Brand New Clutch Slipping?

Discussion in 'Fox 5.0 Mustang Tech' started by Copba1t, Sep 16, 2013.

  1. I have a 90 Notch, Procharged 393 stroker. Put the supercharger on same time I put in the new transmission (Levy Racing built T-5) and the new clutch which is a Quartermaster 8.5 single disk. Clutch is supposed to be good to 700-800 ft pounds but it slipped at around 5200 rpm for 3/4 runs, only the final run did I manage to get a full pull out of it and make it up to 6,000, which made 563 ft lbs, which is about 675ish at the crank.

    What could be causing it to slip? Clutch only had maybe 20 miles on it before I did the pulls but the guy at the shop said that shouldnt affect it. Transmission is also having some issues but would that cause any issues to make it slip? Any help is appreciated, thanks.
     
  2. dumb question but I will ask it anyway. Did you break in the clutch first? What about the cable and quadrant?
     
  3. ruh roh. hit the nail on the head there. No way you broke taht clutch in in under 20 miles. congratulations you just glazed a disc. Its only good for showing off in pottery class now. If your mechanic said that hard pulls are good for a brand new clutch then I would shop for a new mech.
     
  4. I'm no expert but I would agree with glazes clutch or presure plate , Gona have to pull it and find out if clutch quadrant and cable checks out
     
  5. I tried to break it to him gently.. he fried that clutch faster than the Colonel does chicken.
     
  6. Lol that's funny , yeah I did it to my old 93 stang trying to heat tires up with a 5 speed I can't multi task with my feet lol
     
  7. It was actually a speed shop that works on alot of mustangs that said it was fine, guy seemed very knowledgeable too. Kinda disappointed in them now. I had that feeling it should have been broken in first and thats why I asked him. Ive read some things about taking some sandpaper to the clutch disk, is that worth a try first before buying anything new?
     
  8. In my opinion if you go through all that work to get it out , just put a new one in and follow break in procedure by manufacturer and opinions of others and keep old one for back up , or maybe see if you can just by the disc but would be real ****ed if you got it back together and it was presure plate or something best to put new one in and go from there call it a learning curve
     
  9. Well the thing is I cant afford anything new, its either fix it or drive it like it is for the next few months. Also could it be something else thats wrong? It only lets go at 5200/5300 rpm, if it does decide to let go at all. If it was going to slip, wouldnt it be near 2000-3000 rpm where it makes the most torque, instead of at the end? Nothing else is affected, just that it lets go at high rpm. Grabs fine and everything
     
  10. Sure , guess it may be something else maybe fly wheel is below spec or needs replaced , or maybe at high rpm maybe a fluid getting on to the clutch some how , Gona have to go in and look but once your in your Gona need some kind of money to fix it or stay below 5200
     
  11. Awwww man that blows, sorry dude. If you go back in there do it once, check it all.
     
  12. Years ago, when I had my mod motor car. I had a totally new setup, ported heads, cams, blower, new clutch etc. car wouldn't run until it was tuned and I had it towed up to a tuner. In talking with McLeod, because I was worried about clutch break in, they told me to ride the clutch up a hill a few times till it kind if smelled like it was burning and that's it, good to go. I was very skeptical but they said it's a similar process that some of the stick guys uses with a track only car that can't break a clutch in on the street. Needless to say I did it and with less than a mile on my new clutch made 500ftlbs at the rear wheels with no trouble for thousands of miles later. Am I lucky, am I stupid, who knows. Not sure if this is right wrng or whatever but it did work for me and I was instructed tomdomso from the clutch manufacture (McLeod)
     
  13. While it is the beat practice to break in a clutch it is not always possible when you need to tune a car.

    I end up breaking many of them in on the dyno a couple steady pulls of load and we let it cool. Like 84 above they habe less then a mile as I usually am pulling them out of the shop bay and on to trailer for dyno. Double check cable adjustment then give it hell.... just finished a blower car that makes 602rwhp/580rwtq with a SPEC stage 2+.

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  14. I've always just took it easy for the first 500 miles or so and then let it rip tater chip.