I searched the previous posts, and could not identify the possible cause to the heavy clunk that occurs when my 1993 Accord Anniversary Edition auto tranny shifts under medium to hard acceleration to second and third speeds. Any ideas would be appreciated.

 

Could be bad halfshafts or old tranny fluid. Change the fluid with genuine Honda ATF and see if the problem persists.
This thread is similar to your problem but not exactly. It may help...
https://honda-tech.com/zerothread?id=413359

 

Honda automatic transmissions are not among the best. One that old is gonna have problems. Sounds like a failing torque converter or lockup clutch to me. Since it's in the higher gears, probably the lockup clutch. When new, my mom's 90 Civic EX auto tranny failed within a year. It was replaced no charge no problem. The current tranny, now over a decade old, is having the same symptoms.

 

I think you guys are on the right track. It does have 140K miles on it. This is a definite heavy feel like a half shaft or torque converter. I changed the fluid about 12K miles ago when I bought it, and added Lucas transmission fix to it about a week ago. The shifting has smoothed out and the clunk has not returned; however, I limit the intensity of acceleration now. The referenced thread was encouraging to learn that even with a clunking, it keeps on ticking!

 

If the problem persists, there are a few wiring problems that have been found, that cause harsh shifts as well.

 

would you care to share those with us?


thanks.

 

yea, if i could get my 92 to shift more smoothly, that would be great. ah, the joys of driving an auto!

 

That thread helps alot. I have a 1990 Accord EX Sedan with 161k on it..... when you are backing out of your driveway or a parking space, and your car is still cold, if you have no cars driving by in direct proximity switch from reverse-brake-switch to D4 till you hear it click into place. That was already mentioned. I tend to do this alot more often... reverse-neutral (keep it there for like 2 seconds)- switch to D4 and the clunk is removed.
My tranny has the same symptoms that all of you are having but mine also tends to slip when it shifts from 2nd-3rd gear, you can see the rpms jump about 300-500 rpms in between the shift and it will happen when you have your foot on the gas. You know how you can make your tranny shift by giving it gas and than letting it go a little and than give it more gas when it shifts well when i do that it shifts more easily. My dad took my car to a tranny specialist and the guy told my dad that it would cost $1k to fix the tranny or buy a new one or something of that sort (this was like 2 years back) and that its not a big problem just be easy with it and just dont push hard on it. Drive it so that it dont clunk. Alot of the times thats really impossible to avoid.
Anywho, i hope i helped you and whoever else was having this problem out a little. I changed my tranny fluid and the problem still persisted. Just go easy on her and all will be well!

 

The following are some Fixes I have performed in the transmission shop. I have seen this problems on several Accords.
If your Trans. Jerks when shifting, and throws no codes, the ECM can be the cause of the problem, BUT the cause of the problem is usually a short or open in he FAS wire between TCM Terminal D16 and the ECM, This short or open can some how screw up the computer. (Replacing the computer may not be a perminant fix)
Another problem I have found on a few Accords is a defective Mainshaft Speed Sensor, this problem like the one above, will not throw codes sometimes.
Keep in mind the honda automatic transmission is well known for its harsh shifts. But I see very few hondas pass though this shop. They are well built transmissions.

You can also smooth out your shifts by adjusting your throttle control cable to your trans. BUT BEWARE, if you smooth it out to much, it can burn up your clutches, because you are actually backing off the pressure that applies the clutches. If you like to race a lot , boost this pressure for better application (ex. NOS) . Set it where you like it to shift, then stop by a transmission shop and ask them to test drive it, to see if it is applies good enough.
I hope this info helps. Just dont go crazy adjusting your Cable, 1 notch at a time can make a huge differance.

 

How interesting. If only I had known then.