oldsguybry

Ok , hard to believe this transmission has issues with the 455 in front of it . The tranny has been a leaker for quite awhile prior to the 455 swap , this rendered it low from time to time which probably didn't help ....

It started up shifting easier then normal lately with a rumble / shutter feeling , like it's in between gears and not completely engaged with either 1st or second gear . It's also making a noise like there's something loose inside the transmission , getting more noticeable and louder now . I replaced the tranny fluid and filter after I noticed this hoping this would make things better ..... Nope . I didn't mess with the kickdown cable or anything , but there is slop in the accelerator cable . I put a spacer to take up the slop to see what that would do , but it didn't help at all ( as far as the tranny's concerned anyhow ) . I read online about the flexplate maybe being cracked or loose bolts on torque convertor , but I'm thinking that would just take care of the noise issue , not the weird shifting , rumble / shutter . Maybe the torque convertor is bad ?

Any input would be great on how I can possible troubleshoot this issue . Thanks

oldsguybry

Actually after talking to the transmission place , it's probably toast . I'm now looking at a new built 700R4 for $2100.00 including shipping from Monster Transmission . It's either this place or Summit . I would also be needing a Posi rear of course , so I MAY be interested in buying one local to me near Milwaukee . Let me know if any of you have any extras laying around . Any input on this perhaps ?

BangScreech4-4-2

Do a thorough search on Monster Transmission before you commit to them. I've heard some iffy things.

RetroRanger

you can a get a th350 or 400 for alot less plus if you get the BOP case its a bolt in replacement, for the 700r4 youll need an adapter chevy to BOP plus some other trans related items (TV set up i think im no expert)

oldsguybry

I'll have to look into that , they told me it's a direct bolt on and all I'd need was the shortened drive shaft . I really would like something other then a three speed transmission to be honest with you . I can get a basic rebuilt TH400 for around $500 from Borchardt local to me , but again I'm not sure I want the three speed . I was going to call Summit tomorrow and see what they have to say also before I make ANY kind of decision on this . Obviously I'm not extremely knowledgeable when it comes to transmissions , so if there's anything else I should know I welcome the input . Thanks

olds 307 and 403

The 2004R is the direct bolt in. All you have to do is move the cross member back to the TH400 position. The torque converter lock up needs to be controlled on both as well. The TV cable, bracket and geometry is critical on both transmissions or they die quickly.

coppercutlass

You can probably rebuild your th350 with 200 bucks and 1 specialty tool that cost 40 which i can lend out . Pretty basic trans to rebuild.

For the TV cable i dont run one at all but if its in use it has to land right other wise it creates internal cross leaks which will make for an erratic shifting trans and will kill clutches. due to loss of pressure .

I have so many spare parts here i can probably set you up with parts to the point you wont need bushings, seals , and any hard parts. i got wayyyyy too many spare parts.

gs72

[QUOTE=coppercutlass;1046954]You can probably rebuild your th350 with 200 bucks and 1 specialty tool that cost 40 which i can lend out . Pretty basic trans to rebuild.

I agree with Copper, you can rebuild the th350 and install a posi diff
for way less than converting to an o/d trans. These cars ran for years with this trans with little to no problems. Here is where I buy my rebuild kits. They put the hardened parts in the kits nessesary to handle more hp and torque. Check them out.

http://www.makcotransmissionparts.com/350-350c.html

oldsguybry

Do you guys think I should then stay with the TH350 , or get the TH400 . I have a 68 Toro 455 in my car . More importantly , what should I get beefed up in either transmission to handle the 455 ?

coppercutlass

The th350 has a few weak points but unless you have a built 455 the stock 350 should handle it. Im running low 12's in my 72 with a small block and all i have is raybestos HD clutches, an outer race for the direct drum and good clearances and a shift kit. It has well over 75 1/4 mile passes and about 5k street miles all together in that last 3 years no issues.

you should be alright keep the rebuild simple and in stock form it should live behind a stock 455 even mild 455.

oldsguybry

You guys are right , I'm probably going with the TH350 . I've been looking at Summit , Jegs , Monster , and a few other places . It looks like I can get a built up version with cooler , torque converter , and case filled for around $1200 . Let me know anything else I may need to know , or better places to look at . Thanks

oldcutlass

Ask your reputable local trans builder what it would cost to built a T400 to stand up to what your future performance plans are. Get a drive shaft and then drive it like you want.

coppercutlass

You are in Milwaukee you should look at atd transmission in Germantown wi. personally I think your th350 is still a good candidate to be used behind your bbo for your needs. My buddy ran one into the 11's behind a 455. Its a pretty sturdy trans with a few weaknesses that are easily remedied. Biggest being the bushing support. In a few areas extra wide bushings are needed to better support the input and output shafts.

oldsguybry

I appreciate the input , will look into this . I'm not going to necessarily have a drag car and I don't beat the crap out of my car , so i think the TH350 will hold up .

oldsguybry

I would like the TH400 , but there's the drive shaft shortening issue . I'm too impatient to wait around . I figured on getting the TH400 down the road and then maybe sell the other one .

