speedo help and some other transmission advice

[hedz]

hello



here is my monte carlo. i used to get on this site in 2006 i think when i used to have a blue china blue 78 mc. this one is my current mc. here's a pic of my old one.



and i'm sure my friend will appreciate me posting his grand prix sj



anyways enough of that.


so the th200 went bad in my 79 monte carlo. as much as i wanted to build it for performance with a reverse valve body and some high end other parts, my budget took a nose dive. instead i elected to purchase a th350 aka turbo 350 to swap in it's place. i know that it's a direct swap to a certain extent. i won't know till i try to install it this weekend.

the th350 that i bought from a guy for $150 is powder coated orange. it's got a 9' length tail so i guess it's a long tail th350. it's supposed to have a b&m shift kit in it. basic trans.

do i subtract the total length of my th350 from the total length of my th200 and then tell the driveshaft fabricator that i need my driveshaft shortened x length? to determine the length i need to shorten my driveshaft?

which would be 30 5/8 inches minus 28 1/4 inches ?

also can someone recommend a new trans mount for me? should i go with a polyurethane?

also, i have no idea what this transmission was going to be used for but i deffinitely know it wasn't a gbody because i don't see a input on the side for a speedogear speedo cable for g body. is there some kind of adapter i can install onto the side of the transmission to interface a speedometer cable from the original speedo? what should i do about this? :?: is this something i should be looking at? http://www.ebay.com/itm/NOS-GM-1967-91- ... fd&vxp=mtr

if this is the type of part i need to adapt it or if anyone could tell me exactly what it is i need to make this work i do know a old school parts distributor near by that has all kinds of ancient stuff in their shop so i can probably find some ol school nos item if that's what my application needs



just so yall know i'm changing the pump seal and pump gasket, the rear seal, the pan gasket, adding a deep pan, and a external trans cooler and installing this transmission. i expect it to be straight forward.

 

[hedz]

is this mount adequate? http://www.summitracing.com/parts/ptp-7 ... onte-carlo

i don't know anything about the manufacturers of these polyurethane parts and am really not familiar with anything that's not the old school rubber

 

[hedz]

i had no idea all the different tools i would need to get into all the tight spaces. a 2ft extension and a air wrench 9/16s swivel came in real handy that i hooked up to my half inch drive ratchet. also had to hold the front of the engine with some kind of metric socket to keep it from spinning while i took out the torque converter bolts which were 15mm. all this metric mixed with standard is lame. i'm a standard guy, as i'm sure the majority of you are. merica... anyway i got every single thing out, the drive shaft, cut the transmission line(couldn't get to it with any kind of off the shelf wrench that i had so new ones are going in), the torque converter bolts, and got all of the bellhousing bolts out except for one! this last one is a major pita. it's the driver side bolt directly above the lowest bolt - drivers side. i managed to budge it just barely from the engine compartment with a wrench but theres so much crap in the way i can't get to it with the tools i have. i have a friend bringing over a 1/4 inch air wrench swivel with a 9/16s head on it and we hope that will get it.

i'm taking the new turbo 350 into the shop tomorrow to get the front pump pulled and install a couple seals. i already installed the rear seal by using a thick piece of wood, drilling a hole through it so that the tail shaft gear sticking out the back could fit into the hole and move freely. i then placed another block of wood on top of the one with the hole so that i could hit the blocks center over the tail shaft gear. i put a very small amount of rtv around the edge of the seal and hammered it in. worked like a charm. also installed the vacuum modulator. even after unbolting everything on the front pump i still can't pull the booger out. so i'm just going to have to pay someone to pull it out and put my new front seal, front pump oring, and front pump gasket on. unless any of you have any suggestions?

i still need to get my driveshaft cut. i'm just have the driveshaft shortened the length of difference between the longtail th350 and the th200. have the distance written down somewhere. it's precise, don't worry. :shock:

 

[CWPottenger]

I can tell you that the best way to measure shaft is to 1st call you local shop you plan to have it done at. I have found that shops differ which number they need/use and how they interpret those measurements.

Do you have a picture of the speedo output. TH350 should easily work for G-body. If it isn't a mechanical output then it is probably a VSS electronic output sender. Just swap the speedo output heads. The gear drive teeth might be wrong for your rear end.

also I have found that with a swivel 9/16 and a 2 foot extension from rear of car is the easiest way to access all the on trans

 

[hedz]

i wanted to edit my post and update this thread. folks i gave out some terrible info!!!!! please read on.

my poorly applied logic on the driveshaft was just that. never subtract the lengths of the transmissions. the correct operation is to install your new transmission and then measure the length to the input on the rear end. use that distance. never ever do what i did!! the end result was a driveshaft that was too short!

my friend sold me a buick grand national driveshaft from a 200r4 that actually was a exact fit. another tip that someone else told me is that a 87 to 89 driveshaft in a chevrolet truck with a short wheel base has the same driveshaft that would be needed for the th200/th350/and i guess 200r4. don't know if this is completely accurate but worth the effort if you don't have the money or the time to secure a friggin buick grand national drive shaft lol

the torque converter i installed on my mc from oreillys was the cheapest model offered by king pro. this was a terrible mistake. the torque converter not only bent my flywheel but wore out the stator bushing on the end of my front pump. also the torque converter was bad out of the box and spit flakes in my fluid. i have uninstalled the transmission again and put a new flywheel and a remanufactured torque converter from TransStar. also got a stator bushing to go in the front pump shaft and bought a trans filter from them. screw oreillys. they could have cared less about their poor product costing me more money and nearly destroying my transmission. very angry with them at the moment.

while the transmission is out i decided to change the tailshaft gasket. this was a good decision. i found powder coat poorly applied on the gasket seam which should never have happened. i scraped all this out.

so this has been a costly and aggrivating learning process. hopefully by this weekend i will have my transmission bolted back in and have a mc that not only shifts like a brand new car but also has a speedometer to tell me how fast i'm actually going.

thanks for all of your support and remember that dumb mistake i made on the driveshaft so that you won't repeat my mistakes

i ordered a 10 tooth drive gear for the speedometer and a few other trans parts.

 

[hedz]

i'm up and running. my transmission shifts great. i filled up the trans using valvoline high mileage. then i added lubegard transmission additive. i ordered some exhaust wrap. need to wrap my exhaust which is very close to my transmission cooler lines. going to try to keep the heat off of them that way. should help lower temps in the oil pan as well. my shift display isn't on point. i don't know what the problem is. perhaps i didn't assemble my shift linkage exactly. at almost neutral is my drive. and when i'm clearly in displayed in 2nd gear i believe the transmission is in 1st. can't get the column to actually shift to the 1st gear displayed. also my speedomer is 5mph off once i get over 25mph. other than that the transmission shifts great.

i have a suggestion that a friend told me that i thought i would share. the 10' torque converter remanufactured that is available for the chevrolet vega is supposed to be a excellent torque converter for a th350 with any 305 or medium performance th350. my friend told me he has used it in many 350 and 305 sbc applications with great success.

 

[marcar1993]

Ok, wish I saw this earlier... I did this swap in my car years ago. First, a 6" tailshaft th350 is your best option, because there is no need to change anything on the drive shaft. As for the linkage, if you used the 200 shift lever (on the trans the rod slides through), it is different than the factory th350 lever with a different throw, which explains your incorrect dash readings. The distance between the "gears" in a th350 is different than a 200, but it won't cause any issues reading incorrectly but just make sure you know what gear you're in.