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Thread: fan belt slipping [' This thread is 2 pages long: (1) 2 ']
gdw3138


1st Gear
Posts: 39
posted March 04, 2003 08:08 PM

fan belt slipping

Any thoughts on stopping fan belt slipping when not using the air pump? Since there is limited contact on the water pump/fan pulley, I suspect that is where the slipping is occuring. Anyone with experience in using a double pulley on the alternator, since without air pump there are dual pulleys on the main and water pump. Most of the double pulleys I seen for the alternator are underdrives. Any real concerns for street drivng with underdrive pulleys? Would I be better off replacing the stock fan and clutch for an electric fan to reduce resistence on water pump and therefore slipping? Thanks.

       
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Klaus43


Rotorhead
Posts: 1259
posted March 05, 2003 09:33 AM

Get the Gates belt.

All other aftermarket belts stretch out waaaaay too fast! Gates makes the quality one; just keep it snugged up properly and you should be O.K. ...don't personally have the experience with the dual belt setup -yet- tho it sure seems the way to go. Overtightening is as bad as too loose...and a belt that's slipped for a while might not cut it anymore, no matter what. Hope this helps!

       
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wankel_dreams


Redlining
Posts: 293
posted March 06, 2003 06:25 PM

what would overtightening cause? premature bearing failure?
____________
74 wankel panther
77 REPU
79 rx7
89 Vert

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Klaus43


Rotorhead
Posts: 1259
posted March 07, 2003 11:55 AM

Yes, and quite possibly:

Premature belt failure as well, not to mention needless friction and drag...and that would be premature alternator bearing failure, most likely... At the very least, it'll stretch like crazy and need replacing real soon.

       
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nwaco


Redlining
Posts: 407
posted March 31, 2003 01:43 PM

Do they fit a REPU?

Does anyone know if the dual alt pulleys for an RX-7 fit a REPU? I assume it probably does, but don't exactly know.

I kind of hate only having partial contact. I've not had any problems, but I wouldn't mind a little safety.

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brad


Rotorhead
Posts: 1671
posted March 31, 2003 02:06 PM

electric fan

Or you can switch to an electric fan and all will be well.

The stock mechanical fan is spun off the water pump pulley. Removing mech fan and switching to electric fan removes that resistance.


____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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nwaco


Redlining
Posts: 407
posted March 31, 2003 04:20 PM

Electric fan...

Since I pride myself on cost-effective transportation and restorations and since I have a total of less than $400.00 in my awesome and beloved albeight cosmeticlly flawed REPU, I think the cheaper pulley will be the preferred course of action to insure an adequate cooling protection. I will accept the slight loss of power since when I get the need for speed, I step into one of my sevens.

So, the question remains, has anyone linked up a dual pulley to a REPU?

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Klaus43


Rotorhead
Posts: 1259
posted March 31, 2003 06:10 PM

Haven't ...yet...

But perhaps the real question is, on what combination/year of motor and which alternator...? Are you actually driving around an original, stock REPU with only $400 into it? If that's the case, more power to you, that's impressive in and of itself! Next I would suggest you spare nothing to make it the best it can be, since you won't be losing anything by doing so, not having too much in it in the first place. No reason I know of a 'dual-sheave' pulley setup isn't the way to go, regardless. Just possibly a question of what you can get/want to run/need to make work for your particular setup...nevermind the "underdrive" pulley, or the hi-RPM water pump cavitation issues...

       
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nwaco


Redlining
Posts: 407
posted March 31, 2003 06:46 PM

It is somewhat hard for me to believe as well....

But, Klaus, dear sir,

It is true none-the-less that I am wandering about in an original, and might I add stock, less the emissions, a 77 with a transplanted 77 motor. Beholden with a stock 77 alternator.
I purchased the beast in remarkably pristine condition by way of a yard of misfit autos for a mear pitance of $300.00. But alas, it's heart was beating no more, so I blessed it with that of another $100.00 wonder aquired from a man with an extra truck and not enough time. So with those and four days to spare, it breathed life, I tell you "Life", and with that I have blanketed the countryside amid the all to familiar sound of a carbed rotary bestowed as well with none other than an original "Cosmo" 13B header.

So, since I am so attached to my ride, I find it somewhat disturbing to be a single belt away from catastrophy, hence my desire to explore an economical method if insuring my continuity in my chosen method of transportation.

Rest assured I will invest ever more in my truck, but I have two more that are in various stages of construction and as like many of you, funds are in short supply. I want them all mobile before I move to non-essential investments.

