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Adjusting shift points in a TH350... to where?

18K views 33 replies 7 participants last post by  69ssmike 
#1 ·
I went to the track for the first time ever this past saturday. I had a blast, btw. One thing I noticed is that my transmission shifts too soon. The motor is a 385 and the cam is a 234/234 a .05 and makes a whopping ;) .488 valve lift with 1.5 rockers. I have dart iron eagle heads with 2.02/1.6 valves and 200 cc runners. My rear gear is a 3.31. Where should I be looking to make this thing shift? I don't really want to manually shift so I am going to buy one of those B&M kits to make it shift where I want in D. It is currently shifting between 4 and 4.5K RPMs. I think it should run to at least 5500. I am using a stock cast crank if that matters, and recon rods with ARP bolts. My CR is about 10.3:1 and I have no detonation issues.
 
#3 ·
Wow, that is awesome - do you have a pic of the reassembled governor, just so I can see how and where you bent the nail over, or does it not matter?

Also, where can one find the right springs to change to a lighter one if necessary?
 
#4 ·
This has inspired me..been meaning to do this for a long time.
I have a spare TH400 I just robbed the gove. out of.
I ground down the "spears" and took it apart.I will grab the nails at the hardware store and grind the weights down tomorrow and install in my Chevelle.
I'd do it right now,but I need the nails,by daugher is sleeping (she was still up when I ground the off the spears :) ) and the roads are a little wet.
My TH400 in my 'velle shifts around 4500 (even though its a CY code TH400 with high shift points) so I'd be happy with 5200 or so.
Thanks again Jake,I will post my results.
Sure beats spending cash on the B+M kit and the fact you can do it yourself and learn something in the process.

Jake,in the fourth picture down,do both of the weights need to be ground like the one on the left to achieve 5000 RPM's ?
Thanks in advance.
 
G
#5 ·
Clark,
Set the governor on a hard surface, and bend the ends of the nails towards the center, or towards each other. I just tap them over with a small hammer.

Chris,
Yes the weight on the left will usually get you about where you want to be. And yes grind both of the smaller weights to look like the one on the left.
You may have to play with it a bit to get it where you want.
The shift valve springs in the valve body have an affect on this as well, so there isn't a set amount of weight that can be removed.

Also on the factory performance governors, they had a large hole drilled in the outer weight, and some of the weights were thinner, so lighter, even though they didn't appear different at first glance.

The outer weights seem to affect the part throttle 1-2 the most, so if your car feels like it shifts to 2nd too soon when you leave a stoplight at part throttle, work on these.
The inner weights affect the WOT shifts on the 1-2 and the 2-3, but always seem to make a slightly bigger difference on the 2-3.
If you get pretty crazy with them, you may have to go into the valve body and play with the shift valve springs to make it all shift perfect.
You could spend 2-3 full workdays getting one PERFECT but usually a couple of hrs and you can get one pretty close and be MUCH better.
 
G
#7 ·
No trimming necessary.
It will be about maybe 3/16" to 1/4" longer than the governor is wide, just bend it over.
Buy a small box of the nails and they will last YEARS, even if you build trannies often. I bought a box probably 3-4 yrs ago, and still have half of them. I'm talking one of the .79 cent boxes with maybe 100 of the little nails. You can probably pick these up from Wal-mart. I think I bought my box at Ace hardware.
 
G
#13 ·
OK,
So my method costs 1/30th as much :)

The advantage of the kit is it does include springs , gaskets, and the little "axles" instead of using nails, however I would lose the clips anyway, so the nails work better for me.

I have an assortment of springs that I sometimes play with, but usually I just take weight off until I get it where I want it.

It doesn't take me that long to grind the weights, and I have a pretty good idea how much to go so it's not a 90 minute job for me.

http://store.summitracing.com/egnsearch.asp?N=700+4294925134+4294839071+115+4294849137

6500 rpm shifts will need the secondary weights cut down about as much as you can go.
 
#16 ·
that is definatly a cool mod and the price is certainly right, but, why wouldnt you want to shift manually at the track?...wouldnt you then be able to take full advantage of whatever rpm your car works best at?...did i miss something?
 
#17 ·
If I let the trans shift by itself, it reduces the chances of me skipping a gear or shifting into neutral. Also with my shift kit I could never shift as fast as it could. Best for me would be to adjust it until I get it to do what I want every time and leave the stupid human (me!) element out of it.

Any advice on where I should be shifting with this cam and stock bottom end? Does 5500 sound about right?
 
