So I finally broke into my transmission to correct the speedo gears. I got a red 17 tooth drive gear from the local dealer to put in, but now that I've got the old one off I'm confused. The channel for the retaining clip is different. WTF? The old pea soup green one is straight through, seems like it'll work either way. But the new red one has different channels in it. Which way do I put it on? Is it the wrong one?

The bottom of the red channel is bigger than the one in the green, but the top is the same size and fits the fork on the retaining clip perfectly, but then there's that deeper inner channel. Is this the right side to have facing the rear? I don't want to do this job again, I want it on right the first time. Or I want to throw this gear at a dealer parts idiot.

 

it doesn't matter which way it goes on if you're using the clip in the pic. -- just get it on the same distance from the end of the output shaft, so it lines up and meshes correctly with the driven gear. It's better to not get it on far enough and then tap, tap a little more to line it up. Install it until it seems the right distance, then slide the extension housing on all the way and look through the driven gear hole at the red gear, it should be as close to the middle as possible, but it doesn't have to be perfect. It just needs to go on far enough for the clip to snap it on. If it were me, I'd put the larger diameter closer to the trans and the smaller diameter closer to the driveshaft so the clip does its job better. It should be a slight press fit, I use a piece of pipe to tap it in place so it doesn't go on crooked. Does that make sense?

 

hope your speedo was WAY slow and you're trying to make it read faster, cuz going from a 15t drive to 17t drive will make the speedo go faster...

 

My rear was swapped by some P.O. and I'm just correcting the problem. 3.23 to 2.77. I'm changing the driven to a 38 per dealer's advice, but after calculating it myself it looks like I need a 37 to be spot on. I couldn't find one anyhow, and American Hotrod Solutions plans to have some later in the year so I'll just swap that one out when it happens. It's this little bugger that I only want to deal with once. And I couldn't leave it with 15, that'd require a 32 driven which as far as I can tell doesn't exist.

But anyway, yes that does make sense. I shall indeed put it on that way, that's how I was thinking too. Good to know this is a proper part, cuz a google image search found pretty much none like my red here. But as long as it fits and works, I'll be happy. Though if it doesn't work, I'll be under there again anyway in the future, my torque arm bushing is pretty much destroyed.

Thanks for the help!

 

Ok no, this can't be right. The red gear goes on wayyyyy to easily. It slips on and off with no effort at all. The retaining clip barely holds it in place. This can't be the right gear. Coupled with the fact that the clip only has half the grip on it due to the different channels, I'm not confident it will stay in place one bit. Fantastic...

 

I go here for my speedo gears now, the boys at the dealers aren't always reliable, they mean well, but some of them have limited knowledge...

http://www.transmissioncenter.net/sp...n_______va.htm

they might have what you need.

 

it's strange -- I have got all kinds of gears in the past, some are tight, some are loose, the red one you have looks like an old th350 gear, it SHOULD be snug, but sometimes they aren't. Unless you got a th400 gear , or a transfer case gear....

 

That site looks so much like laspeedometergear.com. They must be related.

From the very limited info I can find, this is some other kind that uses a different clip. It is supposed to have the same inner diameter, but it must just be old and worn or something. Can't remember how much I paid, but it better not have been much. I just hope the right one gets here fast, I hate hate HATE being stuck in the middle of a project.

 

Which reminds me, one more question: is it safe to have this car on the tires with no driveshaft or torque arm? It's up on 4 jack stands right now with the jack on the rear, and I'm at a loss of how to get it back into the garage. This sucks...

 

if you just let the torque arm flop up to the floorboard it should be ok to move. I've done that a lot.

 

every 17 tooth 700-R4 gear I've seen was identical to your kinda-grey one except obviously the tooth count and the colour. No weird counterbore or anything like that.

And if it's wobbly or loose at all, it's the wrong one.

 

Good, thanks again greggbruce. You've saved me a lot of trouble.

Yeah jmd, definitely the wrong one. Actually I was told by Kerry @ American Hot Rod Solutions that this is actually from a pre-1970 TH-350. Why the guy at the dealer thought it would work on a 1987 700R4 hopefully is due to inexperience and not lack of intelligence. Oh well, live and learn.

 

So I got the proper gear in the mail yesterday and put it in today. It was a snug fit as it should be, and once everything was back together (including a new torque arm bushing) I test drove it and it works fine. Another project, another lesson learned.