Gain extra benefits by becoming a Supporting Member Click here find out how!
Silver
Gold ***Platinum***
deek01BigDogSS (6)jk56chevy (11)WarrenL (2)Jens (10)
edad2000Custom_Deluxe_20VetteGyrl (2)JohnB (2)
speedygman (7)rickityfiftyMafo971Clifford Lao502drfleetline
Jud Leowish Non-synchronized
gary635g (6)
johnhem (10)
axmaker (3)
socalarch (3)
usmile4 (8)
Classic Performance Products Classic Parts
Ciadella Interiors American Auto Wire Art Morrison.com
Exile® Battery Keeper™ 6/12 volt charger w/ LED battery monitor
Low priced Genuine GM Auto PartsHarbor Freight
Hellwig Products IncPerformance Rod & Custom
Impala Bob's Bob's Chevy Trucks Bob's Chevelle Parts Bob's Classic Chevy

  >> Switch to Mobile Version <<

Recent Hot Topics
Current Quote
"Let's ALL do what we can to TOOT THE HORN for ChevyTalk - OUR BOWTIE BROTHERHOOD IS THE BEST ON THE 'NET!!!"
~ Supporting Member
Recent Topics
Join the Community today







Username Post: TH350 speedo drive gear replacement        (Topic#165567)
thatguy2001 
Senior Member
Posts: 722
thatguy2001
Loc: Oregon
Reg: 07-12-07
07-25-07 01:10 AM - Post#1216243    

Since my fuel gauge still isn't working, I decided that I would really like to get the speedometer/odometer to work. It will cause fewer embarrassing moments if I have at least some idea how far I've driven and what kind of mileage I am getting

I know that the speedometer drive gear is toast. It is completely chewed up and won't grab the driven gear. My question is how to remove the drive gear.



I assume that I need to remove the output shaft housing. Will it just slide off if I have unbolted it and unhooked the driveline? Or do I need to have it in neutral or park?

Do I have to drop the tranny or can I do it with the transmission still in the car? Any help is greatly appreciated.

Thanks,
Seth
'59 Chevy Biscayne 4D: Baby

car photos


Edited by thatguy2001 on 07-25-07 01:25 AM. Reason for edit: cutaway picture added

 
This Forum is Sponsored by
1-800-IMPALAS  *  www.impalas.com
Visit Impala Bob's forum on ChevyTalk
Jens 
"10th Year" Silver Supporting Member
Posts: 6542
Jens
Loc: Iowa.
Reg: 04-21-02
07-25-07 04:26 AM - Post#1216258    
    In response to thatguy2001

No you don't have to drop the tranny. But yes you have to remove the tail shaft so you can slip the drive gear off the retaining clip for replacement.
Very nice picture btw.


 
Hellfish122 
Very Senior Member
Posts: 1430

Loc: Chicago, IL
Reg: 08-22-01
07-25-07 07:32 AM - Post#1216352    
    In response to Jens

I need to do this, too. Does everything just slide out, then slide back in, or are there special adjustments needed?
1959 Bel Air
1948 Fleetmaster Club Coupe
Chicago, IL


 
thatguy2001 
Senior Member
Posts: 722
thatguy2001
Loc: Oregon
Reg: 07-12-07
07-25-07 09:25 AM - Post#1216446    
    In response to Jens

  • Jens Said:
No you don't have to drop the tranny. But yes you have to remove the tail shaft so you can slip the drive gear off the retaining clip for replacement.
Very nice picture btw.



Oh yeah, the picture was from Performance Automotive and Transmission Center.

Seth
'59 Chevy Biscayne 4D: Baby

car photos


 
Chair City 
Contributor
Posts: 361

Loc: Thomasville, NC USA
Reg: 01-24-04
07-25-07 10:24 AM - Post#1216487    
    In response to Hellfish122

The picture shows it pretty well. Watch when removing the tailshaft housing as you will lose some fluid there. If the gear is really torn up you may have trouble finding the number of teeth. My 60 with the 3.08 axle uses the 10 tooth gear.
1960 Impala Spt. Cpe. Daily Driver


 
thatguy2001 
Senior Member
Posts: 722
thatguy2001
Loc: Oregon
Reg: 07-12-07
07-25-07 12:21 PM - Post#1216589    
    In response to Chair City

I can't get it apart! I removed the driveline from the rear axle but now I cannot get the bolts from off of the tailshaft housing! I have tried a 6 side 9/16 socket but the bolts are too shallow to get a good grip on. A box wrench would be fine except that I can't get the leverage in the tight space because the transmission mount overhangs just enough to get in the way of the wrench.
It almost feels like someone used Loctite on them. If it would fit, I would get a bigger hammer!

