Belt Routing 5.0

[mechjames]

Bought a 73" belt for my 86 GT as I have done with my 93 motor I had in my old car, and my friends both run a 73" belt as well in their 88 and 91 with no A/C or smog pump

Unfortunately the tensioner comes down too much and the top part of the belt rubs the bottom.

I have came across another diagram, and from what I can tell, it will fix my issue. Someone has told me not to use it because it will cause the waterpump to run backwards, but I have played it and visualized it in my head and the waterpump in both diagrams are running counter clockwise.

Can anyone spot an issue using the 2nd diagram below? Alternator, Crank and PS pump both turn clockwise, Water pump turns counterclockwise.

[86fiveoh]

Looks fine to me

[weaverkb]

Mine is routed like your drawing, using a 70.5 inch belt. I had to take out the top bolt on the alternator to get the belt on initially.

[horsepowerjunkie]

Mine is routed like the bottom drawing, don't remember the belt size though!

[bwguardian]

I only bypass the smog pump, meaning I still have all other accessories and I route my belt like your sketch to keep the idler pulley away from the belt routing.

[dabeater85]

mine is routed the top with my 3g and underdrives i run 69.5. but iam gonna try and get a 69.25 on there

[cb84capri]

the first belt routing picture needs to disappear from the internet, there are too many issues associated with that routing. been there, done that.

the drawing you made is the only way to do it. i run mine that way now. also anytime a pulley contacts the backside of the belt it spins in the opposite direction.

i made an under drive pulley review thread a while back you may or may not find useful:

http://vb.foureyedpride.com/showthread.php?t=130334

cale

[mechjames]

Mine is routed like your drawing, using a 70.5 inch belt. I had to take out the top bolt on the alternator to get the belt on initially.

Mine is routed like the bottom drawing, don't remember the belt size though!

Thats good, the 70.5 in belt is half the price of the 73 I bought. I'll get the size figured out tonight.

mine is routed the top with my 3g and underdrives i run 69.5. but iam gonna try and get a 69.25 on there

Yea I was able to do that last year with my March underdrive pulley kit. It ended up with only 3/8-1/2 of clearance between the tensinioner/top belt and bottom belt. I didn't like it but it worked.

the first belt routing picture needs to disappear from the internet, there are too many issues associated with that routing. been there, done that.

the drawing you made is the only way to do it. i run mine that way now. also anytime a pulley contacts the backside of the belt it spins in the opposite direction.

Yea, that pic seems to be everywhere. Will work with some pulley combos but you only get 3/8 to 1/2 clearance between the top and bottom parts of the belt. To me the bottom drawing makes a lot more sense, all the accessories are turning the right direction still.

I've only run three past belts: stock with smog and a/c, stock with smog delete but has a/c, underdrive with smog delete and a/c delete, and now i'm doing stock with smog delete or no factory a/c.

[HAD85B4]

My smog pump seized on me a few months so I re-routed around it with a shorter belt using the 2nd diagram routing. I want to say that I used a 75" belt, but can't remember. I'll see if I can dig up the receipt or something.

[HAD85B4]

Found it. I used an 85" belt but my car has A/C, which I just noticed in your picture isn't there.

[weaverkb]

This is with the 70.5

[Tracer]

Top picture is only a problem if you are running higher RPMs as this set up does not contact the water pump pully as much as when you route with smog pump. That way the belt is prone to slip. I added a smog pump eliminator as my motor will see some higher RPMs. Bypass the smog and you have one third contact on water pump. The factory way has two thirds contact.

[mechjames]

Top picture is only a problem if you are running higher RPMs as this set up does not contact the water pump pully as much as when you route with smog pump. That way the belt is prone to slip. I added a smog pump eliminator as my motor will see some higher RPMs. Bypass the smog and you have one third contact on water pump. The factory way has two thirds contact.

Funny you say that about the slip. Sometimes when I ran the top diagram last year, I would notice my temp getting hot.


On this car today, I used the 2nd diagram, and used a 74" belt (73" too short for my pullies). Worked like a charm, and have more grip on the pump.

[Tracer]

I did a lot of reading and talked to other guys with way more experience than me and what I kept hearing and reading was don't just bypass the smog pump. Thats why they build the eliminator kit.

[306gt]

I run the top picture set-up with under drive pulley's and A.C. I re-drilled the locating pin hole for the tensioner and ran a shorter belt. Been like that for 16 years. I never had a problem with the belt slipping even up to 7000 rpm.

[droopie85gt]

I did a lot of reading and talked to other guys with way more experience than me and what I kept hearing and reading was don't just bypass the smog pump. Thats why they build the eliminator kit.

Why? No problem bypassing it. If you add a smog eliminator, you're sticking with a longer belt, more chance to throw it, and you now have pulley with a bearing that can go out. Just take the smog pump off or bypass the belt to it.

[slimj]

Weaverkb is your car dark clove metallic. Looks like you engine compartment is brown.Just wondering.

[SVT Rob]

I run a VERY short belt on mine. No AC/PS/SP, tensioner moved to where the AC/PS would be. I've never had an issue with overheating. 3" crank pulley, stock water pump pulley, stock alternator pulley.

[86GreenStang]

I am glad someone else noticed how small the contact patch is on that routing. Contact on the pulley is very important. Running a standard fan with that routing will also create even more belt slippage.

[Supersonic G.T.350]

This is with the 70.5

Old thread I know but instead of starting a new one.... Is this belt size with under drive pulleys? I have the FR A/C delete and want to drop smog too, preferably without using one of the delete pulleys. Imo the look is cleaner and it never hurts to lose a pound or two off the nose.

[Supersonic G.T.350]

This is with the 70.5

Old thread I know but instead of starting a new one.... Is this belt size with under drive pulleys? I have the FR A/C delete and want to drop smog too, preferably without using one of the delete pulleys. Imo the look is cleaner and it never hurts to lose a pound or two off the nose.

[cb84capri]

You are best off to buy a couple belts at the parts store of varying lengths and return what you don't use. Some cars from the factory got under drive water pump pulleys, so what works for one guy might not work for you.

Cale