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Discussion Starter #21
NOS on a stock car that drives on the streets. Someone has been watching too many fast and furious movies.

;)
Thanks. That's helpful and exactly why I was looking for ideas on this Forum from knowledgeable and experienced people on the pros and cons on performance improvements for the LT1. ............Because I watch too many fast and furious? movies. Being significantly older than 16, I have no idea what these movies are about.
 

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Discussion Starter #22
I currently have a 3.42 in my wagon with a 454. I built the rear myself, and now have the tools to build another one. I am in Largo, and would consider building one for you at your house for a fee. If you get all the correct parts it will not take too long. It is not any different building a 3.42, or a 3.73, other than the gear set. One thing I will suggest is that you buy the very best parts you can afford. I would upgrade the posi, and get new axles/bearings while you have it apart. Moser makes nice axles, and they are about the same price as the Chinese ones. I bought an axle from the junk yard, so I did not have down time while building mine.
Thank you, that's good to know. I'm still kicking around options but will keep you in mind, if and when I make a decision.
 

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Like BALLSS said:
Lloyd Elliott is an LT1 heads and cam guru:


If you can do the wrenching yourself, you can keep the costs down. If not, the rear axle gear change remains the "bang for the buck" winner.
 

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Discussion Starter #24
Yes, sounds like the best option. I like the Lloyd Elliott approach too. Once it cools down here in Florida, I will be ready to start wrenching on that car. Just a bit too sweaty right now.🙂
 

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I installed 3.42 and now have a set of 3.73's sitting on the shelf for install. Wish I'd gone with 3.73 first.
 

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I bought Richmond 3.73's and Moser axles from summit this weekend, was that a good choice? I haven't installed them yet so i'll take them back if not.
 

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Installed 3.42 and now have a set of 3.73 sitting on the shelf for install. Wish I'd gone with 3.73 first.
May I ask, what result do you get from answering the following 3.73 vs 3.42 questionnaire?
 

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Discussion Starter #29
Well, for me, it has to be 3.73 based on all the great Forum information, the decision tree questionaire, and my personal wants.
 

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Well, for me, it has to be 3.73, based on all the great Forum information, the decision tree questionnaire, and my personal wants.
If 3.73 is not enough, but you manage to choose your torque converter carefully, you'll preserve the ability to get decent city / metro / urban MpGs when you do somehow keep your foot out of it.
Choose poorly, and no matter how you drive, you'll always waste MpGs even when you're driving to get decent MpGs.

I enjoyed 3.73 very much while I had them, especially when I was NOT on the highway, especially in Manhattan.
Once I got on the highway, though, cruising over 75MpH for any length of time was extremely difficult and uncomfortable, even using 235/75R15.
 

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I bought Richmond 3.73's and Moser axles from summit this weekend, was that a good choice? I haven't installed them yet so i'll take them back if not.
Richmond gears are very good. They are now made in Italy. Moser axles are also good

I assume you bought ABS compatible gear set and also a reluctor gear for the 3:73's?

If you still have the stock Auburn limited slip diff, assuming you have a LS car, replacing it with a Eaton LS is a no cost labor if you do it during a gear swap. The stock Auburn units are marginal at best

Also get a "Master Install Kit" which includes all the bearings to do on a gear swap. Generally about $100
 

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My 1996 has 40,000 miles and I am considering going to a 3.42 rear end. My question is, how would this affect the way the car drives/performs. Would I find it a noticeable change from the stock rear end?
Also, does anyone have any experience with a good drive line shop in the Tampa Bay area that could do this type of swap for me.
I already have a Hypertech pro, so can easily reprogram for a different rear end ratio. thank you.
I don’t know what all this RPM talk is about?! WE HAVE Overdrive!!! I have a built 96 DGGM 383 with a truetrac posi rearend 3.90 gears on 285/30/20s. I drive around town in 3rd gear. Overdrive on highway. No rpm issues
 

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My 1996 has 40,000 miles and I am considering going to a 3.42 rear end. My question is, how would this affect the way the car drives/performs. Would I find it a noticeable change from the stock rear end?
Also, does anyone have any experience with a good drive line shop in the Tampa Bay area that could do this type of swap for me.
I already have a Hypertech pro, so can easily reprogram for a different rear end ratio. thank you.
I don’t know what all this RPM talk is about?! WE HAVE Overdrive!!! I have a built 96 DGGM 383 with a truetrac posi rearend 3.90 gears on 285/30/20s. I drive around town in 3rd gear. Overdrive on highway. No rpm issues
 

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I went back and forth from 3.42 to 3.73 gears a number of times and really prefered the 3.73. They made the car feel more spirited and fun to drive. I tested for fuel mileage and they both stayed within 1 mpg city and highway of each other driving normally. At the track times were slightly better with the 3.73, but not as much as I thought, but this was due to wheelspin with the 3.73 and stock tires. You will never regret the driving fun with 3.73 gears
 

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I don’t know what all this RPM talk is about?! WE HAVE Overdrive!!! I have a built 96 DGGM 383 with a truetrac posi rearend 3.90 on 285/30R20. I drive around town in 3rd gear. Overdrive on highway. No RpM issues.
With 383 cubes, 3.90 & 26.73" tall tires, at what speeds are you driving 'around town'?
'cause I'm sure that if I had a 6.28L engine with 3.90 gears & 26.73" tall tires, I could be in 4th by 18MpH.
Some overdrives are better than others - same goes for driveshafts.
 

