| Author |
Message |
johnanddes
Satellite Wrangler
Joined: October 17, 2004
Posts: 692
Location: Orcutt CA
|
 Posted: Tue Jun 19, 2018 9:00 pm Post subject: Belt tension |
 |
|
Alright, attempted a search, combed through the first 150 of 353 pages, no luck. My question is is the belt tension 1/4” or 1/2”? Reason why i ask is because half the manuals (to include offical VW Owner’s Maintenance and Repair Guide) say 1/4” while the other half (Bentley, Haynes) says 1/2” delfection. Which one is correct?
_________________
John
1969 documented numbers matching bug
1968 F250
Keepin the ISS from colliding with space junk |
|
| Back to top |
|
 |
Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 24764
Location: Olympia Wash Rinse & Repeat
|
| Posted: Tue Jun 19, 2018 9:13 pm Post subject: Re: Belt tension |
|
|
Should be about 5/8".
From 1970 OM:
_________________
In Stereo, Where Available! |
|
| Back to top |
|
|
Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 24764
Location: Olympia Wash Rinse & Repeat
|
|
| Back to top |
|
|
johnanddes
Satellite Wrangler
Joined: October 17, 2004
Posts: 692
Location: Orcutt CA
|
| Posted: Tue Jun 19, 2018 9:34 pm Post subject: Re: Belt tension |
|
|
Thanks Eric&Barb. Thats my issue though. Some say 1/2”, some say 1/4” like this one:
_________________
John
1969 documented numbers matching bug
1968 F250
Keepin the ISS from colliding with space junk |
|
| Back to top |
|
|
Towel Rail
Horizontally Opposed
Joined: April 15, 2005
Posts: 4622
Location: SE CR IA US NA PE
|
| Posted: Tue Jun 19, 2018 10:16 pm Post subject: Re: Belt tension |
|
|
Surprising to see that (it's gotta be a typo) in an "official" VW manual. Everything I'd read up until now was in general agreement, 1/2" or slightly more.
_________________
1974 Thing -- under the knife
1967 Beetle -- spring/summer/fall driver
1996 Subaru OBW (EJ22, 5-speed, AWD) -- winter car, 3-seasons "don't feel like biking today" car
049 > 070 > 053 > 009
Last edited by Towel Rail on Tue Jun 19, 2018 10:24 pm; edited 1 time in total |
|
| Back to top |
|
|
Tim Donahoe
Samba Member
Joined: December 08, 2012
Posts: 11740
Location: Redding, CA
|
| Posted: Tue Jun 19, 2018 10:18 pm Post subject: Re: Belt tension |
|
|
I’ve never seen the 1/4 inch deflection for the belt. How strange. That’s way too tight; although, when that manual was printed, perhaps they had belts that stretched a lot during the first 100 miles, or so. In that case, you probably wouldn’t have to readjust. But, you’d sure be messing with your generator/alternator bears  .
I’ve always set the deflection to around 5/8 inch—which is just a smidge more than 1/2.
Tim
_________________
Let's do the Time Warp again!
Richard O'Brien |
|
| Back to top |
|
|
johnanddes
Satellite Wrangler
Joined: October 17, 2004
Posts: 692
Location: Orcutt CA
|
| Posted: Tue Jun 19, 2018 10:24 pm Post subject: Re: Belt tension |
|
|
| Towel Rail wrote: |
| Surprising to see that in an "official" VW manual. |
Yeah i thought so too which is why i posted here. Doesnt make sense. Here is the date/print page
_________________
John
1969 documented numbers matching bug
1968 F250
Keepin the ISS from colliding with space junk |
|
| Back to top |
|
|
Tim Donahoe
Samba Member
Joined: December 08, 2012
Posts: 11740
Location: Redding, CA
|
| Posted: Tue Jun 19, 2018 11:14 pm Post subject: Re: Belt tension |
|
|
I suspect they gave the 1/4 inch measurement because the belts at the time would stretch more than a modern one. If you installed it initially at that measurement, after a few hundred miles, the belt would stretch closer to the 1/2 or 5/8 inch mark.
But, as I said before, it seems this initial tightness would wear more on the generator bearings, although maybe not for long. But still ...
Tim
_________________
Let's do the Time Warp again!
Richard O'Brien |
|
| Back to top |
|
|
johnanddes
Satellite Wrangler
Joined: October 17, 2004
Posts: 692
Location: Orcutt CA
|
| Posted: Tue Jun 19, 2018 11:31 pm Post subject: Re: Belt tension |
|
|
| Tim Donahoe wrote: |
I suspect they gave the 1/4 inch measurement because the belts at the time would stretch more than a modern one. If you installed it initially at that measurement, after a few hundred miles, the belt would stretch closer to the 1/2 or 5/8 inch mark.