I have managed to get a good gash on my knuckle though
Seth
'59 Chevy Biscayne 4D: Baby

car photos


 
thatguy2001 
Senior Member
Posts: 722
thatguy2001
Loc: Oregon
Reg: 07-12-07
07-25-07 01:35 PM - Post#1216659    
    In response to thatguy2001

okay, I got them. First I tried (without holding too much hope) some liquid wrench, then I tried heating up the transmission so that the bolts housing would be warm. That's not too easy when you have already completely removed the driveshaft!

What I found was that 14mm socket was a more accurate fit than my 9/16 was. Stupid metrics.

When I get it all apart I will take some photos and post them.
--

Okay, now there're yet another sticky point. I got the tailshaft housing off, finally got the retaining clip off (with vice grips and a hammer) but the rest of everything won't come off!

I thought that the drive gear would just dlide off of the shaft but it doesn't. Do I just need to break it off? If so, I'll probably be done before anyone gets back to me
Thanks
Seth
'59 Chevy Biscayne 4D: Baby

car photos


Edited by thatguy2001 on 07-25-07 01:51 PM. Reason for edit: No reason given.

 
thatguy2001 
Senior Member
Posts: 722
thatguy2001
Loc: Oregon
Reg: 07-12-07
07-25-07 09:13 PM - Post#1216934    
    In response to thatguy2001

Okay, I got it off by prying it back and forth with a hammer. it was a pain to get the new one on with the clip because there isn't much of a ridge for it to go into but I did it.

I put the tailhousing back on and started the engine, put it in drive and... The speedometer moved! Happy dance time.

Hellfish, most everything slides out and back in. Don't forget to unbolt your center bearing in the X like I did. I wouldn't figure out why it was being so stubborn about moving

I also found that the drive gear didn't slide off the way I thought it would. Just have to rap it back and forth to get it free. So just the four bolts on the tail of the transmission (TH350), don't forget to remove driven gear assembly, two bolts from the center bearing, and the u-joint brackets in the back.

I put a rubber sleeve over the yolk before I put it back in because I found that it had picked up dust and dirt inside while I was taking it out. Quite the pain to clean out! I would really hate to try to do that when it was nearly installed.



Seth
'59 Chevy Biscayne 4D: Baby

car photos


 
Hellfish122 
Very Senior Member
Posts: 1430

Loc: Chicago, IL
Reg: 08-22-01
07-27-07 07:32 AM - Post#1217842    
    In response to thatguy2001

So, no adjustments, just unbolt, and bolt back on... and a lot of frustration.

Did you have to drain the transmission first?

I know that the gear that's in there is wrong because my speedometer was reading wrong, but I know that I have to drive the car with a working speedometer to figure out what driven gear I need... so I know I'm going to have to do this twice
1959 Bel Air
1948 Fleetmaster Club Coupe
Chicago, IL


 
raycow 
Honored Member
Posts: 18627

Age: 71
Loc: San Francisco, CA
Reg: 11-26-02
07-27-07 08:41 AM - Post#1217887    
    In response to Hellfish122

You may already know this, but just in case you don't.....
If your transmission uses the large size driven gears (tooth count in the 30s-40s range), there are two different driven gear housings, and they are marked with the tooth count of the gears they are intended to be used with. Using an incorrect gear/housing combination can cause the teeth to get chewed off of one or both gears.

Ray
Bacon is the gateway drug for vegetarians - Bridget Lancaster


 
thatguy2001 
Senior Member
Posts: 722
thatguy2001
Loc: Oregon
Reg: 07-12-07
07-27-07 11:06 AM - Post#1218014    
    In response to Hellfish122

  • Hellfish122 Said:
So, no adjustments, just unbolt, and bolt back on... and a lot of frustration.

Did you have to drain the transmission first?

I know that the gear that's in there is wrong because my speedometer was reading wrong, but I know that I have to drive the car with a working speedometer to figure out what driven gear I need... so I know I'm going to have to do this twice



Woah! if your speedometer is reading wrong but functioning you probably don't have to mess with the speedo drive gear or driveshaft! The drive gear is generally left alone while you can change out the driven gear for different sets of teeth to make adjustments.

Before you rip into it, I would find out how far off the speedo is and try to change the driven gear to compensate. That's totally easy, you just loosen the little bolt holding the speedo cable in and pull the housing straight out. Just a few drips of fluid to loose.

I had to change my drive gear because it was worn out and wouldn't grab the drive gear.


Now, after I get it back together, I will probably have to change out the driven gear for the proper one once I know for sure how much it's off.

No, I didn't drain the tranny. I just worked over something to catch the drips but I didn't loose much.

but before you start, go on a drive with somebody on a cell phone and make notes of how far off it is at different speeds. Then get back to us.
Seth
'59 Chevy Biscayne 4D: Baby

car photos


 
thatguy2001 
Senior Member
Posts: 722
thatguy2001
Loc: Oregon
Reg: 07-12-07
07-27-07 01:15 PM - Post#1218123    
    In response to Hellfish122

If you need to calculate for your speedo gears, this site has a good calculator. My TH350 uses a 10. I am not going to get my new driven gear until I drive it though so I can cross check the math for the best fit.