I figured that a dual pulley would be the best way to go at this time for just that insurance.

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roaddancer


Hauling
Posts: 127
posted March 31, 2003 10:57 PM

In response to the over/under driven pulley ratios. An an old hot rodding buddy of my H.S. days used to toss the windings out of his alternator regularly by pulling 9000 rpm shifts. That was in an early Pinto with the British 1600. The alternator was not meant to spin that fast. Us rotorheads should take note, with our high spin motors.
Gearing slower may reduce output, or cause it to run hotter as the regulator pushes to get voltage. Low output may affect spark and idle stability.
Matching stock ratio on stock motors is a good idea. Shouldn't go wrong. I never tossed a winding on any rotary, so the factory "done good".

       
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Jeff20B


Moderator
Posts: 661
posted April 01, 2003 01:02 AM

I once tried to put a dual sheave pulley on my REPU's externaly regualted alt. The shaft was too large. Then I got an FB alt and all is good. Dual belts, too.
____________
'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7

       
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Klaus43


Rotorhead
Posts: 1259
posted April 01, 2003 06:54 AM

Sir nwaco of mazdarepu:

You are fortunate indeed! We who have paid many times the price to suffer along with less will just have to try our best to not be envious. You have been blessed by the REPU gods... May your oldschool fortunes continue, and may your REPU set new records for longevity, power, and minimal oil consumption. All hail Sir nwaco!

       
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Blake


1st Gear
Posts: 14
posted April 28, 2003 10:55 AM

Yoohoo Belt

The answer to the slipping water pump/alt belt problem is the tried and true "Yoohoo belt" (so named by Rob Golden at Pineapple Racing). This is a simple 3L220 v-belt that you put between the main pulley and the water pump. You put it over the crank pulley and start it on the water pump pulley, then turn the engine over by hand to get the belt to "walk" into the groove. It is a snug fit, but the secret is the increased contact area. I've got one on my Peripheral Port 13B 1st gen and it works flawlessly. Cost: ~$10. No need for double pulleys. Racers have been using this trick for MANY years.



--
Blake Qualley
____________
--
Blake Qualley

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Jeff20B


Moderator
Posts: 661
posted April 28, 2003 10:31 PM

Nice setup there, Blake. Is that an early 13B? Or '86 and later? It looks like your water pump is the older cast iron type. Heh, the EGR hole is filled with Devcon. Is that an REPU fan spacer I see? :)

Question: why does Rob call it a yoohoo belt? Is it because it goes around the water pump pulley, which if you haven't changed the antifreeze in a while, ends up pumping something that resembles watered down Yoohoo? Mmmm...

I'm working on a friend's REPU and it's got a dual sheave pulley on an old stock alt. It's got the larger diameter hole to fit the old style alt shafts. I tried fitting it to an FB alt, which I upgraded his truck with, and it was way too big. I'm gonna tell the owner of this REPU about the dual sheave alt pullies on Mantis' site, for his FB alt. Any comments?

Also, I am curious about the "yoohoo" belt. Can this belt be installed by unbolting the waterpump pulley? Or is it simpler and easier to just get it on there by hand cranking the engine with a 19mm socket on the eccentric shaft bolt? It ends up being a little sloppy, right? I suppose that doesn't matter though with all the contact area.
____________
'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7

       
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Blake


1st Gear
Posts: 14
posted April 28, 2003 11:33 PM

Nice setup there, Blake. Is that an early 13B? Or '86 and later? It looks like your water pump is the older cast iron type. Heh, the EGR hole is filled with Devcon. Is that an REPU fan spacer I see? :)

'86 6-port turned into a 2-port. :) Old water pump, yes. Devcon, yup. REPU fan spacer? Perhaps. The motor was in an REPU once upon a time, then a 2nd gen, and now my 1st gen. Going on 50,000 miles with carbon apex seals.

Question: why does Rob call it a yoohoo belt? Is it because it goes around the water pump pulley, which if you haven't changed the antifreeze in a while, ends up pumping something that resembles watered down Yoohoo? Mmmm...

No idea. I believe it's what the racers have always called it, going back 20 years or more.

I'm working on a friend's REPU and it's got a dual sheave pulley on an old stock alt. It's got the larger diameter hole to fit the old style alt shafts. I tried fitting it to an FB alt, which I upgraded his truck with, and it was way too big. I'm gonna tell the owner of this REPU about the dual sheave alt pullies on Mantis' site, for his FB alt. Any comments?

