Hi Guys...
I took the monaro out for a squirt today and gave it a bit of a hammering.
Appart from my oil pressure problem, Ive found something odd happening with my Diff.
Since ive changed to the mini-spooled 3.7 centre ive noticed that when i try and lay a skid, that the diff hops like it was a leaf sprung car axle tramping.
The question is, Ive never had this problem with the 3.25 LSD diff centre and i didnt feel it in the early days of the 3.7 Spooled centre.
I'm just running normal 28 spline axles ( one tonner ive been told?? I dont know??) so i'm a bit concerned.
I gave it a squirt today and near rattled me fillings out.. VERY violent and the marks on teh road were as if it was a doorslammer tyre shaking!
Anyone have any ideas? The Tyres/wheels havent changed so i dont *THINK* balance is an issue...
Cheers!
HQ Diff Hop question
Started by
_Tiny_
, Apr 25 2006 08:45 PM
30 replies to this topic
#1
Tiny
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Posted 25 April 2006 - 08:45 PM
#2
_CHOPPER_
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Posted 25 April 2006 - 09:06 PM
Easy one Tiny. Sounds like worn rear shockers and/or bushes. The reason you only noticed it snce the new diff is because there is a lot more torque multiplication to the rear suspension. This places more load on the shockers and they are now at the point where they can't do the job. Pedders do a 28 point suspension check including shock test for $28. I feel sometimes that they pick things that aren't always needed to be replaced immediately, but it's better that way so nothing is missed. This may not be the case at all stores, but I had noticed it in the past.
#3
racean69
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Posted 25 April 2006 - 09:09 PM
I have been told by people that axle hop is the result of the shockers not doing there job properly. But I believe it may be a combination of a few things.
My VZ clubby axle hops just as bad as I remember my torana doing it.
Do you have another set of shocks that you could try?
Maybe yours chose this day to pack it in.
My VZ clubby axle hops just as bad as I remember my torana doing it.
Do you have another set of shocks that you could try?
Maybe yours chose this day to pack it in.
#4
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Posted 25 April 2006 - 09:11 PM
Same time chopper. 
#5
micklx
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Posted 25 April 2006 - 09:15 PM
[QUOTE]Pedders do a 28 point suspension check including shock test for $28
Make sure you ask for Ralph!
Make sure you ask for Ralph!
#6
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Posted 25 April 2006 - 09:24 PM
Thanks guys!
All my suspension compenets have had about 12 months of road use... ( are slightly older but yeah.. sitting around!).
They are Koni adjustable shocks so maybe i can stiffen them up a little?
Thanks for the quick replies!
All my suspension compenets have had about 12 months of road use... ( are slightly older but yeah.. sitting around!).
They are Koni adjustable shocks so maybe i can stiffen them up a little?
Thanks for the quick replies!
#7
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Posted 25 April 2006 - 09:32 PM
Just try 1/8 of a turn at a time. If you run out of adjustment, some Koni's are rebuildable. Pull them apart and change the seals.
#8
_Oldn64_
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Posted 19 May 2006 - 02:48 PM
Chopper is smack on teh money here. As soon as you go to the lower ratio diff you end up increasing the torque of the rear. remember a diff is a torque multipler. Therefore more stress is transfered through teh rear end. This is the major issue I had at the drag day, simply due to the car having a 4.11 rear end. You may need to look into your suspension very carefully. Axle hop is very unnerving at the best of times. But I prefer a live rear axle over a IRS when it does get to axle hop areas. man does an IRS setup through the car around.
Check that all your bushes are in good nick. these are what keeps the diff in its right place. so if these are warn they will have a huge reaction to the diff placement. I would suggests that if you do look at replacing the rear bushes with nolathane that only the BOTTOM bushes get replaced with plastic, leave teh top rubber, the ride will be kinder. If not you will potentially solve the axle tramp but reduce the tractablity of teh vehicle (which I am sure you do want as skids all over the place is not fun.....)
