Shimming Trailing Arms... what now?
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Instructor
Joined: Aug 2003
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From: Somewhere in Mo
Shimming Trailing Arms... what now?
Finally, yes finally, the rear end is back under my '71 after what started out to be a noisy wheelbearing. Now, new complete rebuild of trailing arms, new shocks, refurbished springs, repaired differential later, I have but another question. When I put the trailing arms back in, I put 1/4" shims on each side (inside & out) of each trailing arm. Now that the struts are back on and the bolts, shocks,etc are all in place those shims just flop around lose between the outside of the trailing arm and the frame. I realize you must add shims as you adust the rear end alignment, but where is the starting point for putting in "close" to the right number of shims?
Tim
Tim
Pro
Joined: Mar 2003
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From: Valparaiso IN
Put in enuf so that there is no slop. You just need to be able to get it to a good alignment shop. The alignment mechanic will move them around as to what the alignment machine says anyway. Bring extras if you have them.
Steve
Steve
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Joined: Aug 1999
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From: WI
Originally Posted by OldSchool
good alignment shop.
Tim Thorpe 618-632-8080 (Corvette restorer close to St. Louis).
...redvetracr
Thread Starter
Instructor
Joined: Aug 2003
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From: Somewhere in Mo
was..Trailing arms..now...new rear susp. too high stance!
Thanks. I'll give him a call. Side note... It looks like I have a 4" lift kit on this sucker now. Is that normal? Beside longer bolts is there additional ways to drop the stance?
Tim
Tim
Melting Slicks
Joined: Mar 2002
Posts: 2,140
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From: Ohio
It's too late for you but one should tag and write down each of the four shim packs and put the same back in that will get you close. I would just make them about the same and don't put in the cotter key in the bolt. I would leave the big cotter key out also as I trailer to the shop. Make sure to take extra shims.
Melting Slicks
Joined: Jan 2004
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From: New Cumberland PA
Originally Posted by Timbo2
Thanks. I'll give him a call. Side note... It looks like I have a 4" lift kit on this sucker now. Is that normal? Beside longer bolts is there additional ways to drop the stance?
Tim
Tim
About the only way to lower the car is longer bolts or have the steel leaf spring reworked. Drive the car back and forth to see how it sits before doing anything else.
Thread Starter
Instructor
Joined: Aug 2003
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From: Somewhere in Mo
Originally Posted by LYLE
It's too late for you but one should tag and write down each of the four shim packs and put the same back in .
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Joined: Nov 2000
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From: Waterloo ontario Canada
If I am starting from scratch in shimming the back I use a laser level. I just start with something, pack it fairly snug then use the laser level to project the rear tire on the front. I do both sides and get them close to the same. If one tire is really out I remove shims from one side and place them on the other. You need the space filled before tightening the through bolt.
Since I do not use alignment shops I rely on a toe gage and a laser level for doing the back.
Since I do not use alignment shops I rely on a toe gage and a laser level for doing the back.
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Joined: Nov 2000
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From: Waterloo ontario Canada
Originally Posted by redvetracr
Norval, As much as you love to engineer stuff I am a little suprised you still use shims...I would have thought you had a "Guldstrand like" toe adjuster.....
....redvetracr
....redvetracr
As for adjusting with shims I don't seem to have a problem with it. I do like to fiddle and usually pull the trailing arms yearly. They are comming off soon for inspeciton. Everything stays well greased and easy to remove.
I also have the 6 link and it works for small toe changes. Just adjust both rods equally to move the toe without affecting the camber.
Thread Starter
Instructor
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From: Somewhere in Mo
Originally Posted by norvalwilhelm
. I just start with something, pack it fairly snug then use the laser level to project the rear tire on the front. You need the space filled before tightening the through bolt.
what does one do with the adjustment bolts on the strut arms to get started? I just put them in no particular position.
Race Director
Joined: Nov 2000
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From: Waterloo ontario Canada
Originally Posted by Timbo2
there in lies a problem... I went ahead and tightened the bolts, thinking I could just drive in the spacers using the slotted end, rather than the holes.
what does one do with the adjustment bolts on the strut arms to get started? I just put them in no particular position.
what does one do with the adjustment bolts on the strut arms to get started? I just put them in no particular position.
I would then do the other side the same way.
At this point I would check toe, measure front and back on the tire. Find out if the tire toes in or out.
I would also put the laser lever on the side of the tire and project the dot forward. Does it miss the front tire, by how much, compare side to side. You can really get a feel which way you want to move the front of the trailing arm.
Once I know I want more toe in , or toe out I shift shims from front to back on the trailing arm.
This takes a little fiddling but you can do a good job if you keep checking toe and if the wheels are pointing staight ahead using the laser level.
I do my own alignments but you could take it at this point to the alignment shop for fine tuning.
Race Director
Joined: Sep 1999
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From: Plano TX
To do a rough toe setting for the rear you can do this:
Place a string between 2 jacks and set height so the string runs along the center cap on the rim. One jack behind the rear wheel, one in front of the front wheel. Place jacks so the string just touches the tire front and rear. Front wheels pointed straight. The rear of the rear tire should touch the string. The front of the rear tire should be about 0.050" (50 thousands) away from the string.
This will get you very close and will also set the thrust angle correctly.
Place a string between 2 jacks and set height so the string runs along the center cap on the rim. One jack behind the rear wheel, one in front of the front wheel. Place jacks so the string just touches the tire front and rear. Front wheels pointed straight. The rear of the rear tire should touch the string. The front of the rear tire should be about 0.050" (50 thousands) away from the string.
This will get you very close and will also set the thrust angle correctly.
Team Owner
Joined: Sep 2002
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From: California
Guldstrand toe-adjusters the easy way!
Take a torch and cut out the area in the cage. It is weak anyways and then weld-in new metal with the 1" holes. The torch fits and make sure you place a welding/flame blanket so you don't torch the car. The welding leads fit, so weld. The alignment of the holes is tricky but take extra careful measurements and make a dowel. Then weld and gusset area for strength and you are good to go almost. Oh! ya. the bolts are extra long so cut the fiberglass on the outboard side so you don't have to try to slip them in from the inboard side. Now you have toe adjusters without lifting the body. How pretty depends on how good you are with the torch and welder and who cares if you cut some fiberglass, put it back together. 
Race Director
Joined: Nov 2000
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From: Waterloo ontario Canada
Originally Posted by TCracingCA
Take a torch and cut out the area in the cage. It is weak anyways and then weld-in new metal with the 1" holes. The torch fits and make sure you place a welding/flame blanket so you don't torch the car. The welding leads fit, so weld. The alignment of the holes is tricky but take extra careful measurements and make a dowel. Then weld and gusset area for strength and you are good to go almost. Oh! ya. the bolts are extra long so cut the fiberglass on the outboard side so you don't have to try to slip them in from the inboard side. Now you have toe adjusters without lifting the body. How pretty depends on how good you are with the torch and welder and who cares if you cut some fiberglass, put it back together.
Am I missing something??
Looks like Bubba at work big time. Keep the cutting torch away from the car.