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The Chevy hi performance shop here in Atlanta did the install of my 4.56 rear axle ratio into my otherwise stock 04 SSR today, and it seemed to go well.

They have done many rear ends, so this was not new to them, but it still enouraging that there were almost zero glitches (almost - see later below).

They properly corrected for the new ratio in the ECU so the speedometer is still "right on", and correctly adjusted the shift points.

They also did a dyno tune on the SSR, but told me afterwards that it really HAD been set up pretty well at the factory. They got a little more power, 8 hp, but that is not what I consider really noteworthy.

I was anxious to see how the new gearing felt and sounded, but since I picked it up during Atlanta`s rush hour, I sure didn`t get much chance to "hit the throttle".

Iniital impressions:

1. The SSR starts from a dead stop with a much livelier feel.

2. Once underway under street traffic conditions, you really aren't aware that the ratio is 22% higher than before. The transmission still shifts at what feels like similar points, so it's pretty non-noticeable - until you hit the gas!

3. When you hit the gas, the SSR responds a LOT quicker. It's still not a sports car (way too heavy), but it certainly is a lot livelier.

4. I only got the chance to hit the gas hard ONCE, from a dead stop onto a 60 mph highway with traffic flowing faster than that, so I had an excuse to floor it to merge in. The SSR had never accelerated like THAT before!! My last "performance" vehicle was a Corvette Z06, and my quickest bike is low 10s quarter and under 2 3/4 seconds to 60, so anything else seems pretty slow, but the SSR moved way quicker than it ever has before. My gut feel is that the numerical improvements I predicted in my earlier post on gearing have probably been achieved.

I'm going to have to do some controlled timed runs maybe next weekend, somewhere out of the city where there is no traffic at all, and therefore safe (way too unsafe to even think about doing it anywhere in the metro).

5. The SSR feels MUCH better at highway speeds with the much hgiher rpm (2198 at 60 mph, and 2935 at 80 mph) (yes, briefly verified!). No driveshaft vibration, smooooth engine, and RESPONSE without downshifting being required. it also SOUNDS much better on the highway at the higher rpm.

I mentioned there are "almost" zero glitches. I had been warned that a rear end with a much higher ratio can be noisy, and I can definitely hear it way more than before now. It also has a sort of hollow resonance to it, so it is more noticeable. However, I noticed it seemed to become less apaprent as the miles went onto it tonight, so it is POSSIBLE that it is a case of new parts wearing in. Rob, the pro who did the install knew I was concerned about keeping it as quiet as possible, and told me beforehand and after that he was taking the time to really set it very close to perfect, and so we might just need a little time for everything to seat itself and wear in.

Whereas the sound was there all the time that power was being applied initially (not on decel), it is now - after only 20 miles or so, apparent only sometimes. So I'm going to give it a bit of time before I complain. Rob had left by the time I got there tonight, but his Dad told me that Rob had test driven the SSR as I asked him to, and so I will ask him tomorrow what he thinks of the sound.

By the way, the "tink" well and truly is GONE with the new driveshaft that was installed Tuesday, but of course I don't know for how long!

Jim G
 
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Jim,

Thanks for the info. I've been following your threads with interest as:

1) I just got my SSR, which is a daily driving work vehicle and

2) I own an aftermarket accessories shop and have been trying to decide what to do first in mods.

Looks like you may be getting the results I'm looking for. I'm looking forward to your timed runs.
 

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4.56 gear installed...

Hey, thanks for the info and we are all looking forward to seeing some performance numbers as soon as you can do them. What did they end up changing for the new higher gear ratio? Just the ring and pinion or the carrier unit too? Do you mind sharing the cost for the parts & labor too?

Thanks!
 

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hpdjv: They used a ring and pinion from Motive Gear, which does NOT require changing the carrier. The parts and labor total they quoted and charged was $850, which is just a bit less than another Chevy hi-performance shop in Austin had quoted me.

If anyone else does this, be sure to go with a performance shop that has done rear end changes before. It is a mod that requires some experienced expertise to set up correctly. I went with Lamar Walden shop in Atlanta, one of 2 shops recommended highly by local rodders. A bonus that gave me extra confidence was that Lamar Walden himself owns an 04 SSR.

Jim G
 

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That's great.
I was thinking this may solve some of the SSR's sluggishness from the first day I got mine. I just haven't gotten around to tinkering with it. I've got a couple other tricks up my sleeve planned as well, but that is definately on the list.

Let us know when you get a couple 1/4 passes on it!

Ron
 
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Great report Jim

Best of luck with it! You must be a performance nut to go with a 4:56! I had a 62 fuelly vette with a 4:56( way back when) and it was awesome! With the true od in 6th gear on my 05 I bet the 456 would be a great upgrade!Let us us know ya MPG at 55 and 65 mph, please. Keep us posted.Thanks, fredfryguy :thumbs :thumbs :reddevil :cool :cool :flag
 

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It's the DRIVESHAFT making the noise!

See my new separate posting on the new driveshaft not being so great!

That noise I mentioned above: it's the new "hollow drum" driveshaft!

Jim G
 

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Discussion Starter #9
For those that asked, I finally got a chance to look at the Motive Gear part number for the 4.56 ring and pinion set:

Motive Gear part number MTVG885456

Now that I have run this gear set for a day, and realize that the new noise is from the driveshaft and not from the ring and pinion, I can wholeheartedly recommend this setup. Smooth, quiet, and very effective.


Jim G
 
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