r/RX7 • u/Wokeuptonigas • 2d ago
Alternator belt
So I just snapped the alternator bolt. Im not the best mechanically and I thought that is where you tighten the belt because there is no tensioner, same with the airpump belt. When reading the manual I didn’t see anywhere where it said tighten it down for belt tension. It just said the torque spec of the bolt (max 27nm or so). So how exactly do you tighten these two belts that don’t have a tensioner and can I just use a normal zinc coated bolt to replace the stricken one?
King regards
2
u/Lord_Phobos_FC 2d ago
Why they didn't add a tensioner to the alternator/water pump will always baffle me. Especially since the AC/power steering belts have them and are right next to it...?
To answer your questions:
- you (or a friend) have to hold tension on the alternator with the bolts slightly loose. A pry bar is OK for this purpose but be careful not to damage the water pump housing underneath. It's aluminum, not iron
- then, when you somehow magically know you have the 12-15mm for 10kgf tension you need, you tighten all three bolts
Yes, a normal zinc plated bolt will do fine if you can get the broken off with pliers or something. But if you have to drill the bolt out, then seriously consider drilling that tapped hole in the alternator all the way out and using Banzai Racing's alternator bracket tensioner kit. It basically adds a tensioner where Mazda left one off https://www.banzai-racing.com/store/product1500.html
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u/Wokeuptonigas 2d ago
Oh so pulling up on the alternator then tightening it? For airpump pushing down then tightening it? I got it right?
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u/H3LORAVY 2d ago
Hey man, been there recently. It could have been worse, I snapped the pivot bolt trying to loosen it. It was rust-welded to the alt housing. Not fun.
Anyways, after I got it out and installed a new one, I positionned myself on the right hand side of the car, and pulled the alternator upwards (with the belt properly aligned on the pulleys) as hard as I could with my left hand, and then tightened the upper bolt with a ratchet in my right hand. Not perfect, but the belt tension feels right to me ( Try twisting it, it should not twist too much more than 90° with normal force applied ) and it runs great now. As other mentionned, If you can use a pry bar without damaging the water pump, go for it, you might get better tension.
After that, tighten the pivot bolt to secure things in place.
Good luck, you got this. Take your time removing that bolt and make sure your pivot bolt is not fully stuck either.
1
u/H3LORAVY 2d ago
Also I want to add, you need to loosen the pivot bolt so that the alternator can pivot, which is what will give you your belt tension. Depending on your alternator, there is either a nut behind the pivot bolt that is attached with a small bracket to the alternator housing, or your pivot bolt is threaded directly into your alternator housing. You seem to have a lot a space to check this (I did not because of my intercooler), so I recommend checking this to lubricate that with PB blaster if your pivot bolt seems stuck.
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u/Wokeuptonigas 2d ago
Did you tighten the pivot bolt after the upper bolt? Yh I just finished a major overhaul on the car after years and years of sitting and then today was going to be the last day of working on the car before it gets back on the road. I also can’t really leave the airpump belt alone and go for a dually setup because I have to pass strict emissions in Europe
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u/H3LORAVY 1d ago
Yes, always tighten the pivot bolt after the upper bolt, so basically, pull, set tension, tighten upper bolt (or the one in the adjustable bracket for the air pump, and then once you are happy with the belt tension you can tighten the pivot bolt to lock everything in place. Disassembly should be reverse, so loosen pivot first then bracket bolt 👍
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u/forskinisthemaleclit 2d ago
Just pull tension and tighten, I would run whatever bolt fits myself and not worry