Cheers
Check that all your bushes are in good nick. these are what keeps the diff in its right place. so if these are warn they will have a huge reaction to the diff placement. I would suggests that if you do look at replacing the rear bushes with nolathane that only the BOTTOM bushes get replaced with plastic, leave teh top rubber, the ride will be kinder. If not you will potentially solve the axle tramp but reduce the tractablity of teh vehicle (which I am sure you do want as skids all over the place is not fun.....)
Cheers
#9
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Posted 19 May 2006 - 03:32 PM
Thanks for that! I've got rubber bushes in one set of the arms but i'm going to check.
I'm going to double check everything under there.. it's gotto be something that's happened since the diff change cause it simply didnt happen with the LSD and also in the early times with the 3.7s.. I'll be checking the bushes and also mounting points apprently that's a major problem area!
Anyway.. I'll let you all know as i get time to sus it!
Cheers
I'm going to double check everything under there.. it's gotto be something that's happened since the diff change cause it simply didnt happen with the LSD and also in the early times with the 3.7s.. I'll be checking the bushes and also mounting points apprently that's a major problem area!
Anyway.. I'll let you all know as i get time to sus it!
Cheers
#10
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Posted 19 May 2006 - 10:20 PM
Stick a tyre lever between the control arms and diff/ body etc. to check the bushes. Just remember, your Chev 400 in first gear with the 3.7 diff gears is probably placing over 3500 foot/pounds of torque on the rear suspension. If you can place that much effort on the arms, you will be able to see what happens under load. With a bit of luck, you may be able to place 200 foot/pounds of force on the arse end. Another thing to remember is that one or both of the bottom rear arms may be flexing under this load.
#11
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Posted 19 May 2006 - 10:27 PM
Thanks Chop.. will try as much as we can! see what is evident 
#12
_LX406_
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Posted 21 May 2006 - 06:57 PM
Have you boxed your lower arms? Mcdonald Bros do adjustable solid ones.
#13
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Posted 22 May 2006 - 01:19 PM
heya LX406: yeah we've done that already, I'm going to be getting under it in the next couple of weeks to sus it right out... I've made some enquiries into automotive engineers to certify the car and once thats underway ( so i dont get caught by the changing laws) i'll take the car off teh road, get under it and sort out the arse end and oil surge problems!
Do you have any pics/info on the McDonald Bros arms? I had some other brand ( wont say what company) adjustable upper arms in the car and they were pathetic! they twisted and all sorts of nasty stuff!
Thanks for the tip!
Cheers!
Do you have any pics/info on the McDonald Bros arms? I had some other brand ( wont say what company) adjustable upper arms in the car and they were pathetic! they twisted and all sorts of nasty stuff!
Thanks for the tip!
Cheers!
#14
_ChiaLX_
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Posted 22 May 2006 - 01:39 PM
Try this link for the lower arms Tiny
http://www.mcdonaldb...lowertrail.html
This is for the upper adjustable arms.
http://www.mcdonaldb.../upperarms.html
Mick
http://www.mcdonaldb...lowertrail.html
This is for the upper adjustable arms.
http://www.mcdonaldb.../upperarms.html
Mick
Edited by ChiaLX, 22 May 2006 - 01:42 PM.
#15
Tiny
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Posted 22 May 2006 - 01:52 PM
Thanks mick
They look to be a bit better than the ones i used previously. I'll see how my gear looks and wether teh arms are causing the problem and see how it pans out from there!
Cheers
They look to be a bit better than the ones i used previously. I'll see how my gear looks and wether teh arms are causing the problem and see how it pans out from there!
Cheers
#16
gtrboyy
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Posted 22 May 2006 - 05:00 PM
Can you PM me which company that you got the adjustable arms off so I know not to go there.
#17
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Posted 22 May 2006 - 06:51 PM
I paid $520 for the set of 4 arms from macca brothers for the Torry.
