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Author Topic:   Motor setback
race33
Dirt Full Roller

Total posts: 53
posted December 14, 2005 07:45 PM  
I am wondering if setting back a motor 6 to 8 inches is worth the trouble to gain some rear percentage. I know every car is different on how much rear percentage you would gain, but is it really worth moving the mounts, linkage, shortening driveshaft, notching crossmember, etc.? What typical percentage gains is everyone experiencing? Without any lead, my car is a little over 3000 lbs. with me in it and 49% rear. We have a 3000 lbs. minimum weight rule.

john56h
Dirt Full Roller

Total posts: 48
posted December 14, 2005 08:59 PM  
We have two late 70's metric Malibu street stocks. One has the engine in stock position with about 46% rear weight. The other has the engine moved back about 4" (about as far as we could go without notching away the whole crossmember for fuel pump clearance) gives us about 48% rear weight. Honestly there isn't much difference in how the cars handle. Just remember that you do need to have some decent amount of weight on the front tires too or your car will push (especially true if you are on limited tires).

nailed
Dirt Newbie

Total posts: 2
posted December 16, 2005 07:59 PM  
It is worth it. If it 2% is a lot when it comes to rear percent. Need to be in the 50's with that rear percent.

hughes
Dirt Maniac

Total posts: 196
posted December 17, 2005 06:54 AM  
It depends on the track, really. If its tacky it wouldnt be as critical but on a slick track it could help. But its not worth it if your rules don't allow it. Because that is one of the most obivious things to look for in the tech area. All it takes is the tech man or a fellow racer to bust you out. It sure would bite to leave a couple of hundred on the table for the second place car.

race33
Dirt Full Roller

Total posts: 53
posted December 17, 2005 07:20 AM  
Our rules allow setback. The limitation is that the lead spark plug needs to be even or in front of the upper ball joint. Moving it back im my car will require me notching the crossmember for the fuel pump. How have you guys done this?

sideways
Dirt Forum Champ
Total posts: 744
posted December 17, 2005 08:08 PM  
With a saws all.lol Well there is no easy way to tell ya.You have to put the engine in with the pump and see how far ya want to set it back and how high ya want it to set.After you cut it out you have to plate it back in.
quote:
Originally posted by race33:
Our rules allow setback. The limitation is that the lead spark plug needs to be even or in front of the upper ball joint. Moving it back im my car will require me notching the crossmember for the fuel pump. How have you guys done this?


jay116
Dirt Freak

Total posts: 431
posted December 17, 2005 08:12 PM  
Just make sure when you notch for fuel pump clearance to leave enough room to be able to replace the pump without jacking the motor up off the mounts. If you leave the room for that, then you should also have enough room that in a heavy crash the crossmember won't knock the pump loose and cause a fire.

  

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