home register FAQ memberlist calendar

Go Back   Turbobricks Forums > Mechanical > maintenance & nonperformance

Reply
 
Thread Tools Display Modes
Old 11-09-2020, 10:44 PM   #1
spock345
Board Member
 
spock345's Avatar
 
Join Date: Nov 2016
Location: Santa Cruz, CA
Default Speedometer error, Volvo 122S BW35 to M40.

At some point in its life my 122s was converted from a BW35 to an M40. The speedometer is a bit off. Using a GPS speedometer on my phone I have found it reading a bit fast. It will read 35mph when in actuality I am going 25mph. The error is significant enough that I have decided to try to fix it. I replaced the speedometer cable because mine was sticky and the rubber casing had melted away (someone let it sit on the exhaust), that fixed how jumpy it was. I verified it has the 16 tooth yellow gear for a 4.10:1 rear end ratio, which should be the same between an M40 and a BW35.

Is there anything different about the speedometer on automatic cars or is it just badly out of spec? Is there anything in these that can get stuck or need lubrication? I have found information about stuck or slow speedometers but nothing about then running fast.

I am running 165/80r15 tires on the stock 15x4 wheels.
__________________
1967 122s, B18-D, M40
1989 240 B230F (V15 cam, chipped EZK), M47 (Lost a fight with a Chevy express van)
2012 VW Tiguan 6 speed auto
spock345 is online now   Reply With Quote
Old 11-09-2020, 11:21 PM   #2
Redwood Chair
K-jet For Life
 
Redwood Chair's Avatar
 
Join Date: Mar 2007
Location: - Stock PSI Or Bust -
Default

Don't know a lot about 122s but 410s doesn't sound right since 430s were in 140s till 70.

__________________
Raise The Lowered


Image hosted by servimg.com

Quote:
Originally Posted by hiperfauto View Post
Folks on here don't know a good deal when they see it.
how psi stock cna support?

Quote:
Originally Posted by churd9 View Post
Has Biden taken office yet?
Redwood Chair is online now   Reply With Quote
Old 11-10-2020, 12:37 AM   #3
spock345
Board Member
 
spock345's Avatar
 
Join Date: Nov 2016
Location: Santa Cruz, CA
Default

Quote:
Originally Posted by Redwood Chair View Post
Don't know a lot about 122s but 410s doesn't sound right since 430s were in 140s till 70.

I know for sure they put 4.10 and 4.56 rear ends in 122s but I wouldn't be surprised if 4.30 gearing ended up in some cars. There is a little metal tag on one of my differential bolts that says 4.10.

Mostly I just need to know if there is some common problem with these VDO ribbon speedometers or if I am missing something.

Last edited by spock345; 11-10-2020 at 12:42 AM..
spock345 is online now   Reply With Quote
Old 11-10-2020, 04:40 AM   #4
mocambique-amazone
Board Member
 
Join Date: Jul 2012
Location: Germany
Default

Do you know the colour of your speedo gear
nylon drive unit?
Yellow = 16 teeth
Green = 17 teeth
Blue =18 teeth.
The higher the no of teeth, the slower the speedo.
1 tooth changes speedo reading by 5 to 6%.
2 teeth " " " " 10 to 12%


Informations above from the Volvoforums

Good luck, Kay

Last edited by mocambique-amazone; 11-10-2020 at 04:41 AM.. Reason: Not my natural language
mocambique-amazone is offline   Reply With Quote
Old 11-10-2020, 06:46 AM   #5
alschnertz
Enough already!
 
alschnertz's Avatar
 
Join Date: Oct 2009
Location: CT
Default

I suspect your tire size has something to do with your issue.
__________________
Differences of opinions should be tolerated, but only if they're not too different. - Sharon Craig
alschnertz is offline   Reply With Quote
Old 11-10-2020, 08:48 AM   #6
Redwood Chair
K-jet For Life
 
Redwood Chair's Avatar
 
Join Date: Mar 2007
Location: - Stock PSI Or Bust -
Default

Quote:
Originally Posted by alschnertz View Post
I suspect your tire size has something to do with your issue.
Redwood Chair is online now   Reply With Quote
Old 11-10-2020, 10:45 AM   #7
spock345
Board Member
 
spock345's Avatar
 
Join Date: Nov 2016
Location: Santa Cruz, CA
Default

Quote:
Originally Posted by mocambique-amazone View Post
Do you know the colour of your speedo gear
nylon drive unit?
Yellow = 16 teeth
Green = 17 teeth
Blue =18 teeth.
The higher the no of teeth, the slower the speedo.
1 tooth changes speedo reading by 5 to 6%.
2 teeth " " " " 10 to 12%


Informations above from the Volvoforums

Good luck, Kay
Mine is yellow, 16 teeth. Which should be correct for 4.10 rear gearing if the Volvoforums are to be believed.

