TH350 Rebuild Questions

[scenic760]

No, not normal. You probably have a clutch not set all the way in and that makes it bind up when you put the pump on. It should turn freely when all bolted together or you are going to burn it up.

Gotcha...will take it apart and put it back together...like a big Lego set!!

 

[Bextreme04]

Gotcha...will take it apart and put it back together...like a big Lego set!!

I'm not sure what the TH350 endplay is supposed to be, but you should be setting the correct endplay. If it is binding up and hard to turn, you almost certainly have 0 endplay, which isn't right. The most likely cause of that is a clutch not seated all the way, but you will still want to check and set the correct endplay once fully assembled. If you are using a rebuild manual it should have the right settings and procedure to set that. If you are just winging it @Vbb199 or matt probably knows the right value.

 

[scenic760]

I'm not sure what the TH350 endplay is supposed to be, but you should be setting the correct endplay. If it is binding up and hard to turn, you almost certainly have 0 endplay, which isn't right. The most likely cause of that is a clutch not seated all the way, but you will still want to check and set the correct endplay once fully assembled. If you are using a rebuild manual it should have the right settings and procedure to set that. If you are just winging it @Vbb199 or matt probably knows the right value.

Your probably right given that when I went through a dry run the end play was, ahem, correct...

I didn't measure but the value I have is .010-.044"? I've put in many a molding and I know what 1/32 (.030ish) of an inch looks like so I just shot for that

 

[Bextreme04]

Your probably right given that when I went through a dry run the end play was, ahem, correct...

I didn't measure but the value I have is .010-.044"? I've put in many a molding and I know what 1/32 (.030ish) of an inch looks like so I just shot for that

That sounds eerily similar to how I "check" some measurements. I'm still not comfortable enough with engines or transmissions to just give it the eyeball gauge, but I've done it on plenty of other things.

 

[Vbb199]

I'm not sure what the TH350 endplay is supposed to be, but you should be setting the correct endplay. If it is binding up and hard to turn, you almost certainly have 0 endplay, which isn't right. The most likely cause of that is a clutch not seated all the way, but you will still want to check and set the correct endplay once fully assembled. If you are using a rebuild manual it should have the right settings and procedure to set that. If you are just winging it @Vbb199 or matt probably knows the right value.

.020 at the tightest, .040 at the most loose

I use a plunger indicator to check it.


Idk about .01.... once clutches swell from heat and such, that seems like a receipe for failure lol.

For that DD, just do like, .025 or .030, leave it be.

 

[Vbb199]

I also assume the appropriate clutch drum clearances were established also? Or at least i hope?

You stack the steels + clutches, put the apply plate on top + snapring, check drum clearance with feeler gauge.

I'd recommend air checking your drums also to make sure the piston seals arent blown or damaged... 40 psi

 

[Matt69olds]

If it still turns (but with a lot of effort) with the pump fully tight, most likely all the clutches are set in place correctly. The problem is most likely a thrust washer has slipped out of position, you need a thinner selective thrust washer on the pump (or remove a shim from behind the pump bearing) or some other assembly issue.

Did you have to replace any parts? Pumps with and without bearings can’t be directly interchanged. If a pump designed for a bearing is replaced with one for a thrust washer, you have to use a thrust washer instead of the bearing. Since the bearing is thicker than a washer, the pump is machined differently.

There are also design changes in the drive shells. The later ones are thinner. I don’t recall the specific changes made to make up the clearance changes.

If your absolutely sure everything is assembled correctly, you didn’t change any internal parts, and still have no endplay, take a brass hammer a d LIGHTLY give the input/output shafts a couple solid hits. The idea is to make sure assembly grease isn’t taking up excessive clearance.

I had this issue on a 400 I built. They make assembly grease in different viscosity for different temperature. I had a tub of the green stuff (really thick for use in the summer) and it was cold in my garage. The green lube was really thick, didn’t want to squeeze out between the bearings/washers. The blue assembly lube is thinner for colder environments.

 

[scenic760]

I'm not sure what the TH350 endplay is supposed to be, but you should be setting the correct endplay. If it is binding up and hard to turn, you almost certainly have 0 endplay, which isn't right. The most likely cause of that is a clutch not seated all the way, but you will still want to check and set the correct endplay once fully assembled. If you are using a rebuild manual it should have the right settings and procedure to set that. If you are just winging it @Vbb199 or matt probably knows the right value.

I think you nailed it...I pulled everything off down to the sun shell and it spun like clockwork, then I looked at the planetary and it was slightly cocked, stuck in the drum... I didn't get the clutches all the way settled..

I pulled it apart, sttled everything back down and think it good but I didn't have time to stack the other clutches, align the pump gasket etc... to make sure

 

[scenic760]

If it still turns (but with a lot of effort) with the pump fully tight, most likely all the clutches are set in place correctly. The problem is most likely a thrust washer has slipped out of position, you need a thinner selective thrust washer on the pump (or remove a shim from behind the pump bearing) or some other assembly issue.

