Harrop Diff Cover

[10sec_rx7]

after fitting the new Cam in our LS2 maloo a few weeks back the extra power was causing very bad axle tramp, so a quick call to harrop had a diff cover on the way,

what can i say, it has totally changed the car, the back end is nice and tight now and the tramp has gone from shaking the car into a million pieces to 100 times better, we then fitted a set of Custom valved shocks and the tamp is 99% gone,

if anyone is having tramp problems or wants there car to fell a lot tighter on the road i highly reccomend the Harrop carrier!!

Great work guys

Dale

[Ken]

Thanks for the good review ...
Its nice to get the feedback.

[Veeate]

Howdy Ken. What are one of these diff covers worth ?

I have been suffering axle tramp with these cars for years and a proven solution to most of it would be a good addition to my car.

cheers
David

[Smitty]

Howdy Ken. What are one of these diff covers worth ?

I have been suffering axle tramp with these cars for years and a proven solution to most of it would be a good addition to my car.

cheers
David
mate
all explained here-
http://www.harrop.com.au/root_folder/driveline_components/99-acvr6824-00.html

[Veeate]

Cheers Smitty.

[GTO LS2]

Just checked the link........1 question .... is this a do it yourself fit???.I am no mechanic...................

[Ken]

A fundamental mechanical knowledge would be of benefit, but many owners have installed them DIY. There are full instructions included.:deal:

HOWEVER ... I strongly recommend getting a professionsl install done, as the rear cradle should be re-aligned after installation. Most GM workshops should have the alignment jig, as do most Pedders Suspension shops. Call around and you will probably find a shop who has previously done an install.

[hsv-105]

I've got one that I no longer need as I've upgraded to the Harrop 9" IRS.
$250 Pick up only Melb Sth East suburbs.

Mark 0437957775

[10sec_rx7]

the instructions are very very good, with basic tools and skills you should be able to install it no problems then get the car for a alignment

Dale

[hsv-105]

I've got one that I no longer need as I've upgraded to the Harrop 9" IRS.
$250 Pick up only Melb Sth East suburbs.

Mark 0437957775

Sold in a flash

[chops]

I'm sure it did, that was a serious bargain.
I read the post just after you made it, and I was in Vic I woud have called you immediately too.

[NickS]

I've got one that I no longer need as I've upgraded to the Harrop 9" IRS.
$250 Pick up only Melb Sth East suburbs.

Mark 0437957775
Should have stuck it on the Coupe 4 Mark ... Sonny put one on mine yesterday.

[8throttlebodies]

I have been told the Harrop diff cover and the DF twin 3" exhaust will collide if fitted together...

can anyone confirm or discount this?

thanks
8tb

[hsv-105]

I have been told the Harrop diff cover and the DF twin 3" exhaust will collide if fitted together...

can anyone confirm or discount this?

thanks
8tb

Sure does, but not a huge issue to modify the exhaust.
It's only the Right hand pipe where it comes around behind
the diff.

[8throttlebodies]

Sure does, but not a huge issue to modify the exhaust.
It's only the Right hand pipe where it comes around behind
the diff.

Thanks Mark.
Are you running this setup? Do you have any pics of this?

thanks
8tb

[gen3ss]

after fitting the new Cam in our LS2 maloo a few weeks back the extra power was causing very bad axle tramp, so a quick call to harrop had a diff cover on the way,

what can i say, it has totally changed the car, the back end is nice and tight now and the tramp has gone from shaking the car into a million pieces to 100 times better, we then fitted a set of Custom valved shocks and the tamp is 99% gone,

if anyone is having tramp problems or wants there car to fell a lot tighter on the road i highly reccomend the Harrop carrier!!

Great work guys

Dale



How does it work in the sense of stopping axle tramp? What makes it work?

[Ken]

How does it work in the sense of stopping axle tramp? What makes it work?

Its all because of the magic crystals strategically placed in the molten aluminium by the blessed monk ... Sir Antitrampalot.
















Either that ... or the stiffer/wider/better mounting reduces the movement by spreading the load over 4 mounts instead of the standard 3.

[10sec_rx7]

How does it work in the sense of stopping axle tramp? What makes it work?

by supporting the diff and cradle better so it cant bounce as much

[swingtan]

Its all because of the magic crystals strategically placed in the molten aluminium by the blessed monk ... Sir Antitrampalot.

:lol: :lol: :lmao: :lmao: Sir Antitrampalot...... He must be a mate of Sir Not-appearing-in-this-film

[VYSHSV8]

I won one of the enduro covers including fitting but I am going to upgrade it to the race spec one as you have fitted...

