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Discussion Starter · #1 ·
How easy (hard) is it to convert a automatic transmision Opel GT to a Manual? What is a reasonable estimate, as far as parts are concerned, for cost of the conversion (using average going rates for parts)? Thanks-I am looking for a nice/solid '72 GT with manual trans. to drive (found a nice '72 auto).
 

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OPEL-LESS!!!
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mr_udy:

i have TOO many 4 speeds laying around. i can sell you a flywheel, clutch, trans/bellhousing, 4 speed driveshaft and crossmember with the right calibration numbered speedo if you dont have it, and a speedo cable, and clutch cable. you can have it all in good working condition for 100 bucks. the complexity of putting a 4 speed in a car is not too hard, i've done it lots. the automatic is alot bigger than the 4 speed, and a little harder to pull out than the 4 speed is. if you do convert the auto to a 4 speed, keep the auto, as you can probably get your money back out of the flexplate and driveshaft alone!!!
 
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But!

Change it if you wish to BUT a good auto is a rare wee beastie as there were relatively fewer of them made. A nice auto with an upgraded hi-compression motor is very nice to drive as an around town car - I have one and would not change! It is the '72 low compression motor which makes them feel so sluggish. The auto is a good GM Th180 unit for which parts are stil available as they were used in many GM cars - even late model Suzukis.
 

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Discussion Starter · #4 ·
Thanks guys. I will certainly keep both options in mind although I'd really like to have a manual.
Jared-I'll need to keep in touch with you to buy the parts and maybe some "tech support".
GTJim, What is the high compression motor all about (I'm new to GTs but have
a long interest in them as a family member had one and can finaly afford one myself) Thanks.
 

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the high compression motor was used in the early model opels (until 1970) and instead of 7.6:1 comp ratio, it has a 9:1 advertised compression ratio (dish pistons vs. flat top pistons) and the high compression motors had solid lifters also, and it seems i remember something about the cam having a few more degrees duration or something of the such, not real sure. about 70 horsepower vs. 100 horsepower.
 

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changed to a four speed

I converted my automatic to a standard about 13 years ago. Very easy change, I had a parts car. Everything clutch brake pedal, cables just fit right in. Having both, opel gt was meant to be a standard


Doug
 

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I had two 1974 Opel Mantas. One 4 spd and 1 automatic. The Automatic would blow the 4spd away after the first 300 ft. The autos shift so fast and positive that they will catch the 4spd while it is shifting from 1st to 2nd. I confirmed this with several other Opels back in the 70's. The 4spd or 5spd may be more fun to drive, but don't sell the automatic short.
 

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i raced a 72 auto GT today with my 71 4 speed car. i have a few mods, so i shifted at 4,500, let him do whatever he wanted and i still smoked him at the end of the quarter mile. the GT is my old car, i traded it to him a few days ago. compression numbers read identical to mine, all i have is weber, header, and pertronix. its still slower than my GT when it was stock.
 

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Putting in an Opel GT 4 speed in place of the original automatic in a 1973 Opel GT

Greetings to all. I am installing an Opel GT 4 speed into a 1973 Opel GT that originally came with the automatic transmission. I purchased a donor car (1970 Opel GT) and everything looks good except....for...one simple fact: The pedal assembly cross shaft (Or pivot shaft) from the 4 speed car has a shoulder on the bolt that won't allow the bolt to travel but only so far towards the left of the car (Only goes in one way, from right to left). Of all the Fords, GM and Chrysler vehicles I performed swaps on I've never seen this before. The shoulder needs to be trimmed back about .030 to .045 but I haven't measured it just yet. This tells me that at least the 1973 Opel GT bodies were manufactured on the assembly line following pre-determined transmission selections. But....the clutch cable pilot hole/tube is there....go figure! Has ANYONE out there seen this before or....am I the only one? Also, I have the complete automatic transmission, flexplate, driveshaft, brake pedal and even the air conditioner assembly I may put up for sale....any suggestions? Thnaks.
Terry.
 

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I do know that some of the pedal assembles are different, not sure if it is a year thing or not but you might try a different one.

Pat
 
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