Any car whose suspension is worked hard suffers from wear in the bushes, and the Skyline GT-R is no exception. The bushes used in the upper A arms of the Skyline GT-R, last model 300ZX and the (rare in Australia) Q45 luxury Nissan all suffer from accelerated wear when the cars are driven hard. In fact, it's a known weak link in the front suspension of the GT-R, with some cars showing slop after as little as 30,000km. The factory replacements are no better - one GT-R owner had an upper A arm fitted and then removed within the one session, so bad was the movement in the brand new replacement!
Now Sydney (Australia) company Unique Auto Sports has made available replacement upper A arms. The arms are adjustable for length, allowing changes to be made in camber. In an attempt to prolong life, they also use polyurethane bushes complete with grease nipples. The arms cost $400 a pair. We bought some and put them to the test in an R32 Skyline GT-R.
The arms comprise two channel sections, one of which slides within the other. At one end of each piece of channel is welded a tube in which a plastic bush is located. A steel sleeve rotates within the bush, with a grease nipple providing access for lubricant. After adjustment, the channel sections are fixed relative to one another by the use of six Allen-key bolts.
These screw into nuts located within the inner channel, with the nuts prevented from turning by being tack welded to the inner channel. The bolts pass through slots in the outer section, allowing quite a lot of adjustment to be made to the length of the assembly. The whole assembly is plated and gold passivated.
On close inspection, the quality of the workmanship of the arms left something to be desired. The thread of one of the nuts had been burred-over slightly, with the bolt unable to be screwed in using just finger pressure. One of the nuts had been re-welded after the plating had been carried out, with the assembly not then re-plated. The plating was also discontinuous on the inner (hidden sections) of the assembly, where some corrosion appeared to have started. Where the grease nipples had been screwed into place, scratches on the adjoining metal work had been caused.
We returned the two arms to Unique Auto Sports, asking for another pair not exhibiting these defects. They then sent us another set.
The second lot had some of the same problems - scratched, discontinuous plating - but were generally much better in quality. We wire-brushed the inside sections of the channel and painted the metalwork with a spray can.
John Keen of Darlington Auto Tune in Adelaide, South Australia, undertook installation of the arms. With care, the arms can be installed without requiring the disassembly of much of the suspension. The wheels need to be removed, the sway bar links disconnected, and the spring/damper upper retaining nuts removed. The assemblies can then be dropped down 50mm or so and the long "through" bolts that pass through the two A-arm bushes then carefully slid out.
The length of the new arms was adjusted until they matched the old ones (the camber was already set at 1° negative, which was what was wanted) and the Allen key bolts nipped up. The arms installed without problems - the geometry of the new arms was correct.
With the suspension bolts torqued back to original spec, the camber was checked to make sure that it remained at 1° negative and that it was symmetrical left to right. This was the case and so the Allen key bolts could be tightened. However, because there is no knurling on the adjoining faces of the adjustable channels to help prevent any slippage, it was decided to use Loctite on the bolts and to make sure that they were damn tight!
This created two problems. Firstly, the washers used under the bolts are just mild steel, and as the bolts were tightened, they deflected into the slots. Hardened steel washers or sections of slotted plate positioned under the bolts are really needed if this isn't to happen. Secondly, the bolts could not be all removed at once for the application of Loctite, otherwise the arm would immediately have changed in length! This required that one bolt at a time be removed, Loctited, and then screwed very firmly home. As the channel sections came up against each other, some of the remaining bolts could no longer be unscrewed and restarted: with the other bolts tight, their holes no longer aligned. This meant that only four or five of the six bolts could be treated with Loctite.
With the arms firmly in place, a grease gun was used to give each nipple a squirt and with that, the installation process was finished.
Before judging how good the new arms are, a word about the old worn ones. These had quite a lot of bush movement which showed itself in very severe tramlining (a common problem with the GT-R, even with no bush slop!) and some clattering noises over slow speed large bumps.
With the new arms in place, the steering was noticeably sharper, with the feedback also much better. This is the case even when making comparisons with how the car drove when new. The noise was totally gone and tramlining substantially reduced.
However, within three weeks (2000km) a noise developed in the front suspension. This took the form of a "creaking" which occurred when cornering slowly. Inspection revealed that the noise was coming from the new bushes. We added more grease through the provided nipples and the noise went away - but a week later it was back again. The amount of noise generated seems to depend on the temperature of the day - the hotter the day, the louder the bushes. At this stage the noise is just acceptable - but if it gets any worse, the arms are going to come out.
The Unique Auto Sports A-arms are a mixed bag - workmanship nowhere near the top Japanese and American aftermarket suppliers, and with an annoying amount of noise. However they are still effective and relatively cheap. How they wear will be interesting to watch....
Unique Auto Sports +61 2 9634 8000
Darlington Auto Tune +61 8 8277 4222