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84 z28 transmission doesn't match 350

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Old 04-18-2017, 11:13 AM   #1
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Car: 1984 z28
Engine: 350
Transmission: t5

84 z28 transmission doesn't match 350

I recently bought an 84 z28 which has a 350 with some modifications -not sure what all is done to it, the paperwork for the engine is at the shop right now-, and being quite new to this and not very mechanically inclined, thought it was a solid car, until I got it about 40 miles down the road and the transmission blew up. The housing broke and I had to get it hauled to the shop. It's been in the shop for almost a month and a half now. They found a bellhousing that matches the tranny but they said in order to make it fit, it would have to be cut. So i am assuming that the transmission will probably have to be replaced with one that can bolt up to the 350. Now, at this point I don't know what kind of transmission is in it, nor specifics on what kind of 350 it is. My question is, should I just have them yank out that transmission and just find another transmission that will bolt up. Feel free to ask questions as I am sure I left out some pertinent information.
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Old 04-18-2017, 11:27 AM   #2
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Re: 84 z28 transmission doesn't match 350

We really need more information. You didn't say but I'm guessing its a 5speed car?
If so, you just need a bellhousing for a 85-92 F-body.
All sbc uses the same bellhousing pattern.
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Old 04-18-2017, 01:07 PM   #3
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Car: 1984 z28
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Re: 84 z28 transmission doesn't match 350

Yea sorry its a 5-speed.
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Old 04-19-2017, 10:25 AM   #4
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Re: 84 z28 transmission doesn't match 350

We really need more information - with pictures. Either the car is highly modified and takes a non standard transmission or the shop you took it too doesn't know F bodies and so are lost.

This is the kind of car you should consider working on yourself. If you aren't willing to do that then probably something newer will be easier to find reasonable prices and knowledge at random shops local to you. The 3rd gen F body isnt that complicated but its getting old so you need to find someone that knows what they are looking at or can do a simple google search and figure it out.

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Old 04-19-2017, 03:58 PM   #5
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Re: 84 z28 transmission doesn't match 350

Just went into the shop to take a look. We can't figure out what kind of engine it is to match a transmission. The original build had cut the bellhousing to fit. They think it's the original transmission with a 350 put in. The people I bought it from doesn't know where the engine came from either.
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Old 04-19-2017, 04:14 PM   #6
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Car: 1984 z28
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Re: 84 z28 transmission doesn't match 350

So without knowing what type of engine it is. What options are there besides Jerry rigging the bellhousing again. And is there a way to identify the engine? They said they pulled the numbers off the engine and that didn't help either.
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Old 04-19-2017, 04:23 PM   #7
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Re: 84 z28 transmission doesn't match 350

Well, your first course of action is to determine what engine you have. If your mechanic can't figure that out, you may want to consider a new mechanic.

They should be able to pull the casting numbers off the block to identify it.
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Old 04-19-2017, 04:28 PM   #8
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Car: 1984 z28
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Re: 84 z28 transmission doesn't match 350

Yea he said he did that and he said that didn't help? Not sure how that didn't help. I am quite new to this so I am sort of at the mercy of the shop. They are very reputable and I trust them with my main vehicle.
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Old 04-19-2017, 05:09 PM   #9
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Re: 84 z28 transmission doesn't match 350

Another wrinkle...is it a hydraulic, or Z-bar type mechanism for the clutch? Early thirdgens didn't use hydraulic clutch cylinders--which might be why they're thinking they need to cut the bellhousing.
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Old 04-19-2017, 05:10 PM   #10
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Re: 84 z28 transmission doesn't match 350

I am not sure as of right now. I'm speaking with the owner tomorrow about all of this and decide with him which direction we want to go. I'll ask him about the clutch as well.
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Old 04-19-2017, 05:12 PM   #11
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Re: 84 z28 transmission doesn't match 350

What reason would there be that finding the casting number not help in identifying the engine?
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Old 04-19-2017, 05:12 PM   #12
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Re: 84 z28 transmission doesn't match 350

See if YOU can get the casting #'s and either post them here for others to decode, or google them. Plenty of info on the web regarding GM engine casting #'s.
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Old 04-19-2017, 05:30 PM   #13
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Re: 84 z28 transmission doesn't match 350

Yea I'll get those tomorrow when I talk to them. Thanks for that advice.
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Old 04-19-2017, 06:01 PM   #14
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Re: 84 z28 transmission doesn't match 350

It really doesn't matter what the engine is internally if it's a sbc. If the shop can't look at the external architecture and tell whether or not it's a sbc you should definitely find another shop. Why is it that you can't reuse the bellhousing that's in the car currently. You said the tranny blew up, but the bellhousing should be fine unless it blew up literally. Pictures would help a great deal, you can upload them from your phone.
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Old 04-19-2017, 06:17 PM   #15
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Re: 84 z28 transmission doesn't match 350

My apologies, when I went in today, he showed me the old bellhousing, it was shattered, and he also showed me how they had cut it to let it fit with the current transmission and engine. He said the transmission seems to be fine.
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Old 04-19-2017, 07:44 PM   #16
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Re: 84 z28 transmission doesn't match 350

It is a carbureted engine so i assume that means it was made before 85.
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Old 04-20-2017, 12:18 AM   #17
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Re: 84 z28 transmission doesn't match 350

Quote:
Originally Posted by xxcamaromasterx View Post
It is a carbureted engine so i assume that means it was made before 85.
You can't assume that. Intake manifolds are easy to swap. Lots of engines being made every day (after 1985 last I checked my watch) for the aftermarket destined to be carbureted.

