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Deep Groove Alternator pulleys

Started by _liam kelly_ , Mar 21 2021 01:09 PM

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#1 _liam kelly_

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Posted 21 March 2021 - 01:09 PM

Hi,

Anybody know the brand and part number for a deep groove and larger OD alternator pulley I can use for my black 202 motor runing a Bosch Alternator ? having an issue with belts turning inside out at high rpm still after fixing alignment, correct tension etc.

Alternator has a 17mm shaft. Current pulley has an OD of 66mm and width of 20mm.

Belt specs of the 11A0940 are 11mm wide, 8mm high and a pitch of 38 Degrees. Originally running gates belt but changed to Bosch and hasnt done it yet but still want to improve the pulley so the belt sits a little deeper and slows the rpm of the alternator down.

Cheers

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#2 warrenm

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Posted 21 March 2021 - 10:00 PM

I went to an auto electrician & he searched through a box of used pulleys that he had in the corner.

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#3 _liam kelly_

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Posted 21 March 2021 - 10:09 PM

Thanks Mate, thinking i will do the same as there is a large amount of people sellling pulleys online without any dimensions at all advertised from the sellers or the manufacturers.

The after market harmonic balancers like powerbond etc the prescribed 11mm belt sits out of the pulley about 2mm presumably from it being an 3/8 imperial, and the bosch alternator it sits out about 1 mm presumably from it being metric 10mm. the 11mm belt sits great in the water pump pulley (yes its older and more worn than the other two but seems correct).

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#4 _liam kelly_

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Posted 22 March 2021 - 01:08 PM

ended up ordering this one of ebay to try, from USA

https://www.ebay.com...353.m1438.l2649

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#5 warrenm

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Posted 22 March 2021 - 09:42 PM

What sort of revs is the belt coming off at? Pay real close attention to the alignment.

Edited by warrenm, 22 March 2021 - 09:42 PM.

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#6 _liam kelly_

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Posted 22 March 2021 - 10:55 PM

Thanks, its a VK EFI black motor so it has the P/S and ALT as one solid piece. After reading about how the belt turn in on them selves I took this off and grinded back the mounting points for both the P/S pump and alternator so i can fit 3 washers either in front and behind each one to move them back and forward as it did look a little bit out of alignment. I purchased a cheap laser pointer to help try to line up the center of each groove, have fitted the P/S pump back on and aligned that. will do the alternator next after its fitted again. was looking at those laser pulley aligners for $150 but wasnt sure if they are worth it but considering it now.

I was logging at the ECU logs and the belt seemed to come of only at 4000 rpm but before that I went to 5500 and 6000 rpm about 3 times . I have only taken the engine to 6000 rpm in 2nd and 3rd and to be honest it probaly cant do more than that anyway but still tuning the fuel and igntiion maps.

Thought while I am at it i will thorougly look over everything as fitting the fan belt on the side of the road is not very enjoyable, and will try to change the alternator pulley as well to slow it down and keep it in the groove a little more. not overjoyed about the belt sitting so high out of the powerbond harmonic balancer but dont really want to change it at the moment. was driving the car for about a month with a blown alternator bulb in the dash and the alternator not really charging at idle until the engine is revved so thought i would be ok with the wider diameter pulley but only a test will tell.

Was also reading that as a bandaid some people where mounting a stud in the alternator tension adjustment just after the bolt that holds the alternator to help stop it jumping out but dont really want to do that, even though it is a quick and easy one.

To be honest have never really payed that much attention and have just taken it for granted and got away with it before i built this motor. I guess thats how you learn.

Cheers

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#7 warrenm

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Posted 23 March 2021 - 06:14 AM

I use a straight edge(steel ruler) across the face of the pulleys. You can fit double adjuster brace on top top stiffen them up, down shifts can sometimes roll them off. The mount that the alternator bracket bolts to aren't always parallel with the crank, generally 1 or 2 washers fitted behind the front bolt.

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#8 Shiney005

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Posted 23 March 2021 - 09:38 AM

There is a three inch pressed steel pully on some old Sigma's, but I'm not sure of the shaft size.

Someone in here was making replicas of the Bosch 3 inch pully as fitted to XU1's, L34's (and HK 327 Monaro?) but I can't remember for the life of me who it was.