Drew

[gen3ss]

Its all because of the magic crystals strategically placed in the molten aluminium by the blessed monk ... Sir Antitrampalot.


Either that ... or the stiffer/wider/better mounting reduces the movement by spreading the load over 4 mounts instead of the standard 3.


Thank you for your kind wisdom Ken or do you like to be known as Sir Antitrampalot???:lol:

[Animal]

I had mine fitted, it also banished Sir Antitrampalot to the wilderness.

Have you been on the wine again Ken .. that was a crack up :)

[blkV8]

I had mine fitted, it also banished Sir Antitrampalot to the wilderness.

Have you been on the wine again Ken .. that was a crack up :)

r u guys 4 real........ sams performance and harrop engineerin, r u guys jus gettin on here sayin wot u want so u make money.
Me thinks so :lol:


r u guys 4 real........ sams performance and harrop engineerin, r u guys jus gettin on here sayin wot u want so u make money.
Me thinks so :lol:

i tried a harrop 2 mount diff cover.........
still had tramp, it made no diff at all!!!!!!!!!!!!!!

[Animal]

You might also want to upgrade your rear shocks and maybey see Sam for one of his excellent strokers :yup:

[blkV8]

You might also want to upgrade your rear shocks and maybey see Sam for one of his excellent strokers :yup:

exactly!!!
:rofl:

jus makin money arent ya. Cant trust u now haha

[dadem0n]

Hi Ken,

Could you explain the difference between the two diff covers that are available?

One being $250, the other being $500? :confused:

Thanks
Grant

[Ken]

Hi Ken, Could you explain the difference between the two diff covers that are available? One being $250, the other being $500? :confused: Thanks Grant

The Enduro cover is designed primarily for those applications where the differential is suffering due to the oil overheating. The Enduro cover enables a significant increase in the capacity of oil and the ability for the oil to dissapate the heat through the cover. The Enduro cover will have no effect to the suspension and handling. The Enduro cover uses the OE mounts.

The Sports version also has a huge increase in oil capacity, but it also incorporates a substaintially more stable method of mounting the rear subframe than standard. The standard subframe mounting is 3-points, which allows the entire rear end to pivot/rock as load is applied. The Sports cover adds an additional mounting point which increases the stability of the subframe and being 4-points the amount of pivot/rock is significantly reduced. Many owners have reported a noticable improvement in handling and a marked reduction in axle tramp.
The Sports cover comes with a mounting bracket that replaces the OE rear bracket, however it bolts directly up to the vehicle and there is no drilling/cutting/trimming or body modifications required.

Hope this helps, but if not please feel free to call the Sales team on 03.9474-0900.

[HSV249]

Are the mounting points the same for a ute & sedan?

[Ken]

Are the mounting points the same for a ute & sedan?

Yep ... for most cases.

[Martin_D]

Basic physics tells us that the axle tramp proplem with the Holden semi trailing arm suspenion occurs due to lack of control of the UNSPRUNG mass of the vehicle - ie. tyre/rim/brake assembly (this is the bit you can feel bouncing around when axle tramp occurs). The diff centre on the other hand is SPRUNG mass, and is supported directly to the body of the motor vehicle. What I have always wanted to know is in the instance where the differential hosing doesnt bounce around and smash against the floor pan of the vehicle, how is mounting it differently going to affect the way the wheels bounce up and down on the road? :confused:

I had this actual discussion with a suspension engineer the other day when working through ways of controlling the axle tramp on my VX R8, and he was adamant that only the parts acting directly on the mass that is bouncing/tramping (wheel/tyre/brake) being the shock absorber and spring, could have any influence on the severity of the axle tramp. I mentioned the different rear diff cover plate, and he just looked at me confused. Any input on this Ken? :teach:

[10sec_rx7]

the cover didnt 100% get rid of the tramp but it helped a hell of a lot, a set of good rear shocks almost fixed the problem

the cover really made the back end feel a lot tighter on the road

[Ken]

Basic physics tells us that the axle tramp proplem with the Holden semi trailing arm suspenion occurs ...snip... me confused. Any input on this Ken? :teach:

Some input ...
1 - As stated previously, the primary reason we designed the Sport cover is to reduce the compliance (sloppiness) between the subframe and the body structure, and to increase the oil capacity. The resulting reduction in axle-tramp is a byproduct, because;

2 - The subframe can be condsidered at least partially unsprung as in its standard form it is riding entirley on rubber and certainly has a measurable amount of "spring". We did quite a bit of measuring the movement of the subframe in the Brock Targa Monaro when we were developing this product and it is significant. The "bounce" in the rear mount alone contributes to axle tramp.

