thought it was about time for an update
Over the last week or so I've been working on the diff. What was supposed to be a pretty simple job has turned into an annoying saga of small, crappy little things that have just slowed me down for no good reason. Figured I share it
It started off by me thinking I'd make sure there were no issues with the diff I'd bought, before I spent money on it. So, I did the mod to it that's needed to fit it into the Harrison, and tried to bolt it in. It didn't fit. More specificaly, the cradle didn't fit on the car. The front two bolts went in fine, but the rear ones were about 20mm out. Here's a pic with the front bolted in properly and the rear cabled tied for dramatic effect.
After a quick call to Warwick to check if there was any reason it shouldn't fit (wrong type maybe, check on how it was jig welded ect) I came to the conclusion it was probably bent. The fact the upper control arm didn't fit nicely on the hub seemed to confirm this. So, I needed to take it back to the wrecker, except by the time I'd noticed it was pretty much weekend and it'd have to wait till next monday. So a weekend where I expected to get a lot done wasn't as productive as I'd hoped.
I finally got to take the cradle down to the wreckers and swapped it over for a GTR one, no dramas there. But having had a GTST cradle for the first one, I noticed there were a few small differences between the two diffs that may interest other Harrison builders. Firstly, the bushes are different - the GTR ones are about 10mm longer than the GTST ones. The housing is the same, but if you use GTST bushes it holds the cradle 10mm closer to the chassis, effectively lowering the car a little. Secondly, the GTR diff has a reinforcement plate welded in the area of the cradle where my GTST cradle was bent.
Having got my new diff, I wanted to get to work replacing the bushes. The whiteline ones I'd ordered had arrived, and I wanted to have them replaced. Unfortunately, no workshops around my local area wanted to touch the job - once they heard it was a R33 diff, they either said that they were too busy, or quoted so high that I almost laughed down the phone. One shop wanted $150 for the job!
So after call number 7, I decided **** it, how hard can it be? And decided to try it myself.
Turns out, it's pretty bloody hard...
I tried using a bit of pipe and a lump hammer to drift them out. Nothing. They weren't going anywhere. So I had to get a bit more drastic. First, I drilled out the rubber part of the bush with I think an 8mm drill bit.
Then, I used a pin punch and punched one area of the lip inwards, and punched the now loose bush center out.
After that I modified a large standard blade screwdriver, taking the sharp edges off ect with a bench grinder, and used it like a wedge, hammering it down between the bush wall and the cradle. This bent the soft bush metal inwards, and allowed the old bush to fall out with little effort. See how the old one was slightly rusted in - it wasn't going anywhere in a hurry!
Once they were out, it was a simple matter of figuring out how to install the new ones without a large hydraulic press...
Although none of the shops here were interested in work, one was kind enough to say "we are too busy, but the way we do it is..." Turns out, they installed the new ones by lubing them up and smashing them in with a spacer and a sledgehammer.
Now I wasn't keen to try oiling them, pretty sure it's not a good practice if you can avoid it. I asked the guy about it and he suggested using detergent as a lube, and washing it off with boiling water later. Thought that seemed like a good idea.
However I certainly didn't think much of the sledgehammer idea. Instead, I made up my own jig using an M20 x 160 bolt, some 69mm internal diameter pipe, some left over scrap steel from other projects and a welder.
It worked well, and I tried using the detergent idea. I quickly gave it away and used old engine
oil to lubricate it. Even with that, it was BULL **** tight to get it home - I was using a 3ft bit of RHS as a breaker bar on my 1" 1/4 ring spanner and I was still struggling! There is no way at all those bushes are working thier way loose,
oil or not...
Got it all done, for a total cost of $10 in scrap steel and $2.50 for an M20 bolt (That I destroyed - it was so tight it got stretched) and a fair bit of time. Happy with that - take that rip off merchant suspension shops!
So, tomorrow I paint it and install it, finally! I did get an adjustable upper arm for it too (thanks guys, good advice). Also, today I went to the wreckers and got the steering rack and column, the other front end bits I need and pedals. They will be modified, painted and installed to in the next few days. I'm hoping there will be a lot more updates coming before my holidays end at the end of jan