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#9 _liam kelly_

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Posted 23 March 2021 - 11:03 AM

Thanks Guys, appreciate the help

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#10 rodomo

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Posted 24 March 2021 - 09:15 PM

There is a three inch pressed steel pully on some old Sigma's

Single top bracket. Never had a problem and revs to 7. I'm pretty sure it's Sigma.........been a while....

Removed the cooling fins as they bent with centrifugal force.

Attached Files

alternator 002.jpg 227.1K 6 downloads

Edited by rodomo, 24 March 2021 - 09:16 PM.

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#11 _liam kelly_

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Posted 25 March 2021 - 08:50 PM

thanks mate

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#12 Shiney005

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Posted 26 March 2021 - 09:30 AM

Removed the cooling fins as they bent with centrifugal force.

I found a neutral in the Group A while I was giving it the berries once. I don't know how many revs it went to, but all the fins bent in far enough to hit the alternator body.

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#13 _liam kelly_

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Posted 17 April 2021 - 04:06 PM

Fitted the underrun and deep groove pulley i got from ebay, its a little bit thicker so had to space the alternator back towards the rear of the car a few mm. Lined all the pulleys back up with a laser line from sides, below and top and spot on alignment even with a quick engine idle with rotating pulleys with no belts on.

Belts set to correct initial tension, ran in. Engine cooled down and belts retentioned.

Took the car for a drive and gave it to it in 1st, 2nd and 3rd only going to 6000rpm, everything really smooth with no vibrations. Stopped and opened the bonnet and the belt has still turned over ! At least with the deep groove alternator pulley it stayed on but upside down and ran fine enough for me to get back home.

Still sus on the harmonic balancer as the top width of harmonic balancer is only 10mm and the 11mm belt sits noticably proud. Water pump pulley is fine and no noticeable wear, with the belts not able to physically bottom out.

Does it with a gates, Dayco and Bosch belt (all internal cogs) . Want to try a 'Top Cog' belt but apparently Dayco Australia don't do them anymore so I have to bloody get them from the USA.

Driving me nuts lol

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#14 _liam kelly_

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Posted 17 April 2021 - 04:28 PM

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#15 _liam kelly_

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Posted 17 April 2021 - 04:38 PM

IMG_2412.jpg 245.18K 6 downloads IMG_2410.jpg 171.76K 5 downloads

Edited by liam kelly, 17 April 2021 - 04:41 PM.

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#16 LJ RB30

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Posted 17 April 2021 - 11:25 PM

Now ive seen a engine bay pic ( noice :spoton: ) the only thing i would suggest is remove the fan & try again with a new belt.

Ignore if you've tried this

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#17 _liam kelly_

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Posted 18 April 2021 - 07:56 PM

Thanks Mate, havent tried that yet. I was hoping to keep the simpleness of the clutch fan but I'll get some thermos and see if the belts and pulleys behave better. I can't or the life of me see any movement in the water pump bearing but might replace it anyway.

The belt must be rolling over on the slack side of the pulley system, upper side of harmonic balancer, water pump pulley. Think ive eliminated the top side of the alternator pulley by replacing it with a deep groove.

Ive contacted Dayco to ask why the top width of the pulley groove is only 10mm, what resonant frequency the 'race balancer' has and to confirm their statements that this balancer is physically locked from moving forward and backward.

Cheers

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#18 rexy

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Posted 19 April 2021 - 07:11 PM

Do the pulleys run true? No subtle warping?

Have you tried adding a bit more belt tension?

Are you sure there isn’t any flex in that alternator mount?

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#19 _liam kelly_

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Posted 19 April 2021 - 09:44 PM

Thanks mate,

the Harmonic balancer and alternator pulley are new and are machined steel. I had a 5m long laser line on all the H/B, water pump and alternator pulley and spun them by hand and couldnt see anything obvious. Idled the motor without belts on when cold with the laser and a timing light strobe on them and still couldnt see anything. So not that i can see with my eyes but still looking.

First time round set the belt tightness as i normally do just be feel on an already run in belt. Second time around Have only tensioned the belt as per the belt manufacturers specs and retentioned after run in, purchased a dayco krikit tension measuring device. After reading how the belt exerts force against the pulley i was going to try more tension but dont want to kill my water pump bearing. So will do soon but need to do a bit more checking first.

I doubled up the alternator top mount, so the top adjuster part is now 10mm thick. Its connected to the alternator, P/S solid bracket that connects to the block with three bolts as its a black motor. So i dont think so.

