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Transmission Bang

caleb22

caleb22

1/2 ton status
Joined
Apr 15, 2005
Posts
243
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Location
South Carolina
Hi all...new here. Man I'm glad I found this site. What an awesome place to hang around in and learn from.

Just bought a 89 Blazer Silverado. Runs great, looks great, but I've started to notice that the transmission going from say 1st or 2nd will "bang" into gear. Also, when you slow down, just before coming to a stop, it will "bang" again. I know "bang" could mean anything to anyone, but the transmission jerks into 1st I guess is what I'm saying. Whether or not I use OD doesn't matter.

I paid next to nothing for it, so if I have to do tranny work that's cool with me. I'm just curious if anyone has any ideas as to what it could be.

I assume it's a TH400 tranny based on my VIN, but I'm not sure.

Thanks!

Bill
 
BTW, I'm new to the Blazer family also. I'm not a mechanic by any means. I originaly had a 76 CJ7 a few years ago that I tore down to the frame, but once my little one came along I had to sell it in pieces.
 
If it's an 89, you have a 700R4. When my 89 started doing that, I ended up with a new tranny and an empty bank account...
 
If its a th400 , you wouldn't have overdrive . Its a th700r4 if you have overdrive .

Now I do not know who went through mine for the previous owner , but I have simmilar things going on .

Mine will shift pretty snappy on the 1-2 , and downshift pretty hard when not in overdrive at stoplights .

It got more pronounced with lower gears .

Mine doesn't downshift like that in overdrive , but when you take off , sure enough if its the right gear .

Doesn't neccessarily mean the tranny is bad . Firm shifts mean less friction and cooler temps .

I have over 40,000 miles on mine , including wheeling , plus whatever were on it when I got it .

Perhaps a simple inspection by a tranny shop is in order .
 
I think they tend to shift softer when low on fluid...but I'd still check that first. I would have someone in the know look at it...mine just took a dump on me and it cost me $160 to get it towed home. What kinda milage does it have on it?
 
Post up your mileage and that whould help some, as stated check your fluid level. Also smell it to see if its smelling a little burnt.....if it shifts fine after first and down to first you may check your u-joints for play. 700r4's are strange creatures however they tend to lose OD and reverse first.
 
God help me if I lose reverse :)

Mileage is 164K...but since I just bought it I don't know the history of it or any repairs that may have been done. You'd be surprised how good the motor and exterior are for it's age. Only issue that I have is the shifting part.

In the other gears it shifts ok, but once in a while it will "bang" with the others too. I haven't really driven it far yet, since I'm having a mechanic go completely through it Friday.

I'm just prowd to be part of the Blazer family...I've wanted one of these things for 15 years since I graduated HS...friend had one in HS with 38" tires, and I loved riding in it...especially after a few cold ones :)
 
If it bangs from the 2 to 1 downshift when in D and not in OD then it has a corvette servo in it. Meaning it has been rebuilt with some good stuff in it. Mine does this and it also has a really crisp 1-2 shift.
 
If you have a TH700R4, you might want to make sure the TV (throttle valve) cable is properly adjusted--have it checked by a shop that's in the know. It's pretty critical on the 700.

Jeff
 
Well, took it to a mechanic and they weren't sure what it could be. Said I would need to take it to an Aamco. My in-laws took their Buick to Aamco about 2 months ago and it cost them $2100 for a rebuilt tranny. I only paid that for the Blazer...jeez.

Mechanic said I had a t-case leak and my power steering is leaking somewhere. They put dye in them both but said it may take a while to find.

Anyone a mechanic or in the know in upper SC that wants to help me?

Really banging hard now...especially when I come to a complete stop.
 
caleb22 said:
Well, took it to a mechanic and they weren't sure what it could be. Said I would need to take it to an Aamco. My in-laws took their Buick to Aamco about 2 months ago and it cost them $2100 for a rebuilt tranny. I only paid that for the Blazer...jeez.

Mechanic said I had a t-case leak and my power steering is leaking somewhere. They put dye in them both but said it may take a while to find.

Anyone a mechanic or in the know in upper SC that wants to help me?

Really banging hard now...especially when I come to a complete stop.
Click to expand...


when i lost my 700r4 the first thing was that is started to shift real hard going into 2nd and 3rd. Also this might sound dumb but are you sure its your tranny? Do you still have auto hubs? When i would go backwards then drive for a while my auto hubs would do somecrazy things while i was driving that first sounded like my tranny, also check your u joints
 
When mine did that, it was a combination of a misadjusted TV (throttle valve) cable and old fluid. I adjusted the cable, replaced the trans filter, flushed the old fluid, and added a 30k GVW trans cooler. It's been fine ever since.
 
Well, thanks for the tips guys. Looks like though the tranny issue may not be the big one. When I drive around smokes comes out of the tailpipe every time I hit the gas. Guess it could be rings or something going bad.

Crap...have only owned it 4 weeks and all this crap happens :(
 
what color is the smoke? If its just at WOT, dont worry about it. If its constant, then yeh could be probs. Take off the oil fill cap and put your hand over it. You are feeling for blowby, a strong breeze, yeh rings are shot, just a little, its just age, and could be something else leakin in. How much oil is it using?
 
It doesn't use much oil at all, but the guy I bought it from said it used 1/2 a quart a week and he was driving 100 miles a day with it. The smoke is light gray, and it only smokes while I'm going down the road giving it some throttle.

I'm going to have a local guy give me a free tranny inspection tomorrow.
 
Dropped the blazer off at a local tranny repair place. They assessed the problem as a bad valve body so they are rebuilding it and changing the tranny filter for under $200. Evidently the guy who had it before used some cheap parts and had it all out of adjustment.
 
700R4's are very sensitive to throttle valve cable adjustment. Very sensitive! This is easily adjusted. Check out these sites... http://www.transmissionhead.com/, and http://www.eatmyshift.com/, or http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33727&item=7968722524&rd=1. Lots to read about in trasmissionhead.com . I wonder if MadDogLou is the right guy, as he is "small". Never dealt with any of these shops, but it's only a matter of time... :frown1: . As far as your hard downshifts are concerned, one of the many complicated things a 700 does is "dump" oil via a solenoid in the valve body. This is to unlock the torque converter that usualy "locks up" above 35ish MPH. If it's sticking, it might even stall the engine, like a stick-shift that you've forgotten to push in the clutch. This is one of many scenarios, I'm far from an expert. Though that problem is easily and $cheaply$ repaired. :o
 
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