transmission/linkage ?'s

[1986supreme]

Hey guys I put a th350 in my 86 cutlass and i knew i had to adjust the linkage. i adjusted the linkage in drive and the car seemed not to want to "lock" in park....then i adjusted the linkage in park but when i went to shift into drive the car went into 2nd gear.....so i have to put the indicator on the gauge cluster between neutral and drive which bothers me because i think ill end up burning my steels/clutches....the car drives and shifts fine like that but im pretty sure the transmission isnt all the way in drive because i can tell a difference between the shifts when i change gears.....for example ill drive it to the store park my car and when i come back out i shift back between neutral and drive but i might not get into the same spot as before and it might shift harder or softer than before......what can i do to correct this??? another question i have is about my speedometer along with my th350 i swapped my stock rear end to another stock rear end out of a monte ss which i was told had a 3.73 rear gear...and i have noticed that my speedometer is around 20 mph off...i have the stock rims and tires from the cutlass on it and i think the total diameter is around 26 inches....anyone know what speedometer gears would correct my speedometer?

Thanks for any help

 

[327mali]

you have to take your speedo housing out and read the number on the gear itself. then your gona need to go up in numbers. you can pick the gear up for like 2 bucks at napa i believe. adjust your linkage in neutral. that should clear your problem with the indicator. if its still a little off dont adjust the rod by pushing down on it. you need to adjust the shifter up or down by that little 13 mil on the steering collum.

 

[bowtie81]

Whenever i adjust the linkage i do it in neutral, always had goodluck like that.

 

[t5montecarlo]

It sounds like the lever on the transmission is too short and is moving the pushrod too far. Ensure you are using an OEM lever and not one meant for an aftermarket shifter.

 

[1986supreme]

oh ok haha i was just skipping over the gear that I needed to actually adjust It in.....thanks and with the gears i was told that i would have to change both gears i think i seen a link on here a while ago about my problem ill look for that again and ill do the formula and ill post my results to see if that sounds about right....i would like to get it closer than 20 mph....

 

[1986supreme]

I found the formula on here along with the charts needed. the formula ended up looking like this 3.73x20.2=75.346
75.346/26=2.8979 so i rounded to 2.90

on the charts supplied below had to different types of gears Large and Small gears. so I got the closest ones

Large gears.......transmission gear.......Speedometer gear
#2.87......................15..............43 teeth
#2.92.......................12..............35 teeth
#2.92......................13..............38 teeth

Small gears.........transmission gear........Speedometer gear
#2.88........................8..................23 teeth

which gear set sounds about right for my th350? And about the linkage im pretty sure its oem I got the transmission from my uncle which he had just laying around it was just a spare transmission that he wasnt going to use also i talked him into rebuilding it for me as long as i got the parts...he had the rebuild kit laying around also....the bad thing is he didnt know what year or what it had came out of....but i think everything is stock on it

 

[327mali]

none of thats gona help untill you find out what gear you have in the trans. take the 10 mil bolt out of the tail stock and pull the speedo housing out. your gona lose some fluid. but pull the gear off and get the number off it. or the tooth count. the number should be the tooth count. if it doesnt have one just count the teeth. after that it sounds like your gona need to speed the gear up. so your gona need to go with a high number.

 

[1986supreme]

so i need to count the teeth on the drive gear or the driven gear? i talked to a guy at a gm parts dealer and he had told me i had to buy both gears so they would match up and not grind the teeth off of each other so thats why i was using that chart.....this is where i got confused because one of my teachers at a mvctc told me i just had to buy a new driven gear.....he told me that 1 tooth = about a 3 mph change.....in order to correct my 20 mph difference (which is in my terms faster than is should be the speedometer is reading 60 when im doing about 40) i would need to increase or decrease the teeth by about 6 or 7 teeth if 1 tooth = about a 3 mph difference? :?:

 

[Phoneguy]

If the th350 is a chevy it should take the small gears. If you order the 8 tooth drove and 23 tooth driven it should be right if you did your math correct. You should also order a new "bullet" for the driven gear. I got all my stuff from summit in tci brand.

 

[t5montecarlo]

tooth differences do not equate to mph changes; they equate to a % change. The mph change will depend upon the speed at which you are referencing.

You only need to buy the driven gear if you already have a compatible drive gear. It may also be possible you have a drive gear that will not result in the ratio you need because the driven gear you need doesn't exist. Therefore, you really need to look at what you already have (re 327mali). It may save you the cost of a drive gear and having to take off the tailshaft (gasket) and change the drive gear.

I agree you should also buy a new sleeve (bullet).