But, as I said before, it seems this initial tightness would wear more on the generator bearings, although maybe not for long. But still ...
Tim |
I think i have figured out why they said this. According to the Clymer one, there was a belt made with different materials introduced in 71. Ill still use the 1/2” method, but its still intriguing.
_________________
John
1969 documented numbers matching bug
1968 F250
Keepin the ISS from colliding with space junk |
|
| Back to top |
|
|
Frodge
Samba Member
Joined: October 04, 2006
Posts: 1991
Location: Dump
|
| Posted: Wed Jun 20, 2018 3:45 am Post subject: Re: Belt tension |
|
|
| If your belt is too tight it probably definitely puts too much tension on the generator bearings. But I have a question about being too loose. Would the generator light flicker if the belt is too loose? I never understood how to get the tension just right. Everyone presses with a different strength. Would in fact the generator light flicker if the belt was slipping and too loose. |
|
| Back to top |
|
|
jeffinohio
Samba Member
Joined: February 02, 2017
Posts: 197
Location: Scio Ohio
|
| Posted: Wed Jun 20, 2018 5:38 am Post subject: Re: Belt tension |
|
|
| johnanddes wrote: |
Thanks Eric&Barb. Thats my issue though. Some say 1/2”, some say 1/4” like this one:
|
8 sided nut anyone?....
_________________
64 Sunroof
73 Standard
70 Convertible
67 Cougar
3 Subarus |
|
| Back to top |
|
|
Matt Wilson
Samba Member
Joined: November 14, 2005
Posts: 2408
Location: Colorado
|
| Posted: Wed Jun 20, 2018 7:21 am Post subject: Re: Belt tension |
|
|
I would run the belt looser rather than tighter. In my experience a belt too tight can flip inside-out. Running too tight probably won't wear bearings any faster than the pulley exploding (also from experience).
The formula-vee guys purposely run their belts on the loose side. Think of it this way: the belt is transmitting HP through it. It spins the generator and the fan. The tighter you make the belt, the more power you transmit through the belt. Too tight and you stress out the pulley with too much heat. It also creates some HP loss, which is why there's not much sense running a tensioned serpentine belt on these engines, as well as risking blowing up the fan.
Your belt is your mechanical fuse in the system - you'd rather throw a belt, then break a pulley, bearing, or fan blades. Ideal belt tension can be calculated, and the measured deflection method is just a ballpark for the shadetree mechanic.
_________________
1972 Standard Beetle
1969 Baja Beetle |
|
| Back to top |
|
|
Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 24764
Location: Olympia Wash Rinse & Repeat
|
| Posted: Wed Jun 20, 2018 8:13 am Post subject: Re: Belt tension |
|
|
| Frodge wrote: |
| If your belt is too tight it probably definitely puts too much tension on the generator bearings. But I have a question about being too loose. Would the generator light flicker if the belt is too loose? I never understood how to get the tension just right. Everyone presses with a different strength. Would in fact the generator light flicker if the belt was slipping and too loose. |
Only if the belt is super loose. If one is in doubt that the belt might need to be tightened more:
1. Engage parking brake.
2. Shift into neutral.
3. With socket turn the generator pulley CW so in turn the crankshaft is turned. You are not trying to turn the crank quickly as if you were trying to crank start the engine, instead turning the crankshaft one RPM in about 5 to 10 seconds. If belt slips it needs tightening.
Belt is designed to slip some with sudden huge RPM change.
_________________
In Stereo, Where Available! |
|
| Back to top |
|
|
hitest
Samba Member
Joined: September 30, 2008
Posts: 10296
Location: Prime Meridian, ID
|
| Posted: Thu Jun 21, 2018 5:37 pm Post subject: Re: Belt tension |
|
|
Every time I change a belt I toss the wrench in the car and keep it with me for the first couple drives. That way the tension will settle in and you can easily re-torque the nut wherever you are. Chicks dig it.