I am just not a fan of dual sheave alt pullies. Too much stress on alt shaft, no way to equalize tension between the two belts, and less effective than a $9.95 "yoohoo belt". Just my opinion.

Also, I am curious about the "yoohoo" belt. Can this belt be installed by unbolting the waterpump pulley? Or is it simpler and easier to just get it on there by hand cranking the engine with a 19mm socket on the eccentric shaft bolt? It ends up being a little sloppy, right? I suppose that doesn't matter though with all the contact area.

Easiest to simply start the belt on the pulley and turn the engine over by hand to "walk" it into place. No need to remove the pulley or to even use tools of any kind. The belt has a little stretch, so it ends up with the perfect tension. I've run my PP13B up to 11,000 rpm with no signs of slippage.

BTW, the designation 3L220 stands for a 3/8th inch wide, V-belt that is 22.0 inches long. I got mine at a hardware store, since this is a common lawn mower size belt, but you can also get them at autoparts stores and elsewhere, so long as the guy behind the counter knows standard belt terminology (some seem to think it is a part number and tell you they don't carry it).
--
Blake Qualley
____________
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Blake Qualley

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Jeff20B


Moderator
Posts: 661
posted April 29, 2003 01:04 AM
Edited By: Jeff20B on 29 Apr 2003 01:11

'86 6-port turned into a 2-port. :) Old water pump, yes. Devcon, yup. REPU fan spacer? Perhaps. The motor was in an REPU once upon a time, then a 2nd gen, and now my 1st gen. Going on 50,000 miles with carbon apex seals.

The REPU fan spacer is just a stamped piece of sheet metal that's not very long. It barely spaces the fan away from the water pump pulley. Ironically, I'm using an '83 FB 12A aluminum fan spacer (fairly long) and stock FB clutch fan with dual belts on my REPU and they still slip above 5.5k RPM. My old REPU fan clutch was bad and would slip the belts quite easily. Is it possible to wear out the water pump pulley sheaves from lots of belt slippage over time? I'm begining to think maybe my luck with fans is not very good. Even my Cosmo's fan is going out. I've got an FC fan and pump to try though (I guess they only work together due to the larger 8 bolt pattern on the later water pumps).

50,000? Where did you get those apex seals? I'm going to do a bridgeport 13B after I finish the 4 port 13B for the REPU. I'd like to get at least 9 to 9.5k RPM out of it. Should I just stick with an iron 1st gen water pump for the yoohoo belt? Is the FC WP pulley larger in diameter?

No idea. I believe it's what the racers have always called it, going back 20 years or more.

I am just not a fan of dual sheave alt pullies. Too much stress on alt shaft, no way to equalize tension between the two belts, and less effective than a $9.95 "yoohoo belt". Just my opinion.

Interesting. I've noticed that the forward-most belt is usually looser than the inner one on mine. There's obviously some slippage occuring here.

Easiest to simply start the belt on the pulley and turn the engine over by hand to "walk" it into place. No need to remove the pulley or to even use tools of any kind. The belt has a little stretch, so it ends up with the perfect tension. I've run my PP13B up to 11,000 rpm with no signs of slippage.

Do you have to remove the clutch fan? My guess is yes seeing as how hard it is to get 31513 belts around the blades. Also, does the belt come back off as easily as it goes on?

BTW, the designation 3L220 stands for a 3/8th inch wide, V-belt that is 22.0 inches long. I got mine at a hardware store, since this is a common lawn mower size belt, but you can also get them at autoparts stores and elsewhere, so long as the guy behind the counter knows standard belt terminology (some seem to think it is a part number and tell you they don't carry it).
--
Blake Qualley


I think this belt will solve my slippage problem permanently. I'm gonna hunt for it in my local auto parts stores, but until I locate one, I've got another FB fan to try on my REPU and test for slippage (it's from the other REPU that I'm rebuilding, which is where I first saw the long FB fan spacer used with success, and it never slipped audibly with only one belt on the FB alt; never overheated either).
____________
'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7

       
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Blake


1st Gear
Posts: 14
posted April 29, 2003 03:30 PM

50,000? Where did you get those apex seals? I'm going to do a bridgeport 13B after I finish the 4 port 13B for the REPU. I'd like to get at least 9 to 9.5k RPM out of it. Should I just stick with an iron 1st gen water pump for the yoohoo belt? Is the FC WP pulley larger in diameter?

