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View Full Version : Harrop sports diff cover review



gts071
29-11-2008, 11:47 AM
Well as it was raining today so I decided to give the ole girl a drive and test out my Harrop cover (and noltec rear crossmember mounting bush kit)!

Here is a quick run though my suspension setup:
King springs (Ultra Lows) front and rear
Koni adjustable shocks set to around half way between soft and stiff both front and rear
Shameless plug for my car thread (if you want to read more): Australian LS1 and Holden Forums (http://www.ls1.com.au/forum/showthread.php?t=56377)

Previously I could barely take off on most road surfaces in the wet without chipping a tooth or having the windscreen wipers come on (that's if they were not already on) and it sounded horrible. Under light or heavy acceleration it would happen and no amount of feathering the throttle would tame it down, the only thing that really seemed to work is ride the clutch and get it into 2nd gear at around 20kmph and accelerate gently from there.

So here is my first impressions, I was putting down the road and turned left and gave the throttle a little dab while I was in 1st gear and there was the sound of minor axel tramp and I could feel it ever so slightly. So around the next corner I lightly accelerated and held it on for a little bit with some axel tramp still happening and I would at this stage say there is about a 70-80% improvement. So down some back roads and so forth to test out some heavier acceleration in the wet. So I apply about 50-60% throttle from take off and there is a fair bit of axel tramp happening, I would still say at this level it is around a 40-50% improvement but still annoying never the less.

Now the acceleration tests are done I move on to another and start putting down the road in 1st and stomping on the gas, again the axel tramp is still present (and this is a good time to remind you this it designed to reduce axel tramp it may not actually stop it completely) but much more bearable than previously and I would say it's a good 70-80% improvement compare to me doing it prior to the install. At this stage I wasn't going to try 2nd gear at high speed so I was putting around at 30kmph or so and gave the throttle a stab and it was about at 60-70% improvement.

The biggest thing I noticed after playing around a bit there was a huge difference when I would feather the throttle once the axel tramp had started and I can now almost control the car enough to reduce the axel tramp by a good 80-90% by using the right foot as this really seems to make a difference compared to no harrop diff cover. Before, the axel tramp was that bad my automatic reaction was to take my foot off the go pedal and start again, when taking off from some intersections before it could take 2-3 goes just to get moving with limited axel tramp. Now it is just a small amount of throttle control once it starts and I can keep it to a minimum without too much trouble at all!

To give people an idea of what the axel tramp would feel like before was like driving over the cattle crossing doing about 60kmph! So it is something you definitely felt!
Now it would be compare at best to driving over a couple of garden hoses and at worst maybe some broomsticks? (never actually tried that but it is all what came to mind!)

So here is my summary:

Did it make a difference: Sure did. Overall I would say about an 80% improvement
Would I recommend it: Yep! It is a great product and so far I’m very happy :D
Cost: Cover was $400 (I think) landed as it was 2nd hand but never used. Crossmember bushes were about $100 and installation would be around $100-$120 + oil + additives.
Overall rating: It is hard to give it a full rating at this stage as I haven't used it down the strip yet so as above I would say an 80% improvement (so far)

The big test is going to be the 20th of December when I take it down the strip as that is where I noticed axel tramp the most! So I’ll be back then :)

taztassio
29-11-2008, 12:21 PM
sounds good mate, maybe down the koni's ot a bit softer (i set mine at 1/2 and its a bit firm, if you have the yellows like me, u just use the tap ;))

the next step for you would be the other bushes.

I am doing the lot soon.

Cheers

nick

Ken
29-11-2008, 12:26 PM
Great unbiased & well-worded review.
Thank you.

gts071
29-11-2008, 12:30 PM
sounds good mate, maybe down the koni's ot a bit softer (i set mine at 1/2 and its a bit firm, if you have the yellows like me, u just use the tap ;))

the next step for you would be the other bushes.

I am doing the lot soon.

Cheers

nick

I will play with the settings a bit more but I just wanted to leave everything as it was until I head out to the strip as I got extractors, cats and u/d pulley fitted and want to compare how it was before to now. Once I have done that I will slowly find my sweet spot with the settings and see if I can make it even better!


Great unbiased & well-worded review.
Thank you.

Thank you Ken for a great product!

Its a cheap mod for those with axel tramp and so far I am seeing great results and I know there are 20-30 other things I could change to get it perfect but this was a great place to start.

CRAIG LS2 GD
29-11-2008, 12:36 PM
Would be interesting to see how much difference if you were to raise the car a few inches, (maybe so you could roll a coke can under it bud LOL) as i would be very suprised if there is much travel hence giving the shocks very little time to do anything, just a thought as i think at the track not much will change as to the extra traction versus road surface...

gts071
29-11-2008, 12:43 PM
I will be running my stock GTS springs in the rear at the track as that is what I run last time. Best way to give some honest feedback for anyone thinking of this mod.

dwaynE (TAKEITEZ) fixed his by changing springs so I am thinking about getting a set of super lows and seeing if that makes things better again.

CRAIG LS2 GD
29-11-2008, 12:50 PM
I am guessing it will chris i would imagine after looking under your imaculate machine when it was on the hoist that there would be all sorts of strange angles happening under there under load, i think just a little lift will fix this prob. 100%.. i would also reccomend doing front and back though, know were there is a set you can use as next time i am out there mine will be in 4 be 4 stance ....

BLOWN R8
03-12-2008, 04:53 PM
just installed the diff cover in my maloo and have had no axel tramp what so ever, can now actually put my foot flat to the floor without worrying about the car shaking me to death!

gts071
21-12-2008, 10:55 AM
I took the ole girl out to the drags yesterday and managed to get 4 runs.

1st run was a 13.2 will a small amount of axel tramp. huge improvement compared to before about a 60-70% increase from memory

2nd & 3rd run had minimal axel tramp but I had problems on both. A light failure on one and I missed 3rd gear on the other.

4th run was a new PB of 12.88 with no axel tramp after some practice and adjusting my launching with the new diff cover & bushes. So this is a must have product if anyone is experiencing axel tramp.

So all up i'm as happy as a pig in s..t!

TAKEITEZ
21-12-2008, 11:22 PM
good work chris :)... its good to see the tramp decrease so much...
the few runs i managed to watch you do it was great to see that the back wheels weren't jumping up and down everywhere!!!

going another inch or two higher in the back would see it go completely though... but if you like the low look and can put up with what little tramp you've got then its cool hey :)

SupremeVT98
22-07-2009, 10:21 AM
I've got a VY II automatic and am planning on upgrading my diff to a diff ratio, would this be the best time to install this Sports diff cover?

Also, what diff ratio would I be looking at for my VY2 auto?

I never take it to the track - I just want a little bit of an aggressive response from it.

Thanks.

Cobalt
23-07-2009, 12:24 PM
Yes do the install when you do the diff......

Save on labour. Fluids .....

Both my cars have Harop Covers.... My wife has a VZ Clubby and the Tramp is SO BAD..... But I rarely drive it and she dosen't notice. Harop cover all the way. It still manages 12.7 at the strip. Just have to launch with Drag Radials and 6000rpm on board.

3.73 for an auto...... But I have 20's on my auto VZ Senator Wagon so that makes a difference with the so it is probably closer to 3.6 with standard size wheels.

Cheers

Chad

APCLB
23-07-2009, 05:09 PM
Anyone got one for sale per chance?:)