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All this handwringing over a couple hundred rpm difference on the highway. Why spend the same money to go halfway? It's the deeper gears that allow the 9.5" torque converters with better driveability, instead of worse. Converter should be locking up above 45-50mph. anyway making stall speed on the highway equally irrelevant.
 
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I don’t know what all this RPM talk is about?! WE HAVE Overdrive!!! I have a built 96 DGGM 383 with a truetrac posi rearend 3.90 gears on 285/30/20s. I drive around town in 3rd gear. Overdrive on highway. No rpm issues
Curious. What is the ABS reluctor part number and source for 3.90 ratio with stock pinion on 8.5"?

Some of the RPM hoopla is about MPG. My rule of thumb has been that 250 RPM cost you about 1 MPG on these cars on the highway. I noticed a 1-2 MPG drop on the highway going from 3.08 to 3.42. This is non-linear, non-scientific, only applies to 4th gear with lockup engaged from 1800-2300 RPM. As soon as you cruise above 2500 RPM on these cars, MPG drops like a rock.

On the other hand, going to 3.42, I gained a tenth in the 1/4 mile. Assuming my tires would grab, I'd likely gain another tenth going to 3.73.

I'm sure with a 383 stroker build, you don't care about MPG and I don't blame you. Going to a 383 possibly gained you quite a few tenths depending on how you set it all up :). So it really depends on what you intend to do with the car. And thus that's why the aforementioned questionnaire is good!

Another aspect of why veterans often talk RPM here is with a stock or mildly built 4L60E, each shift costs you about a tenth (an aggressive build or manual valve body can fix this). I've seen guys race with 4.10s back in the day and using a mildly built 4L60E and stock tires, they'd be in 3rd gear on the big end at redline with 4.10 gears. Usually you feel the need for that last shift. And the shifts can cost you. A stock LT1 starts running out of steam around 5200. And has nothing left at 5500. Finally, if you go with anything more aggressive than 3.73, then you really need to build the entire setup around it to make use of the RPM... cam, torque converter, transmission, intake, exhaust, driveshaft upgrade.

And that brings me to my final point. Going to 3.42+ may also require a driveshaft upgrade. I needed one for my 9C1 when I upgraded to 3.42 because I had a vibration (ironically, the 9C1 is supposed to have a "specially balanced driveshaft for high speed pursuit" which I think is bunk). Going to a higher ratio will certainly require a new driveshaft or a high-end balance job on the stock one if you want to risk it.

I'm happy with my 3.42 gears. They really woke the car up without needing other major upgrades. I just got away with an engine and transmission PCM tune, torque converter, intake, exhaust (typical mild bolt-ons). That was all my budget allowed back then. If I were racing more often these days, I'd entertain 3.73s. I'd have to go to a bigger money build to make use of anything above that.
 

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I absolutely agree that checklist is pretty sweet! My DGGM is restomod/prosthetic type set up, not a daily driver. I have (2) neighbors with mustangs. Yesterday, the ******* with the newer mustang drove by my garage overrevving in first gear giving me the stare down... My sole wish in life is to gap their FUCKING ass with this 4500# monster every chance I get! So yeah I can give two schitts about MPG and emissions

I’m pretty sure my reluctor came off an 1990 454ss truck. I’ll see if I can dig the p/n up,, it was discontinued last time I looked. I’m building an 11.35sec car (I ran 14.85 with stock set up + hooker shorty headers rolling in 20s). Since, I’ve upgraded to LT4 block with Forged internals, AFR 210 heads (1.6RR) and CIA long tubes. I’m Running about 11.5:1 compression with rev-limit of about 6500prpm.

transmission has been completely upgraded with 5 pinion planetary gear sets. Firm/aggressive shift. I also manually tuned the shift points in cold/hot/wot modes going up and down.

I also swapped in a 2004 crown Vic (police) driveshaft.

currently getting dynotuned for 200hp shot of nitrous.
 

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With 383 cubes, 3.90 & 26.73" tall tires, at what speeds are you driving 'around town'?
'cause I'm sure that if I had a 6.28L engine with 3.90 gears & 26.73" tall tires, I could be in 4th by 18MpH.
Some overdrives are better than others - same goes for driveshafts.
Research and a good tuner goes a long way!

For example,, factory tune shifts out of 1st gear at 11mph - car was a dog if autoshifted. mine shifts between 20-38mph (Or 6000rpm).

I found a couple drivetrain calculators off the forums and designed the combo that worked for what I was trying to do. road tested, took notes then reprogrammed computer for tire size/rearend, Etc.
 

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I’m pretty sure my reluctor came off an 1990 454ss truck. I’ll see if I can dig the p/n up,, it was discontinued last time I looked. I’m building an 11.35sec car (I ran 14.85 with stock set up + hooker shorty headers rolling in 20s). Since, I’ve upgraded to LT4 block with Forged internals, AFR 210 heads (1.6RR) and CIA long tubes. I’m Running about 11.5:1 compression with rev-limit of about 6500prpm.
Sounds like you have a nice build there! After I discovered 383s, I'd never rebuild a 350 into a 350 again. LOL. The 383s are cheap(ish) if already doing a build and much more fun! Of course big blocks and LS swaps are fun too. But if sticking to a SBC, 383 is the easiest way to go with tons of options.

And this reinforces my previous point. Gear selection is much more than just a discussion about RPMS. 3.42 versus 3.73 is about the best choice we have with a stock or mildly upgraded engine/drivetrain. Anything more than 3.73, you need a bigger build! (IMHO)
 
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