They're just regular, single-piece Mazda race seals -- Aluminum impregnated carbon, just like the old school street seals used before the steel ones. They are also the cheapest seal available, plus are very light and self-lubricating. Great for racing, but not very long-life.

The aluminum water pumps are a nice upgrade as they are very light. I would have used one, but my $2,003 budget was too tight for that luxury.

Interesting. I've noticed that the forward-most belt is usually looser than the inner one on mine. There's obviously some slippage occuring here.

Yes. It is impossible to equalize the tension, so either the outer belt starts slipping or the inner belt is overtensioned, which causes other problems. Plus, they hardly get any more contact area on the water pump and it's all on one side, potentially leading to water pump problems.

Do you have to remove the clutch fan? My guess is yes seeing as how hard it is to get 31513 belts around the blades. Also, does the belt come back off as easily as it goes on?

Well, yes. There is no way to get it over the fan. I've never removed a Yoohoo belt, so I can't comment on the difficulty, but I do not imagine it would be hard -- cut it and buy a new one, if that's what it takes!

I think this belt will solve my slippage problem permanently. I'm gonna hunt for it in my local auto parts stores, but until I locate one, I've got another FB fan to try on my REPU and test for slippage (it's from the other REPU that I'm rebuilding, which is where I first saw the long FB fan spacer used with success, and it never slipped audibly with only one belt on the FB alt; never overheated either).

Just get the Yoohoo belt and be done with it, IMHO. Seriously, it is an under $10, 5 minute fix that is better than dual sheeve pulleys, even if it doesn't sound or look as cool.
--
Blake Qualley
____________
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Blake Qualley

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Jeff20B


Moderator
Posts: 661
posted April 30, 2003 12:08 AM

They're just regular, single-piece Mazda race seals -- Aluminum impregnated carbon, just like the old school street seals used before the steel ones. They are also the cheapest seal available, plus are very light and self-lubricating. Great for racing, but not very long-life.

Are these seals the ones you're talking about?
http://www.mazdatrix.com/getprice.asp?partnum=11013
http://www.mazdatrix.com/getprice.asp?partnum=11011

The aluminum water pumps are a nice upgrade as they are very light. I would have used one, but my $2,003 budget was too tight for that luxury.

Ah man, now you're convincing me to use my FC waterpump on the bridgey. I was saving it for a 20B. But then again, if I can fit my spare FC pulley set to the 20B, and simplify the thermostat weirdness (20Bs came with dual thermostats), then I'd be able to keep the 20B's water pump. It'll work if the 20B's water pump will accept an FC pulley. The main reason for changing the pullies is because the 20B has an odd sized serpentine belt. I think FD pullies will work if I can't get the FC ones to.

Yes. It is impossible to equalize the tension, so either the outer belt starts slipping or the inner belt is overtensioned, which causes other problems. Plus, they hardly get any more contact area on the water pump and it's all on one side, potentially leading to water pump problems.

It started slipping at 5k today, and there's a new noise at idle. It sounds like the waterpump is acting up. Man, this yoohoo belt info came along at the right time!

Well, yes. There is no way to get it over the fan. I've never removed a Yoohoo belt, so I can't comment on the difficulty, but I do not imagine it would be hard -- cut it and buy a new one, if that's what it takes!

Ok. Any particular brand I should look for? I've seen some that are fabric covered. You're in Portland, right? Do you have a Schuck's, or Checker or Kragen nearby? Is that where you got yours?

Just get the Yoohoo belt and be done with it, IMHO. Seriously, it is an under $10, 5 minute fix that is better than dual sheeve pulleys, even if it doesn't sound or look as cool.
--
Blake Qualley


Whoever said a slipping dual belt setup sounded cool? j/k :)
____________
'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7

       
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Klaus43


Rotorhead
Posts: 1259
posted April 30, 2003 10:10 AM

Gates is the #1 brand of belt!

It's been my experience that no other brand lasts as long... (even tho I have yet to try the "yoo-hoo" setup...)
Back in the '80's I used to work at a Kragen's... my experience there was also not one of quality, in general... my take ever since has been they're an el-cheapo outfit, and if it's not a brand-new name-brand part of reputable, quality manufacture, I wouldn't buy it there.

       
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Jeff20B


Moderator
Posts: 661
posted April 30, 2003 01:19 PM
Edited By: Jeff20B on 30 Apr 2003 13:23

Is this a good one?

http://www.statesupply.com/displayItem.do?sku=VA1060
____________
'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7

       
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