I am going to double check today.

165/80r15 is the closest to the stock tire you can get now.

Last edited by spock345; 11-10-2020 at 11:36 AM..
spock345 is online now   Reply With Quote
Old 11-10-2020, 11:54 AM   #8
alschnertz
Enough already!
 
alschnertz's Avatar
 
Join Date: Oct 2009
Location: CT
Default

Quote:
Originally Posted by spock345 View Post
165/80r15 is the closest to the stock tire you can get now.
I stand corrected. For some reason I thought you were talking about a wagon.

122S sedan, original tire size was 5.90 X 15 which is approx. 165/80 X 15.
122S wagon, original tire size was 6.40 X 15 which is approx. 195/75 X 15.
alschnertz is offline   Reply With Quote
Old 11-10-2020, 12:58 PM   #9
Redwood Chair
K-jet For Life
 
Redwood Chair's Avatar
 
Join Date: Mar 2007
Location: - Stock PSI Or Bust -
Default

Typically RWD Volvo speedometers were calibrated ~2% - 3% conservatively but it sounds like you're a bit outside that range.
Redwood Chair is online now   Reply With Quote
Old 11-10-2020, 01:26 PM   #10
hiperfauto
The Librarian
 
hiperfauto's Avatar
 
Join Date: Nov 2011
Location: So Cal
Default

What's the part number for the trans? It's on the metal tag near the trans mount.
hiperfauto is online now   Reply With Quote
Old 11-10-2020, 03:14 PM   #11
spock345
Board Member
 
spock345's Avatar
 
Join Date: Nov 2016
Location: Santa Cruz, CA
Default

Quote:
Originally Posted by hiperfauto View Post
What's the part number for the trans? It's on the metal tag near the trans mount.
Type: M40
Part NR: 254498
Fabr NR: 375262
spock345 is online now   Reply With Quote
Old 11-10-2020, 04:26 PM   #12
hiperfauto
The Librarian
 
hiperfauto's Avatar
 
Join Date: Nov 2011
Location: So Cal
Default

That should have the correct metal speedo drive gear so that's not the problem.
hiperfauto is online now   Reply With Quote
Old 11-10-2020, 09:52 PM   #13
spock345
Board Member
 
spock345's Avatar
 
Join Date: Nov 2016
Location: Santa Cruz, CA
Default

Quote:
Originally Posted by hiperfauto View Post
That should have the correct metal speedo drive gear so that's not the problem.
I have to take out the cluster to repaint the bezel. While I have that off I'll take a look inside and see if anything looks off. Maybe something is rattling around in there or some piece of plastic broke.

Last edited by spock345; 11-10-2020 at 10:53 PM..
spock345 is online now   Reply With Quote
Old 11-12-2020, 03:55 AM   #14
OttoB
Board Member
 
Join Date: Aug 2006
Location: E(Seattle!Vancouver! San Francisco!LA!) Helsinski
Default

Does odometer give reasonable values? Einstein figured out that that there is correlation between speedo and odo error.
OttoB is offline   Reply With Quote
Old 11-12-2020, 11:21 AM   #15
Shinchan
Board Member
 
Join Date: Jun 2018
Location: Lafayette, CO
Default

Might I suggest that you save yourself a lot of heartache and misery:

https://www.speedhut.com/ecommerce/p...able-Included)

I'll never go back to a transmission-driven speedo system ever again...
Shinchan is offline   Reply With Quote
Old 11-12-2020, 01:40 PM   #16
spock345
Board Member
 
spock345's Avatar
 
Join Date: Nov 2016
Location: Santa Cruz, CA
Default

Quote:
Originally Posted by OttoB View Post
Does odometer give reasonable values? Einstein figured out that that there is correlation between speedo and odo error.
The trip odometer behaves oddly. So there may be a problem there. I'll know more when I take the bezel off for a repaint.

The electronic speedo also seems like an interesting idea. What do you use to trigger it on the drivetrain end? I don't like relying on just GPS for the speedometer.
spock345 is online now   Reply With Quote
Old 11-12-2020, 05:39 PM   #17
Shinchan
Board Member
 
Join Date: Jun 2018
Location: Lafayette, CO
Default

You don't, which is kind of the point. If you had a trans that supported an electronic speedo, then you could use that as well. I haven't had any issues with GPS, other than it takes a bit to lock a signal after starting. You shouldn't be driving your car right after you start it anyway

Tire size changes, rear end differences, speedo sender gearing, none of that makes any difference to the GPS box.

Quote:
Originally Posted by spock345 View Post
The electronic speedo also seems like an interesting idea. What do you use to trigger it on the drivetrain end? I don't like relying on just GPS for the speedometer.

