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Advice before buying macdonald trailing arms


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#1 _SLR Goat_

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Posted 16 February 2012 - 03:58 PM

Im about to drop the diff(nine inch) out for a clean up and replace the oem trailing arms which look to have factory bushes and a dodge boxing job done to them and replace them with a set of mcdonald bros arms my question is i was going to get adjustable uppers and non adjustable lowers is there any advantage of spending the extra $100 and getting adjustable lowers aswell the car will be used for cruising and strip work mainly did a search and someone quoted they got adjustable lowers so they could adjust wheel position in the guard to suit rideheight the car sits 1 inch low atm dont think ill lower it anymore due to exhaust running under the diff

Also is there any visual difference between the torana and hq upper control arm diff mounts

any advice much appreciated

cheers dennis

#2 ls2lxhatch

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Posted 16 February 2012 - 05:20 PM

9" with Torana upper control arm mounts with McDonald Bros arms binding before the bump stops.

Posted Image


9" with the ends cut off HQ trailing arms and used as upper control arm mounts.

Posted Image


For an extra $100 I would go adjustable just because I like adjustable things. :)

McDonald Bros usually use SuperPro bushes. If you want to use SuperPro then check the duro that McDonald Bros fit. You may want to go a softer duro (check the SuperPro recommendations on their website ) or have rubber fitted instead. McDonald Bros will supply without bushes.

Edited by ls2lxhatch, 16 February 2012 - 05:26 PM.


#3 _SLR Goat_

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Posted 16 February 2012 - 05:30 PM

I do believe i have torana mounts so some modding will be required

I like adjustable thingys aswell so i may go for the adjustables

#4 enderwigginau

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Posted 16 February 2012 - 08:47 PM

Is the car lowered?
The wheel moves backwards with lowering, so you need to pull it forward if that's the case.

And the angle of the diff changes so having adjustments top and bottom can allow you to push the snout of the diff up.......

#5 _SLR Goat_

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Posted 16 February 2012 - 09:39 PM

Im pretty sure i have standard height springs in the front(HQ stubs drop it a inch) and 1 inch low in the rear in any case ill get adjustable uppers and lowers

#6 _SLR Goat_

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Posted 17 February 2012 - 01:36 PM

Just placed the order should have them by next wednesday very happy with the service

Also they asked if i had torana or hq mounts on the diff as they now make the upper arms to suit what mounts you have should be a straight bolt in job

#7 ls2lxhatch

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Posted 17 February 2012 - 11:30 PM

What bushes did you decide to have fitted to the arms?

#8 _SLR Goat_

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Posted 18 February 2012 - 08:52 AM

superpro comfort i figure the softer bush would help the rear end squat down more on the strip correct me if im wrong

#9 ls2lxhatch

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Posted 18 February 2012 - 01:11 PM

Sounds reasonable to me, I was planning to do the same. The bushes in the rear suspension seem to last a lot longer than the front so a soft duro urethane bush or rubber should do the job.

#10 _SLR Goat_

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Posted 18 February 2012 - 06:42 PM

Okay the diff is out and i need to replace the upper control bushes located on the diff any tips for doing this i have a theory that involves some pieces of pipe and threaded rod any suggestions

cheers dennis

#11 ls2lxhatch

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Posted 18 February 2012 - 07:45 PM

Air chisel/hammer is the easiest.

Something like this.

SCA Air Hammer Kit

Otherwise make your own puller. See this thread.

#12 _SLR Goat_

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Posted 19 February 2012 - 07:26 AM

cheers mate

#13 _cruiza_

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Posted 20 February 2012 - 09:16 AM

9" with Torana upper control arm mounts with McDonald Bros arms binding before the bump stops.

Posted Image


9" with the ends cut off HQ trailing arms and used as upper control arm mounts.



Without looking at a unmodified diff it looks to me like someone has mounted the the bracket on the diff back to front, if it were the other way around it would not foul and has the cut out for clearance

#14 ls2lxhatch

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Posted 20 February 2012 - 11:04 AM

The mounts are correctly fitted. The photo below shows the same arms on a stock banjo with a factory arm to compare. Apparently McDonald Bros now make a version to suit the Torana mounts.

Just placed the order should have them by next wednesday very happy with the service

Also they asked if i had torana or hq mounts on the diff as they now make the upper arms to suit what mounts you have should be a straight bolt in job



Posted Image

Edited by ls2lxhatch, 20 February 2012 - 11:07 AM.


#15 76lxhatch

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Posted 20 February 2012 - 11:23 AM

The cutout visible above is only on one side, it allows access to the factory breather on the Banjo housing

#16 _Whiteline_

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Posted 20 February 2012 - 11:27 AM

Hi ,

We seen this and thought we would let you know we do two versions of the trailing arm bush and one is street soft and the other is competion hard.

The street version is 85 duro and the competition is 93 duro.

We also have adjustable arms and you can view them all on link below or email us at [email protected] for futher questions.

http://www.whiteline...vehicle=3/74-79

#17 ls2lxhatch

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Posted 20 February 2012 - 11:44 AM

Photobucket appears to be having problems.

Posted Image

#18 _WUNLWUNT_

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Posted 22 May 2012 - 11:27 PM

I have the original Mcdonald Bros upper ( adjustable ) and lower ( tube, non adjustable ) arms on my LX sedan and i had to notch the lower part of the rear of the upper arms to stop it binding on the diff bracket. Adjustable arms are well worth the extra dough as they enable you to adjust the diff to driveshaft angle so that the uni joint is at a better angle, the diff should point down a couple of degrees so that under load it will be close to a straight line with the driveshaft.




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