finally driven my car after 2yrs build up but...

[Jonuk]

I finally got to take it out on the road on Sunday for its maiden voyage, basically a fault finding trip so i can keep improving it, but one thing has me stumped !

When driving (pretty slow and calmly) i get a load of shudder when the car shifts from 1-2, its fine the rest of the time, if i drive it harder, i get less shudder, almost as if its shuddering at a specific RPM. The sudder is like the pinion angles are screwed and its eating a UV joint !

I'm completely new to Auto box's having only ever had manuals so any advice would be great.

P.S its a bog stock 231 3.8 N/A bolted to whatever gearbox they put in those 1980 regals

 

[TwinyTwin]

Does this happen only when you are accelerating or does it also happen when you are decelerating? I had some what the same problem with my car a little while back and found out my u-joint for the drive shaft was busted. The car would shutter very bad on accel and decel and would smoothen out at higher rpms but still have a shutter just not as bad. My suggestion is check your drive shaft and see if its bent, check to see the drive shaft bolts to the tranny and diff are secure, and take a look at your u-joints. GOOD LUCK!

 

[Jonuk]

Its only on acceleration during the change up from 1-2 but i'll check out the drive shaft and all the fittings, thanks for the tip

 

[JDSfastGN]

sounds like maybe the TCC solenoid is locking right when it hits the 1-2 shift making the car shudder due to the load and low rpms. Unhook the connector on the side of the tranny and take it for a quick spin (don't drive for to long with it disconnected) If it doesn't shudder then thats what it is. (the solenoid could be stuck as well so unplugging may not keep it from locking)

 

[Jonuk]

TCC ? i'm guessing throttle cable connector ? (excuse my ignorance i'm new to all this)

Will try that first as it sounds easiest :redface:

Thanks

 

[JDSfastGN]

TCC ? i'm guessing throttle cable connector ? (excuse my ignorance i'm new to all this)

Will try that first as it sounds easiest :redface:

Thanks

TCC= Torque converter clutch lock up.

 

[Jonuk]

Ahhh the tcclu LOL... D'oh !

 

[Jonuk]

Hmmm so i went up to the garage last night to unplug the TCC.... Two things:
1) i have no idea what this thing looks like !
2) i have no real idea where to find it !

These two things combined made it impossible to unplug. I looked through a Haynes manual and a Chiltern manual and there was no mention of it, i layed under the car looking at the transmission and saw nothing, took the air cleaner housing off and looked all over the engine bay for something connected to the transmission and found nothing.

From the post above it should be on the side of the trans, but there was only some brackets and springs etc nothing that would 'unplug' ?

any ideas what this thing looks like and where it is ? a picture would be a great help right now. :redface:

 

[QUIP'6']

Hmmm so i went up to the garage last night to unplug the TCC.... Two things:
1) i have no idea what this thing looks like !
2) i have no real idea where to find it !

These two things combined made it impossible to unplug. I looked through a Haynes manual and a Chiltern manual and there was no mention of it, i layed under the car looking at the transmission and saw nothing, took the air cleaner housing off and looked all over the engine bay for something connected to the transmission and found nothing.

From the post above it should be on the side of the trans, but there was only some brackets and springs etc nothing that would 'unplug' ?

any ideas what this thing looks like and where it is ? a picture would be a great help right now. :redface:

its on the driverside of the tranny its a square plug

 

[Jonuk]

knew it wouldnt have been that easy

ok so i'm laying under the car and on the drivers side of the trans i can see, in the following order from front to back:


the linkage:

then this overflow looking pipe up the top:

this odd cover with a spring clip (normally means there's a gasket and oil underneath so i didnt pop it off although i was tempted !

what i assume to be the speedo cable ?:

then when i crawl further under the car and get the passenger side of the trans i see:

what looks like the oil lines to the cooler upfront and the dipstick tube?

this wierd looking pink thing that looks like a valve but has a stainless hardline attached to it (oil temp maybe ?) noted its covered in oil so probably not registering too well either , i'll clean it up !

(all pics taken with a phone so please excuse the crap quality)

i also noted down a 'part' or serial number from the side of the trans, i'll post it here, but i'm off to hunt it down in google or whatever... its 4A7118240 not sure if this specifies anything.

