1967 427/390hp--speedometer gear cable fitting in transmission
I have a new speedometer cable with a rebuilt transmission and the speedometer and odometer are not working on the dash. I removed the speedo cable from the transmission and turned the cable with a drill and it does move on the dash. I'm thinking it his the gear cable fitting that goes into the tranny. How hard is it to replace? It appears it screws out. I noticed corvette central has this part and the part number is 532574. Is this a standard part or is it dependent on the rear axle ratio??
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Re: 1967 427/390hp--speedometer gear cable fitting in transmission
The part you listed is the same for all ratios. Rear end ratio determines which plastic gear that slides into it is used. Did your speedo work before you had the transmission rebuilt? -
Re: 1967 427/390hp--speedometer gear cable fitting in transmission
Hey Jim...thx for the reply. Yes it did work previously. I suspect it was either the original gear cable fitting or at least from the early 70's. Is this an easy swap out?Comment
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Re: 1967 427/390hp--speedometer gear cable fitting in transmission
If the transmission was rebuilt, it is possible that the speedometer drive gear was not positioned correctly on the shaft, and that the driven gear is not engaging it.
1963 Corvette Conv. 327/360 NCRS Top Flight
2006 Corvette Conv. Velocity Yellow NCRS Top Flight
1956 Chevy Sedan. 350/4 Speed Hot RodComment
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Re: 1967 427/390hp--speedometer gear cable fitting in transmission
More than likely. I bought a 67 427/390 coupe many years ago with the same problem. Whoever rebuilt the trans didn't even get that gear close to where it needed to be on the shaft.
TomComment
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Re: 1967 427/390hp--speedometer gear cable fitting in transmission
Chuck------
YES! A real problem with 1963-67 and 71-74 Muncie 4 speed transmissions. The speedometer drive gear has to be correctly positioned on the mainshaft. This has to be done by accurate measurement since there is no otherwise indicated proper position on the shaft (i.e. the raised area on the shaft is much wider than the gear itself).
This is not a problem for 1968-70 Muncies, though. These transmissions used a nylon drive gear which was "locked" to the shaft by a special retainer that snapped into a special groove machined into the shaft. This system insured the exact proper location of the drive gear on the shaft.
Inexplicably, for 1971-74 it was back to the same design as used for 1963-67 although the drive gear, itself, was not the same (larger OD and ID).In Appreciation of John HinckleyComment
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Re: 1967 427/390hp--speedometer gear cable fitting in transmission
Dave------
Removing the fitting is easy. Just remove the small bolt that affixes the retainer to the transmission extension housing. Then, remove the retainer and simply pull the fitting out. It might take a little effort to pull it out because an annular o-ring seals the fitting to the extension housing. When you do this be very careful that the driven gear does not fall out of the fitting and into the transmission.
If you have to adjust the position of the speedometer drive gear on the mainshaft, that's a whole different story. You have to at least remove the extension housing and this is difficult, if not impossible, to do with the transmission in the car.In Appreciation of John HinckleyComment
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Re: 1967 427/390hp--speedometer gear cable fitting in transmission
That's where I was going when I asked the OP if the speedo worked prior to the rebuild. However, the correct placement is not that difficult. If you have a drivers side speedo fitting, the drive gear goes to the forward position of the machined surface like Chuck pictured. For a pass. side fitting that started in 1965, it goes to the rear of the machined surface
as pictured below.
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Re: 1967 427/390hp--speedometer gear cable fitting in transmission
Dave - Once you get the 'bullet' out of the tail housing, there's a chance that the plastic 'driven gear' will be chewed up a bit and in need of replacement. I've had that happen on a 66 Coupe that had the speedo working fine for years and then...no so much. Back then, I found that 'drive gear', the one pressed on to the trans shaft, was a bit off center and not making great contact. Enough contact to work for a while but it finally chewed the plastic teeth on the driven gear. If that's what happened, those plastic driven gears are cheap and easy to replace. Let's hope that's the issue.
Moose 17T Gear Pic 2.jpgMoose 17T Gear Pic 1.jpgMike T. - Prescott AZ.Comment
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Re: 1967 427/390hp--speedometer gear cable fitting in transmission
Still dealing with speedometer and odometer not working. Finally had a chance to look at it. How is the speedometer drive gear held on the mainshaft? I removed the fitting that goes into the tranny and the nylon drive gear (19 teeth, 4 spd 390hp) was present and appeared to be in excellent shape. I did see the drive gear on the main shaft and it appeared to be directly in front of the opening where the fitting is. One thing I noticed was that the nylon drive gear does not have the raised center piece that is ~ 1/4 " above the teeth--not sure if it wore down and became flush with the teeth?? Would this affect performance? I did connect the speedo cable to the fitting and turned the nylon drive gear with my hand while in the fitting and it does move the speedo needle on the dash. When the fitting goes back into the tranny is the nylon drive gear suppose to be fully pushed onto the fitting or should you leave it stick 1/2 way out of the fitting as you putting the fitting back in? I believe my fitting is original as well as the nylon drive gear. I'm wondering if I should just buy a new fitting and nylon drive gear to see if that is the problem? Otherwise maybe the drive gear on the mainshaft is not positioned correctly but it looks good to me?????Comment
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