Why Use diff drop kits and upper control arms on your Toyota Hilux?

Author: Rod Webster   Date Posted:6 June 2016 

Learn the ins and outs of these often misunderstood components used for high lifts and long travel suspension on the Toyota Hilux 2005-2016 and on

Diff drop kits and upper control arms serve very different purposes but together enable you to run much more capable suspension on the Toyota Hilux 2005-2016 version.

 

Diff drop kits are probably easier to understand as they only have a single purpose in life. That is to drop the front diff below factory height. This is done to reduce front CV angles to prevent binding, broken CV’s and damaged CV boots which tend to splatter grease all over the underside of your vehicle. Diff drops allow you to run longer travel shocks and higher lifts than what can be achieved when the Front Diff is in its standard location.

 

Upper control arms on the other hand are a bit harder to get your head around because they are essentially a wheel alignment product that restores camber and caster that are thrown way out of whack when doing a high lift utilising long travel suspension.

Manufacturers have a wheel alignment specification for a reason, tyre wear, return to centre steering, tracking, high speed stability, it’s a geometry thing. Well designed Upper Control arms as a bolt in system will have 5 key points that make them worth the investment.

  • Will give you 4 degrees of caster correction,

  • Give more clearance with larger tyre diameters.  

  • Shock and strut clearance to allow more wheel travel up and down.

  • Angled ball joint cup to work with the extra travel and restore camber..

Lets have a look at caster first. By increasing caster on your Hilux, as well as improving on road performance, you actually move the wheel further forward and away from the body mount situated at the rear of the wheel well and therefore make room for larger tyres. The diagram below will help understand what caster is.

Camber is also significantly affected with higher lifts. As you lift the suspension, the bottom of the tyre rotates inwards resulting in  increased positive camber. This reduces the contact patch on the road which in turn results in excessive tyre wear and poor road handling.

 
 

So by angling the top ball joint realigns steering geometry for both camber and caster. As long as an aftermarket upper control arm gets caster back within factory specs, there is sufficient adjustment to get a perfect wheel alignment for Camber.

 

Caster on the other hand does not have much adjustment available. Some upper control arms have an adjustable ball joint, and the reputable brands usually do a reasonable job, some of these balljoints are expensive (up around $150 or more) and seem to have a short service life. Also, the top nut that secures the balljoint has no locking mechanism to secure it and they frequently come loose. Not only is this a bit risky, you also loose your wheel alignment so you are up for added cost to fix that! So on balance, we favour fixed ball joint upper control arms for the Toyota Hilux provided they have been well designed to cope with the changed suspension geometry that comes with a suspension lift. So a good set of UCA's are important important when you are chasing the last millimetre of lift you can squeeze out of your suspension kits setup on your Toyota Hilux.

 

I recall the first time I drove my Hilux after fitting upper control arms, I immediately noticed a much firmer steering feel that also made the steering feel much more precise. I put this down to the larger contact patch on the road. I’ve been enjoying the benefits of improved handling and better tyre wear ever since.

 

Just one final note on Upper control arms. Look for ones with a ball joint with a sealed rubber boot. Don’t be tempted to by a set with exposed uniball style top ball joints. These are totally unsuited to Australian conditions and have proven over the years to be an expensive to maintain high maintenance part. If you aren’t involved in the desert racing scene where these ball joints are considered a consumable part, don’t be tempted to fit them to your Hilux.


Comments (7)

Blackhawk UCA vs VMN Option UCA

By: on 18 May 2019
Hi I have a 2010 N70 with 3" lift with 285/75 r16 no zero off set and need to change UCA to get correct wheel castor. Can you give me the pros and cons of both of these UCA do I need to go to the Blackhawk or save the cash to put into the diff drop? Thanks Brett

VMN 4X4 Marketplace Response
Brett, We introduced the VMN Option UCA becasue we had feedback from workshops and customers was that some fixed ball joint style gave too much caster (well beyond the manufacturer's published specs). This moved the wheel too far back and lead to clearance issues at the rear. This was typically limiting the tyre size able to be fitted to 32". We have fitted 33" tyres on standard +30mm offset factory rims to a 2018 Hilux (current spec) with the Option upper control arms and found that they worked well. You may have a different experience with the your wider offset and earlier model as there are so many variables.

Toyota Hilux 2015 4x4 2.5

By: on 7 May 2019
Hi, I had lifted the front of my hilux 2 inches using Pedders springs and absorbers. I did this to fit a 31/10.5/R15 All-Terrain Tyres. I wonder if I should change the UCA and upgrade the brake lines? Is there a test that can be done to determine if I need the changes?

VMN 4X4 Marketplace Response
We say UCA's are recommended at 2" but not mandatory. We have some reasonably priced one on our web site. To see if brake lines need extending, its easy to check on a hoist but you can do it at home by jacking up the left hand side of the vehicle by the chassis until the wheel is off the ground (eg hanging on full extension). Observe the brake lines to see if they are tight and pulling on the mounting brackets. If they are, you need to replace the brake lines.

UCAS & DIFF DROPS

By: on 9 April 2019
Hello, I have a 2012 SR5, I am looking at getting 32” muddys and a 3” lift in the front and a 2” lift in the back. I am no extreme 4x4er, barely doing ‘hard’ tracks. More a camping rig, just a question. Say I put the lift, tires and a diff drop in. Could I put upgraded UCA’s later down the track without coming across any issues? Cheers mate Reply via Email if possible, appreciate your time

VMN 4X4 Marketplace Response
If you are going to run a 3" lift, you need the upper control arms. We often find people need them at 2"

2014 hilux

By: on 21 February 2019
I'm new to this. I have a 2014 hilux (facelift) UK model. And I want to go 3inch suspension lift from dobinsons. The kit I want doesnt come with the ball joints but drop dif and UCA. Would I need to get the ball joint that you spoke of in your article ? Also another thing. Do I need to get longer brale lines.? Or the factory brake lines would work with the 3 inch lift?

VMN 4X4 Marketplace Response
At 3" of lift you need the Upper control arms to correct steering alignment or you will have very short tyre life even if you can make things fit. We recommend extending the brake lines as even with 2" of lift our brake line pulled away from our Hilux Vigo. Alternatively, space the lwser mounting bracket up with some washers and a longer bolt.

Vibration

By: on 28 August 2018
Had a suspension upgrade on my 2012 Hilux to firm up the back end when towing a 2 ton caravan.It came with a 2 inch lift.Ever since I feel vibration,through the seat not the steering wheel,at 35kph and 7kph. It passes pretty quick unless stuck in traffic then it becomes annoying.Is there a fix for this and could it cause damage in time?

VMN 4X4 Marketplace Response
The only thing I think it might be is vibration in the tail shaft. Check the Universal joints and also the centre bearing. Sometimes you need to space it down but not normally required on a Hilux.

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