1975 monza

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1975 monza

Postby mirage_brat » Sat Feb 21, 2015 12:01 pm

what kind of automatic transmissions were in 1975 monzas with the 4.3l engine?
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Re: 1975 monza

Postby cjbiagi » Sun Feb 22, 2015 4:41 pm

I believe they had a Turbo 350
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1975 Chevrolet Monza

Re: 1975 monza

Postby mirage_brat » Tue Feb 24, 2015 2:48 am

i wasnt sure if they had a metric transmission or a turbo 350 but im pretty sure its a turbo 350. :th:
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Re: 1975 monza

Postby cammerjeff » Mon Mar 02, 2015 5:24 pm

I am pretty sure all the V-8 automatics were T-350's from the factory, but in the last 35+ years you never know what a previous owner has done. It is easy to spot a Metric 200 as it will have "METRIC" stamped into the pan. But here is a link to a site that has all the different was to tell GM Automatics apart.

http://www.maliburacing.com/auto_tranny_id.htm
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Re: 1975 monza

Postby Monza Harry » Tue Mar 03, 2015 11:52 pm

You may have a THM 250 as well. It looks the same as the THM350 but it has less plates and discs in each clutch pack. I believe the "General" tried to tell us it was for lower parasitic loses, (as you see that 262ci. of fury just didn't need 350ft/lbs of torque capacity) but I am sure the all mighty DOLLAR was the real reason. My '76 GM repair manual lists this tranny as a possibility, but with the lead time for publication/production the two (car and book) don't all ways match up. Harry
Last edited by Monza Harry on Mon Jan 18, 2016 8:47 pm, edited 1 time in total.
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Re: 1975 monza

Postby MonzaRacer » Sun Jan 17, 2016 9:14 pm

The difference between the th250 and 350 is 100 ft lba torque capacity and the fact the th250 needs periodic band adjustments, the nut and adjuster are on the side of the trans. While they operate similar the 250 is a weak kitten for hopped up mills.
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Re: 1975 monza

Postby TTait » Thu Dec 02, 2021 2:03 am

This is as good a thread as any, let me revive it for a question or two. I can't find a decent write up in the manuals or in this section.

I've got the '75 Monza with a 4.3L and the TH-350 - which is leaking pretty profoundly. I've got to get things cleaned up under it and see where all the leaks are but I'm optimistic that it might just be the pan gasket - I've got a new one inbound as that looks to be at least the major source.

It appears to pull the pan off the bottom of the transmission in the car that I need to pull the crossmember, and that the crossmember is part of the mounting system - right?

Can I support the rear end of the transmission with a jack and leave it bolted up at the front and then drop out the crossmember to access the full pan? What other obvious steps am I missing there? Is supporting the transmission necessary or do transmission mounts actually carry the load?

Once the pan is off are there solenoids or a filter inside I should be servicing or replacing, or just inspect an the contents of the pan, clean the surfaces and install the new gasket?

Your help and patience are appreciated.

Tom
On my third H Body - 1975 Monza 2+2 4.3L Orange/Black (Current State: Running great - needs the AC finished before summer hits hard)
76 Monza 2+2 L4 (1982-1987)
77 Starfire V6 (1987-1987)
82 Delorean - Universal Raffle Car (2005-2013)
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Re: 1975 monza

Postby cosvega76 » Thu Dec 02, 2021 8:26 am

Tom,

There should be no problem supporting the trans by the tailshaft housing when you have the crossmemember removed. There is a filter inside the pan that should be replaced, it'll be part of the trans filter kit, along with the pan gasket. While you have the fluid drained and pan off, you might also want to replace the dipstick tube o-ring, as that can be a source of a substantial leak, as well.

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Re: 1975 monza

Postby TTait » Thu Dec 02, 2021 9:55 pm

Excellent - will do! Thank you!
On my third H Body - 1975 Monza 2+2 4.3L Orange/Black (Current State: Running great - needs the AC finished before summer hits hard)
76 Monza 2+2 L4 (1982-1987)
77 Starfire V6 (1987-1987)
82 Delorean - Universal Raffle Car (2005-2013)
81 Delorean 2009 - Present
17 Chevy Bolt 2017- Sold back to GM for almost a full refund
22 Mustang Mach E on order
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Re: 1975 monza

Postby monzaaddict » Sat Dec 04, 2021 6:24 pm

Transmission-Automatic: Dipstick / Fluid Filler Tube Seal ATP SO33 O-Ring; 7/8
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Re: 1975 monza

Postby TTait » Fri Jun 16, 2023 1:13 pm

I've got a leak at the speedo cable, going to order a th350 bullet with seal and replacement drive gear.

I've got the 262 engine, the th350 the standard rear end and am running stock diameter tires. Can anyone tell me which color speedo drive gear should be in there stock from the factory so I can just order the part in advance?
On my third H Body - 1975 Monza 2+2 4.3L Orange/Black (Current State: Running great - needs the AC finished before summer hits hard)
76 Monza 2+2 L4 (1982-1987)
77 Starfire V6 (1987-1987)
82 Delorean - Universal Raffle Car (2005-2013)
81 Delorean 2009 - Present
17 Chevy Bolt 2017- Sold back to GM for almost a full refund
22 Mustang Mach E on order
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Re: 1975 monza

Postby cosvega76 » Sat Jun 17, 2023 8:37 am

That should have a 2.56 ratio rear, so the speedo gear should be the 3987922, 22-tooth, silver gear, according to my info.


Chuck
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Re: 1975 monza

Postby TTait » Sun Jun 18, 2023 1:32 am

Thank you Chuck!
On my third H Body - 1975 Monza 2+2 4.3L Orange/Black (Current State: Running great - needs the AC finished before summer hits hard)
76 Monza 2+2 L4 (1982-1987)
77 Starfire V6 (1987-1987)
82 Delorean - Universal Raffle Car (2005-2013)
81 Delorean 2009 - Present
17 Chevy Bolt 2017- Sold back to GM for almost a full refund
22 Mustang Mach E on order
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Joined: Sat Feb 20, 2021 1:47 pm


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