Rear Axle Position.

-
SSing

SSing

Well-Known Member
Joined
Feb 24, 2012
Messages
1,108
Reaction score
341
Location
upland, sweden
Not happy with my old goat now... why isn't she one bit cooperative here.
Picture shows measurement from center of rear axel, to lower front lip of rear right wheel well.
Well, 15"+ is fine, but on the other side it´s more than half an inch less.
I haven't done any cross measuring yet, but really see no issues with the body what so ever.
Axel can only bolt up in one way, so am I just unlucky with poor assembling?
And yes, I know a quarter of an inch is probably what you will find on other ´68 FB´s, but this...
I need every bit of an inch, since I hope to be able to run 29,5" tall slicks.
As soon as I can have an extra hand, I´ll do some cross measuring.
Putting shims between leaf spring front hanger and body, is the best way to cope with this problem, or...?
If you thing 15"+ is more than most ´68 Barracudas? Yes, I all ready have a 10 mm aluminium plate to shim out (front hanger) the rear leaf spring bolt eye, since rear schackel did not have an acceptable angel.
20170809_143547.jpg
 
SSing said:
Not happy with my old goat now... why isn't she one bit cooperative here.
Picture shows measurement from center of rear axel, to lower front lip of rear right wheel well.
Well, 15"+ is fine, but on the other side it´s more than half an inch less.
I haven't done any cross measuring yet, but really see no issues with the body what so ever.
Axel can only bolt up in one way, so am I just unlucky with poor assembling?
And yes, I know a quarter of an inch is probably what you will find on other ´68 FB´s, but this...
I need every bit of an inch, since I hope to be able to run 29,5" tall slicks.
As soon as I can have an extra hand, I´ll do some cross measuring.
Putting shims between leaf spring front hanger and body, is the best way to cope with this problem, or...?
If you thing 15"+ is more than most ´68 Barracudas? Yes, I all ready have a 10 mm aluminium plate to shim out (front hanger) the rear leaf spring bolt eye, since rear schackel did not have an acceptable angel.
View attachment 1715080806
Click to expand...
its not uncommon for it. Tolerances back in the day were horrible. I've seen this before and much worse in some cases. Heck, I measured the distance between the rear axle and the gas tank on two identical, unrestored/molested A bodies of the exact same year with the same options and there was a 3 inch difference.
 
if your talking front to back then the passenger side is supposed to be forward of the drivers side to a compensate for the movement created by torque loading .ie when you atep on the gas the load side compresses causing the axel to move backwards .If there wasn't any offset the car would hook to the left everytime you stepped on the gas , this is also why SS springs are arched more on the passenger side .
 
I found if you get a tape measure and use some batter boards and string to create a perfectectly square rectangle in the yard like laying out a building you will be able to determine everything .
 
cannucky said:
if your talking front to back then the passenger side is supposed to be forward of the drivers side to a compensate for the movement created by torque loading .ie when you atep on the gas the load side compresses causing the axel to move backwards .If there wasn't any offset the car would hook to the left everytime you stepped on the gas , this is also why SS springs are arched more on the passenger side .
Click to expand...

Interesting, and make sense too. Now my car is even more off. On mine, drivers side is more forward.
I´ll really have to look in to this.
Thank you.
 
Mine the passenger side was a full inch forward and the string lines showed both rear wheels toed in at the front , so my tubes must not be straight and somehow the bearings are 90deg to the axels in the tubes so it isn't eating them or anything else -yet . I have another housing that is going to be built to replace this one .
 
cannucky said:
Mine the passenger side was a full inch forward and the string lines showed both rear wheels toed in at the front , so my tubes must not be straight and somehow the bearings are 90deg to the axels in the tubes so it isn't eating them or anything else -yet . I have another housing that is going to be built to replace this one .
Click to expand...
Guess I got a good one, it was only off a 1/8" , I shimmed it to get it square, doesn`t drive any noticeable diff.
 
