Transmission

[86cut]

I have a th350 tranny that shifts quickly and firmly. The only thing that bugs me is that I can feel the first shift (1-2). It kinda jerks the car sometimes. Is there anyway I can get rid of that? I wanna hear the shift, not feel it.- Rick

 

[Freddie's Buick]

I've got that same tranny, (THM-350C), and the same problem though I learned to live with it. Try the Tranny Tech forum, maybe they'll get off of the later 'GN' tranny bandwagon and give you some pointers, (hopefully they won't try to steer you into buying that 'other' 'better' tranny).

 

[84ZZ4]

That seems to be pretty normal. Every TH350 I've ever been in does that. Cheer up, you could have the opposite problem--my TH-250C has a shift you can hear but not feel--and with the 4bbl conversion, it comes with the free "burnt tranny fluid" option.

 

[86cut]

Actually I am starting to like it. I learned to control the feeling of the shift....If I drive like a sane person I don't feel the shift; If I drive like I normally drive it has a nice necksnapping feeling.

 

[Freddie's Buick]

So,

I assume you got a 3-speed THM-350C. Can you check and see at what speeds, (MPH), the gears change?

Thanks!

By the way, I think I got that same 4-barrel conversion....

 

[86cut]

1-2 is around 17-23 +/- depending on how hard I hit the gas.
2-3 I think is around 30+, I gotta check next time.

 

[84ZZ4]

WOT shift points with the 2bbl were 42mph 1st-2nd, 73 mph 2nd-3rd. 2.41 rear gears.

With the 4bbl, it seems to be shifting into 2nd closer to 50mph. I haven't checked the shift into 3rd yet.

 

[86cut]

why does yours shift at those speeds and mine shifts so early?

 

[Freddie's Buick]

84ZZ4,

I would double check on those shift points you wrote. Mine are just like 86cut's. I have the same 2.41 rear gears and the Q-Jet 4-barrel conversion....

 

[b4black]

Have you tried adjusting your TV cable? Start by resetting it to the factory setting, then maybe a one click in or out.

 

[84ZZ4]

Freddy;

I drive the car everyday to and from work, so I'm pretty sure about the shift points. I will check again on the way home tonight. I have verified the speedometer is accurate (when it isn't bouncing) through those nifty little police "Your Speed Is" billboards.

Using a scanner the 1st-2nd shift point was at 4800-ish RPM. If the converter was locked (which it isn't), I calculate that to be about 59mph. That's a lot of converter slippage, so it could be my numbers are slightly off somewhere. Either that or the burnt tranny fluid option's rearing its head again.

If you're shifting at 23 mph, you're talking about shifting under 3000rpm. That can't be right. Those shift points seem right for my car if I'm only giving it about 7/8 throttle, since these trannies seemed to be "programmed" to shift early unless they are absolutely 100% WOT. Throttle not opening all the way (carpet, floor mats, stretched cable?), TV cable adjusted right?

 

[Freddie's Buick]

O.K. 84ZZ4,

Feeling mighty confused about those figures you wrote about I went and found known gear ratios for the THM-350,
(http://www.montecarloss.com/SSThunder/drivetrain.htmland). I plugged these figures into a transmission gear program I got. Here's what it came up with:

1st gear shift point is at 23.5 MPH
2nd gear shift point is at 39.40 MPH
3rd gear shift point is at 59.60 MPH

Tire size, (R-14's), and rear gear ratio, (2.41), are contributing factors and yes, all these shift points are below the 2000 RPM range. Pretty surprising . No wonder launch sucks in these cars, look at the huge leap it has to travel just to shift into 1st gear!

Yep, I was wrong with the 15 MPH for first gear. But at 25 and 50 MPH these are definate 1st and third shifts on my car. I'll have to double check at 39 mph to verify the final 2nd shift estimate.

Lock-up is easy to verify but can trick one into believing its a shift change if on does'nt have an OTC moniter like I do. On another thread I posted, (.....Idea), I gave a nifty trick on verifying lock-up....check it out!

 

[86cut]

hey, I'm confused about lock-up....sometimes when I'm accelerating and approach about 10mph I feel something that feels like a shift, but its not.....is that lockup?

 

[Freddie's Buick]

On the '81 there is a place on the fuse box that indicates the TCC test light source. According to my manual this is were one has to place the test light. It's to the left of the ECM fuse. I tried it and it works perfectly! See if you have one in your Olds.

Wire up a fused link to this point in the fusebox to any light bulb source one can buy in the electronics section of an auto parts store, (one that you think looks nice). Drill a hole to any panel area that is visable and looks good to your liking. Ground the other end of the light bulb. No 'on' or 'off ' switch is needed. The light goes on whenever the converter locks up. Click on the link for a picture of the fusebox.....

http://members.telocity.com/~familiadiaz/Fusebox.jpg

 

[84ZZ4]

Oh, I definitely wasn't trying to tell you that you were WRONG on where your car was shifting. What I was trying to say is that shifting that low just can't be right.

My Olds is pretty slow up to about 20mph, but from there to the 2nd gear shift point it really starts picking up steam. By the time it gets to 40mph it's pulling pretty decently for what it is.

Heck, I've been cruising along at about 35mph, and pressed the gas down slowly. You can feel it shift from 3rd to 2nd at about half throttle, and if you push the pedal down all the way it will shift into 1st. Same thing at 60mph, I can feel it unlock the converter and then downshift to 2nd.

I can't for the life of me figure out why your cars are shifting so early. Mine shifts at those points at about 3/4 throttle, but WOT is a different story. I still think there's something not quite right with somebody's car, and at this point I don't know whose!

As far as the lockup, mine won't lock up until 40mph and the engine above some specific temperature (never checked to see what the temp is though). Since my speedometer cable bounces, it's really frustrating to drive near 40mph because the converter will lock and unlock once every 5-6 seconds.

 

[RustyFrame83GP]

I don't know, to me it seems like they were talking about shift points under 'light' acceleration, and you were talking about full throttle acceleration. Big difference. If they were really shifting that early under hard acceleration I'm pretty sure they would know that something is wrong.

 

[84ZZ4]

:shrug: I specifically said WOT in the first post I made, whereas no-one else specified either way. I guess I simply assumed WOT. For part throttle shifts, I don't care when it shifts as long as it doesn't stall out.