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The perfect Gilmer belt set up, does it exist?

Started by _Matth1000_ , Mar 02 2020 03:32 PM

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6 replies to this topic

#1 _Matth1000_

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Posted 02 March 2020 - 03:32 PM

So I have done a bit of reading and I may have come up with a mix match of parts that might actually work so the alternator will charge while at lights.

My original setup was 39 tooth 115mm water pump and crank pulleys and 21 tooth 62.5mm alt pulley.

In this config i was getting an alternator speed of 1380rpm at the alt with 750rpm at the crank, not quite enough to provide 13.8 volts at a set of lights, I was getting anything from 10.5 to 12v depending on head lights and stereo, fans.

I have recently got the diecrest engineering alt pulley that is 17 tooth 50mm, ($70)

http://www.diecrest.com.au/

Bung that in to the pulley calc and I should be getting 1725rpm alt rpm @ 750 crank rpm.

https://www.blocklay...ulley-belt.aspx

I had to buy a 24mm tube spanner as you wont fit a regular socket in the pulley to tighten the 24mm nut.

https://www.gasweld....le-ended-576298

20200302_120939.jpg 80.93K 15 downloads

20200302_120947.jpg 81.24K 11 downloads

I'm waiting on the 390L belt as my 420L was to big and the alt was hitting the chassis rail.

I will let you all know how it goes when I get it all back on.

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#2 dattoman

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Posted 02 March 2020 - 07:17 PM

Not sure why people want to run gilmer drives

Without a supercharger they are just noisy wank that wears pulleys and throws belts

You've gone the opposite of most people by speeding up your alternator

Likely to have issues at higher cruising rpm with overcharging

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#3 Cook

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Posted 02 March 2020 - 07:37 PM

Hi Matt. Good on you for doing the research etc. I'm no authority on anything auto but obviously the issue, with anything other than standard is differentials between revolutions, between the pulleys that interfere with flow, whether that be water, fuel or charge and heaps of people run them so there should be a lot of interest. Personally I am going to run a serpentine system as it seems to be the norm for modern day cars (so I'm assuming it's a good thing). Cheers Ron

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#4 76lxhatch

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Posted 02 March 2020 - 08:05 PM

You can't really go too far with the pulley ratio on these as there just aren't the options for street use. Most are geared down so the alternator spins slower for high rpm use only, causing the problems you've experienced. I ran one for years with similar ratios (and the 390 belt, should do the trick) using large crank and water pump pulleys with an alternator pulley from a different kit, it was about as close to the factory pulley ratios as you can get. They don't throw belts if set up right but need to be a lot better aligned than V belts.

They really are mostly just for the looks and the noise but if that's what you like then who cares. Mine did eventually wear out the pulleys which in turn caused the belt to move around and start chewing out the edge so I gave up on it.

What sort of alternator is that though, do you know what the output curve is? Some of those cheapies offer very little output at low rpm.

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#5 _Matth1000_

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Posted 02 March 2020 - 11:40 PM

I have had the glimmer setup for over 10 years with no drama except the under charging. Mine is not that noisy as it’s tensioned properly. If you can hear it then it’s probably to tight. I like it more for the look.
I also have a m22Z rock crusher that has gear noise with the straighter cut gears and a pretty rowdy 355 so the belt is pretty much silent compared to everything else but yeah if you had a quiet car then the belt noise would get annoying quickly.
Correct with the new set up I have now I am pretty much bang on the stock ratio of 2.3 to 1 so that shouldn’t be an issue on the freeway.

I should be getting the 390L belt later on in the week so I should be able post some results by the weekend.

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#6 Braderunner2

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Posted 07 August 2021 - 06:52 PM

Hi Matt, thanks for the post…i run a VS 5L with an 85A alternator. I bought the 50mm alternator pulley from Diecrest… the boss was 6mm longer than my one (would have pushed the belt off the crank pulley by 5mm, and probably wouldn’t have been able to get many threads engaged on the pulley retaining nut). Peter from Diecrest was adamant he had sent the right pulley, so I had to remove 5mm from the boss. When I installed the new 390L belt, the plug on the alternator could not be fitted as the alternator was hard up against the block. Luckily the old 420L belt was able to fit without the alternator hitting the chassis rail. Cheers Paul.