V belt slipping

[70383ChargerSE]

I am having some issue with my v belt(s) slipping right at 3000rpm. I just installed my classic auto air AC kit and still have the V belts. This is on a relatively stock 440 engine in my Charger. I have power steering. The belt(s) do not slip until I reach 3000rpm. The belt(s) slip whether I am at WOT and reach 3000rpm under load or if I slowly rev it up to 3000 rpm in park. The belt will continue to slip until i am below 3000rpm. Any ideas?

 

[ruffcut]

More info and maybe a picture of the setup would be helpful. ruffcut

 

[RJRENTON]

I am having some issue with my v belt(s) slipping right at 3000rpm. I just installed my classic auto air AC kit and still have the V belts. This is on a relatively stock 440 engine in my Charger. I have power steering. The belt(s) do not slip until I reach 3000rpm. The belt(s) slip whether I am at WOT and reach 3000rpm under load or if I slowly rev it up to 3000 rpm in park. The belt will continue to slip until i am below 3000rpm. Any ideas?

Which belt (s) are slipping....PS, A/C, Alternator, Water pump/fan drive. Usually, slipping dtive belts are due to worn drive-driven sheaves especially in rhe flank area of the sheave. The slipping glazes (almost polishes) the belt surface to the point of no matter how tight it is, it will not transmit the HP the driven requires at the higher speed. The double belt on the A/C-alternator drive has always been troublesome due to the span, or center distance between sheaves. Sometimes, internally segmented belts, DAYCO Top Cog may help due to greater flexibility. Just my opinion of course.
BOB RENTON

 

[70383ChargerSE]

Thank you for the responses, I'm at work for a few more hours so I only have photos a few photos on my phone. As for more info, this is a 1970 Charger with a 440. It has a new aftermarket CVF raving crank pulley and a new AC compressor from classic air. Prior to installation of this classic air AC kit, I did not have any belt slip. I'm not sure but I think it may be the alternator belt that may be slipping. After running the car, the alternator belt which also is run off the ac compressor was a lot warmer than the other belt. The belt numbers I currently have are 15500 and 15590.

 

[70383ChargerSE]

Photos

 

[RJRENTON]

Photos View attachment 1236568 View attachment 1236569 View attachment 1236570

Superficially, without any measurements, it looks like the crankshaft drive sheave is a SMALLER O.D. (Pitch Diameter) than the origional Mopar setup. And the drive sheave APPEARS to have a flat surface, rather than the traditional "V" groove arrangement. This will also drive the alternator at lower RPMs reducing the idle voltage and current it produces. The origional A/C setup used a separate water pump drive sheave with its own idler/take up sheave and the PS pump had its own sheave. One of the secrets in a successful belt drive system is the contact angle or wrap of the belt on its respective sheave, the more contact angle or belt wrap, the more HP can be transferred at the RPM of drive sheave. The existing belts look to be a "flat" type (maybe not) rather than the more traditional "V" belt..... just thinking out loud....
BOB RENTON

 

[MoparLeo]

You are only showing the alternator but you said the same belt drives the a/c compressor.
Is the slippage when the a/c is on or all the time regardless of the a/c being on ?
Have you checked with a straight edge for proper pulley alignment ?
Are the grooves on the aftermarket pulleys the same depth/ width/belt angle as the other pulleys ?
All of these things can cause belt noise. Notice the 2 groove pulley on the alternator ? That is because the factory a/c needed 2 belts that were a "matched set" to drive the compressor and not slip.
If you are going to use aluminum pulleys, all pullies driven by the same belt need to be the same type.
Also the belt tension is critical.

 

[70383ChargerSE]

Thank you to everyone for the help! I just switched to a pair of matched Gates belts and the belt slip is gone. Thanks again for all the help an suggestions.