transmission help please or advise

Ricks79bu

Daily Driver
May 19, 2012
25
0
0
Hello fellow malibu lovers. I have a 79 malibu. Just got new bbc fired up today and running. Question is I got a new th350 with a 2800-3200 stall converter. Questions is it. Feels like it just dosent shift right or at all. I have a stock rearend with stock gears. Probably freeway gears. Im gonna be changing asap. Questions is could it be because or my stock sad rear would that be causing me not to shift. I can provide any other info to help. Will be changing to 4:11 asap. I still thought it should shift thru the gears tho. Not sure if its a transmission problem or a rearend to swap first?
 
With factory rear gearing (probably a 2-series), you're putting a tremendous load on the torque converter and experiencing extreme converter slippage. The high percentage of slippage in the converter is going to absorb any shift firmness that you may normally feel from your transmission. Double check your shift linkage/cable adjustment and vacuum modulator connection (if applicable) just to be sure, but the problem you're experiencing is most likely related to the incompatible rear gear ratio. You're also going to be a generating a tremendous amount of heat in the converter and transmission from all that slippage. Hopefully you have a good transmission fluid cooler installed on the vehicle and are running a high quality ATF. I would change the gears immediately.
 

Ricks79bu

Daily Driver
Thread starter
May 19, 2012
25
0
0
Thanks for the quick reply. I was thinking the same thing about the rearend. Yea I had double checked the shift linkage and the modulator already. Yea I do have a hefty transmission cooler with a fan on it also mounted under the car. Will be swapping those gears and carrier asap. Will have to get what I can for this 7.5 rear untill I track down a 8.5 that I can just swap out. Thanks for everything guys. Will keep you updated as it goes.
 

bowtie81

Moderator
Mar 28, 2008
5,008
0
36
sarnia, ontario canada
If you can save the money and buy a 8.5 or 12 bolt do that, don't waste it on a 7.5
 

Ricks79bu

Daily Driver
Thread starter
May 19, 2012
25
0
0
Yea im gonna save up for a new rearend but gonna spend a little on this 7.5. Gears going in tomorrow and will see how it shifts. Hope for the best
 

Ricks79bu

Daily Driver
Thread starter
May 19, 2012
25
0
0
Sorry for the delay. Ok so gears are in and man what a difference that made. She runs like a wild beast. So glad I changed gears and have to say thanks to you guys also for the advice. You guys are great. Thanks again.
 

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