www.RX7fb.com

I have been experiencing problems with alternator V belts for my 1985 series 3 rotary ( 12a motor ). At over 4000 rpm belt slippage eventually wrecking the factory belt. The alternator drive pulley (63mm diameter, 11mm wide) was replaced with an after market 80mm diameter steel item running running 2 x 11mm belts. The crankshaft accommodates the 2 standard factory belts & they handle
up to 8ooo rpm without slipping or adopting a more expensive flat belt pulley conversion.
Happy motoring, Les Marshall

Hi Les,

fan belts shredding at higher revs is typically caused by the viscous coupler on the cooling fan going bad...... at higher engine speeds the fan should start to freewheel... if the coupler goes bad, the fan doesn't freewheel and as the fan is a big heavy load on the belt, the belt can't cope so slips and eventually shreds.....

RX7's that have been off the road for a long time or cars which get little use seem to suffer more from these fan problems although due to their age, most of them are on their way out.

check out this thread...

http://www.rx7fb.com/viewtopic.php?f=23&t=137

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Leslie wrote:I have been experiencing problems with alternator V belts for my 1985 series 3 rotary ( 12a motor ). At over 4000 rpm belt slippage eventually wrecking the factory belt. The alternator drive pulley (63mm diameter, 11mm wide) was replaced with an after market 80mm diameter steel item running running 2 x 11mm belts. The crankshaft accommodates the 2 standard factory belts & they handle
up to 8ooo rpm without slipping or adopting a more expensive flat belt pulley conversion.
Happy motoring, Les Marshall

It is important to get 2 toothed V belts with exactly the same length. I bought 5 contitech AVX 10x785 toothed V belts and interchanged as long as they fit. Max 9000 rpm most 8000 rpm with no problem since 10000 miles and viscous fan. Take the racing beat Double sheave pulley set for race and high rpm http://www.racingbeat.com/RX7-1975-1985 ... yset2.html

Aluminum Main Pulley - Double Sheave :: 74-92 Rotary Engines (All)
The Racing Beat Aluminum Double Sheave Main Drive Pulley for virtually all 1974-92 12A and 13B engines is designed for high performance/RPM street and moderate racing use, slowing the water pump and alternator 13-15 %, thereby reducing cavitation and ...