PG to TH350 x member problem - Team Camaro Tech
Transmission & Driveline Transmissions and Differentials

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post #1 of 24 (permalink) Old Jun 18th, 19, 03:18 PM Thread Starter
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PG to TH350 x member problem

Pulled the PG and got the TH350 (6" tail shaft) all bolted in. The tranny mount on the 350 is about 1/2" ish further forward than the PG and the slots in the X member for tranny mount have no more room to allow the x member to land on the 2 original holes in frame on either side

On frame there is one slot access hole for X member bolts and one round hole (rear). The front slotted access does have a 2nd hole in the frame which with PG was unused.

With X member moved about 1/2 forward I could use the 2 holes in the frame in the slot cut out access but they would be fairly close together and I would have to drill 2 new holes in x member either side. Moving the X member forward brings it further forward than the width of the X member that the rear hole on it is then to far forward to use the small rear frame hole access as there is not enough width of the X member front to back has any metal to drill into so I would have to drill another rear access hole about 1" wide to then drill through the upper frame into the X member.

Before I swiss cheese the X member and or frame to do that is there a "better" way?

different X member??

Offset tranny mount available??

The overall length of the 350 vs PG is within 1/8" so drive shaft should be OK

Comments from those who have done the swap appreciated
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post #2 of 24 (permalink) Old Jun 18th, 19, 05:23 PM
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Re: PG to TH350 x member problem

Yes. done this before and back again.
Ensure the crossmember is correctly placed onto subframe, meaning the three holes for the OE manual shifter are on driver side as this placement puts the right slope of trans mounting surface.
All holes should align then.
I had PG for awhile, then installed THM350, broke intermediate outer sprag five times, then put PG back in and never looked back.

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post #3 of 24 (permalink) Old Jun 18th, 19, 07:26 PM Thread Starter
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Re: PG to TH350 x member problem

If you mean these 3 holes (2 rear, 1 front), I had those on DS. While this was the direction the x member was in with the PG I even flipped the x member to see if it was directional. Same problem, actually a little worse



I can line the x member perfectly across frame rail but it lands to far back, at least 1/2" from the tranny mount holes. Can't even see the holes on the tranny mount. I can bolt tranny mount and one side of x member but the other side is cocked and does not line up. Yes the motor & tranny are straight in the tunnel

Thought about elongating the slotted holes on x member so it can slide forward some but I don't think I can get enough distance even without a washer.

I thought PG to TH 350 was a plug & play swap...which it was until I tried to bolt up x member.

Looking at this adjustable mount. Not a fan at poly though

https://www.summitracing.com/parts/sum-773200/overview/

FWIW the TH 350 case is GM/Pontiac so it has more bolt holes on front (GM/Pontiac motor) but otherwise, I would think, should not affect the tranny mount position
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post #4 of 24 (permalink) Old Jun 18th, 19, 07:40 PM
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Re: PG to TH350 x member problem

Roger, Somethings screwy. There's only 1/8" difference in the mount locations between
the PG and the TH350. I'm not sure what's wrong. I can't imagine it but the motor didn't
somehow shift forward did it?
https://www.chevellestuff.net/tech/a...dimensions.htm

Al

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post #5 of 24 (permalink) Old Jun 18th, 19, 07:47 PM Thread Starter
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Re: PG to TH350 x member problem

Al

No I can't see that the motor shifted forward. Looked at motor mounts and they look "OK" and fan us still in same position in shroud

From rough measurements the distance from front of tranny to mount are the same. I have a Tranny chart showing sizes and yes the tranny mount distance appears to be the same in all but on search I found one printout...that showing about 1/2" difference
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post #6 of 24 (permalink) Old Jun 18th, 19, 07:48 PM
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Re: PG to TH350 x member problem

I've had a multi bell trans in mine before without issues so it's not that. IIRC the trans mount will interchange between the 350 and the glide but don't quote me on that one. That trans have a small bullet for the speedo like the gide? That's the only thing I can think of that might move the mount.

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post #7 of 24 (permalink) Old Jun 18th, 19, 07:54 PM
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Re: PG to TH350 x member problem

Roger, At some point GM added a lockup converter to the TH350. The mount may have
changed at that time. I think the lockup started around 1980. I'm just guessing because
this should't be a problem. Does your 350 have an electrical connector?

Al

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post #8 of 24 (permalink) Old Jun 18th, 19, 07:59 PM Thread Starter
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Re: PG to TH350 x member problem

Quote:
Originally Posted by allanjs View Post
. Does your 350 have an electrical connector?
No electrical, it's not a lock up converter

It came out of a 1970 GM Van, I was told from my friend who pulled it. It has the TC that came with it. Its the 1600-1800 stall one, not the 1300-1500. I had it rebuilt and the fins brazed
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post #9 of 24 (permalink) Old Jun 18th, 19, 08:01 PM Thread Starter
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Re: PG to TH350 x member problem

Quote:
Originally Posted by yellow69RS View Post
IIRC the trans mount will interchange between the 350 and the glide but don't quote me on that one. That trans have a small bullet for the speedo like the gide? That's the only thing I can think of that might move the mount.

Jeff
Jeff

It has the small bullet for speedo. Same location area (DS) as Glide. I had a 8 tooth drive and 20 tooth driven gear in Glide and that is what was put in the 350 when I had it rebuilt so speedo would be on for my tire size.

Tranny mount is same size as Glide. I used a new one (Pioneer) as the Glide mount was done.
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post #10 of 24 (permalink) Old Jun 18th, 19, 08:11 PM Thread Starter
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Re: PG to TH350 x member problem

Appreciate the responses guys

That "adjustable" tranny mount would be a plug & play fix although the $99...

