1984 monte carlo ss 305v8 with the th350 transmission. I get it is only a 3 speed I get on the freeway and it gets up and go but at around what speed should I feel 3rd kick in . At around 45 or so it is just screaming down the freeway. How do I know if 3rd went out ?
3rd gear
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1984 SS with 305 HO should not be TH250 but check it any way. TH250 and TH350/TH375 look very similar from the outside. On the passenger side near the cooling line connectors if you see a stud with a lock nut sticking out you have the TH250. Not bad, but definitely not a very strong unit. If you are sure, it's a TH350 and not sure of third, manual shift 1 to 2 and watch Tach, then manual shift to 3rd and watch Tach. You should feel shift and see drop in Tach RPM.
Make sure your kick down cable is hooked up properly, and make sure you have good connection to the vacuum modulator. This will be steel line with rubber line connection or 9/32 vacuum line from manifold vacuum to the modulator. Modulator is on Passenger side rear of trans just above the pan.
On the driver's side, remove the small round cover near rear of trans. This cover looks like a small hub cap with a bail wire holding it on. Move bail wire out of the way and remove cover. Behind this is the governor. On the TH250/350/400/700 the shift is controlled by the governor. Pull it out and check that it is clean, not rusty or gummed up with dirt etc...
Check the gear to see if missing teeth, this is common problem on older trans. Move the weights. They should move freely, and you should see the valve inside move up and down when you move the weights. If this valve does not move its stuck, just replace the governor, comes as one complete unit. Note the color of the gear and order replacement with that color if you can.
The other possibility is stuck valve in the valve body itself. Don't mess with the valve body unless you feel competent with doing so. If you remove the Valve Body while still in the car, make sure not to lose any of the check balls (3/8" steel balls) you can replace them with ones from Dodge same size, but they are rubber coated. Just don't lose any and make sure you know where they belong when reinstalling the Valve Body.
Prior to doing any of this: Watch some YouTubes on TH350 rebuild, one of the best out there is Precision Transmission, but there are other few good ones out there.
Hopefully you just have a worn-out gear, that's an easy fix.
This link is for 700R4, but this is a good one from Monster Transmission:
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Don't forget that if everything is stock on that '84 Monte Carlo SS, it will have 3.42 rear gears from the factory. If you're not accustomed to having a performance gear and a trans that has a 1:1 drive gear, it will seem like it's singing at freeway speeds.
Yes its 1984 with stock motor and transmission.
Yea thats what I figured . Stock engine and transmission i do have 20 inch rims which im sure don't help out.
Rim size doesn’t really factor into it. It’s tire circumference that matters. It’s something like 26.1” diameter for a stock Eagle GT so even if you have 20s on the car, if your diameter’s only 26”, you don’t change anything as far as rpm on the road.
It will be a factory TH350C. It will be running 2700 rpm at 60 mph with the stock 26" tire. Less height will raise it more plus put your speedometer off.
Thanks i made another post on my tach running to high and I guess it just seems like the engine is over doing it but I guess its normal since it only has 3 shifts .
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