TCU with A/T compatibility

[jszuba]

Hello again
I'm back to my old CB7 after a very long break, and trying to resurrect it because it - although still driving - has developed a few issues, main one being the A/T shuddering/thumping when shifting from first to second gear (changed fluid to little/no improvement).

So I'm considering buying a used tranny I have [miraculously] found nearby, and replacing it.
The original failing one is a MPXA and I've found a PX4B.
Sources say that these are a H4A family trannies for the 90s Accords, Preludes, Odysseys and what not.

Question: Can I keep my original TCU? Or will I be needing a specific one for the PX4B?
Can anyone also confirm the trannies are interchangeable?

As always, input/help greatly appreciated.

[deevergote]

You should be able to keep your old TCU with no problems whatsoever. Before you replace your transmission, inspect your mounts (transmission and rear engine mount especially). That sort of behavior could be indicative of a bad mount, rather than a bad transmission. Could be both, too. Bad mounts could be making transmission issues seem more severe than they really are.

Glad to see you've still got the CB!

[jszuba]

Thanks! This is great news!
Sourcing parts here and these days is a royal pain in the... trunk

I was going to dismiss the mounts as the source of the thump, but I will follow your advice just to make sure.

It is my belief that the source of the failure is a WOT when coasting in neutral. First, the shudder would manifest itself badly when reversing, to what felt like the engine stalling, until I changed the fluid and drove some. Now it just shudders/thumps when going 1st > 2nd, unless I keep the revs down/let off of the pedal for a precisely timed moment just before the shift to 2nd. Under hard acceleration, it feels like being hit with a wrecking ball... :/

[deevergote]

That may be a transmission issue, then. Check the mounts to be sure, since they're certainly cheaper to replace.
Are there any transmission error codes showing? If you still have your 92, the codes should be indicated via the D4 light. I'd think that if there's a major issue, an error code might be present.
I've only ever had manual transmissions in my CB7s, though... so any knowledge I have is only what I've learned from people here on the forum!

[jszuba]

It hadn't occurred to me to check the error codes
None have shown up i.e. D4 is on when in gear, but not blinking.
Will check tomorrow and keep posted.

Ah, manuals... I wish this was a manual. Would have made things sooo much easier.

[deevergote]

You could always convert! (though I'm sure finding a donor in Poland is a bit more difficult than finding one in the US...)

[jszuba]

Hah, yes, converting would be the way to go - of all 4 (yes, FOUR) cars available for sale in the whole country, all are manuals.

However, I'm not a fan of cutting and welding the transmission mount :/ and I do want to keep it VIN accurate.
Here in Poland you can register a car that is over 25 years old with historical yellow plates. The car has to be 75% original and you have to document this and get it appraised and approved by the local equivalent of DMV - which I'll be aiming for once I sort my CB out.
Benefit? Cheaper insurance, which can be suspended say, for winter, and a one-off technical inspection (instead of mandatory yearly).

Back on topic:
Oh, I did check for CELs and D4 codes - nothing. The motor mount as far as I could see in the tight space seems fine, but I will get my mechanic to double check to rule it out.