How do I put in a 40 tooth speedo gear?

I've been changing my speedo gears, but haven't got the right one. Used Go Jeep's charts and took the plunge to 40 tooth. I know I have to index the housing. The range I am in is 34-38. The next is 38-42. My question is this. There is a dot on the case that I assume is the reference point, but the range I am in now is not lined up to it. I can only rotate in 90 degree increments. should I just rotate the housing 90 and put the 38-42 range close to where it is now, or does it have to line up with the dot on the case. Is my speedo going to be off if I don't get the right range? Thanks

Just did my 40 tooth a few days ago. Just pit it in so that the plug is close to the bottom. In other words just put it in where it fits and it works.

Ya, I know what you mean. That looks around the same orientation that mine would have if I was to do that. What do you need a 40 tooth for. The dealership started me at a 36, but then I found out that is as high as their chart went! I have 4.88s w/ 33s. Last gear I had was a 37 and after being clocked, was about 10% off. This goes along with Go Jeep saying I need a 40 for 4.88s and 33s. Thanks for your response. does anyone else run a 40 tooth?

Sorry, just saw in your sig you run 4.56s

I have 4.56 and 32"s. I checked it off of my gps and it's within 2 mph's

Concur on the indexing - since the pitch of the gear teeth is (has to be!) constant, the diameter will increase as you increase the number of teeth. This is why the housing is indexable.

What gear are you pulling out? I'm collecting speedo gears to see about making them out of something more substantial than plastic (I'm thinking brass or bronze...) and I've got a few on the way already, but I'd like to accumulate a full set to measure.

5-90

5-90 said:

Concur on the indexing - since the pitch of the gear teeth is (has to be!) constant, the diameter will increase as you increase the number of teeth. This is why the housing is indexable.

What gear are you pulling out? I'm collecting speedo gears to see about making them out of something more substantial than plastic (I'm thinking brass or bronze...) and I've got a few on the way already, but I'd like to accumulate a full set to measure.

5-90

Click to expand...

Sorry Charlie, I returned the wrong ones to the dealership. I have my original 36, but you probably have plenty of those.

Nope - no got. Besides, I didn't want the ones you'd taken back (you paid for those, didn't you?) just the one you were done with.

If you're willing, PM for my address. I'll cover shipping if you want - but it seems to be less than a buck by First Class Post...

5-90

I think mine is a 29 you want it?

Sure! Same note - PM for address.

I've only just gotten started - once I get a few in, I'll put a list up on my site. I got the idea from Mambeu, actually - he suggested that I put out a list of donor parts that you all may be getting rid of. Send them to me, so I don't feel so bad when I start hacking them up and measuring things, you know. I'd sooner cut up an old, worn-out part than buy a new one and hack it up - someone else might need the new one!

Granted, I don't have to cut these up, but if people are replacing them and just going to toss them, might as well toss them my way if I need them...

5-90

jwtrapper said:

Just did my 40 tooth a few days ago. Just pit it in so that the plug is close to the bottom. In other words just put it in where it fits and it works.

Click to expand...

Why did you silicon it since there is an o-ring in there? Seems like silicon would only make it tough to change out the speedo gear in the future.

I cut the o-ring somehow when I put it back together the first time. So I went and picked up a new o-ring and did the same thing again. I put some atf on it to try to get it to slide in like it is suposed to do but it just didn't work out. So after I had atf leaking all over my fresh paint on my belly pan I pulled out the tube of rtv and did it that way. No more leaks. It works for me. The silicone should come off easy enough if I need to change it out again.
I think it might have something to do with it being a porc sye it has kindof a sharp edge and when I would put the spedo back in the o-ring would not go past and it would cut easily.
18 1/2 hrs before some one asked about the silicone, that was longer than I expected.