I shimmed mine to the recommended 1/2 using SS springs and it launchs straight and stays straight when I blow the tires off romping on it .
 
My 68 Barracuda is closer to the front on the drivers side also. And yes , best way I know to correct a small difference is by shimming the leaf spring hanger.
 
cannucky said:
I shimmed mine to the recommended 1/2 using SS springs and it launchs straight and stays straight when I blow the tires off romping on it .
Click to expand...

Ok, and you put shims by the front hangers?
Would relocate hole in the pad (U-bolts) be a way also?
 
AJ/FormS said:
You could take in for a 4-wheel alignment; the sensors will tell you what's going on.
Click to expand...

Yes, that would be a safe way to do it, but body is in the rotisseries, so I want to get this as close as perfect as I can now.
To determine rear axel is angled with the body, I took this stainless steel rod, and hook in to passenger side rear k-member bolt hole.
20170811_161343 axel angli.jpg


I measure to the drivers side leaf spring center bolt, since this bolt will determine the location of the axel, and I don´t have to spend time to adjust the axel assembly in exact position side ways.
This numbers was well in line with my first picture in my tread, and show (to me) axel of driver side is behind.
20170811_162912 axel angli center bolt.jpg


I made this block of 10mm alu to move center bolt back, and it was just about enough...
20170811_162653 axel angli block.jpg


To get some Rear Steer, I will drill a new hole in the drivers side leaf spring perch, to move axel 3/8" further back, witch of cause will result in passenger side wheel ca 1/2" front.
20170811_163935 axel angliment perch.jpg
 
BTW, how much concern should I pay to these front eye bushings? They are from the seventies, but used very little (some racing)... Some cracks, yes, but not that much can happen... or?

20170810_214020 front spring eye.jpg
 
Did u guys ever stop to think that maybe the diff isn't out but the body panels are. One way to find out is a 4 wheel alignment by someone that knows our cars. By shimming the diff u may be causing it to dog track slightly. 1 wheel will be toed in while the other will be toed out. I see it all the time. 72 blue blue is right, I forgot to mention that the thrust angle will be off also from shimming the diff, unless ofcource u corrected it. Lol. Kim
 
Last edited:
oldkimmer said:
Did u guys ever stop to think that maybe the diff isn't out but the body panels are. One way to find out is a 4 wheel alignment by someone that knows our cars. By shimming the diff u may be causing it to dog track slightly. 1 wheel will be toed in while the other will be toed out. I see it all the time. Kim
Click to expand...

Yup. Frame tolerances weren't great but they were definitely better than the body tolerances were. Gotta figure out the thrust angle before you shim the axle.
 
oldkimmer said:
Did u guys ever stop to think that maybe the diff isn't out but the body panels are. One way to find out is a 4 wheel alignment by someone that knows our cars. By shimming the diff u may be causing it to dog track slightly. 1 wheel will be toed in while the other will be toed out. I see it all the time. 72 blue blue is right, I forgot to mention that the thrust angle will be off also from shimming the diff, unless ofcource u corrected it. Lol. Kim
Click to expand...

Yes, but as described in post 19, I don´t think this is the case here. This is a race car, and with the slight rear steer needed, witch means negative Thrust Angle (post #22) and dog tracking, I see no other way to deal with this problem on my car...
Thank you for your in put.
 
dukeboy_318 said:
its not uncommon for it. Tolerances back in the day were horrible. I've seen this before and much worse in some cases. Heck, I measured the distance between the rear axle and the gas tank on two identical, unrestored/molested A bodies of the exact same year with the same options and there was a 3 inch difference.
Click to expand...
The gas tank is a terrible place to measure from, the trans crossmember is probly the best , for both ends of the car. the gas tank can be manipulated quite a bit !
 
famous bob said:
The gas tank is a terrible place to measure from, the trans crossmember is probly the best , for both ends of the car. the gas tank can be manipulated quite a bit !
Click to expand...
I know. I was trying to see if I could run a stock gas tank with my watts link.
 
You must log in or register to reply here.
-

Back
Top