matt69olds

The th350 will handle some serious power if built right. Dual feed the direct clutches, machine the direct clutch piston to fit 5 frictions instead of the factory 4. Do some simple valve body modifications, install a wide direct clutch drum bushing, pay attention to clearances and end play, not much more is needed. I have built many that live in the low 11s/high 10s with no issues. The biggest weakness is the intermediate sprag, there are aftermarket drums with upgraded sprags If the factory part breaks.

oldsguybry

Bought a rebuilt TH350 today with a mild TC . Rated for 500HP at around 450FPT . Will chime back in on details when I get the time .

oldsguybry

Ok,I installed the TH350 I bought from Borchardt and the car has tons of power now . However I did notice it shifts a bit weird , I think it may be the vacuum lines from the modulator to the intake perhaps . Here's a picture of the routing I have now , please let me know if anything looks wrong to you . Thanks .....

coppercutlass

Define weird

oldsguybry

Not very helpful , this was a 68 Toro 455 , and this is what was set up on the motor when I installed it . I have no idea what was done from the PO , or what the original routing is supposed to look like in the first place . I'm still learning about certain things when it comes to how this beast ticks .

coppercutlass

The routing wont affect it unless its pinched,kinked or disconnected.

oldsguybry

I'm going to replace everything I can then . The hoses are all new but will replace anyhow , including the small metal line going to the modulator , Thanks .

76olds

I had my TH350 rebuilt a couple years ago for $1150.00 at a local trans shop, I supplied the converter. HD clutches, thicker flex plate, hardened shafts, new bell housing 2 quart deeper aluminium pan and other things that I forget now.
I'm just running a 350, however I had it built to handle a decent BBO build or max effort 350 build with no issues.
Hope this helps,
Eric

coppercutlass

You suppied all that stuff and paid over 1k ? Thats high. A good rebuild kit with hd clutches cost about 250 add another 250 for the upgraded drum assembly and 75 bucks for a better center support like fron a 700r4. Labor wise its like 250 bucks for a bench job. I built my own and between parts and 3500 stall converter (used) i have 350 bucks i ended up with a drum assembly in a parts deal.

76olds

I just supplied the converter and summit deep trans pan, The $1150 covered the RE & RE as well.
I didn't look at the costs of the rebuild kit, new bell housing and the thicker flex plate etc but I thought it was a fair price.
Now that my son is 19 and has an interest in Oldsmobile's, I'm sure we will get a father son project in the spring.
He's already bought a 26 gal compressor , sandblast cabinet, welder and socket sets.
He's eyeballing up the 70-72 cutlass supreme's so their will likely be one in the garage soon haha. Unless I fire him for coming into the shop late at least 3x per week lol. That will put a damper on his dream car haha.

coppercutlass

3x late per week !!!!!! that's uncalled for. work makes money and money buys what I want. you take care of the hand that feeds ya and the rest falls into place he needs to learn that lol. Even in my younger years I never showed up late and rarely took sick days and or personal days. 10 years into my trade and yeah I'm finally taking vacations.

olds 307 and 403

We get raped up here. My old boss charged $900 for a trans R+R with a used trans supplied 20 years ago. I would be surprised if our local shop would do my TH350 for that price. I am glad you guys have so much faith in the TH350. After seeing two fail behind a stock 75 and 76 Olds 350's, I am surprised a basic rebuild plus a couple of better parts is all that is needed to live behind big power.

oldsguybry

Yeah I paid too much for mine also , I never tried to rebuild a transmission myself , so that would probably be out of my league . I paid $900 for a rebuilt TH350 ( 500HP rating ) with a mild torque conv .

OLDSter Ralph

I have a local shop that may not be cheap......$1,000 for overhaul and improvements (clutches, shiftkit, etc.).....for a Turbo 400. I suggest finding a shop that is a drag racer or ex-drag racer. They seem to know what stands up best.
Ralph

coppercutlass

Oldsguybry. The th350 is pretty basic. It seems intimidating but a few good tech reference books and perhaps 2 or 3 specialty tools that cost under 120 bucks for all.

coppercutlass

olds307&403 clearances and end play are huge with the th350. I have had my th350 apart after my rebuild for a pump ring that split and caused a cross leak where I started to loose 2nd gear . 25 cent part I had to yank and fully dis assemble and clean my th350. Got to see it holding up though which gave me peace of mind. still running strong.

OLDSter Ralph

If you don't feel confident doing it, then it was money well spent. Maybe next time you can watch the shop do it and learn while watching them.

olds 307 and 403

Same as any trsns and the bushings also in the TH350. I say 4L80E is the way but far from cheap or bolt in.

coppercutlass

I got lucky and the junkyard trans I bought was rebuilt at one point. It had all new bushings and all within spec. But it must have been for a v6 because it had 3 and 4 clutch pack drums. I had to cut them all and get different selective plates to accommodate the extra clutches. Burnt up cores are cheap so I bought a bunch with good pumps and hard parts that where good specially to avoid replacing the bushings. That's the worst job of the rebuild.

gs72

If you really want an overdrive in the future here you go.
https://www.gearvendors.com/cg2wd3s.html

VinMichael

$900 for a th350 rated for 500 hp with a torque converter is a good deal.

I rebuilt mine with Ron Session’s book and a guy named jakeshoes’s specs. It took me 7 months to build it between studying how to do it and sourcing tools.
And I still paid around $500 in parts.

So the difference is $400 plus 7 months of your time and you hopefully have a warranty with the unit you bought.