3 - As any good race-car Engineer will confirm, the less compliant (stiffer) the body structure, the better the vehicle control.

4 - It works ... proof is in the results. There are far more cars with the Sports kit installed whose owners have reported a marked improvement than those who have noticed no difference. On its own, the cover is unlikely to be a "cure" to axle tramp, but the evidence certainly supports it contributing to a reduction.

PS ... I dont think too many skilled suspension Engineers would like us referring to their craft as "basic physics". :D

[SSidewayz]

Just a bit of imput from my personal experience. I dont have the sports cover at the moment, but I got a nolathane insert for the rear diff mount and nolathane main rear frame mounts. The improvement of axel tramp was noticably better. I think that as is stated above the actual frame and diff itself does have a fair amont of movement. Making the diff more rigid to the body does, if not eliminate, definately help the problem. I also think that the springs and shocks are major factors aswell. Id love a sports cover kills 2 birds with 1 stone, cooler oil and reduced tramp.
Cheers

[CalaisRider]

A fundamental mechanical knowledge would be of benefit, but many owners have installed them DIY. There are full instructions included.:deal:

HOWEVER ... I strongly recommend getting a professionsl install done, as the rear cradle should be re-aligned after installation. Most GM workshops should have the alignment jig, as do most Pedders Suspension shops. Call around and you will probably find a shop who has previously done an install.

Have you put one on a VE yet or is development still coming - like most things VE?? I have a Calais V 6 litre.

Pete

[Ken]

Have you put one on a VE yet or is development still coming - like most things VE?? I have a Calais V 6 litre.

Pete

There is one on a VE ... but it will be a few weeks before we have the production version released.
We need to complete the durability testing, and there are still some calibration issues to overcome.

We intend to have kits for sale before Christmas.

:driving:

[Martin_D]

What do you think of the decent sump and rear cover on the stock VE housing Ken? Looks pretty good to me, dont you reckon :)

[Ken]

There is one on a VE ... but it will be a few weeks before we have the production version released.
We need to complete the durability testing, and there are still some calibration issues to overcome.

We intend to have kits for sale before Christmas.

:driving:

BUGGER !!!
:cussing: :kill:
I posted this on the wrong thread ... I was referring to VE Superchargers, not diff covers.
That'll teach me to have so many windows open !!

Sorry about that ... no diff covers for VE yet, still in design phase.

:banghead:


What do you think of the decent sump and rear cover on the stock VE housing Ken? Looks pretty good to me, dont you reckon :)

Absolutely ... a big improvement over pre-VE.

Still some room for better tho' ... we've got a couple of thing were experimenting with which will make a few drivers smile. ;)

[grubb]

Have you put one on a VE yet or is development still coming - like most things VE?? I have a Calais V 6 litre.

Pete

Do the VE's still have the axel hop problem????? I would hope they don't!! Anybody with a VE fill me in??

[Brockfan05]

According to Warren Luff who was MOTOR mags pro driver for BFYB, yes the VE's still suffer from axle tramp and still have an overly aggressive ABS actuation point.

And once I have mine and get an opportunity to track it, I will let you know from first hand experience.

[cosmo vyss]

the instructions are very very good, with basic tools and skills you should be able to install it no problems then get the car for a alignment

Dale

Why do you need an alignment after its fitted?
JB

[Darkrayne]

Why do you need an alignment after its fitted?
JB


from watching mine get fitted .. i wouldnt like to try it without a decent workshop and help at hand! :|

[hurricane]

Hi 10sec rx7, i have a 03 vyss and had lots of tramp had harrop diff cover proffesionally installed but i seem to still suffer tramp, depending on what road surface i am on , smooth okay but anything with a bit of grip seems to still be a problem cheers Ian.

[APCLB]

Hi 10sec rx7, i have a 03 vyss and had lots of tramp had harrop diff cover proffesionally installed but i seem to still suffer tramp, depending on what road surface i am on , smooth okay but anything with a bit of grip seems to still be a problem cheers Ian.



the cover didnt 100% get rid of the tramp but it helped a hell of a lot, a set of good rear shocks almost fixed the problem

the cover really made the back end feel a lot tighter on the road


Maybe this will help? "shocks"

[T_Kiwi]

kaaz diff with the harrop diff cover will fix it

[hsvfreak]

I have a KAAZ 2 way centre and harrop diff cover and whilst it did help,
I found trialing different rear spring and strut combo's fixed the tramp.