Weird it is not lining up. I just lowered motor using a floor jack about 5" (tail), maybe less. Just popped off distributor cap and lowered ,motor until distributor was about 1/4" away from firewall to get top bolts and slide tranny out using a scissor tranny jack

New dipstick, massaged tranny lines minimally to connect. Cut & bent the PG vacuum line to vac mod to fit. Yeah otherwise it was a plug & play install until this. Tranny is held up higher with tranny jack now as x member is out so motor is forward now. I can put x member back in again tomorrow and check, again, at fan position in shroud but before it was exactly where it was. Motor mount bolts were and are all on and nothing appear to be amiss in that

FWIW the x member to mount bolts were basically all the way forward in the slotted center holes on X member with the Glide but now I need the tranny mount about 1/2" further back so no more "adjustment in the center slotted holes of x member...which is why I thought of elongating those slots but not sure if I can get 1/2"
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post #11 of 24 (permalink) Old Jun 18th, 19, 08:13 PM
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Re: PG to TH350 x member problem

Roger, There is 2 sets of holes in the frame rails. At least there is in my 67. I can't quite
follow your first post talking about those holes. I know one set is easier to access than
the other. If that makes sense. I'll get under mine tomorrow and gather more info for you.

Al

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post #12 of 24 (permalink) Old Jun 18th, 19, 08:23 PM Thread Starter
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Re: PG to TH350 x member problem

Quote:
Originally Posted by allanjs View Post
Roger, There is 2 sets of holes in the frame rails. At least there is in my 67. I can't quite
follow your first post talking about those holes. I know one set is easier to access than
the other. If that makes sense. I'll get under mine tomorrow and gather more info for you.
Al

appreciate you looking when you can....but since my car is up on stands :-)

DS frame. the long slot has 2 holes and the rear small round hole has the 1 hole.



That 2nd one in the front is of no use to me as I need X member to move forward and moving the x member that far it passes the rear hole so no more X member to drill

Also the X member is thicker (double wall) in-between the front & rear holes so even if I could drill through there is not enough space in that part of the X Member to get a nut in between frame/X Member and floor pan
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post #13 of 24 (permalink) Old Jun 19th, 19, 09:12 AM
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Re: PG to TH350 x member problem

Roger, I just looked at my frame holes and they're just like yours. I have a Bowtie Overdrives
xmember for use with my 2004-r trans. The xmember has an additional mounting slot giving
2 options for placement. I'm just perplexed as to why your having a problem. This swap has
been done many times and I've never seen or heard of the mount location being a problem.
Let us know how it turns out for you.

Al

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post #14 of 24 (permalink) Old Jun 19th, 19, 10:09 AM Thread Starter
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Re: PG to TH350 x member problem

Yeah Al it is weird why it is not lining up....it was noted the engine "could have shifted forward"??

I looked at motor mounts which are not new but do not look worn nor was the engine "racking" to one side either on acceleration. I was going to put x member back in and double check fan position in shroud to see if it is in further with motor/trans sitting on x member. All I did was lower motor/trans the normal 4-5 inches to remove/install trans then back up against tunnel to get x member back in so IDK if that movement somehow pushed the motor mounts into submission allowing the motor to move forward...1/2" ish

The old tranny mount on the Glide was worn though so I suspect the motor would now sit up about 1/8" more than it was max if that much at all.

Sucks to hit this road block at this point in the swap and drilling the x member, to me, is not the way to proceed and getting the adjustable tranny mount would resolve the issue it is a fix that should not be needed.

Maybe the motor did shift forward but not seeing how/why at this moment...and if it did not sure how to move it back to bolt the x member in to then move forward and put in new motor mounts if in fact those would be the cause. Don't want to jack front of motor up to R&R motor mount without having the tranny/x member bolted in first

IDK if I can "pry" the motor back if I needed to

The exhaust is still disconnected from manifold but I will also push it up to see if it is lining up with manifold or is also about 1/2" short....that would certainly point to the engine shifting forward but I am at a loss as to why that would happen unless the motor mounts had that kind of slop in them and I had no engine movement prior to this swap that I ever noticed. If I had that much slop I would suspect the fan blade would buzz the shroud when engine racks over on acceleration

My back is pissed from being under the car this much...just want to connect the kick down cable, put distributor cap back on and start this thing :-)

I still need to install the Shiftworks kit. I have already disassembled the stock shifter and done all the drilling on it (PIA to get those spot welds out for the new detent). I put the new lever on the new machined shaft in the kit....and just using a 1/2" box wrench by hand the threaded stud broke. Shift works is sending me a new one but said that is hardened steel. I did not go all Gorilla on it, just turning a short box wrench by hand. Anyway that part should show up today or tomorrow so I can reassemble the shifter.

Someone remind me its fun and rewarding to work on the hot rods :-)

I have a BTO x member on my Impala I put a T56 in when I pulled out my 4L60E. They make a great part
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post #15 of 24 (permalink) Old Jun 19th, 19, 10:36 AM
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Re: PG to TH350 x member problem

Roger, I hear ya on crawling in and out from under the car. Try this if you haven't already.
Bolt the x-member to the trans and then let it down on the frame rails. It may shift backwards.
If it doesn't see if you can pry it rearward. I'm thinking something is hanging up or slightly misaligned.
The only other thing I can think of is the trans mount on this particular trans is in a different location
than most 350's. I did read where not all are the same but I can't find any specifics to back up that
statement. Maybe you've got an odd duck.

Al

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