Last edited by Shinchan; 11-12-2020 at 05:44 PM..
Shinchan is offline   Reply With Quote
Old 11-14-2020, 11:30 PM   #18
spock345
Board Member
 
spock345's Avatar
 
Join Date: Nov 2016
Location: Santa Cruz, CA
Default

I just got the cluster out of the car, not a fun job.

The speedometer looks fine, nothing fell out while I was taking the faceplate off. Nothing rattling around. Took at look at the odometer. It was a bit sticky due to old grease. Cleaned that up and put some new grease on the little gears. Also lubed the little piece that the speedometer cable sticks into.

The only abnormality that I could find is that the 100s digit on the trip odometer doesn't work. It doesn't tick over or reset properly.

The thing moves freely when you turn the hookup for the speedometer cable.
spock345 is online now   Reply With Quote
Old 11-15-2020, 09:14 PM   #19
spock345
Board Member
 
spock345's Avatar
 
Join Date: Nov 2016
Location: Santa Cruz, CA
Default

Popped it back in the car. Hopefully just lubing a few bits will fix it. If not then I will be in search of another cluster or sending this one out to a shop after taking some readings for the exact error.
spock345 is online now   Reply With Quote
Old 11-19-2020, 06:05 PM   #20
spock345
Board Member
 
spock345's Avatar
 
Join Date: Nov 2016
Location: Santa Cruz, CA
Default

Nope, still off.
spock345 is online now   Reply With Quote
Old 11-20-2020, 09:17 PM   #21
spock345
Board Member
 
spock345's Avatar
 
Join Date: Nov 2016
Location: Santa Cruz, CA
Default

After a highway trip that had the speedometer reading 80 when I was really doing 58, I popped open the cluster again and decided to take a look at the tension spring on the left side of the speedometer. I found a small kink in it. I guess that may lessen the tension enough that the magnetic part on the other side easily overpowers it. Leading to a 20%+ error. I doubt it is worth it to fix it given how much I have seen speedometer repair places cost.

Given that the part already seemed fubar'd I rotated the little tab holding the spring end about 10 degrees tighter. This tightened it up enough that I now will be going 45 and the speedometer reads between 55 and 60 if my phone is to be believed. Improved, but not by much. If I tighten it much more the speedometer starts reading the lower speeds as too slow.
spock345 is online now   Reply With Quote
Old 11-20-2020, 09:54 PM   #22
Jack
junkman
 
Jack's Avatar
 
Join Date: Jul 2011
Location: The Ass Cheek Of History
Default

sounds like you ****ed it good.

what cluster do you have, there's 3 that I can think of
100mph one and two 120 mph ones - I havent checked yet but I think the later ones might have different gearing inside them

pictures help in these threads otherwise it's anyones guess
__________________
85 245 | 82 242| 75 245| 69 145 |66 122| 67 220




Quote:
Originally Posted by paul buck View Post
I love you even more Jack.
Quote:
Originally Posted by BritishBrick
Don’t bother, I would literally rather throw them away than give you the pleasure. I will never sell to you.
Quote:
Originally Posted by Tuesday View Post
I expect nothing less from an incel like you, Jack.
Jack is offline   Reply With Quote
Old 11-20-2020, 11:16 PM   #23
spock345
Board Member
 
spock345's Avatar
 
Join Date: Nov 2016
Location: Santa Cruz, CA
Default

It is a 120mph one with the larger blinker/amp/oil lights. Doesn't say "VOLVO" on the chrome bezel. This cluster seems correct to the car. Different gearing or calibration for an automatic transmission makes sense. I just can't find any mention of that being the case.

At least the odometer is accurate.

I'll get a part number off of it tomorrow.

Slightly adjusting the spring tension improving the problem is some progress but still annoying.

Instead of monkeying around I should probably just find another speedometer.
spock345 is online now   Reply With Quote
Old 11-20-2020, 11:18 PM   #24
Jack
junkman
 
Jack's Avatar
 
Join Date: Jul 2011
Location: The Ass Cheek Of History
Default

Quote:
Originally Posted by spock345 View Post
It is a 120mph one with the larger blinker/amp/oil lights. Doesn't say "VOLVO" on the chrome bezel. This cluster seems correct to the car, but I may be wrong. Different gearing or calibration for an automatic transmission makes sense. I just can't find any mention of that being the case.

I'll get a part number off of it tomorrow.

Slightly adjusting the spring tension improving the problem is some progress but still annoying.

Instead of monkeying around I should probably just find another speedometer.
sac has a good speedo repair shop and they're cheap

if you need speedos ... I have some restored and some unrestored but not TB cheap
Jack is offline   Reply With Quote
Old 11-20-2020, 11:26 PM   #25
c1800
Board Member
 
Join Date: Jun 2014
Location: Alberta
Default

Even with the correct speedo gear the Speedo head could have “worn out” internals. Google for that. An expert rebuild of the Speedo could be in order...
c1800 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


All times are GMT -4. The time now is 06:29 PM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.