[10sec_rx7]

we had a set of custom valves bilstiens fitted to the car as well as a few other rear suspension parts, 99% of the tramp is gone, and with 1.54 60' out of a M6 ute it shows the rear suspension is working a treat,

when compared to my setup which has all the same bits less the diff cover and shocks and i struggle to get into the mid 1.6 60' mark with out blowing off the tyres,

put it this way, with the cover, shocks, bushes and a few other things the car has gone from a axle tramp POS that would open the hard cover if not locked it shook that much to a nice gental slide accross the top of the road,

[Gen3Man]

So guys, what have you been paying for a Harrop Sports Cover ?
Curious to hear what average prices are.

cheers

[WOMBIE]

M8 i don't know about an "average" price but i payed what Harrop
are asking(check out their website for pricing)as well as rear crossmember mounting bushes and had it fitted yesterday by CHE......money well spent imho.

I would say about 95% less axle tramp thus far:thumbsup:

[iamhappy46]

Basic physics tells us that the axle tramp proplem with the Holden semi trailing arm suspenion occurs due to lack of control of the UNSPRUNG mass of the vehicle - ie. tyre/rim/brake assembly (this is the bit you can feel bouncing around when axle tramp occurs). The diff centre on the other hand is SPRUNG mass, and is supported directly to the body of the motor vehicle. What I have always wanted to know is in the instance where the differential hosing doesnt bounce around and smash against the floor pan of the vehicle, how is mounting it differently going to affect the way the wheels bounce up and down on the road? :confused:

I had this actual discussion with a suspension engineer the other day when working through ways of controlling the axle tramp on my VX R8, and he was adamant that only the parts acting directly on the mass that is bouncing/tramping (wheel/tyre/brake) being the shock absorber and spring, could have any influence on the severity of the axle tramp. I mentioned the different rear diff cover plate, and he just looked at me confused. Any input on this Ken? :teach:

^^ Regarding this... after some feedback on the following

CV joints/driveshafts would be transmitting lateral forces from the suspension as it travels up and down. As the rear end squats and rotation of the CV joints keeps the driveshafts spinning which makes driveshaft rotation hard to change direction/position as they become gyroscopic. The intermediate shafts are forced to stay on a fixed angle due to the gyroscopic force, which tries to alter the position of the diff carrier laterally as the suspension squats. By stiffening the carrier mounts/etc, the diff can no longer move which forces the CV joint intermediate shafts to change length(move in and out of the CV joints inside the CV boots)

As the CV joints/driveshafts are 'unsprung' and the diff bushing are hardling stiff, this could account for the axle tramp?

I can do up a pic if you need to clarify what I am thinking...

[Mungrel]

^^ Regarding this... after some feedback on the following

CV joints/driveshafts would be transmitting lateral forces from the suspension as it travels up and down. As the rear end squats and rotation of the CV joints keeps the driveshafts spinning which makes driveshaft rotation hard to change direction/position as they become gyroscopic. The intermediate shafts are forced to stay on a fixed angle due to the gyroscopic force, which tries to alter the position of the diff carrier laterally as the suspension squats. By stiffening the carrier mounts/etc, the diff can no longer move which forces the CV joint intermediate shafts to change length(move in and out of the CV joints inside the CV boots)

As the CV joints/driveshafts are 'unsprung' and the diff bushing are hardling stiff, this could account for the axle tramp?

I can do up a pic if you need to clarify what I am thinking...

I actually understood most of that! I didnt think the CV joints would have much movement in the boot? Obviously there would be a minimal amount to account for the angle of the shaft but not enough to move in and out?


Ive got a VU, Koni adjustables in the rear, and Lovels superlow springs, i've only encountered axle tramp once in all the time ive driven it, would the normal enduro cover be the best bet for me? just to provide extra oil capacity i mean. I see no point changing to the sports cover when the problem it solves, isnt one im currently confronted with? Thoughts? Opinions?

[TAKEITEZ]

i would say you are about right there...

i have a few mates with utes and sedans, and of all the ones who complain about axle tramp the question "what springs/shocks are you running" is usually followed by "just some superlows and standard shocks"...

all the guys i know with decent shock and spring selection usually go "tramp, what tramp? its all gone"

i personally i have not encountered it on the road or the strip yet in my maloo......

[iamhappy46]

Think about it this way.
When the two hubs are in line with the diff, the length of the intermediate shafts is the shortest. When the hubs are higher(or lower) than the diff, the shaft needs to lengthen as the angle increases as they move further apart. The CV joints usually have a cup arrangement inside them to allow the shaft(and bearings) to move freely to alter the length.

