When I bought my 58 the previous owner stated the speedometer was working but and had just recently quit working. After trying to trouble shoot the problem we found it was missing two things, the plastic gear that goes into the transmission and all the guts to the speedometer but remember he said it was working – yea right. I do have a functional speedometer now.

Here is my question – I need to install the plastic gear in the transmission and the listing in CC catalog are:


Do I need this and what is it for.
Speedo Drive Gear extension

These I assume are the plastic gears.
Speedo Drive Gear (18 Tooth – Brown)
Speedo Drive Gear (20 Tooth – Blue)
Speedo Drive Gear (21 Tooth – Red)
Speedo Drive Gear (22 Tooth – Green)
Speedo Drive Gear (24 Tooth – Yellow)

Also listed:
Speedometer Steel Drive Gear (3:08-3:55)
Does this one cover all and is it better to use steel and what is the advantage/disadvantage of using steel gear.

I have 15” rims with Coker Classic 15” tires and a stock BW T10 transmission with a nonstandard 3:55 rear end.

If I was to guess which gear to use I would take blue since it is my favorite color but can any make a educated guess on where to start.

Next question – my rebuilt speedometer odometer read 00000.1 miles and the one that I took out read 26500 miles. I’m sure the old odometer is incorrect mileage also. What is the legality of a replacement speedometer with basicly 0 miles showing? I don’t think it would make any difference due to the age of the car.

 

Can't answer your questions but I think I bought my '56 from the same guy. A lot of things didn't work because the car had been sitting for so long, he said, found out most things were not hooked up and missing parts, etc.

 

A plastic gear is fine, no need for a steel one.

I can't remember what color you need. I have an orange one in mine with 4:11 gears (I believe 26 teeth). I should have gotten brown I think, 25 teeth. CC should be able to tell you the proper number of teeth/color when you call. You can tell them you have stock tires with 3:55 rear. They will get you the right one. If they can't tell them you want a tech guy. That is a simple question.

Can't help you on Speedo Drive Gear Extension. I didn't need it.

I know in the state of Pennsyvania you don't need to worry about millage on antique cars. They are exempt. :D

The job is an easy one. It is pretty much plug and play. I went with a steel cable ('59) and I would recommend that if you didn't already buy one. There were some very cheap cables made in the past with plastic inners. If you have one of those send it back or buy a new one. They are more trouble than they are worth. Mine broke off in the back of my speedo. What a pain in the butt to get it out.

Enjoy,
Curt

 

First of all, what transmision do you have?????????

 

Its a 1958 BW T10 transmission 4 Speed....

 

The "steel drive gear" is inside the tailshaft and drives the plastic gear, which is called the "driven gear." Drive gears are designed to work with a range of driven gears. Unfortunately for me, I crossed the line on mine and now to get the speedo right will have to replace the drive gear.

Sorry I don't know the answer to the rest.

 

If you have an original or a correct type 58 B-W T-10 4sp, then it probably has the long sleeve for the speedo gear, same as a 3sp. Later trannys use a shorter sleeve and subsequently, the plastic gears which are still available from Chev are all of the short variety (3/4in shorter). If you use a currently available, short plastic gear, the end of your speedo cable won't reach into the end of the gear. The extension which was mentioned is a short piece which goes into the long sleeve between the end of the cable and the plastic gear. Now, there is another way to accomplish the same thing, WHICH I PREFER. Have your local speedometer shop make up a new inner cable which is 3/4in longer than your existing cable. If you don't have a speedo cable now, then have one (inner) made which is 3/4in longer than it should be. This method works great and you don't have to mess with an extension.
Below are listed ALL of the plastic gears which are available from Chev Parts Dept and their colors. The first six are just a tiny bit smaller in diameter than the last 4. There are also 2 different sizes of drive gears inside the tranny on the tail shaft, big and small which mate with the different size plastic gears. The BIG gear INSIDE and the first SIX plastic gears are the MOST commonly used gears.
3987917-purple-17 teeth
3987918-brown-18 teeth
3987919-natural-19 teeth
3987920-blue-20 teeth
3987921-red-21 teeth
3987922-gray-22 teeth
All of the above are the smaller gear and the MOST commonly used.
3860345-green 22 teeth
3860346-black-23 teeth
3860347-yellow-24 teeth
3860348-orange-25 teeth
There have been times in the past where I have used the the big plastic gear with the big inner gear and it seems to work fine.
Hope this helps.

 

DZ what if it is not a T-10? One of my projects it to get the speedo working. I know my trans is a M20 or 21? The first thing I was going to do was put a cable on it and see what happend? Then thought it would be as easy as changing the plaxtic gear to match 26" tires and 3.70's. Am I way off in my thinking?

 

Nope. Not at all. The plastic gears that are available, as I said, are the short ones which were made for the later trannys with the short sleeve, so you will be OK. That is, as long as the gear INSIDE the tranny is OK. ALLLLLLLLLL earlier trannys had a steel inside gear which lasts forever. Then, some later trannys had a plastic inner gear which was retained on the shaft with a clip. The later, plastic, inner gears will wear, but seldom do they wear noticebly under normal conditions. So your chances are excellent that all you need to do is install a plastic driven gear. I've provided ALL the part numbers for the different gears. Many Chev parts depts stock some of the most common gears and they can order the others. These gears fit 3sp, 4sp, PG, turbo 350, so they are quite common. There may be a tranny shop in your area which has some good used ones which will be cheaper than brand new from Chev.