Hot Rod Forum banner
1 - 7 of 7 Posts

·
Registered
Joined
·
65 Posts
Discussion Starter · #1 ·
Hey guys,
I have a 85 Impala with the carb'd 305 and 700r4

Its been about a week since I drove it but today I decided to use some SeaFoam and take her for a spin.

Before today it would shift fine without a problem but after I used the SeaFoam it seems to hold 1st a lot longer, around 3k it shifts from 1st and it jerks a tad like I have a shift kit:sweat: (I don't )

The only things that changed since the last time I drove is the outside temp(got colder), installed headers and used SeaFoam.

So what do you guys think is goin on? Is my trans going out?!
 

·
Registered
Joined
·
357 Posts
I assume from your description that it shifts normally from 2-3, 3-4. If its shifting late in all gears, it could be a sticking governor, or you TV cable or valvetrain may be sticking or faulty. If it's only shifting late from 1-2, I would suspect a sticky 1-2 valvetrain. Has the trans ever been rebuilt? If not, it will have a fair amount of clutch material built up in the pan. This gets into the fluid and collects throughout the transmission. This can cause valves to stick. Also, the valve body uses aluminum bushings around steel valves. The aluminum wears and the valves begin to catch on the ridges formed in the aluminum bushings. Some of these units used an aluminum valve body that wears in the valve bores and needs to be either repaired or replaced.

You could try servicing the trans fluid and filter and adding a product like Lubeguard. The Red Lubeguard is good for transmissions that take Dexron II or III. Lubeguard adds a little extra lubrication to the fluid and can help things move a little better. However, if this is a high mileage unit, you most likely need an overhaul which includes a thorough inspection of the valve body.
 

·
Registered
Joined
·
65 Posts
Discussion Starter · #4 ·
I assume from your description that it shifts normally from 2-3, 3-4. If its shifting late in all gears, it could be a sticking governor, or you TV cable or valvetrain may be sticking or faulty. If it's only shifting late from 1-2, I would suspect a sticky 1-2 valvetrain. Has the trans ever been rebuilt? If not, it will have a fair amount of clutch material built up in the pan. This gets into the fluid and collects throughout the transmission. This can cause valves to stick. Also, the valve body uses aluminum bushings around steel valves. The aluminum wears and the valves begin to catch on the ridges formed in the aluminum bushings. Some of these units used an aluminum valve body that wears in the valve bores and needs to be either repaired or replaced.

You could try servicing the trans fluid and filter and adding a product like Lubeguard. The Red Lubeguard is good for transmissions that take Dexron II or III. Lubeguard adds a little extra lubrication to the fluid and can help things move a little better. However, if this is a high mileage unit, you most likely need an overhaul which includes a thorough inspection of the valve body.
Thanks for your reply Doc,

Yes its only the 1-2 shifts that hold too long, the car only has 55k on the dash, trans has never been rebuilt at least to my knowledge (bought last year).
The T.V cable is fine, I didn't change it since I bought the car.

Changing the fluid and filter sounds good, any tips to do so?
I've never changed atf or even dropped the pan (my first car)
 

·
Registered
Joined
·
65 Posts
Discussion Starter · #5 ·
I just got back from a ride around town and now its completely fine, I don't get it.
It now shifts 1-2 at 1500rpm around 15-20 mph just like when I bought it.
I'm now starting to think the t.v cable setup is getting caught on something :(
 

·
Registered
Joined
·
357 Posts
If all other shifts are normal, it's more likely a sticking 1-2 valvetrain. To change fluid, you need to drop the pan. You will also want to replace the filter while you're in there. The trick to dropping the pan is to do so without bathing in ATF. The best way to do this is to use a large drain pan and loosen the pan bolts in a pattern, starting from the front. Generally, the fluid will begin to drain from the front of the pan as you loosen the bolts. Once the bolts are loosened, remove all but one bolt on each side close to the rear of the pan. Then, while supporting the pan with one hand, remove the last two bolts and gently roll the pan towards the front, allowing the remaining fluid to pour into the pan. On some installs, the rear crossmember restricts access to the rear pan bolts so that you have to raise the rear of the trans slightly to get those bolts. On these units, I generally remove those bolts first, then move to the front and follow the pattern I detailed earlier. The filter just pulls loose by hand with a little twisting back and forth. The filter to case seal may be either rubber or rubber embossed steel. Using a large screwdriver, you can carefully pry it out. Do not dig the screwdriver tip into the case or you,ll create an internal leak.
Recognize that the 700R4 holds about 12 quarts of fluid. Much more than the pan holds. When at rest, the fluid is way above the edge of the pan and will begin to drain as soon as the pan seal is broken. In a pan drop service, you'll replace about 5 quarts of fluid. You can have a shop that is so equipped perform a fluid exchange, using a machine that is designed for this. I do this here at my shop. We run 16 quarts through the trans via the cooler lines. In reality, with intermixing of old and new in the trans, it probably actually replaces about 7-8 qts of the total fluid. But it's better than nothing. Remember the Lubeguard. Lubeguard is a great product that doesn't have any affect on seals and doesn't try to be a fix all. It's just a combination of friction modifiers and lubricants that improves valve operation and reduces wear of bearings and bushings.
 

·
Registered
Joined
·
65 Posts
Discussion Starter · #7 ·
If all other shifts are normal, it's more likely a sticking 1-2 valvetrain. To change fluid, you need to drop the pan. You will also want to replace the filter while you're in there. The trick to dropping the pan is to do so without bathing in ATF. The best way to do this is to use a large drain pan and loosen the pan bolts in a pattern, starting from the front. Generally, the fluid will begin to drain from the front of the pan as you loosen the bolts. Once the bolts are loosened, remove all but one bolt on each side close to the rear of the pan. Then, while supporting the pan with one hand, remove the last two bolts and gently roll the pan towards the front, allowing the remaining fluid to pour into the pan. On some installs, the rear crossmember restricts access to the rear pan bolts so that you have to raise the rear of the trans slightly to get those bolts. On these units, I generally remove those bolts first, then move to the front and follow the pattern I detailed earlier. The filter just pulls loose by hand with a little twisting back and forth. The filter to case seal may be either rubber or rubber embossed steel. Using a large screwdriver, you can carefully pry it out. Do not dig the screwdriver tip into the case or you,ll create an internal leak.
Recognize that the 700R4 holds about 12 quarts of fluid. Much more than the pan holds. When at rest, the fluid is way above the edge of the pan and will begin to drain as soon as the pan seal is broken. In a pan drop service, you'll replace about 5 quarts of fluid. You can have a shop that is so equipped perform a fluid exchange, using a machine that is designed for this. I do this here at my shop. We run 16 quarts through the trans via the cooler lines. In reality, with intermixing of old and new in the trans, it probably actually replaces about 7-8 qts of the total fluid. But it's better than nothing. Remember the Lubeguard. Lubeguard is a great product that doesn't have any affect on seals and doesn't try to be a fix all. It's just a combination of friction modifiers and lubricants that improves valve operation and reduces wear of bearings and bushings.
Wow, thanks for the info. I really appreciate it :thumbup:
:D
 
1 - 7 of 7 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top