1965 Muncie Tail housings - 3846429 to 3857584 which is correct

[Ronald L.]

From some web sources the 7584 was not used until 1966 (5speeds.com).

Al Colvin book By the numbers says February was the change over month.

I've recently seen originals un-molested Early November dated, with all casting dates, aligned, never been opened 65 Corvette Muncie with VIN, with the 7584 tail housing.

Both sources are wrong?

What's the 65 JG or other understanding of when the change over occured?

[Ray K.]

Re: 1965 Muncie Tail housings - 3846429 to 3857584 which is correct

Ronald,

All 1965 Muncie should have the #7584 extension housing. This housing moved the speedometer fitting position to the right side versus the left side as used by the #3846429 housing used for 1963 - 64 years.

Ray

[Jim D.]

Re: 1965 Muncie Tail housings - 3846429 to 3857584 which is correct

Both my April built and May built 65's have the #7584 extension housing. To add to what Ray said regarding the speedo fitting, the new position has the bullet pointing slightly downward and that allowed trans. fluid to wick up the cable and into the speedometer causing all kinds of problems. It took a year or two for GM to come up with a recessed seal around the plastic gear to prevent this. Be sure to use the newer style with the seal.

[Joe L.]

Re: 1965 Muncie Tail housings - 3846429 to 3857584 which is correct

Both my April built and May built 65's have the #7584 extension housing. To add to what Ray said regarding the speedo fitting, the new position has the bullet pointing slightly downward and that allowed trans. fluid to wick up the cable and into the speedometer causing all kinds of problems. It took a year or two for GM to come up with a recessed seal around the plastic gear to prevent this. Be sure to use the newer style with the seal.

Jim------


The fitting was last available under GM #345215. It's discontinued now but an identical replacement is easily available in the aftermarket. All that I've seen have the internal lip seal.

[Jim D.]

Re: 1965 Muncie Tail housings - 3846429 to 3857584 which is correct

Jim------


The fitting was last available under GM #345215. It's discontinued now but an identical replacement is easily available in the aftermarket. All that I've seen have the internal lip seal.

Joe, I believe the extra seal was added in 1966 so all those made in the last 50+ years would have one. My warning was aimed at those 65 owners that may still have the original speedo bullet without the seal. Both my 65's had the original bullet and both had issues caused by no seal.
One had 60K miles and trans. fluid had made it all the way up to and into the speedo. The other only has 30K miles so the trans. fluid only gummed up the bottom half of the speedo cable but didn't make it all the way to the speedo. I've talked with other 65 owners that have had the same issues. It's a $15 fix to keep from having to pull the cluster and having your speedo rebuilt.
Here's a pic. of what can happen:

[Ray K.]

Re: 1965 Muncie Tail housings - 3846429 to 3857584 which is correct

Jim,
The problem that you describe is how it developed with my '65. After 2 or maybe 3 years ownership the speedo stopped working and when disconnecting the cable it flowed an amount of trans oil from the cable and the speedo, This required removing the cluster and flushing all the fluid out and re-calibration of the speedo. The new design housing with the internal seal was available so I purchased and installed it as well. All was good for another year ( or maybe 2 ) when the same problem presented itself again and required cluster removal once more.. The speedo shop in San Diego that was the GM authorized repair facility for our dealership and all others suggested making a reverse wound speedo cable that would prevent the siphoning effect of drawing the trans oil up the cable into the speedo. We did this and never a problem again and it is still in the car today with the original cable stored along with my other Corvette supplies.

Ray

[Jim D.]

Re: 1965 Muncie Tail housings - 3846429 to 3857584 which is correct

Ray, That's interesting. I've never heard of a reverse wound speedo cable.The addition of the seal eliminated the problem in later cars. I haven't had any problems and one of my 65's was restored over 7 years ago. The other has only been 2 years. I can't see how trans. fluid could enter the cable with the "new" seal. It sure looks like a positive fix to me.

[Joe L.]

Re: 1965 Muncie Tail housings - 3846429 to 3857584 which is correct

Ray, That's interesting. I've never heard of a reverse wound speedo cable.The addition of the seal eliminated the problem in later cars. I haven't had any problems and one of my 65's was restored over 7 years ago. The other has only been 2 years. I can't see how trans. fluid could enter the cable with the "new" seal. It sure looks like a positive fix to me.

Jim and Ray------


I don't see how, either.

By the way, the seal, GM #3869910, is also discontinued without supercession. I expect it's available in the aftermarket, though.