Did you have to replace any parts? Pumps with and without bearings can’t be directly interchanged. If a pump designed for a bearing is replaced with one for a thrust washer, you have to use a thrust washer instead of the bearing. Since the bearing is thicker than a washer, the pump is machined differently.

There are also design changes in the drive shells. The later ones are thinner. I don’t recall the specific changes made to make up the clearance changes.

If your absolutely sure everything is assembled correctly, you didn’t change any internal parts, and still have no endplay, take a brass hammer a d LIGHTLY give the input/output shafts a couple solid hits. The idea is to make sure assembly grease isn’t taking up excessive clearance.

I had this issue on a 400 I built. They make assembly grease in different viscosity for different temperature. I had a tub of the green stuff (really thick for use in the summer) and it was cold in my garage. The green lube was really thick, didn’t want to squeeze out between the bearings/washers. The blue assembly lube is thinner for colder environments.

I didn't replace any of the parts and I actually left out two thin selectives just because everything was new and I wanted to make sure I started from a baseline..

Going back to the dual feed, I'm going to try it (and your right, it looks like it's 50/50 from the posts I see of it working on the 350c) and I left out the drum seal, sealing ring and plug the hole...worst case scenario is just that the TC doesn't lock up right? Can't really do any damage other than to my MPG, haha?

 

[scenic760]

Ok...so I think I have everything put back together correctly and it spins by hand (it is a little stiff though?)...I checked the shaft movement with a known thickness washer and a mark on the shaft, probably could have just bought the indicator with the amount of time it took me to rig up something that was going to stay put...it's right at .030"

On the torque convertor... I'm not looking for anything exotic here and I think a stock rebuild replacement is going to work but I'm finding the ones readily available say they don't fit my year/make/model. I went directly to the website of the company who rebuilds the TC's (pro-king) and their online catalog says it was updated 2011 (which I'm coming to find out in the world of auto-parts isn't all that uncommon) and for whatever reason it's only showing their part # GM16 for use on a 1986 350C. I called their tech line and the guy answered right away and said that the GM16 is the one I want to use and its good for 1979-1986...which actually makes sense to me

I didn't think there was any physical difference on the TC from 1981-1986 on a 350C...maybe the stall speed was different in 1986 and that is the one they technically rebuild the spec too?

Edit: I think the 350c was only built from 1981-1986? It looks like it only survived until 1984 in cars and 1986 in trucks?

Here are the specs from the catalog...

1986 5.7L, 6.2L TH350C Transmission; Lockup; 12" Diameter; 30 Splines; 1.704" Pilot; Slotted Hub; 3 Lug Mount; 10.7" Bolt Circle; Medium Stall-1568 GM16

 

[scenic760]

Ran into yet another hmmmmm.... moment....I was going to drill the 1/8" holes in the separator plate at the 2nd and 3rd but it looks like someone had gotten there before me.. the only problem is that they drilled the holes to 5/32"... that seems way too big and it would shift like a kicked mule? Do I need to get another plate!?

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[Matt69olds]

I drill the feed holes to 3/16 (.185) on street/strip units. The decimal equivalent of 1/8 is .125, the current holes at 5/32 (.156) is right in the middle. It will definitely have a firm shift, but won’t be too bad, especially if you have a aftermarket higher stall converter.

If you can find a stock plate, might as well use it. If not, I don’t think it will shift too firm.

 

[scenic760]

I drill the feed holes to 3/16 (.185) on street/strip units. The decimal equivalent of 1/8 is .125, the current holes at 5/32 (.156) is right in the middle. It will definitely have a firm shift, but won’t be too bad, especially if you have a aftermarket higher stall converter.

If you can find a stock plate, might as well use it. If not, I don’t think it will shift too firm.

Sweet, I'll keep it that way! Give some of the Range Rovers around these parts a good run stoplight to stoplight, haha

 

[scenic760]

Hey All,

So the place I ordered my kit from said it was good for a 350/350C...come to find out they didn't include the correct separator plate gaskets so they sent some out and they showed up today...I'm realizing that the lockup solenoid gasket wasn't in there either...can I just cut a new one from the gasket material from the extra th350 gasket?

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However now the delay has me second guessing my pump gear assembly...

After looking at several pics and descriptions, I see they are all saying the same thing except for the fact that the pictures of the pump gear installed are actually upside down because they are in the top half of the pump! Just to verify, this picture is the way it should be installed:

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And I found a more explicit description on another thread:

Some gears have a mark like the one shown in Young Pup's pic, some dont. What his photo angle dont show is the bevel on one side of the drive tangs, thats what your looking to orient away from the seal, toward the rear of the vehicle.

So the bevel on the tangs go toward the rear of the transmission, which would make sense if installing it backwards would not allow the torque converter to fully engage?

 

[Matt69olds]

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