The "stock" idler pulley setup on the Coldside has always been a weak link. One bolt holding it all on, no good way to tension, and the fact that if/when you lose that one bolt, you lose your whole pulley setup... there was room for improvement. Thanks to Edward Smith and "Hamez" of the BRP Forum, I was able to put together something a little more sophisticated.
Lexan prototype of the new idler system.
This photo doesn't quite show the three points of attachment defining the plane of the new pulley plate. Instead of using the alternator adjustment bolt, now the alt. is positioned as far down in the range of travel as possible. The water pump bolt on the right provides strenght to the system. And on top, the bolt through the front of the blower defines the plane.
Another view of the lexan prototype.
The clear lexan allowed me to figure out exactly where I needed to drill each hole. For example, the top pulley hole (empty in this shot) was dangerously close to my fuel line. This is a bad angle, but I was able to put that hole right between the fuel line and the alternator ground wire.
Water pump bolt and the alternator ground.
One thing about this new pulley system I wanted to maintain was usability. The old system was anything but usable. I wanted quick belt changes, lots of belt wrap, and no problems adjusting tension. I didn't want any stock parts to become hidden out of reach, thus, you see the alternator ground in its final position in this pic. It just needed to be bent a little to the right.
Parts needed to make your own revised pulley system.
The tensioner and the idler.
That's one JRSC nylon pulley in the back, and one VW timing belt tensioner. It tensions around a cam bolt with a little tool (the red handle to the right). This is an unfortunate picture in that you can't see the offset of the hole in the VW pulley. These both needed to be offset from the idler plate by a decent distance, and as you can see, I used only the most hightech spacers available. As for the VW tensioner, it's supposedly for an early 90s VW Golf 1.8. I found a listing at autohausaz.com for several pulleys and just ordered the one I thought looked closest. It was part number 026-109-243e.
The completed idler system installed.
Anyone familiar with the Coldside idler system should be immediately impressed. This new system gives you more than 180* of belt wrap on both the blower and the alternator. No more belt squeal, no more crazy 135+ lbs of belt tension, and most importantly, no more threat of losing the whole pulley system if one bolt breaks.
The idler (top) and the tensioner (bottom) installed.
At the bottom, you can see the offset of the VW cam pulley pretty nicely. It's tensioned through the holes on the left. On the top pulley, you can see the stack of washers behind it, giving it a little offset to keep the belt lined up perfectly.
Notice the straight belt path.
This shot shows the belt lined up perfectly. I also highlighted (very lightly) two points of attachment. On the bottom is the hole that used to have the alternator tensioner bolt. It now just has a single bolt that holds it in place on the new bracket. On the top, you see the bolt going through the blower. This bolt is not for strength, it only defines the plane. Notice how it's spaced out with washers behind the bracket.
Belt wrap on the alternator.
Lack of alternator belt wrap was a weak point of the original pulley system. I dare the alternator to find a way to slip now! That is a lot of belt wrap.
Finally, this is how we tension.
That's it. One special tool twists one pulley. No fiddling with pinch bolts or tweaking alternator brackets. One special tool, and one bolt to tighten (the one going through that VW pulley). Simple. Easy. Uncomplicated. Just like the Coldside.
Visiting Flyin Miata
Posted on Wed, 12 Jun 2019 01:45:00 +0000
I got to visit Flyin' Miata! Warning - much fanboy babbling lurks inside.
Mona Visits Arches
Posted on Thu, 06 Jun 2019 02:00:22 +0000
Ramona straightens out the curves in Arches National Park.
XIDA ND Suspension Install
Posted on Tue, 21 May 2019 03:50:25 +0000
Mona dumps the soft GT suspension in favor of a set of XIDAs from Supermiata.
ND Miata/MX-5 Oil Change
Posted on Mon, 13 May 2019 03:21:22 +0000
A quick ND oil change blog... mostly so that I can look up torque specs here later.
CarbonMiata ND Spyder Grille Install
Posted on Sun, 12 May 2019 03:47:58 +0000
Mona gets a new grille from CarbonMiata.