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Old 02-24-2016   #1
Kevs87ta
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GTA Year: 1990
GTA Engine: 350 TPI Automatic
9 Bolt Question

Hey Guys, there is a guy selling a 9 bolt 3.42 rear end . I know that the gear ratio is suppose to be 3.45 in the 9 bolts, but, he is telling me it was in an automatic car, not standard. My question is, did the Trans Am's come with the 3.45's in the auto's, or was it just in the std trans.
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Old 02-27-2016   #2
merc3065
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Re: 9 Bolt Question

If its a 10 bolt its 3.42
If its a 9 bolt its 3.45

Both ratios were only available in the 5 speed.

If you put it on an auto, you'll have the best out of acceleration and fuel economy.

If the price is right and its a nine bolt with no issues on the spider gear, leaks or the positrac, I'd go for it.
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Old 03-01-2016   #3
soarestransam19
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Exclamation Re: 9 Bolt Question

The standards came 3.45 and the auto cars came 3.27 rear ratio I always wondered if u could get a auto car with the 3.45 rear
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Old 03-01-2016   #4
86TA355SR
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Re: 9 Bolt Question

Kevin,
Too bad you're so far away-I have a Currie Ford 9" sitting in my shop....
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Old 03-02-2016   #5
MunsonGTA
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GTA Year: 1987
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Re: 9 Bolt Question

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Originally Posted by 86TA355SR View Post
Kevin,
Too bad you're so far away-I have a Currie Ford 9" sitting in my shop....
Is it set up for a thirdgen?
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87 GTA: Forged 408 LSX short block, TEA stage 2 cnc ported 243 heads, BTR Stage 3 stroker cam, Fast 102 intake, NW 102 TB, Longtube headers, custom 411 ECM, custom harness, custom tuned, Performabuilt stage 2 4l60E with PTC 2800 stall, 9 bolt rear with 3.70 gears and TAP girdle.

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Old 03-03-2016   #6
Kevs87ta
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GTA Year: 1990
GTA Engine: 350 TPI Automatic
Re: 9 Bolt Question

Well the guy who has it is going to pull the cover off and try to see if it is a 3:45 or 3.27. I told him he could just turn the axles and count the revolutions of the yoke, but he wants to actually count the teeth on the ring gear. And he is asking $200 bucks complete with PBR brakes...
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Old 03-05-2016   #7
TTOP350
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Re: 9 Bolt Question

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Originally Posted by Kevs87ta View Post
Well the guy who has it is going to pull the cover off and try to see if it is a 3:45 or 3.27. I told him he could just turn the axles and count the revolutions of the yoke, but he wants to actually count the teeth on the ring gear. And he is asking $200 bucks complete with PBR brakes...
The PBRs are almost worth 200
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Old 03-07-2016   #8
merc3065
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Re: 9 Bolt Question

The PBRs are really a much better brake design than the older cast irons. Little bit lighter too.
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