[vxclubby85]

i would say you are about right there...

i have a few mates with utes and sedans, and of all the ones who complain about axle tramp the question "what springs/shocks are you running" is usually followed by "just some superlows and standard shocks"...

all the guys i know with decent shock and spring selection usually go "tramp, what tramp? its all gone"

i personally i have not encountered it on the road or the strip yet in my maloo......

I have adjustable koni's with king springs in mine and suffer BAD axle tramp, shakes everything really bad... not liking it either..

not sure what else to try, might look into the diff cover and some new bushes?

[SupremeVT98]

So how do I get an axle tramp? Chances are,, I already have it but don't know when it strikes.

How do I experience this axle tramp?

[Gen3Man]

So how do I get an axle tramp? Chances are,, I already have it but don't know when it strikes.

How do I experience this axle tramp?

A horrible shuuddering of the arse end of the car on a massive launch !

Feels like the car is jumping/bunny hopping in the rear end.

Has to be quick acceleration.
:burnout:

[SEDUCE]

What are the diff covers worth for a vu???

[HSV249]

about $500

[nqcv8]

http://www.harrop.com.au/root_folder/driveline_components/99-acvr6824-00.html

[Gen3Man]

Yeah, prices are pretty consistant. About $500

Try our forum Sponsors, they will look after you.
And do the job right.
Its important to use the right additive in the oil after refilling, to maximise diff life.

cheers

[jacks_6l]

ive got a 2006 Thunder ss ute with super lows monroe shocks and the sports diff cover and mount and mine still tramps, also whilst my car was on the hoist today i found a large crack all the way across one of the four mounting points on the bracket, ive emailed harrop with pics but they want me to pay for another bracket and send the old one back to them. i installed it myself but followed the instructions meticulously. not happy with it at the moment.

[Ken]

ive got a 2006 Thunder ss ute with super lows monroe shocks and the sports diff cover and mount and mine still tramps, also whilst my car was on the hoist today i found a large crack all the way across one of the four mounting points on the bracket, ive emailed harrop with pics but they want me to pay for another bracket and send the old one back to them. i installed it myself but followed the instructions meticulously. not happy with it at the moment.

I trust that our Customer Service team explained to you that if we found the material or workmanship to be faulty, you would receive a full refund for the replacement.

We do not send replacement products free-of-charge without having the suspect product returned first ... previous experiences have proven it unwise. Imagine the mayhem Holden would experience if they sent replacement warranty components to vehicle owners without a dealer first determining the validity of the issue, or the likelihood of Sony sending a replacement television because an owner claimed the purchased unit was faulty.

We look forward to receiving the failed unit and restoring your faith.

[throttlehappy]

does it hit with other exhausts or just the df?

[macca33]

does it hit with other exhausts or just the df?
I'day the D/F twin 3" only TH - this is due to the fact that the right (driver-side) pipe goes around the rear of the differential with this system, not to the left of it as most other systems do.
Cheers,

Macca

[APCLB]

I wonder if there is enough punters out there for a group buy for these covers?

[throttlehappy]

I'day the D/F twin 3" only TH - this is due to the fact that the right (driver-side) pipe goes around the rear of the differential with this system, not to the left of it as most other systems do.
Cheers,

Macca

cheers macca, be good if someone could confirm though
thinking about getting one at some stage because of my tramping issues lately

[Blown 540]

Hi Ken,
Any news on the VE sports cover yet ?.or did i miss it ,regards dave

[throttlehappy]

Hi Ken,
Any news on the VE sports cover yet ?.or did i miss it ,regards dave

be good to know about that diff cover too

[Blown 540]

hello:stick:

[Ken]

Hi Ken,
Any news on the VE sports cover yet ?.or did i miss it ,regards dave

In this instance ... no news is bad news.
We have decided to cease development of the VE Sports Diff Cover as the technical merit does not justify the development expense (aka, the product will cost too much for minimal gain).:bawl:

However ...
We will be doing (at some future stage):
- TureTrac LSD upgrade.
- 12-Bolt Chev complete diff upgrade.

:bow:

[Ron SS]

Ken, do you have any advice for a tramp cure for VEs?? I was under the impression that you were working with Walkinshaw to come up with a bushes set or some trick to minimise or hopefully cure completely the VE tramp. The Walkinshaw supercharged cars must tramp. What is the latest thinking?

[Ken]

Ken, do you have any advice for a tramp cure for VEs??
More Power !!


I was under the impression that you were working with Walkinshaw to come up with a bushes set or some trick to minimise or hopefully cure completely the VE tramp.

The commercial viability of the project didn't add up, so we have shelved it for now.

[throttlehappy]

???????????