8 replies to this topic

[Tao]

Hi all, After setting up my '92 and setting the front toe out by 1/16. To. 1/8. It never fails to change after a couple of session on the track........just by looking at it I can tell it is different......when I throw the plates on, sure enough it will be toed out a full. 1/4". or more.........I will notice a decrease of 1 to 3 mph down the straights......
I use a lift to raise/lower the car on the scales but always bounce all four corners and roll it back and forth (about 8-10") every time it is lowered to the scales........also all suspension pieces only get tightened when the car is down at ride height.......
Nuts and bolts get gorilla tightened and the ball joints are almost new....bearings are good (no play)......
This happens after every set up check/adjustment........any thoughts?

[Mark]

8"-10" for roll out is not enough. Roll out is critical (or use slip plates) to avoid tire or bushing bind and it takes a surprising amount of movement to work all the bind out. Bouncing won't do jack unless the car is on slip plates. Floor tiles or sheet metal squares with oil/grease between them make good low buck slip plates. Plastic bags not so much but better than nothing. Do you get the same results after doing a setup and taking a victory lap around the block or parking lot? 

[Steve Scheifler]

And discount the observed loss of straightaway speed as supportive, that's something else unless you are losing even more than that at corner exit due to push. More likely it is increased intake temps as ambient and under hood temps rise, less lift as oil gets hot lowering viscosity and lifters go soft, tires going off, etc.

As for toe, when using plates that lean on the tire, be aware of the raised letting. I think it is less of an issue with Hoosiers than some of the Toyos but if you happen to hit opposit extremes from one check to the next and it can be enough to throw off your measurements a bit. But so can just a little flex in the bushings.

[Erik Hardy]

How many gorilla tightening cycles have the crash bolts gone through? After a few strong arm tightening contests the bolts need to be replaced otherwise they will start moving around on track

[Mike Collins]

Raising and lowering a 1.6 on the scales will change your toe.  are you checking it after your adjustments?  Roll it out more or use slip plates.

[Jim Drago]

Hi all, After setting up my '92 and setting the front toe out by 1/16. To. 1/8. It never fails to change after a couple of session on the track........just by looking at it I can tell it is different......when I throw the plates on, sure enough it will be toed out a full. 1/4". or more.........I will notice a decrease of 1 to 3 mph down the straights......
I use a lift to raise/lower the car on the scales but always bounce all four corners and roll it back and forth (about 8-10") every time it is lowered to the scales........also all suspension pieces only get tightened when the car is down at ride height.......
Nuts and bolts get gorilla tightened and the ball joints are almost new....bearings are good (no play)......
This happens after every set up check/adjustment........any thoughts?

A few things...

Check for bent wheels, bad hubs and bad ball joints and bent tie rods first.

Make sure eccentric bolts on arms are marked, extremely tight and not moving. 

make sure you are jamming the tie rod ends, check tie rod ends for excessive play.

Are you using slip plates when adjusting the toe?

[davew]

Everything Jim said, plus:

 

Compare your tape measures. Measure the toe as normal, then flip flop the tape measures front to rear. Recheck, and the reading should be the same. I have seen tapes with 1/8" difference.

 

The allignment cams from Mazda are a replacement item. The washers are fairly thin and over time they "cup". You end up with only the center of the washer contacting the subframe. A quick/no cost check is to flip the washers so the cup is now the other way. This gives contact along the outer edge of the washer and torqueing will make them flat again. This only works for 1 or 2 cycles and they cup back again.

 

I worked with an aftermarket suspension company to develop allignment cams with a thicker washer to eliminate this problem. Look below and I bet you can figure out where to get them.

 

On a couple occasions, I have found the slots in the subframe to have a groove worn in them. No matter how tight you get the cams, eventually they fall back into the groove. Also check the subframe surface for wear. This is hard to explain, but along the slot, the metal is worn down thinner than the metal 1/8 away from the slot. No amount of force will keep the cam from moving if the surface is not flat. You have to look at both the outer surface wear the allignment cam rides, but also at the inner surface where the bushing sleeve contacts the subframe. This drove me nuts (short trip) the first time I found it.

 

dave

[Tao]

Thanks guys......I will check the cam washers ans sub frame.......
I do use skid plates (two pieces of plastic with grease between---very slippery)......
If I move the lift arms I could roll the car back @14".-16".....would that be enough?

[davew]

I would think you are fine using your slip plates. If not using slip plates, I was taught to roll one complete tire revolution. That is about 7 feet on our cars.

 

dave