TPI, T5, 3.42 swapped

79 Goon

79 Goon

Not-quite-so-new-guy
Aug 28, 2018
10
12
3
MN
#11
I have no idea wh
Welcome to the site from Houston. Cool car! I'm surprised you find the gearing to be tall. Are you sure its a 3.42? I really like this rpm calculator....

http://www.csgnetwork.com/multirpmcalc.html

Use the bottom section so you can plug in your overdrive ratio.

According to it, a 25.6" tall tire with a 3.42 rear gear and a .63 overdrive should turn 1838 RPM at 65 and around 2404 RPM at 85. That doesn't seem that tall to me which is why I ask if you are sure it is a 3.42. I don't doubt its an 8.5 but who knows if the gearset has been changed. Maybe a 3.08?

Is the identification tag still on the trans? If you can identify the transmission for certain (thereby identifying the gear ratios) and confirm the rear axle ratio (jack up rear end and see how many turns of the driveshaft = one turn of the rear wheel - will be close enough to tell if it is 3.42 or something else) that will help in identifying what change to make to get the car more to your liking.
I have no idea what RPM I drive at. It doesn’t have a tachometer. It’s in my plans though.
 
79 Goon

79 Goon

Not-quite-so-new-guy
Aug 28, 2018
10
12
3
MN
#12
That's a good shifter but it's usually used in Fords so I would suggest you get a AAA membership....:)
Lol. Well, I can’t confirm it, but that’s what the previous owner said.
 
Turbolq4

Turbolq4

G-Body Guru
Sep 25, 2017
798
715
93
Boise Idaho
#14
That's a sweet powertrain setup! I like the car, welcome to the site!
 
Longroof79

Longroof79

Geezer
Oct 14, 2008
9,406
2,548
113
Gainesville, Fl
#15
Welcome aboard! That's a cool looking wagon. Looks like most of the hard work has already been done. I'm sure you'll dial it in more to your liking.
I'm also thinking the rearend gears may have been changed out to 3.08's. I would think a T5 with 3.42 gears would be a nice combination.
I would definitely put a tach in it. ...even a factory in-dash tach would be beneficial....that's if you have the round gauges, not the sweep style speedo.

Thanks for sharing the pics of your ride. Keep us up to date on your updates and progress.
 
64nailhead

64nailhead

G-Body Guru
Dec 1, 2014
756
451
63
Upstate NY
#16
A T5 is nice transmission with your 305. I agree with others that you probably don't have 3.42 gears. But a tach would confirm what you have without puling the diff cover.

Here's the downside to a T5 : in your car (weight) that T5 is not going to withstand much if you ever decide to crank up any motor beyond 275-300HP. There are stories of T5 with aftermarket clusters and rear bearing supports, etc.. None of them will take HP at your car's weight.

If you're happy with the TPI 305 though, that trans is GREAT! BTW, welcome to the site and nice ride :)
 
pontiacgp

pontiacgp

Canadian Prime Minister
Mar 31, 2006
23,156
4,045
113
Kitchener, Ontario
#17
A T5 is nice transmission with your 305. I agree with others that you probably don't have 3.42 gears. But a tach would confirm what you have without puling the diff cover.

Here's the downside to a T5 : in your car (weight) that T5 is not going to withstand much if you ever decide to crank up any motor beyond 275-300HP. There are stories of T5 with aftermarket clusters and rear bearing supports, etc.. None of them will take HP at your car's weight.

If you're happy with the TPI 305 though, that trans is GREAT! BTW, welcome to the site and nice ride :)

I have around 400 hp with a T5 WC, I don't bang the transmision and if I put down a little rubber I make sure the car is rolling. The 5.0 Mustangs in the 80s came with the T5
 
64nailhead

64nailhead

G-Body Guru
Dec 1, 2014
756
451
63
Upstate NY
#18
I have around 400 hp with a T5 WC, I don't bang the transmision and if I put down a little rubber I make sure the car is rolling. The 5.0 Mustangs in the 80s came with the T5
Here's my point respectfully - you baby yours with slippery tires. Put on a set of drag radials and launch it to see what gives. And regarding fox bodies, they're almost a 1000lbs lighter than OP's wagon.
 
pontiacgp

pontiacgp

Canadian Prime Minister
Mar 31, 2006
23,156
4,045
113
Kitchener, Ontario
#19
Here's my point respectfully - you baby yours with slippery tires. Put on a set of drag radials and launch it to see what gives. And regarding fox bodies, they're almost a 1000lbs lighter than OP's wagon.
I know the T5 won't put up with that abuse in it's stock set up and that is why I don't abuse it. I know what it's capable of and I don't bang on it and then say what a POS it is when it breaks. I like driving it and I spend more time on the highway than I do at stop lights plus I was never interested in street racing or drag racing so I'm happy with what I have...:)
 
79 Goon

79 Goon

Not-quite-so-new-guy
Aug 28, 2018
10
12
3
MN
#20
A T5 is nice transmission with your 305. I agree with others that you probably don't have 3.42 gears. But a tach would confirm what you have without puling the diff cover.

Here's the downside to a T5 : in your car (weight) that T5 is not going to withstand much if you ever decide to crank up any motor beyond 275-300HP. There are stories of T5 with aftermarket clusters and rear bearing supports, etc.. None of them will take HP at your car's weight.

If you're happy with the TPI 305 though, that trans is GREAT! BTW, welcome to the site and nice ride :)
Yeah, I know the T5 is weak. I’m not building a drag car or racecar. It’s going to be a fun daily driver with plenty of spirited driving. I’m not getting drag radials either. As far as weight, it’s NOT a heavy car. According to automobile-catalogue.com, with a 350 and a TH350, it’s under 3500 lbs. The ‘91 TA that the motor & trans came out of was 3343 lbs (edmunds.com). And a convertible would be 100-200 lbs heavier, so weight isn’t a concern. Now, the weight TRANSFER on a launch would be more stressful, but like I said, it’s not going to be a drag car. It also has a hydraulic clutch conversion from a 2001 camaro, so a future LS, LM, etc. + a T56 swap shouldn’t be overly extensive or expensive. The main things have already been done. AAAAAANYWAY, for now, my T5 will be just fine...hopefully. I can always upgrade to a TKO500/600 too. Or get my T5 built with a G Force case. They’re much stronger than a stock case. 👍🏽
 

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