Javascript Disabled Detected

You currently have javascript disabled. Several functions may not work. Please re-enable javascript to access full functionality.

Help!! Ugent Advice/ Confirmation needed

Started by _jklumpp_ , Feb 07 2007 06:52 PM

Please log in to reply

7 replies to this topic

#1 _jklumpp_

Guests

Posted 07 February 2007 - 06:52 PM

As you may know from my previous posts, I was doing the 'Drop the top arm by 1"' mod to my LJ crossmember.
A guy I know with a long history of playing with Torana's got on this web site the other day, & found my post & picture about dropping the top arm 1"
He tells me this is wrong, and that it should only be 5/8"!?!?
He says;
-Car will bump steer under brakes (toe out)
-Wont be able to run enough caster or toe in to correct
-Russel Skaife tried this on Marks Torana in the 80's (unstable)

Any posts that I have seen on this site in regards to this mod have always stated 1", so can someone please confirm?

I have just put the engine & crossmember back in the car, so I'm hoping it doesn't have to come out again - I was just trying to get some reasonable camber on the front wheels last night (rough enough to get it to the aligners), but seems as though it's still in negative camber, with about 20mm of wedges in there.... so now I'm worried....

Original post & picture here:http://www.gmh-torana.com/forums/index.php?showtopic=9666&st=15 (for some reason can't get a link to work...)

Edited by jklumpp, 07 February 2007 - 06:57 PM.

Back to top

#2 _rorym_

Guests

Posted 07 February 2007 - 06:59 PM

Klump...sleep tight..its 1 inch...FULL STOP!..Tell him hes dreaming! :clap:

Datto...help him out. I have the GMH newsletter confirming that was the XU1 mod...pretty sure they know better than "some guy with a long history of playing with Toranas"..His car is wrong..yours is right.
R

Edited by rorym, 07 February 2007 - 07:05 PM.

Back to top

#3 _jklumpp_

Guests

Posted 07 February 2007 - 07:19 PM

Thanks for that Rory, but let's not get personal here... he also happens to be a mechanic, and the long time owner of a 73 bathurst, so it's not like he's got no cred!

He's given me a copy of the GMH Service Bulletin, which has the same diagram as someone posted in my previous post, and if you look at it it does seem as thought the 2 holes are closer together than the ones in my picture.....

Did you do the 1" drop on yours? and if so, did you have any troubles getting the right camber/caster? (I seem to remember from photo's of yours, you had some pretty wild camber on the fronts??)

Back to top

#4 Toranamat69

Forum R&D Officer

Members
2,117 posts

Location:Brisbane
Joined: 07-November 05

Posted 07 February 2007 - 11:09 PM

I don't have an LC/LJ front end here to play with so probably best to get someone with an Xu1 to post a pic for you (I have never actually looked on an XU1 to see where they mount either) I would use that as the best guide without taking any mesurements as Holden has gotten it pretty spot on all the later front ends I have measured - when they are running the factory alignment specs.

Those pics do look close to the edge of the metal where you drilled the new holes.
It will make the bump steer tend toward toeing out a bit more in doing this mod but in general a slight toe out is better than a slight toe in with respect to bumpsteer.
Without actual measurements it is only speculation though as you don;t know the starting point - which is why I went and bought the gear to measure mine - you get far too many conflicting stories.

The difference between bumpsteer for a 5/8 drop and a 1" drop would be SFA anyway, to give you an idea, on a UC front, if you do the full 1" lower thing it changes the bumpsteer by 1mm at 2" of suspension bump and it actually improves it to pretty much zero bumpsteer rather than toeing in slightly. If you only dropped it by 5/8" it would be roughly 0.4mm different at 2".
This would also be effected by the castor you run but the toe in adjustment won't help you with bumpsteer.
If you want to run more castor, UC upper control arms look like they will go on the LC/LJ fronts too maybe with a slight mod to the height of the bumpstop but likely not required.

I am a little confused by your comments on trying to adjust out the negative camber, you need to remove shims to get rid of negative camber and with 20mm more there, you have tons to take out.

What stub does the guy run up front Torana or HQ?? that would make a more significant change to the bumpsteer.

If I ever finish my LX/UC front end games I will get my hands on an LC one and do some measuring.

M@

Back to top

#5 _rorym_

Guests

Posted 08 February 2007 - 06:42 AM

I have always had the holes 1 " lower on XU1s...Yes I did measure them..they were that from the factory so I did it to the Yellow car. Now dramas getting angles I wanted..It sits now just under 4 degrees neg. I add small steel tubes to pick up gaps on the bolts...then I only run one or 2 shims each side. As Chopper says..saves some falling out.
R

Back to top

#6 _gtr161s_

Guests

Posted 09 February 2007 - 03:20 PM

the question is when measuring your 1" are measuring centre to centre for holes or the gap left after you drill the new hole.

Just from memory (haha) the holes looked like 1" from centre to centre.

If you drilled 5/8" from to centre to centre there wouldnt be enough support metal between the 2 holes.