VWDiesel.net The IDI, TDI, and mTDI source.

Engine Specific Info and Questions => IDI Engine => Topic started by: scrounger on November 06, 2021, 09:44:38 am

Title: Stock diameter of alternator pulley, 86 idi TD
Post by: scrounger on November 06, 2021, 09:44:38 am

The title says it all. I know that the previous owner (11 years ago) had installed a non standard alternator and he said that the pulley on the alternator he used was not the same as stock. I am thinking that I would like to get the tach working again and think it might be good to have the right pulley.

Since the alternator isn't right, perhaps the engine pulley that he used isn't correct either. The pulley closest to  the crank does not have a belt on it

Yeah I could have looked at this problem years ago but the car ran the way it is but am tired at looking at the dead tacho.

Title: Re: Stock diameter of alternator pulley, 86 idi TD
Post by: fatmobile on November 06, 2021, 10:19:42 pm

Must be a non-AC setup eh?

Title: Re: Stock diameter of alternator pulley, 86 idi TD
Post by: scrounger on November 07, 2021, 05:06:47 am

Well it had an ac but the compressor came in a box. So no AC installed.

edit:

The alt pulley in mine is  3" OD .

Here is  the belt arraignment currently, Looks like the empty pulley is for the power steering pump.
(http://veloliner.com/vw/vwbelts1.jpg)

So more than one issue.

Title: Re: Stock diameter of alternator pulley, 86 idi TD
Post by: fatmobile on November 07, 2021, 11:29:17 pm

The tach is adjustable.
 So maybe you can turn the potentiometer to calibrate it.
 Without having to change the pully.

Title: Re: Stock diameter of alternator pulley, 86 idi TD
Post by: ORCoaster on November 08, 2021, 04:43:05 pm

Yeah, Fatmobile it is adjustable, but to get at that pot he needs to pull the cluster.  It is not readily accessible through a hole on the backside either.  So pull the tach off the cluster, hotwire a positive, negative, and signal jumper to it with the hood up, and calibrate with a reference tach. 

Title: Re: Stock diameter of alternator pulley, 86 idi TD
Post by: scrounger on November 08, 2021, 08:54:09 pm

Thanks fellow idi enthusiasts.

Title: Re: Stock diameter of alternator pulley, 86 idi TD
Post by: fatmobile on November 08, 2021, 10:51:04 pm

 I took the pot off the board and ran it outside the cluster on my Rabbit.
Sits to the side of it.
 On the digi 2 cluster in my '91 golf I drilled a hole through the front for a screwdriver.

Title: Re: Stock diameter of alternator pulley, 86 idi TD
Post by: scrounger on November 09, 2021, 02:24:59 pm

That sounds reasonable fat.
 I thought that I could calculate the rpm at say 60mph and adjust for that. 

Have had the entire dash out last month and rebuild the ugly parts and installed vdo gauges in the radio area.

Title: Re: Stock diameter of alternator pulley, 86 idi TD
Post by: ORCoaster on November 09, 2021, 07:43:10 pm

Use the quick calculator on the right of the site for gears.   You do need to know the inputs to make it work. 

http://www.scirocco.org/

Title: Re: Stock diameter of alternator pulley, 86 idi TD
Post by: scrounger on November 10, 2021, 06:27:44 am

Yeah thanks, I was just going to use 5280/ circumference of wheel times final drive ratio times top gear ratio

With the ags transmission ratios of 3.94 and .745 would give something around 2600 at 60mph