with my kids on Memorial weekend, but I don't know if I will get it done in time. So, any advise or tips and tricks, either as far as the rebuild process or the getting it going again, are greatly appreciated. I will be pulling the trans out tomorrow (Friday) and hopefully rebuilding Saturday then installing Sunday.
 
It is customary to add about a quart of fluid the converter prior to putting it up into the pump. Once the trans is reinstalled into the truck, add 3-4 more quarts via the dipstick tube(if you add any more fluid it will come out of the vent at the top of the case) . The trans pump can only pick up fluid from the pan when the trans is in gear. It will help to have someone working with you here because you will need to add additional fluid while the transmission is in gear.Start the engine and with your foot firmly on the brake, put the trans into reverse and add 3-4 more quarts of fluid, then put the trans in it's forward ranges then back into park and recheck. If you are using a 400 converter and an additional trans cooler you could use as many as 12 quarts total. Put a couple quarts more into the system then run the trans through the gears once more before doing a final fluid level check in park. It is adviseable to only fill to the halfway point between add and full marks so you can allow for fluid expansion when the trans gets good and hot.

As far as building tips go, that could fill a book, just pay attention to clutch clearences and make sure you don't have any ring wear in drums, excessively worn pump or stator, and that the bushings look good as they not only support the internal components but also seal and help distribute lube flow. A small box shift kit such as those from Superior or TransGo will go a long way with shift performance and increased operating pressure. Good luck on the build, PM me if you have any questions I can help with.
 
books can and have been written on this question......

but basically it boils down to a few things....

how much torque the engine produces and at what rpm range does it start to produce it at...the same converter will operate totally different behind two different engines. Camshaft selection can even factor into it...

My BBC with 6-71 blower is going to stall at a completely different RPM that a 350 with a carb...same converter...different engines... different stall speeds..
I use a TCI with an anti ballooning plate advertised stall of 2800 rpm...

actual stall is 2200...at which point it will begin to break the tires loose with light progressive throttle...

If I drop the hammer from a stand still,,, it will flash up to 3200 rpm and launch like a rocket..

also higher stall = more slippage =higher fluid temps...if you run a loose converter...run a lot of cooler as well...

just my .02
 
Lol I have a 2600 Summit brand TC in front of my TH350
My 355 can stall it up to 3100 :rolleyes:

I love it though. I'm going to get 4mpg with it but I love it.
 
The torque converter should roughly match the cam. If the cam is close to stock, so should the stall speed be. And a heavy vehicle needs extra low gearing to work right with higher stall speeds.

If you only do high speed blasts (mud pits, sand climbs, drag racing) then a higher stall should work well (with your high rpm engine). For low speed technical wheeling the compression braking and throttle response of the low (~stock) stall speed is the only way to use an automatic transmission.
 
The cam should be fairly close to stock, it is just a Goodwrench 350 I believe the 290 horse setup. Although I would be surprised if it could push 100 HP to the rear wheels at this point. The tc is a low stall unit and will be going in whenever I get this thing going.

Right now I have fixed the brake issue so I can run down get all the mud cleaned off and start tearing it down. I am running behind schedule, but shouldn't really be an issue.
 
Greg Ducato said:
It is customary to add about a quart of fluid the converter prior to putting it up into the pump. Once the trans is reinstalled into the truck, add 3-4 more quarts via the dipstick tube(if you add any more fluid it will come out of the vent at the top of the case) . The trans pump can only pick up fluid from the pan when the trans is in gear.
Click to expand...

I don't know where you ever got that idea but it is wrong. The trans pump is constantly pumping fluid while the engine is running (try disconnecting a trans line and then start your engine and watch the mess that WILL be made because the pump IS pumping fluid.

Also the trans fluid ALWAYS comes from the pan and nowhere else.
 
Almost ready to drop the transfer case out. Took it to the car wash and cleaned all the mud off from the last trip out, and found that she no longer shifts to second, first to third slipping all the way. Good thing I was already gearing up to do this.
 
4X4HIGH said:
I don't know where you ever got that idea but it is wrong. The trans pump is constantly pumping fluid while the engine is running (try disconnecting a trans line and then start your engine and watch the mess that WILL be made because the pump IS pumping fluid.

Also the trans fluid ALWAYS comes from the pan and nowhere else.
Click to expand...

Yes, the pump gear is always turning whenever the engine is running and always draws from the sump. The point I was making is that you cannot fill the trans unless it is in gear.
 
Greg Ducato said:
Yes, the pump gear is always turning whenever the engine is running and always draws from the sump. The point I was making is that you cannot fill the trans unless it is in gear.
Click to expand...

That is wrong once again. The ENGINE has to be running before you fill the trans so that the trans pump will pump the fluid into the convertor and not overfill the trans to the point that fluid starts coming out the breather vent.
 
Transfer case is out, and it appears the trans was leaking a bit of fluid into the case. All the oil that spilled had a more than slight red color to it. Also found out that one hole on the transfer case goes all the way through, and the oil came right out when I removed that bolt. Of course there was no way to get a pan underneath it while the jack was there, so I need to give some time for the oil dri to absorb it all.

Will start disconnecting the trans and remove it hopefully tomorrow after I get up. As much as I want to have it done for next weekend, I think it is going to be pretty unlikely that it will happen.

I also think I will remove the slip extension on the 205 before putting it back in, I am hoping with it out of the way I can clear the exhaust pipe that crosses over from the passenger side. Really don't want to bugger up my new exhaust system.:grin:
 
Dredging this back up with a new question.

I have always heard that you are supposed to soak the clutches in trans fluid overnight before installation. Is this something I am misunderstanding or is this something I should do? Tomorrow the trans will be out, Saturday I will be tearing it down and rebuilding it, and ideally I want Krusty operational by the time I come back to work on Wednesday night.
 
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