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Author Topic:   rear metric control arms
25JHenry
Dirt Full Roller

Total posts: 73
posted February 04, 2004 06:19 AM  
If I shorten the rear upper links (arms) by lets say 1/8" each to give me a little more pinion angle, would that be benificial and be worth my time? I'm working on a 86 buick regal. Also, should I shorten the left lower link (arm) by 1/2" or so to get into the turns better?? Thanks for your time.

Leadfoot#8
Dirt Full Roller

Total posts: 44
posted February 04, 2004 06:31 PM  
It will help,,,,but sometimes can be a pain to get bolts in.

wrenchturner10
Dirt Forum Racer

Total posts: 80
posted February 04, 2004 06:36 PM  
I don't know about the upper arms but we shortened our lower left by .5" by accident. It helped the car corner better but our track is dry and slick most of the time and the car was loose on exit. I don't know if it was a true benifit or not becuase of our horse power issue. We ran a 86 monte last year which is also a GM metric.

Racer13T
Dirt Full Roller

Total posts: 46
posted February 04, 2004 06:49 PM  
i would do it alot more bite run3.5 5 degrees pinion angle, use a angle finder that will help u alot

racer17j
Dirt Forum Champ
Total posts: 5390
posted February 04, 2004 07:40 PM  
Do what you want to the top links, but leave the rearend square to the centerline of the car. Stagger gits you in. You can change the angle of the lower control arms to build in roll steer. If lower control arms run uphill from the rearend to the frame, when the body rolls through the corner the right rear will be pushed back and the left rear will come foreward. When you're coming off the corner and the car is leveling back out the opposite occurs and this tights the car back up. If you shorten the left side the car will be loose all the time.

25JHenry
Dirt Full Roller

Total posts: 73
posted February 05, 2004 11:46 AM  
When I stripped the old car from last year I kept the arms. That way I can make them any lenght that I want. If they do not work well I can always put the original ones back on. Thanks for your input everyone.

25JHenry
Dirt Full Roller

Total posts: 73
posted February 05, 2004 01:13 PM  
To measure the pinion angle should I measure it relative from the centerline of the pinion to the driveshaft or the track???

zeroracing
Dirt Forum Champ
Total posts: 1875
posted February 05, 2004 02:13 PM  
driveshaft to pinoin
not the track.

25JHenry
Dirt Full Roller

Total posts: 73
posted February 05, 2004 02:16 PM  
Thanks. I'll give it a try..

waltonjr1
Dirt Forum Champ
Total posts: 516
posted February 05, 2004 02:18 PM  
Put the angle finder on you crank pully to check the angle of your drive line.If you get 10* from the crank, set your pinion angle around 5*.If you get 13* from the crank, set your pinion angle at 8*.You want your pinion about 5* of a flatter angle than your driveline.Most people just set it at 8* b/c if your engine is where it should be you will end up setting close to 8 any way but this is the correct way to do it.I just learned this myself b/c I was wondering the right way also.Hope this helps.

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DEANJR#22

zeroracing
Dirt Forum Champ
Total posts: 1875
posted February 05, 2004 02:54 PM  
Why do you set it off of the crank? i have always set mine off of the driveshaft, b/c you want it to be almost striaght up when you are on the gas, like with our pull bar we set it at 8deg and a torque arm around 5 deg.
i am just woundering why you set it off the crank? any special reason or sectret?

waltonjr1
Dirt Forum Champ
Total posts: 516
posted February 05, 2004 03:12 PM  
The crank is the most accurate place to get the angle of the driveline.The angle of the driveshaft will vary depending on where the rearend is set at to start with.Imagine if you had a solid shaft coming from the transmission with no u joints and not connected to the rearend.The angle of the shaft and the crank will be the same.I will try to find the link where I got this info from and post you the link.

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DEANJR#22

fast_crew
Dirt Forum Racer

Total posts: 99
posted February 05, 2004 03:37 PM  
The crank angle and driveshaft angle have nothing in common. The drive shaft does not come straight out of the tranny, it should be angled down about 3-5 degrees from the trans. In the perfect world the front u joint and rear u joint should be within .5-1 degree to cancel the change in speed of the u joint, But for racing that would be pretty tough due to the large amount of axle wrap up. You could measure driveshaft angle using the crank angle. Hope this helps

Josh K.

waltonjr1
Dirt Forum Champ
Total posts: 516
posted February 05, 2004 03:46 PM  
The driveshaft angles down b/c of the position of the rearend.That is your driveshaft angle.The true angle of your driveline is measured from your crank.

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DEANJR#22

o5racer
Dirt Freak

Total posts: 402
posted February 05, 2004 09:21 PM  
Pinion angle has no affect on traction. never has never will.

waltonjr1
Dirt Forum Champ
Total posts: 516
posted February 05, 2004 10:09 PM  
Thats a first!


Eljojo
Dirt Forum Champ
Total posts: 968
posted February 06, 2004 05:24 AM  
No....that's not a first-----nor will it be the last! That "pinion angle" arguement has been around longer than this forum.

flatfoot27
Dirt Maniac

Total posts: 103
posted February 06, 2004 06:59 PM  
Just my 2 cents worth, I have built alot of cars for myself and my family and not once have we ever found it to be benificial to change anything in any car. What we have found is what cars work the best. We are currently running 3 Malibu's and 1 Monte Carlo and the Malibu's out corner the Monte hands down. And we are currently racing against pro built cars and they have NO advantage on us. We dial our cars in with stagger,springs,shocks and weight and we get out of the corners as well as anyone and better than most. It also helps to gear right. The worst thing you can do is over power the track.

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