Ackerman angle on 2" longer spirit frame

[HELLRAISER79]

Ok guys, help me out if you can. I've ordered a spirit 23t frame. I got it set up for a bbc so its 2" or so longer than their standard small block frame. Will i have to bend the steering arms to correct the ackerman angle or am i being too anal beings that its only 2" longer wheelbase? Do i even have to set the ackerman angle or do you think they do this? I got the whole stage 3 kit and then some. It uses 37-41 spindles and bolt on steering arms with the tie rod behind the axle(i believe, i havent got it yet). Also, while we are on the subject of the 2" longer frame, I have a sbc but it uses a long water pump. Thats why i ordered the big block frame(and for when i slip a big block in it one day). Correct me if im wrong but a sbc and a bbc motor mount would be in the same place on the frame, right? So even though i ordered it for a big block, i should be able to drop my sbc right in there. I wanted to have the option to run whatever chevy motor in this thing without having any clearance issues. Anyone else done this? went from a bbc to sbc or reverse? Thanks in advance.
Ken

 

[EX JUNK]

Ackerman is checked by running a line through the center line of the tie rod mounting bolt and the center of the kingpin on both sides and extending it rearward. The lines should intersect at the rear end. If your tie rod is mounted behind the king pins the distance between the centers of two tie rod bolts will be shorter than the distance between the centers of the two king pins. However, if the tie rod is mounted ahead of the king pins the distance between the centers of the two tie rod bolts will be greater than the distance between the two king pin centers.

In my opinion I don't believe that a 2" longer frame will interfer with proper Ackerman. The main thing to be concerned with is that the steering arms are altered if you put the tie rod in front of the axle. If not, then you will have a "reversed" Ackerman.

 

[Ted Brown]

First, your worry about ackerman adjustment, The steering arms bolt onto the spindle, any adjustment needed is done with washers between the arm and spindle at whichever end needs to go in or out, that will make your tie rod longer or shorter whatever is needed to be correct.. Take a string, tie it around the king pin, pull it tight and hold it over the center of the pinion, your tie rod connection point should be directly in that line to be correct for any givin wheelbase, and Yes it is important for good road handling and tire wear.. Ever try and hand push a car with the tierod in front of the axel, when turning?? You will then see and feel why it is important, and to maintain control when cornering... As far as BB and SB engines, mounts are the same, only the front of the BB engine is 4 inches longer, to the radiator... same with the trans mount, between the turbo 400 and glide... any other questions you can always e-mail me, tedabrown@juno.com is that OK to do??

 

[oldtman]

The serious problem is when someone runs the steering arms pointed the wrong direction from what the original design was of the donor car. then the tires really scrub when they turn.

 

[Humidi-T]

2", I wouldn't worry much about it. My Ackerman is completely reversed and I've only had minimal scrubbing when turning at the stops. Not enough for me to worry about in this light of a car.

 

[HELLRAISER79]

Thanks guys, i just wanted to confirm what i was thinking. I will check it with a stringline like i read in youngsters frame plans. I never even thought of using washers or shims to adjust the steering arms, i was thinking of original spindles which had to be heated and bent. Thanks again for the help, alot of my friends think they know alot about cars, but when i mention something like ackerman angle they look at me like im from mars.

 

[LKE]

I wouldn't worry about it at all. Two reasons... Running a line thru your king pin centerline, steering arm tie rod hole, and centering it on your rearend gives 100% ackerman. In real world use, anything above 70% will be just fine. The 2" length wil not matter at all.
Second, Having your ackerman off, even way off, doesn't really upset a car. You may get a little tire squeal at low speeds. But there is no adverse handling affects. Be more concerned with getting the car straight and square, with the caster and steering (draglink) correct.
Earlier this year there was a thread here on ackerman, with a lot of good replies. Maybe do a search for it.

 

[Ceec]

In my opnion, as stated elsewhere in this thread, it is unlikely that the extra wheel base will effect your application. HumidiT states his Ackerman is reversed. If the angle is reversed, measure FORWARD to an imaginary point and compare that to the dimension to the rear axle. I feel the outcome would be the same. Minimal scrub and tire wear. Unless you drive the car as far as Ted has, I don't think you will see abnormal tire wear. I further feel that Ackerman Geometry is more effective and important on a side steer car.

Cecil