20V Silvertop gearbox probs with 2nd gear

[CILAchainsaw]

G'Day guys, I have a problem and searches have come up with nothing. It looks like my Aussie Granny-spec AE101 is gonna get written off after a rear-ender, and for my next car I was considering another AE101/2 from my mate's wreckers which has had a Silvertop 20V conversion done to it, which he will sell to me for $1800 (minus rego). But being a mate of mine, he was upfront and told me that it was having problems with second gear, saying it "crunches" when shifting into second. He said he doesn't believe it is a sticking clutch, it is more likely to be "a loose syncro". Has anyone experienced this before? What are the most likely causes of this and the best fix? I have heard that there is some magic gearbox oil around that can solve minor problems like that and make notchy boxes heaps smoother, and it wasn't just some Supercrap Auto marketing scam either, it was mentioned in a few reliable performance magazine publications. I don't particularly want to replace the box, as I can't do that sort of work myself with a buggered shoulder, but this is going to be my daily so I want it to be reasonably reliable. Thanks guys, any input appreciated

[foamy]

He probably has a C52 gearbox attached to it. Most likely pieces of the syncro are floating around at the bottom of your gearbox. Luckily they are cheap gearboxes and can be bought for very little. Alternatively you can have it rebuilt (anywhere from $600-$1200+) depending on what actually needs replacing. It's usually syncro's and seals...
You can put a thicker oil in the gearbox, but it's only going to mask the problem and make shifting harder for other gears.

[CILAchainsaw]

The C52 is the gearbox that comes stock on the 7A-FE's isn't it? That would be pretty junk shoved onto the Silvertop wouldn't it? (remember mine will be a daily)
Is there a simple way of knowing which box is in it? Is it stamped on the outside somewhere? I'm under the impression that the conversion was done properly with the Silvertop's box and all (the C56 is what comes with that, isn't it?)
I'm really starting to get keen about this car, I can get another box for $350 if this one is buggered...

[BLK_20v]

The c52 isn't too bad behind a silvertop, it'll work and last As long as you don't abuse it. Ratios aren't too far off the c56 either. It's mostly 3rd you notice the difference

Though the 6spd c160 is much better, you'll need the box plus shifter mech if you go down that path, but they'll set you back about 800

[banana_socks]

C50 was for the 4/7AFE, C52 came with the standard 4AGE, C56 with the ST, C160 with the BT.

Its almost certainly the synchro causing problems. Most older boxes tend to wear them out, especially the C series. It can be difficult to get into gear, but if you learn to rev match it will be much easier. There is no fix apart from tearing the box down and replacing the synchros, or swapping boxes.

[JP]

C52 comes stock on the Gen1 AE101 20V's, they got the C56 on the Gen2 AE101 silvertop 20V's. Will just be a worn synchro which is fairly common on old C series boxes.

[TERRA Operative]

Apparently putting the box into reverse a lot helps wear out the 2nd/3rd synchros. Dunno how or why, but it's just what I heard.

Also, running Royal Purple in my E58 got me another year or so out of the thing. Now it's well and truly due for a rebuild though...

[CILAchainsaw]

I'm pretty sure my Gregory's says the C50 box comes on the 4A-FE and the C52 for the 7A-FE, the only difference is the taller 1st gear in the C52, assumedly because of the extra torque from the 7A. I'll have to phone around and see who will replace the box for the best price, too much work for me with a dud shoulder and I don't have a rattle gun for the CV end nuts. I doubt that will happen by the time Saturday's cruise to Harry's comes around, so I'll have to turn up in my old ride with the battle scars...

How can you visually tell the difference between the C series boxes? I'd want to put the proper one in, the 6 speed conversion's not really worth it for a daily...

[Hiro]

7As (at least the AE102s) definitely have the C52

[CILAchainsaw]

Change that, probs with 3rd now I have driven it, not second. Might just track down a box from an AE112 and whack that in, ought to have less miles on it than a Silvertop box...

[Xauterus]

I think you need to remember the age of these cars. An ae112 one still has quite a few years under its belt. A reco one will sort out those issues. The 20v should have a shorter final drive too.

[CILAchainsaw]

Checking the Gregory's, the only difference between the C50 and C52 is the 1st gear: 3.545 for the C50, 3.166 for the C52.

After driving it, it actually does seem really lazy, at least down low (I wasn't going to rev it past about 5500rpm after just buying it). I think firstly it would need a real good service, it looked a bit black and gunky when I took the oil cap off. But secondly, it seems like it would be worth it to put a C50 in it to give it a little more takeoff in first, if the C52 is the box that origonally came with it. My C50 does seem heaps smoother than the one in the 20V, but then again I know it's been looked after and I had some Lucas additive put into it when I first bought it.

Unless the C56 would fit in without any modification? It figures to me that they would have changed the box in the second generation because it goes better than with the previous generation's box. But that is a 6 speed, right? Sorry about all the questions, but I'm the sort of guy that needs things spelled out and to have the crap analysed out of it all...

[CILAchainsaw]

Oh, and Xauterus, I take it that a "shorter" final drive means that it has a higher top speed? Coz I'm not really looking for that, this will only be a street car, so I want it to be fairly responsive. Certainly more so than my first drive of it, although it had been sitting around for a while...

I think the first thing I will do though (after rego, of course) is to get it home and drain the box out. If there aren't any major pieces of metal in there I will just put some additive in and see how it goes, otherwise I would make it a priority to get a new box in. By the sounds of it, I want to go for a good C50 if it comes to that, unless I can get a C56 for a good price and without modifying the shifter mech or anything...

[Xauterus]

A shorter final drive means that you will have a lower top speed. I means that you will get decent acceleration out of the car. Remember that the 20v is quite a peaky engine, even with the vvti. A c56 will slip straight in. The linkages are the same. Its is the same series gearbox. I think the 20v has around 4.3:1 final drive, where the afe series engines have under 3.9:1. This is cause the 4afe etc have a lot more bottom end power. Have a look around kit car forums and ae86 forums for ppl doing conversions that wont need the import gearbox.

[CILAchainsaw]

Meh. Lucas "Oil Stabiliser" poured into box in copious amounts, delaying for a second before shifting up into 3rd, and not downshifting into 3rd where possible. Problem solved
Alternatively, rev engine right up to 7500+rpm, slam into gear
WARNING: Will only work above 100kph, best utilised at WSID