therock

iTrader: (2)

I replaced my Radix supplied tensioner with a Gates unit and its plastic pulley with a grooved steel wheel. I also replaced the plastic idler with a steel smoothie.
I'm sure the supplied equipment is fine but I have my own ideas. I posted here looking for numbers with no success so I decided to put them up.
The Gates tensioner is known for the better coil spring design and more tension.
Steel pulleys sink heat out of the bearings better than plastic and are less prone to hold dirt or break.

Below are the Gates p/n's my notes and a pic.

Gates 38131 Belt Tensioner Assembly. - Comes with a plastic smooth pulley. I removed it to make way for the steel grooved wheel. The radix supplied tensioner mounting bolt works fine. Removing the plastic sleeve from the locating pin is required. When removing the plastic pulley brace the tensioner carefully because the bolt is tough to break loose. $39.79

Gates 36100 Belt Tensioner Pulley. - Steel 75mm 6 Rib steel with 17mm bearing bore. $23.06

Gates 38042 Idler Pulley. Steel 90mm Smooth/Backside, 17mm Bearing Bore with 10mm adapter (not used, the radix standoff replaces it). $16.64 - This took some adjustment on mine. Maybe there are other part numbers that will not need the adjustment, or yours will align better, I dunno.
The Radix pulley spacer or mounting standoff had the pulley too far outward allowing some belt to be off of the pulley's backside (about 3mm). Being a machinist I took 5/32 or 4mm off the Radix bushing/standoff for a perfect alignment.

Update: Gates 38002 100mm idler Pulley.

The pic.

white lightning SS

iTrader: (3)

Nice work and thanks for the info!!!

therock

iTrader: (2)

Just an FYI,

I have been experiencing some belt slippage noise at rapid decelerations. Its been 60k + miles so I ordered a new tensioner.

The new STYLE unit - same p/n is A total revamp.

In pull weight testing the newer unit took less to start it to move but after 1/4" of rotation they both pulled equal weights. You can see my sharpie marks on the new one in the shot showing the part numbers.
The new design is heavier and feels smoother. It seems better built.

therock

iTrader: (2)

10 years later I'm still breathing on my 2005 Radix M112 installation.

I put on the new style Gates 38131 tensioner in hopes the 10 year old one was tired letting me get slip on rapid decelerations.

The Blower pulley is a 3.4".

Well I report no change to speak of.

So I found part numbers for Gates 100mm vs. the 90mm Steel smooth pulleys and installed them.

I think I may have cured it but need to drive it more.
I got a little more wrap and a tensioner position change.

I am just about at the 70k miles point. I changed the Blower oil yesterday. Jegs had the best price. I pumped her out with an oil sample extraction pump and it took all of one bottle and almost all of the second.
GM 12345982 p/n.

With the Gates 38042 90mm Idlers.


With the Gates 32008 100mm Idlers


Pulley Side By Side Comparison

TIM Z

iTrader: (12)

Those 100mm will def help , but if not I would add an adjustable pulley like member Gadgetized did when he had his 112 .

Also I would think about doing an 8 rib setup if you want to go farther boost wise.

And when I was 6 rib I had best luck with dayco poly cog and gates green HD belts .

N20zuki

I went ahead and added a 63mm pulley under the snout of mine getting more belt wrap. I had already did the 100mm pulleys and Gates tensioner. But I am running a 3.0 pulley and its in a car with a T56 and the rapid drop of RPM's when shifting would let the belt slip and I ate up 2 gatorbacks in a 6month period of time and 3500 miles. Now I have a Gates HD belt and this extra pulley and so far 4500miles on this setup with no issues anymore.

therock

iTrader: (2)

Thanks Guys,

@N20zuki =
Were you trying to defeat acceleration or deceleration slip in adding the pulley?
Also, does the Gates Green Belt provide more grip or durability?

Thanks

therock

iTrader: (2)

I have a 3.4" pulley on the supplied Gates K061120 belt. I cannot find a Performance-Blue, or Heavy Duty-Green Gates equivalent.

I can go a touch longer but not any shorter with those 100mm idlers. The current belt is 112-1/2 " or 2859mm long.

N20zuki

Initially I was trying to stop acceleration slip, My boost pressure would drop off up top in the high RPM as well as rubber residue all over under the hood (around alt, p/s pump and timing cover. After putting in the extra pulley I have no more rubber residue. So I feel that with HD tensioner and extra pulley cured all my issues.

therock

iTrader: (2)

Just wanted to let you guys know that the larger 90mm idlers all but eliminated the chirp I would get under sudden throttle let off when goosing her.

I was worried about over tension and wearing out water pump or other bearings.

But having heard an itty-bitty-tiny cherp once when winding her out good and thinking I seen a radar/laser trap and letting off, I feel better.