Does not roll the power steering belt at all, only the fan/alt belt. Although P/S belt much shorter and sits in the driving pulley flush and not riding out like the H/B pulley.

after i get it back together, ill try running it whle watching and put a strobe on it to see if i can see anything. Last time i did that it was dancing around everytime it received a shock and you can see the slack side of the pulleys double.

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#20 warrenm

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Posted 19 April 2021 - 11:33 PM

Do you use a lightened flywheel? The last time I had issues with throwing a belt was when I had a super light flywheel.

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#21 LJ RB30

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Posted 19 April 2021 - 11:35 PM

Thanks Mate, havent tried that yet. I was hoping to keep the simpleness of the clutch fan but I'll get some thermos and see if the belts and pulleys behave better. I can't or the life of me see any movement in the water pump bearing but might replace it anyway.

I wouldn't bother fitted thermos yet, just remove the fan & shroud & go for a squirt to see if it helps (though thermo's would be my choice anyway)

Fans are only need when in slow stop start traffic. Once your moving the natural airflow will do the job.

You've really covered most things, if you cant feel any movement in the water pump bearings then there's no point replacing it.

Your alignment methods are above & beyond :spoton: so i doubt that's the issue and as long as there is no movement in the alternator & balancer my thoughts come back to the fan.

The donk looks like it been build to boogie :rockon: so im thinking as the engine spins up quickly & the fan clutch may not be fully free & the little belt may not like the extra load.

Another idea is put a gopro under the bonnet & see what you find.

Just a few ramblings after a few beers

Cheers

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#22 _liam kelly_

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Posted 20 April 2021 - 10:04 AM

Thanks Mate,

Its a yella terra lightened flywheel at 8.6kgs not the ultralight one. I was recently reading the other post about just what you mentioned about balancer and flywheel weights and trying to digest it all. The balancer is a powerbond 'race series' black motor machined steel version which is sliglthy heavier than the factory one. I may have to put a standard weight one back in next time i change the clutch as i guess the factory engineers would have designed the stock balancer for the crank with that flywheel weight on it. If my problems are being caused by the harmonic balancer moving around to dampen vibrations im not sure if i should be happy i'm seeing it at the front of the motor rather than the rear but need to digest all that info in that other post some more. Was considering spacing the alternator and P/S forward enough to use one pulley forward each so that the fan/alt belt is running on a pulley that isnt the out ring of the harmonic balancer, need to see if this is feasable. More learning required lol

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#23 _liam kelly_

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Posted 20 April 2021 - 10:18 AM

Thanks Mate,

I'll give that a go on a cold night and try and replicate exactly where i drove last time and when i gave it to it so its an accurate as possible test. I was trying to get my head around what could be happening with the fan when i accelerate and it has not much momentum and then when decelerating and it already has momentum. The clutch part is relatively new when i put the motor together and appears to be behaving as intended for a stock motor.

I have installed a relay in my fuse box controlled by the ECU for thermo fans and just need to run power wires out but was hoping to keep the simplicity of the clutch fan if possible. I guess time will tell.

Lol, i like the idea of the go pro installed under the bonnet. Nothing like having accurate data on what is going on rather than guessing ! The head has been ported to allow approx 250hp at 0.500 lift, running a 0.525 lift but the flow only slightly increases after 0.500, so its not the biggest beast out there by a long shot but its how i picture the VK EFI should have been lol.

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#24 warrenm

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Posted 20 April 2021 - 11:34 PM

If it's 8.6kg, that's the same as a blue/black/XU1 flywheel, I was using a 6kg flywheel when I had problems. I'm also using a Dayco Top notch belt which has been on for something like 10 years(at a guess) which is a long time at 7000 rpm.

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#25 _liam kelly_

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Posted 20 April 2021 - 11:57 PM

Thanks Mate,

Still digesting all of that torsional vibration info on this site, appreciate the help.

I spoke to Dayco in Australia and appraently the factory in the USA that makes the top cog belts has closed down or something and from now on you can only get the internal cog belts. I keep reading posts from old american drag racers from the 60s, 70s saying stuff like 'its an old secret to use top cog belts to stop them being thrown off'. Not sure how true it is but i guess they would have found out from experience. I ordered some new old stock from the USA so at least i can try a 11A0950 top cog belt to see if that makes any difference..

They do appear to have the threads in the v itself and not in the band above the v so it guess the belt itself would have a lower centre of gravity so may behave difefrently. Just speculation.