_________________
| EverettB wrote: |
I wonder what the nut looks like.
|
'62 L390 151, '62 L469 117, '63 L380 113, '64 L87 311, '65 L512 265, '65 L31 SO-42, '66 L360 251, '68 L30k 141, '71 L12 113, '74 ORG 181
FU#5 |
|
| Back to top |
|
|
PuddleRainbow
Samba Member
Joined: April 13, 2018
Posts: 288
Location: The Dirtiest Of Jersey
|
| Posted: Fri Jun 22, 2018 5:24 am Post subject: Re: Belt tension |
|
|
| Quote: |
| That way the tension will settle in and you can easily re-torque the nut wherever you are. Chicks dig it. |
LOL, I check the oil a lot or futz with the choke in the work parking lot for the same reason. |
|
| Back to top |
|
|
bluebus86
Banned
Joined: September 02, 2010
Posts: 11075
|
| Posted: Fri Jun 22, 2018 7:47 am Post subject: Re: Belt tension |
|
|
| Frodge wrote: |
| If your belt is too tight it probably definitely puts too much tension on the generator bearings. But I have a question about being too loose. Would the generator light flicker if the belt is too loose? I never understood how to get the tension just right. Everyone presses with a different strength. Would in fact the generator light flicker if the belt was slipping and too loose. |
It may flicker, it may not, it depends how loose is loose and how much load is on the electric system, headlamps, wipers operating will cause the light to illuminate at a lower threshold of slip than if those accessories are off.
Bottom line is dont use the generator light as a check for belt tightness.
for the thumb pressure test, push as hard as you can with thumb on the midpoint of belt between the two pullies on the left side of the loop of belt. about half inch deflection of so is correct unless you have the new kind of belt. Unless you have a physical condition that precludes pressing hard, you will be close enough. Once the belt is pushed a given amount, it wont move that much more even with more pressure, it is not a linear response, pressure verses deflection.
you could use a belt tension test tool, I use them on serpentine belts, and they can be used on vee belts.
good luck, Bug On Under Correct Tension.
_________________
Help Prevent VW Engine Fires, see this link.....Engine safety wire information
Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022 |
|
| Back to top |
|
|
slave1pilot
Samba Member
Joined: February 22, 2010
Posts: 943
Location: Tehachapi CA
|
|
| Back to top |
|
|
glutamodo 
The Android
Joined: July 13, 2004
Posts: 26324
Location: Douglas, WY
|
| Posted: Sun Jun 24, 2018 10:40 am Post subject: Re: Belt tension |
|
|
| jeffinohio wrote: |
| johnanddes wrote: |
Thanks Eric&Barb. Thats my issue though. Some say 1/2”, some say 1/4” like this one:
|
8 sided nut anyone?.... |
By the way, there's no need to scan anything from that flippin 1972 additional "Guide" booklet, The entire book is in TheSamba archives...
https://www.thesamba.com/vw/archives/manuals/72bug_guide.php
What's this about 8 sided? I don't see it there. 13/16 is a valid enough SAE hex size (spark plug) socket and does not refer to how many sides the fasteners have. While it's a bit snug it does work for the generator pulley nut.
Now, that IS a booklet prepared after VW really "dumbed down" the glovebox owner's manual for model year 1972. Not sure where they came up with 1/4 inch on the belt adjustment though...
_________________
Andy T.
IMAGE NOTE: It has been noted that Chrome based browsers may have issues in displaying my vast image library, which use non-secure links and are on an FTP server. Images should still be viewable if the link is clicked though.
I do not know how to fix this. All I can say is it all works fine for me with what I use, Firefox. |
|
| Back to top |
|
|
slave1pilot
Samba Member
Joined: February 22, 2010
Posts: 943
Location: Tehachapi CA
|
|
| Back to top |
|
|
glutamodo
The Android
Joined: July 13, 2004
Posts: 26324
Location: Douglas, WY
|
| Posted: Sun Jun 24, 2018 1:06 pm Post subject: Re: Belt tension |
|
|
Oh, the cover! Yeah okay. I'm a technical sort of dude, I look at text, actual illustrations and specifications, and hardly pay attention to artsy-fartsy cover art. Obviously I never paid any heed to that one. hah (my comment was looking over the indicated specifications)
It's not like double-square (8-point) sockets don't exist. I have some in SAE sizes. Hell a 5/16 8 point socket rather works nicely for the 4-point fill plug on early steering boxes.
_________________
Andy T.
IMAGE NOTE: It has been noted that Chrome based browsers may have issues in displaying my vast image library, which use non-secure links and are on an FTP server. Images should still be viewable if the link is clicked though.
I do not know how to fix this. All I can say is it all works fine for me with what I use, Firefox.
Last edited by glutamodo on Mon Jun 25, 2018 4:52 am; edited 1 time in total |
|
| Back to top |
|
|
|
