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Robson spring loaded tensioner
Posted by: illinicorsa ()
Date: May 11, 2016 12:41PM

I have a Robson spring-loaded fan belt tensioner on my “new” 1966 Corsa (tensioner did not come with any instructions). After I had the car a few days I tossed a fan belt (well below 3000 RPM). The tensioner seems to otherwise be working as it should – it has plenty of movement (and not binding) – which can be observed at idle. I’m wondering if there is sufficient belt tension. There is an allen head bolt projecting about ½” from the unit, which appears to adjust the tensioner travel.

Any suggestions?

Steve
’66 Corsa
St. Louis area

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Re: Robson spring loaded tensioner
Posted by: vairmech ()
Date: May 11, 2016 04:11PM

Are you running stock pulleys?

I ran into a situation with the race car where the aluminum pulley on the alternator would cause the belt to come of on shifts. I changed to a polished steel alternator pulley and the problem went away.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Robson spring loaded tensioner
Posted by: bought1 ()
Date: May 11, 2016 04:23PM

If you have rust on your pulleys that will throw belts as well.

Dave

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Re: Robson spring loaded tensioner
Posted by: SoloCP ()
Date: May 11, 2016 05:52PM

If I remember correctly the belt being used can have an effect. I do not remember but Lon might chime in about the best belt to use on the spring load tensioner, I have the same problem on mine but with the car just coming back from paint it will be awhile before I reassemble and do some test driving.

Don
Kansas City
HACOA
Broken Halo Corvair Garage.
61 Lakewood
62 Monza aka (Flicka)
62 Rampside
63 700 Sedan 3 Speed
64 Spyder Coupe (Bill Pierson Car)
64 Monza Convertible,140/4 Speed,Electric Heat,Kelsey Hayes Wheels
64 Spyder Blown, (Dave Bolduc Car)
64 Monza Convertible 110/Auto (Future Project)
65 Corsa 3.1 Liter Triple Weber (aka Unsafe)
65 Corsa 140/4 Speed with Triple Weber
66 Avenger, Corvair Turbo, Fuel Injected, Air to Water intercool 140. (Michael Mann Car)
67 Monza 110 Auto. Sugar Bear

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Re: Robson spring loaded tensioner
Date: May 11, 2016 06:03PM

As I told Steve on the phone today - we are always interested in feedback on these units - especially since they are now seeing 16 years of service in some cases.
I'm sure when Steve gets the unit back together we'll get some more reports from him and work on the solution as needed.
So far failures of the unit (that means throwing a belt) can be pretty much chalked up to people tightening the mounting bolt/nut too tight thus causing a reduction in needed movement. In Steve's case this doesn't seem to be the problem.
In the early days when I traveled a lot I could sometimes actually see the car at an event and the fix was almost always obvious. By phone - email etc it's a bit more difficult.

Lon Wall
www.corvairunderground.com
ONLY 5 MORE IDLERS LEFT OUT THE LAST RUN!

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Re: Robson spring loaded tensioner
Posted by: VegasVair ()
Date: May 11, 2016 09:16PM

Lon - Steve asked what that long Allen head bolt is all about.
For all of us that have your tensioner please explain the purpose
and correct setting(s) for that bolt.

65 Corsa 140/4 A/C convert.
CORSA+Vegas Vairs

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Re: Robson spring loaded tensioner
Posted by: Seth Emerson ()
Date: May 11, 2016 09:33PM

On my race motor, I installed a stud in place of the remaining bolt. With two studs, washers and double nuts, the tensioner can be restrained from almost any side to side movement, yet still have the "in-plane" rotational freedom to perform its job. I do use the belt guide at the top pulley. The tensioner has a built-in guide at the pulley. Photo of the installed unit. (Cute distributor, eh?)

Seth Emerson

Check my new Performance Corvair Web site [www.perfvair.com]

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Re: Robson spring loaded tensioner
Posted by: illinicorsa ()
Date: May 12, 2016 04:09AM

I’m running a stock pulley. Just ordered a new belt from Lon, which I will try. Regarding the allen bolt position, see pic – how does it look? I’m just wondering if there is an optimum position (in/out) of the allen bolt?

Steve
’66 Corsa
St. Louis area

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Re: Robson spring loaded tensioner
Posted by: vairmech ()
Date: May 12, 2016 04:50AM

The tensioner position looks fine from all that I have had. You can ask Lon, I have bought a few of them. As I said I ran one on my race car and I learned a lot about what works. I have one on the current race car also and I have 3 of these on the shelf!

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Robson spring loaded tensioner
Posted by: vairmech ()
Date: May 12, 2016 05:05AM

The one thing that I have done is to size the length of the bushings to take out any side movement of the pulley. I have used SS washers that I have filed out to fit over the bushing to take up some of that play and then another SS washer as a bushing support against the housing. Then look at the bushing length that is left and if you need another large ID washer to fit over the bushing, make one, then another SS washer then the lock nut, not a plain nut. Do not over tighten as the pivot needs to move freely.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Robson spring loaded tensioner
Posted by: illinicorsa ()
Date: May 12, 2016 05:22AM

Thanks Ken.

