Speedo question -

[Brian Lohnes]

Since I swapped the transmission in Buford from the 700R4 to the TH350, I have not had a functional speedo. The cable fit in and the retainer cap screwed on, but the needle just lays sadly on 0.

Is there a difference with the cable between a 350 and 700R4? Maybe the gears took a dump? Any ideas?

[TC]

Let me get this right, you have a problem with your needle just laying there after you stick your cable in the hole??........

If the drive part of the cable doesn't match what's in the trans it's no going to work, not sure if there is a difference.... Most likely the gear in the trans is worn out....

[squirrel]

You might be missing some parts in the transmission. Pull off the cable, and remove the "slug" that holds the speedo driven gear. Inspect stuff....

[Brian Lohnes]

Jim, how does that slug come out?

[squirrel]

A bolt holds the retainer plate, after you remove the retainer plate, you just pull it out. There's an O ring seal around the outside of it.

Be careful not to drop the gear into the transmission.

The gear could be missing, stripped, could be missing the driving gear, or the square hole in the end of the gear could be rounded out, or the speedo cable could be messed up, or maybe there's something wrong with the cruise control or something.

Also the gears need to be correct for your particular rearend gear ratio and tire size....

[Brian Lohnes]

I still have the blowed up transmission so I am going to pull those gears out (original to the car and should be correct for gear ratio...shorter tires will throw them off). If there is a problem with the gears, the ones out of the old trans should work (speedo worked when the old trans was in).

Will do this when I get back from the junkyard. I am pulling the intermediate steering shaft to swap it for one from a Jeep Cherokee. The rag joint is totally screwed in the car and a new stock shaft is like 200 bucks. The Jeep shaft has u-joints and is a direct bolt it swap...for like $25 when bought out of the 'yard.

Brian

[SuperBuickGuy]

the gear on the shaft and the gear on the cable drive are a matched set - don't mix and match..... that's yet another thing I did wrong a couple decades ago.

[squirrel]

and the TH350 gears should be different than the 700R4 gears.

You can use the old gears to figure out the ratio you need, however

[kyhunter89]

And if theres not gears in it, it should be leaking oil.

[STINEY]

Oh thank God........... I was afraid to read this one...........thought maybe Brian had a wardrobe change and was unsure of how his new attire "worked".....

Did you check the end of the speedometer cable to see if it is still square? Maybe chuck it up in a cordless drill to verify that everything upstream of the trans is stll functional, a cordless on high should register about 10 mph or so.

[squirrel]

a cordless on high should register about 10 mph or so.

mine usually gets about 35 mph

1000 rpm = 60 mph.

btw the drill needs to be in "reverse"

[Loren]

I had a speedometer not work once, just because the end of the cable where it's shaped square didn't engage into the square hole...it's like the cable wasn't quite long enough. I disconnected the end and pulled the cable out of it's housing aways, then pushed the cable alone in while twisting a bit and visually checked engagement, then I brought the housing back down to clamp into it's place and that fixed it.