Wheel Back Space

[Mike]

Since I have owned my VW based TD , driving over 50 MPH on the straights felt a little squirrelly. When taking a good curve at higher speed was like the car was fighting to pull straight.  I always attributed it to the light front end and front fenders like wings as ball joints  and tie rod ends checked fine. I even put a new steering stabilizer on thinking that may be the problem. I recently had my tires popped off the rims so I could sandblast and paint them. Thats when I noticed even though they were all 4-1/2″ wide, one of my wheels had a different back space. There was 1/2 difference and it was one of the front wheels. This had to be a flub of the manufacture. I had bought two new stock steel wheels as two of the old ones had seen better days. I put the new wheels on the front and what a difference! The car handles as well at 60 as it does at 40. Other than the wind beating me up a little more it handles the same. I would not have thought 1/2 would have made a big difference, but on the front it did. I am pretty sure it was an aftermarket stock steel wheel as only one of mine was stamped made in Germany. The two new wheels I bought were made in China reproductions, but run great. Just posting this as something to check if your car doesn’t handle as you think it should.

[edward ericson]

That is very interesting.

I could see how the different wheel spacings could mess up the steering geometry on your turns; the scrub radius would be different side to side, and then the vectors (toe-in/out) would also be a little off.

But I did not know the same width wheels could be so for off.

I think mine are all different too–some Brazilian, some German. I didn’t measure when I re-painted. Will now.

I also had some handling issues when I first got the car–mostly to do with understeering tendencies. Installing the adjustable front beam with lower spring rates, and running very low tire pressure up front (18 lbs, I think), has made a world of difference.

[Royal]

Mike, When I got my car it drove like yours did at first.  But…..it handled like a 1948 Jeep CJ2A that I once had.  My wife would not ride in my jeep without first donning her sports/jeep bra – even on the highway it was an exceptionally rough ride.  And, MiGi’s front end was cranked up in the air so far that it looked un-natural (5-1/2″ from the bottom of the fender lip to the top of the tire).  I decided (after looking at some of the photos posted and reading the posts here on the forum)  to take some of the torsion leaves out.  It was a fairly easy job and it fixed both problems:  Now the geometry looks right and it rides very nicely up to 65mph – it is far more stable.  (I also reduced my tire pressure from about 30psi to 18 per Ed’s recommendation.)  I have never pushed MiGi over 65 but expect that it wouldn’t care.  I have never had MiGi out on the four lane big road.  I really don’t like driving in gusty wind…..it’s me, not the car. 

[Mike]

Ed it is probably worth checking if you have any handling problems. I would bet this was manufacturing defect as I can only find different wheel spacings on different width steel wheels yet all my wheels were 4-1/2. A fellow I worked with was the one that discovered the offset difference when I had all the tires off and was sanblasting them at work. He asked me if all the rims came off the same car. It was obvious without measuring them. The bad wheel did not have the German stamping and could have been made anywhere. The two new Chinese wheels run great.

 

Roy, I like you have never had my car on a 4 lane. I am lucky to live in a state where there are plenty of rual two lane highways. I like driving in the 45 to 50 mph range and like you stated dont like the gusty wind, but thats just me. The car is handling good now, but my next project is removing some torsion leaves to get the best that can be had out of the car. Is there a general concensus on how many secondary springs should be removed from each tube? I also am going to do as you and Ed suggested and lower my front tire pressure from 22 to 18lbs.

[Dan Ogle]

OK, I know this is a dumb question,but what is back space ?

[ray10]

 Backspacing is the distance from the inside bolting surface of the rim to the outer edge of the inboard side of the rim. Offset is the distance from the exact center of the rim to the outer edges of the rim. Positive offset means that the center of the wheel is moved towards the vehicle. Negative offset means that the center of the wheel is moved away from the vehicle. The included graphic image illustrates this.

Read more: http://www.fourwheeler.com/techarticles/wheels/129_0602_wheel_backspacing_etiquette/index.html#ixzz1rk9Q7M1j

TDREPLICA Map

http://www.arcgis.com/home/webmap/viewer.html?webmap=7f9174ad614e43b680deba085b0abf48

[Royal]

Mike, there is a lot of discussion on the forum about removing leaves.  Rockyx did a nice job with great photos.  I posted a few also.  Everyone removes all but the four big leaves in each tube.  Worked perfectly for me. 

[Dan Ogle]

Thank you Ray, for explaining this to an old dummie.

[ray10]

Your  welcome. I was always told if you don’t ask you will never know? So i use

 http://www.ask.com

TDREPLICA Map

http://www.arcgis.com/home/webmap/viewer.html?webmap=7f9174ad614e43b680deba085b0abf48

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