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Old 04-20-2017, 12:57 AM   #18
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Re: 84 z28 transmission doesn't match 350

Ah very true.
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Old 04-20-2017, 06:18 AM   #19
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Re: 84 z28 transmission doesn't match 350

Pictures would help a ton
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Old 04-20-2017, 09:26 AM   #20
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Re: 84 z28 transmission doesn't match 350

Ok so I'll get pictures of everything next time they have it up.
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Old 04-20-2017, 12:44 PM   #21
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Re: 84 z28 transmission doesn't match 350

The casting number is 3970010 GM 85 and it had a t5 tranny

Last edited by xxcamaromasterx; 04-20-2017 at 12:56 PM.
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Old 04-20-2017, 01:00 PM   #22
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Re: 84 z28 transmission doesn't match 350

There's several possibilities with that block.

69' 302 Z/28 4 bolt main
327 truck and industrial
350 from 1969 - 1980
The block can be either 2 or 4 bolt main.
You have to look at suffix letter in front of the block on the pass. side.There two or three letters. That will tell you the history of the motor. If it was manufactured in 1970 or later, it's most likely a 350.
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Old 04-20-2017, 02:25 PM   #23
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Re: 84 z28 transmission doesn't match 350

I'll grab the suffix letter and post that as well.
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Old 04-20-2017, 02:52 PM   #24
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Re: 84 z28 transmission doesn't match 350

Quote:
Originally Posted by Jorlain View Post
There's several possibilities with that block.

69' 302 Z/28 4 bolt main
327 truck and industrial
350 from 1969 - 1980
The block can be either 2 or 4 bolt main.
You have to look at suffix letter in front of the block on the pass. side.There two or three letters. That will tell you the history of the motor. If it was manufactured in 1970 or later, it's most likely a 350.
In the context of transmission bell housing etc. it doesn't matter. All of those are "internally balanced" two-piece rear main seal SBCs (OK, not sure about a 327 industrial but my guess it is as well...).

Is it possible this is a V6 bell housing T5 trying to mate to a SBC?? Not sure how the hell they cut it to fit though!
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Old 04-20-2017, 02:59 PM   #25
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Re: 84 z28 transmission doesn't match 350

He showed me that the housing doesn't fit over the flywheel. So they made a idk like 3 inch 90 degree cut and continued the cut around probably halfway so it would fit. Sure was a hatch job. He thinks he found the correct bellhousing today though. So we will see there.
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Old 04-20-2017, 03:05 PM   #26
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Re: 84 z28 transmission doesn't match 350

That cut around the flywheel is probably why the original bellhousing fractured. You can't do that, and get away with it for very long.
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Old 04-21-2017, 03:53 PM   #27
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Re: 84 z28 transmission doesn't match 350

Sounds like it may be a large SBC flywheel? There are 2 flywheel sizes & the T5 bell housing only works with the smaller one if I recall correctly. If this is indeed your issue you'll need.

1)correct size flywheel for 2 piece RMS SBC
2)correct starter for that size flywheel
3)correct clutch for that size flywheel
4)bellhousing for T5/SBC with the correct clutch previsions for your car (hydraulic or Z-bar)


Again, if the shop can't figure that out find a different shop to work on this car. Just because they know about your daily driver, which I would assume is a more modern vehicle, doesn't mean they know the classics.
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Old 04-21-2017, 03:56 PM   #28
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Re: 84 z28 transmission doesn't match 350

Just found this tidbit of info on the internet
"That's because the 168T flywheel is 11" diameter compared to the 153T at 10.4""
Have the shop measure the outer diameter of the flywheel, if it's 11" you have the wrong flywheel.
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Old 04-22-2017, 08:10 AM   #29
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Re: 84 z28 transmission doesn't match 350

Quote:
Originally Posted by Formula 305 View Post
Just found this tidbit of info on the internet
"That's because the 168T flywheel is 11" diameter compared to the 153T at 10.4""
Have the shop measure the outer diameter of the flywheel, if it's 11" you have the wrong flywheel.
Exactly what I was going to post, they bolted on a 168 tooth flywheel. Only correction here is that the 10.4" and 11" refers to the clutch diameter, not the flywheel diameter. IIRC, a 168T flywheel is something like a little over 14" in diameter.

RBob.
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Old 04-22-2017, 08:30 AM   #30
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Re: 84 z28 transmission doesn't match 350

agreed. guaranteed that the motor has the staggered bolt pattern for the starter and instead of adding the second bolt hole to fit the starter for the 158 tooth flywheel the PO hacked the bell housing.
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Old 04-28-2017, 01:35 PM   #31
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Re: 84 z28 transmission doesn't match 350

Got the bellhousing on, it fits great, its extra thick so should be much stronger. Cars running great
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