Izuzu trans with knock - Transmission Forum

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Izuzu trans with knock
Wednesday, December 14, 2011 1:17 PM
Hi guys,

I have a 97 Cavalier Z24 my 17 year old drives. It has an Isuzu 5 speed manual in it.

I needed to change the tranny (ironically due to similar noise). So I got a core from the local PnP, and decided to go through it before I put it in the car. Everything looked fine internally, but I did change all the shaft/diff bearings since I had it apart. I utilized much of the info on this website to help me along with the re-build. I reused the same shims as the trans originally came with.

Anyway the short story is the tranny has a knock when it is coasting. Not as noticable if deceleraring in gear, and is quiet when accelerating. I put the car on jack stands and checked it while I had a helper accelerate/coast the tranny and it definately seems to be coming from the tranny. You can even feel it a bit on the tranny case.

What are the odds 2 different trannys do the same thing.

I have since changed to LH driveshaft, which had no effect. But as I said I fairly sure the knock is in the trans.

Any ideas?

Re: Izuzu trans with knock
Wednesday, December 14, 2011 2:22 PM
I should also mention the knock is in sync with wheel speed, not engine RPM. The knock is heard right until the moment you stop.
Re: Izuzu trans with knock
Wednesday, December 14, 2011 2:35 PM
Re: Izuzu trans with knock
Wednesday, December 14, 2011 2:42 PM
-Z Yaaaa- wrote:its probably rod knock.


I assume that is your attempt at humor.
Re: Izuzu trans with knock
Wednesday, December 14, 2011 7:22 PM
very poor humor.

does it also happen in neutral? car moving or not with the clutch released.
Re: Izuzu trans with knock
Wednesday, December 14, 2011 9:34 PM
Car must be moving. As I said it follows the tire speed. It has to be driveline related.

Coasting in neutral it is loudest. If in gear slowing down it is not as loud, but still there. Once you accelerate it goes away completely.

Just took apart the trans that came out of it previously, and it wasn't in bad shape, except the spider gears were totally trashed.
Re: Izuzu trans with knock
Thursday, December 15, 2011 6:39 PM
So I looked through what I could find on this board, and it seems spider gears are a common denominator. The spider gears I put in were in decent shape, but top of the backlash spec the Service Manual gave.

So a trip to GM revealed parts for this are mostly discontinued, but the thrust washers are still avaiable, however only in a bag of 10 for $10 each. (or $100)

I have read that 90-93 GEO Storm parts will work, and are better. This gear kit is actually available, but landed cost is about $450.

Is there an aftermarket source for spider gears?
Re: Izuzu trans with knock
Sunday, December 18, 2011 5:48 PM
70barracuda wrote:So I looked through what I could find on this board, and it seems spider gears are a common denominator. The spider gears I put in were in decent shape, but top of the backlash spec the Service Manual gave.

So a trip to GM revealed parts for this are mostly discontinued, but the thrust washers are still avaiable, however only in a bag of 10 for $10 each. (or $100)

I have read that 90-93 GEO Storm parts will work, and are better. This gear kit is actually available, but landed cost is about $450.

Is there an aftermarket source for spider gears?


I've got a 95 trans all apart in the shop doing nothing. I've done the Geo Storm GSi swap and it's not always simple. If you're interested in just some spider gears, I'll ck to see if any of the ones I have laying around are any good.
I'm in Knoxville TN area.
dennis
Re: Izuzu trans with knock
Sunday, December 18, 2011 6:52 PM
MasterFlight wrote:
70barracuda wrote:So I looked through what I could find on this board, and it seems spider gears are a common denominator. The spider gears I put in were in decent shape, but top of the backlash spec the Service Manual gave.

So a trip to GM revealed parts for this are mostly discontinued, but the thrust washers are still avaiable, however only in a bag of 10 for $10 each. (or $100)

I have read that 90-93 GEO Storm parts will work, and are better. This gear kit is actually available, but landed cost is about $450.

Is there an aftermarket source for spider gears?


I've got a 95 trans all apart in the shop doing nothing. I've done the Geo Storm GSi swap and it's not always simple. If you're interested in just some spider gears, I'll ck to see if any of the ones I have laying around are any good.
I'm in Knoxville TN area.
dennis


I think there is a Storm at the local PnP right now. I will look tomorrow for sure. So it has to be a GSi to have the stronger spider gears?