Good luck,

Seth
'59 Chevy Biscayne 4D: Baby

car photos


 
Hellfish122 
Very Senior Member
Posts: 1430

Loc: Chicago, IL
Reg: 08-22-01
07-27-07 02:54 PM - Post#1218172    
    In response to thatguy2001

Ha! I thought drive gear = driven gear!

My speedo worked (well, it moved and made a lot of noise), but I sent it off to be rebuilt and I haven't been able to get it work since. It may be the driven gear or the cable, I haven't fully investigated yet, but I know it was a little off when it was working
1959 Bel Air
1948 Fleetmaster Club Coupe
Chicago, IL


 
thatguy2001 
Senior Member
Posts: 722
thatguy2001
Loc: Oregon
Reg: 07-12-07
07-27-07 03:23 PM - Post#1218191    
    In response to Hellfish122

I think that you can pull the cable out of the housing (pull the metal part out of the tube,) clean it, lube it, and put it back in so that it spins easily without binding.

I know I read a thread somewhere about what to use as lubricant but I don't know if it was here or not. I do know that you have to be careful about what kind you use.

So who rebuilds speedos? I kind of assumed that once it was broke it was broke. anyone know if it's spendy? I have an extra one that needs some work.

just FYI, in the first photo I posted, the drive gear is the green one around the shaft. The gray one below it is the driven gear. It sits in that small metal housing that plugs into the case.

What I had found with mine was that the gears would only connect if the driven gear was pushed further in or pulled out slightly. My photo of the drive gear shows why that was, it was just rubbed away in the middle.
Seth
'59 Chevy Biscayne 4D: Baby

car photos


Edited by thatguy2001 on 07-27-07 03:29 PM. Reason for edit: No reason given.

 
Hellfish122 
Very Senior Member
Posts: 1430

Loc: Chicago, IL
Reg: 08-22-01
08-01-07 10:14 AM - Post#1221786    
    In response to thatguy2001

i forget who rebuilt my speedo, but they were in Michigan... I think it cost me around $200-$300, but I haven't gotten it to work since. All signs point to the cable or the gear though
1959 Bel Air
1948 Fleetmaster Club Coupe
Chicago, IL


 
thatguy2001 
Senior Member
Posts: 722
thatguy2001
Loc: Oregon
Reg: 07-12-07
08-01-07 11:06 AM - Post#1221827    
    In response to Hellfish122

If you have a chance to get the rear wheels off the ground and on jackstands, I found it helpful to unhook the speedometer and get the car in gear. This let me watch and feel the movement of the speedometer cable.

When I did this test, I found that if I pulled the cable in or out a little bit, it would turn. That turned out to be due to the wear on the drive gear (see photo above). If it just doesn't turn at all, try unscrewing the cable at the transmission and you can see if the the driven gear is moving. I think I put a matchstick into the cable hole to let it stick out for visual reference. Best to do this without the engine running if you're under the car in drive - you can just spin the wheels to make it move.

Good luck,
Seth
'59 Chevy Biscayne 4D: Baby

car photos


 
427SS65 
"10th Year" Platinum Supporting Member & Moderator
Posts: 13352
427SS65
Age: 68
Loc: St. Louis, MO
Reg: 12-11-03
09-21-10 10:45 AM - Post#1979033    
    In response to thatguy2001

While you are at it, take the tailshaft to a machine shop and have them change out the bronze bushing that's probably worn out. It's not expensive to have it done.
Tom 65-70 Full Size Team Moderator

View My Photos Here

65 Impala SS Tahitian Turquoise


 
Delray_58 
Contributor
Posts: 876
Delray_58
Loc: Scotts Valley, CA
Reg: 03-20-10
09-21-10 12:06 PM - Post#1979069    
    In response to thatguy2001

Thatguy2001, I had my speedo rebuilt at Palo Alto Speedometer. Although it's not in Oregon, at least it's on the West Coast so a little easier to ship and get in contact with them. I don't recall the cost, but it was in the $200-$300 range. They did a great job: the speedo is nice and stable, calibrated, and painted. I would certainly use them again. http://www.paspeedo.com/.

Have fun!
'58 Delray 283 3-speed OD
In the family since new


 
This Forum is Sponsored by
1-800-IMPALAS  *  www.impalas.com
Visit Impala Bob's forum on ChevyTalk
Icon Legend Permissions Topic Options
Report Post

Quote Post

Quick Reply

Print Topic

Email Topic

21900 Views
FusionBB
FusionBB™ Version 2.1
©2003-2006 InteractivePHP, Inc.
Execution time: 3.614 seconds.   Total Queries: 23   Zlib Compression is on.
All times are (GMT -0800) Pacific. Current time is 03:43 PM
Top