I will check pulley sideways movement when I install the new belt. And try to address if too much movement.

Steve

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Re: Robson spring loaded tensioner
Posted by: VegasVair ()
Date: May 12, 2016 06:35AM

Bump.

Anybody know anything about that Allen head bolt
on the top of the tensioner?

It isn't mentioned in the instructions.

Anybody? confused smileyconfused smileyconfused smileyconfused smileyconfused smiley

65 Corsa 140/4 A/C convert.
CORSA+Vegas Vairs

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Re: Robson spring loaded tensioner
Posted by: Seth Emerson ()
Date: May 12, 2016 02:29PM

The socket-head lock bolt - along with its double-locking nut on the adjustment shaft are there to keep the assembly together when the belt is removed. Adjusting it - which involves loosening the nut first - has no effect on the belt tension or idler effectiveness. The position of the bolt head only determines how far outwards the pulley will travel - usually when the belt has come off. It also keeps the whole thing together when a belt does come off. (Trust me, it can still happen!) If the bolt is not there, it is possible that, at a far-back position - which is where the spring will push the pulley towards if the belt comes off - the spring will pop off the assembly. Then, when you are trying to re-install the belt, or put on your spare, you will also be looking around the engine compartment for the recently jettisoned spring. This is not a fun thing to do between rounds at an autocross - take my word for it! When you are installing the idler assembly, use a 7/16" open end and make sure the locking nut is tight, securing the socket head screw. (see photo.)

Seth Emerson

Check my new Performance Corvair Web site [www.perfvair.com]

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Re: Robson spring loaded tensioner
Posted by: Sir Thomas ()
Date: January 11, 2018 05:39PM

Any new insights on why the belts get thrown occasionally? My car is literally throwing my belt about every third time I drive my car. It's driving me stir crazy.

Thomas Ratliff
Marion, Indiana
Fitch Sprint (in progress)
'66 Monza convertible with EFI
ThomasMRatliff@yahoo.com

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Re: Robson spring loaded tensioner
Posted by: davemotohead ()
Date: January 11, 2018 05:46PM

Belts get tossed for a couple of reasons:

1 Wrong belt, Should be a 3V560

2 Bad bearing in a idler, fan or alternator that seizes up when hot.

3 Rusted pulley inside on the belt track, either one of the 4 pulley grooves has rust your belt will fly!

4 Wrong alternator fan or alternator mounted to a generator oil filter housing.

5 Wrong height on the fan bearing making the belt ride at the wrong angle.

6 Bent Pulley.

7 Having the belt too tight.





Email me at: Dave Motohead

1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

-----------------------------------
Rust Free Lancaster Ca

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Re: Robson spring loaded tensioner
Posted by: illinicorsa ()
Date: January 12, 2018 03:32AM

The other day it happened again --belt off. But this time when I went to put the belt back on, the tensioner was stuck all the way in the "down" position, fully compressed! It released it immediately. I lubricated every tensioner surface that looked appropriate. It had worked OK since but yesterday, a very cold morning, the belt came off again -- cold, stiff belt???

My family had a 62 (my first car)Monza and a 66 Monza -- these cars rarely threw a belt.

Steve
66 Corsa

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Re: Robson spring loaded tensioner
Posted by: davemotohead ()
Date: January 12, 2018 06:25AM

Toss the Robinson Tensioner in the trash and install the stock one, Read my check list and find what problem you have? If you do as indicated your belt will not fall off any more. smoking smiley





Email me at: Dave Motohead

1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

-----------------------------------
Rust Free Lancaster Ca

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Re: Robson spring loaded tensioner
Posted by: caroseiii ()
Date: January 12, 2018 06:38AM

I sold mine a few years back. I found it did not work well with loping idle or steel fans. Seemed to work best with smooth idle or magnesium fans.

Crawford

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Re: Robson spring loaded tensioner
Posted by: tboltkc ()
Date: January 12, 2018 07:13AM

When my Corsa was my daily driver I would have problems throwing a belt if it sat for a couple days in cold weather - presumable from a cold, stiff belt as you mentioned. That is the only time I ever had a belt come off with the spring loaded idler installed.

-Travis


'65 Corsa; '63 Convertible; '62 Wagon; '65 4 Door
Heart of America Corvair Owners Assocation (Kansas City, MO)

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Re: Robson spring loaded tensioner
Posted by: ralph65corsa ()
Date: January 12, 2018 09:31AM

I run stock pulleys, correct belt and no other modifications.

I NEVER toss fan belts. I have a 140 4-speed.

I've been driving my Corvair for decades with no belt issues.

I do change the belt every couple of years or so.

I personally cannot see any reason for me to install that Robinson thing.

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