#18
_LJ355_
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Posted 29 May 2006 - 08:21 PM
Has anyone got a LC/LJ set in there car how does the springs sit on the lower ones ?
#19
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Posted 30 May 2006 - 06:33 PM
From memory the ones I saw had a thick flat plate with a hole in it for the spring clamp & the nut went underneath like the std set-up,
#20
_Lostit_
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Posted 10 June 2006 - 09:34 AM
Just a few more questions Tiny . Does it do it on acceleration always .. does it do it normal driving ?
#21
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Posted 10 June 2006 - 08:45 PM
Gday Denis,
No mate it doesnt happen when accelerating ( even hard acceleration) or at any speeds at all!
It ONLY occurs when you loose traction! That's the weirdest thing! I cant pin it down to anything but the diff moving around because of this...
Unis, tailshaft balance even a bent axle would all show up during normal driving and not ONLY under lost traction situation!
Anyway i'm FINALLY getting the car engineered.. waiting for the engineer to ring me and THEN i'll be fixing this problem!
Cheers!
No mate it doesnt happen when accelerating ( even hard acceleration) or at any speeds at all!
It ONLY occurs when you loose traction! That's the weirdest thing! I cant pin it down to anything but the diff moving around because of this...
Unis, tailshaft balance even a bent axle would all show up during normal driving and not ONLY under lost traction situation!
Anyway i'm FINALLY getting the car engineered.. waiting for the engineer to ring me and THEN i'll be fixing this problem!
Cheers!
#22
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Posted 14 June 2006 - 10:28 PM
I made a post ages ago about my HQ doing the exact same thing, i replaced all bush's springs and shocks rebuilt the diff and put a slightly taller ratio centre in her (single spinner, was 2.78 now 3.08) and it still axle tramps when i do a skid. It used to be really really bad and axle tramp on any traction loss around corners but since the rebuild it only tramps when i rev her up and dump the clutch, it bouces 3 or 4 times then settles down while im slowly crusing along with my foot on the brake. I think my problem could be solved with good quality shocks like koni. Ill be interested in knowing what fix's your problem, i wont be spending money on mine trying to track it down because it cuts down on me being stupid.
#23
_Oldn64_
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Posted 15 June 2006 - 03:49 PM
Tiny the Galant does eachly the same thing, but might was an easy fix with caltracs. Yours being a coil rear will be different again, as I have leaf rear. Axle tramp is very very unnerving not to mention the shear noise produced. My VR SS (with IRS) also axle tramps everywhere. It is just something I have learnt to live with.
Cheers
PS: The only other thign I have thought of tiny is knowling that your car has been played with are you sure the pinion angle was setup correctly?
Cheers
PS: The only other thign I have thought of tiny is knowling that your car has been played with are you sure the pinion angle was setup correctly?
#24
Tiny
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Posted 18 June 2006 - 02:45 PM
Hey guys,
I've got koni adjustables all round in the monaro anyhow, so i don *THINK* it shoudl be the shocks.
It really only started to do it after a few good blasts witht he 3.7 ratio and after the skid pan day's hammering etc.
I'll be trying to get under it as soon as i can to sus it out, but work's been SO BUSY at the moment that the car has had to take a back seat for a while!
Anyhow, I'll definitely let you know how it goes!
Cheers
Tiny.
I've got koni adjustables all round in the monaro anyhow, so i don *THINK* it shoudl be the shocks.
It really only started to do it after a few good blasts witht he 3.7 ratio and after the skid pan day's hammering etc.
I'll be trying to get under it as soon as i can to sus it out, but work's been SO BUSY at the moment that the car has had to take a back seat for a while!
Anyhow, I'll definitely let you know how it goes!
Cheers
Tiny.
#25
makka
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Posted 19 June 2006 - 05:31 PM
you havnt gone to stickier tyres by any chance? my mate with the Mandarin HX from the drag day had big axle tramp problems when he ran wider tyres on the back
Edited by makka, 19 June 2006 - 05:31 PM.
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