I do have 2 thrust washers for the spider gears that are the second thickest of the 4 possible choices ordered, coming from a place called Vintage Parts that should be here end of end week (they will sell them indivdually). As I said the spider gears I have in the trans right now are decent, but not the stronger ones and gear backlash is max. I was just thinking that if possible to get stronger ones it would be preferable since clearly based on the trans that came out of the car, they are a weak point.

My plan is to at least use the gears I have, with the hope the thicker thrust washers will tighten them up enough to stop the knock when coasting. If I find a set of better gears, I will put those in with the new washers instead.

For your offer, thanks, but for now I'll stick to my plan and hopefully it works out. Plan B will probably be to run that Isuzu trans until it grenades, and put in a Getrag instead. Getrags seem to be easier to find these days, the Isuzu is getting harder.
Re: Izuzu trans with knock
Sunday, December 18, 2011 7:23 PM
70barracuda wrote:
MasterFlight wrote:
70barracuda wrote:So I looked through what I could find on this board, and it seems spider gears are a common denominator. The spider gears I put in were in decent shape, but top of the backlash spec the Service Manual gave.

So a trip to GM revealed parts for this are mostly discontinued, but the thrust washers are still avaiable, however only in a bag of 10 for $10 each. (or $100)

I have read that 90-93 GEO Storm parts will work, and are better. This gear kit is actually available, but landed cost is about $450.

Is there an aftermarket source for spider gears?


I've got a 95 trans all apart in the shop doing nothing. I've done the Geo Storm GSi swap and it's not always simple. If you're interested in just some spider gears, I'll ck to see if any of the ones I have laying around are any good.
I'm in Knoxville TN area.
dennis


I think there is a Storm at the local PnP right now. I will look tomorrow for sure. So it has to be a GSi to have the stronger spider gears?

I do have 2 thrust washers for the spider gears that are the second thickest of the 4 possible choices ordered, coming from a place called Vintage Parts that should be here end of end week (they will sell them indivdually). As I said the spider gears I have in the trans right now are decent, but not the stronger ones and gear backlash is max. I was just thinking that if possible to get stronger ones it would be preferable since clearly based on the trans that came out of the car, they are a weak point.

My plan is to at least use the gears I have, with the hope the thicker thrust washers will tighten them up enough to stop the knock when coasting. If I find a set of better gears, I will put those in with the new washers instead.

For your offer, thanks, but for now I'll stick to my plan and hopefully it works out. Plan B will probably be to run that Isuzu trans until it grenades, and put in a Getrag instead. Getrags seem to be easier to find these days, the Isuzu is getting harder.


All OK by me but here's what it takes to swap to a Getrag: http://www.j-body.org/forums/read.php?f=41&i=38103&t=36216&p=1 I have a 97 Z24 engine/isuzu hanging on the cherry picker right now. I set a 2.2 isuzu next to it and took a pic. PM me your cell and I'll forward the pic for you to see. The mounts are exactly in the same place. the only difference is the bell housing, and the internal gearing. The axles are even the same.

Do searches on spider gears and Storm and Impulse. There are several vehicles beside the GSi that had the better spider gears. BTW, don't lash the spiders too tight if it's a daily driver. That can chew them up just as good as too loose.
BTW, my conversion to the GSi trans was for improved performance. I wanted a closer ratio and the 4.12 final drive so I took the entire guts and transplanted them into 2.2 OHV Isuzu. Gas mileage dropped a couple miles, but the performance picked up a lot. 4 mph in the 1/8 mile. My daughter has a Z24 and my 2.2 is now just about as quick, although she's got an automatic.
dennis
Re: Izuzu trans with knock
Sunday, December 18, 2011 7:44 PM
Robert,
For all the blabbing I've been doing about spider gears, etc. I forgot to mention a common problem I've seen that makes a sound like you've described.

The wheel hub bearings are not the longest living part on a Cavalier. I've gone through a few. Don't depend on being able to feel much of anything wrong when turning them over by hand either. I can think of two that made a lot of noise, but felt smooth. It seems to take having weight on the wheels to produce the noise.

The first time (several years ago) when I first replaced them on my 95 Cav., they did not come with a seal for water/trash. They looked like they were sealed bearings. Even the old hubs had no seal to remove. I kind of wonder if it was some sort of change done by GM because they were having problems. Every hub I've gotten since has come with a new seal.

Anyway, They're not too hard to change. BTW, I'm of the opinion that once the spiders are changed, the Isuzu is equal to the Getrag. You will find arguments both ways, but mine went 278,000 miles before it broke a shift cable and I'm not the easiest on trannys.

dennis

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