I've also been reading about TCC's and apparently they operate by a feed from the ECU, my car doesnt have an ECU its a carbed 3.8 N/A does this change things a lot ?

thanks for the help so far

 

[A. G. Olphart]

knew it wouldnt have been that easy

this wierd looking pink thing that looks like a valve but has a stainless hardline attached to it (oil temp maybe ?) noted its covered in oil so probably not registering too well either , i'll clean it up !

I've also been reading about TCC's and apparently they operate by a feed from the ECU, my car doesnt have an ECU its a carbed 3.8 N/A does this change things a lot ?

thanks for the help so far

The wierd looking can you found is a vacuum modulator... it raises presures/ firms up shifts under heavy throttle, low vacuum driving. It should have an air tight diaphragm in it, and no oil inside the line itself.
The reason you can't find the TCC plug: Your 3 speed transmission doesn't have one.

(The guys on this board are used to the 200R4 that comes in the turbo Buicks- You are on your own)...

 

[LV GN]

it sounds like the 2nd gear clutchs or sprag is bad. does it do it on the shift from 2nd to 3rd?

 

[Jonuk]

it sounds like the 2nd gear clutchs or sprag is bad. does it do it on the shift from 2nd to 3rd?

no, it only does it from 1st to 2nd. :frown:

so i'm guessing my gearbox is a straight th200 then ? i may have to look into rebuild kits.

Suprising no-one on here has asked about the fluid, it could be old or on its way out, its a golden brown colour with a hint of red (hard to describe really) and it smells of RUBBER !???

I'll change it today to see if it helps, but i think a rebuild is on the cards.

 

[LV GN]

its a th350 trans.

 

[DeltaT]

Can you take a shot looking up at the bottom of the pan? Then I could tell for sure what the tranny is...

Jim

 

[Jonuk]

Can you take a shot looking up at the bottom of the pan? Then I could tell for sure what the tranny is...

Jim

is that to identify it by the pan shape ? its the square one with one corner shaved off, i can try and get a pic tomorrow, but i reckon you may be right about it being a th350 as i found this website with good diagrams etc http://charlietranny.com/GM.htm and it seems to match up prefectly ! (except mines dirty !)

the gasket:

drivers side:

passenger side:

well at least i know what it is !

 

[Jonuk]

scrap that, i've just been looking more at that site with all the transmissions on it and looked up the th200 to double check and they're identical to the TH350 except:

It had an aluminum case. Pan shape was similar to 350 THM, but was embossed "METRIC". It had no modulator and there was no removable extension housing

mine has "METRIC" embossed on it.

ho-hum.

 

[A. G. Olphart]

scrap that, i've just been looking more at that site with all the transmissions on it and looked up the th200 to double check and they're identical to the TH350 except:


Quote:
It had an aluminum case. Pan shape was similar to 350 THM, but was embossed "METRIC". It had no modulator and there was no removable extension housing


mine has "METRIC" embossed on it.

ho-hum.

Not exactly ho-hum... Your first set of pictures show both the vacuum modulator (last picture) and a bolt on extension housing (pictures 3 and 4). I'd say it is a 350; will the pans interchange?

 

[Nordbert]

Transmission ID

I've never seen a TH350 pan with " METRIC " on it, but the bolt-on tail-
housing, the modulator, lack of a TCC plug on the left side of the case, the governor cover and the small diameter kickdown cable housing tell me that the pictures you posted are of a non-lockup TH350.

 

[Jonuk]

guess what.

i think i've fixed it..... with all your posts and a lot of reading.

the shuddering was obviously when it was under load, what else happens when the car is underload, the pinion angle changes... so i thought i'd investigate that at little on the off chance. I've fitted Edelbrock adjustable upper trailing arms that 'apparently' come adjusted to stock length ! got the measure out, the stocks are 11" from bolt hole to bolt hole mine were almost 12.5" from bolt hole to bolt hole and they were not even even !

I found that the pinon was increasing enough to make the shuddering and also if your adjustable arms are more than 3mm out it screws the whole back end up !!

thanks loads for your help, it has been a real eye opener. :smile:

Now i need to cruise the car around a little to confirm that all the shuddering has disappeared <fingers crossed>