#18 ·
Any advice on where I should be shifting with this cam and stock bottom end? Does 5500 sound about right?
5500 seems pretty close, but 234@.050 is a fairly big cam for a small block, and you have the 200cc heads, you might pick up a little by shifting at 5800 or so. My 350 has a completely stock bottom end (stock oil pan, stock oil pump, stock pickup, 1976 2-bolt block, original cast crank, original 1976 nothing-special rods, all with stock fasteners) and I've got a couple hundred drag passes shifting at 5600-5800 with no problems.
 
#21 ·
OK..I went and bought the nails after work (6D)
Anyway,the nails fit thru the top plate but not the thru the gov. nor the weights,so I had to drill the the holes out a hair to fit (no big deal)
then,the nails kept bending length wise when I was trying to bend the ends over with a hammer on a block of wood.After doing this several times,I ended up using a pair of pliers to bend them without bending the whole nail.

Jake,does this look OK?

grinding the weights was the easy part :)

I didn't get a chance to install the gov...ran out of time when the Wife came home and the hatchback on her Passat wagon wouldn't open.
After I fixed that (cable came off) I was in no mood to deal with a bunch of trans fluid :D
 
G
#22 ·
Re: Adjusting shift points in a TH350... to where?g

I would try to get them bent over a bit more.
I wonder if your nails are harder than what I got. Or maybe softer and they bend too easy.
Mine fit easily through everything. May just be the brand. Like I said I've been using the same small box of nails for the last 3-4 yrs (and probably will be for at least another 1-3 yrs..
 
#24 ·
Just ordered the B&M kit last night, on my doorstep at 10 this morning, now that's SERVICE!!!!:thumbsup: Took 2 tries but ended up with the 4 and 5 weights with the yellow spring, 1-2 shift is 55-5600 and it shifts later when just cruising also, much better than before. Have to find a little more road to check the 2-3 shift. This should make racing MUCH easier. Thanks Mike (Georgia69)
 
#25 · (Edited)
"If the driver manually shifts at 5800, or you leave it in Drive and program the governor to shift at 5800, what's the difference?"

well, for one it'll be easier to smoke my cig, drive with one knee and take a drink of soda while waving to the (by now) cheering grandstand audience, if i let it shift itself, seriously, first let me say i have nothing but respect and admiration for jake, ive tried to follow some threads hes been involved in (at least untill my head was spinning) concerning auto transmissions
suppose you rejet (or recurve the ignition or one of a bunch of other tuning tweaks) and surprise! you find a couple of tenths, but your peak rpm went up or down? (which, i think is likely)...pop the gov out and redo it? i guess you could, for next weekend...but, what if you find yourself at a slick track (or, even more likely) in a slick lane and you find yourself spinning when it shifts at a set point?...i'm would guess theres plenty of other possible/probable scenario's and i dont remember if he said the car is also street driven, but if hes still wrasslin a column shifter, i would assume so, and i'm no auto trans wiz (in fact its probably the only thing i still consider some sort of "black art", hence the afore mentioned admiration) so, im trying to learn here and i dont know/remember from reading if this mod changes the cars street manners, but i think its safe to say you dont want it shifting in traffic like you want it to at the track ...i totally understand worrying about missing a shift with a stock setup ..ive had a b&m pro ratchet sitting in my garage for over three years and finally installed it just recently and found out the only real question was "why did i wait so (bleepin') long?"...as some one whos gone from a tree mount to a good shifter, i think this advice is valid ...get a decent shifter and tach and have some fun rowin' through the gears as you semi-blaze down the quarter mile...ten and two is for grandma, fast though the old gal might be

one more thought...am i wrong in thinking that an automatic shifts automatically wether you tell it to or the govenor tells it to, thus, you'll still reep the rewards of the "faster shifting than you" shift kit?
 
G
#26 ·
There's a bit of difference in the function of the trans between a manual shift and an auto shift.

I'll first say that for better consistancy, a shift light, and manually shifting is PROBABLY better in a bracket racing scenario.

But I will also note that the TH400 or TH350 in auto mode does not apply the low band (TH400) or clutches (Th350). They also do not apply the intermediate band in auto mode.
Both apply these devices in manual mode.
So there may be some very minor gains to be found from a lack of frictional loss during the release of the bands or clutches when using the auto shift mode instead of manually shifting. Also maybe some quicker fluid routing to the apply devices since the low band or int band doesn't have to be "knocked-off" or released.

My opinion is that on a Th400, the low band doesn't cause much frictional loss during the release, so I think a Th350 might see these potential gains more.
I don't have any real scientific stuff to back this up but just looking at the operation I can see how it could have an effect.

One of the racers here who runs a consistant car and usually manually shifts should get the governor to execute auto shifts at the same rpms and try it out for us :)
 
#27 ·
thanks jake, i never fail to learn something reading your posts
 
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