Chevy SSR Forum banner

1 - 20 of 29 Posts

·
Supporting SSR Hobbyist
Joined
·
10,122 Posts
Discussion Starter #1
I am interested in replacing the 3.73 ratio with a 4.10 set. This should net a 10% rear wheel torque increase (physics laws prevail). I don't see the need to change the torque management of the transmission and this should actually reduce the load on the drivetrain.

I have a 2005 with an automatic.

Key Questions:

1) How do I identify the type of axle assembly installed in my truck?

2) What reprogramming of the computer systems is required? (speedo, traction control, etc)

3) What brand of gears would you recommend and why?

4) Does Chevrolet offer a factory set of gears?

5) Can I get the work done at the dealer and maintain the factory warranty?

6) What installation "lessons learned" can you share?

I'm sure someone has done this already and this forum is great for sharing.


Thanks in advance for your support,

Mike
 

·
Tu-Tone club member
Joined
·
5,780 Posts
Ahh-Oh

Jim G is gonna talk you out of going this way....not much improvement.

P/P

Peace :flag
 

·
Registered
Joined
·
166 Posts
410 gear

On to my favorite dealer on Thur my mechanic has already checked the parts for a 410 gear for the zexel torsen rear that is in yours as well as my 05 its same as trailblazer v8 which has same rear end as the 05 SSR....towit its a $458.00 set nothing else needed except maybe new crush bearing ...anywho its what Im going with installed and computer ajusted right at dealer good enough 4 me.
 

·
Supporting SSR Hobbyist
Joined
·
10,122 Posts
Discussion Starter #4
P/P

Thanks for the heads up. I think it may make more difference on the 6.0 liter motor than the 5.3.

The 390HP motor is currently limited most in the first two gears to keep from shortening the life of the tranny. As we decrease the output shaft load on the transmission through lower axle ratio gears, it makes sense that we can change the torque management system to keep the transmission loading the same. The result will be a 10% increase in torque through the gear ratio change (3.73 x 1.1 = ~ 4.10) plus whatever additional torque management changes that can be made.

I know it won't be the same as adding other equipment, but it is a simple way of putting a little more HP to the rear wheels without invading the warranty territory. It also will keep the 50 MPH downshift from going all the way down to first and then an immediate upshift to 2nd at 55mph.

Best Regards,

Mike
 

·
Supporting SSR Hobbyist
Joined
·
10,122 Posts
Discussion Starter #5
Jetcop,

Is the $458 for parts & labor at the dealer?

Are you taking any data on 0-60 time before and after? Have you planned to check your "instantaneous fuel economy" numbers at 60, 70 and 80 in a before and after comparison? It would be really interesting to know what the change results look like.

Best Regards,

Mike
 

·
Registered
Joined
·
166 Posts
Mike

Gonna run it all thru the wash at the dealer with my mechanic tommorrow cost is higher sounding than gears from another source but they are the GM gear sets from them to US for our car wont change warranty and puter can be adjusted etc,,, I will let you know everything as I learn them myself...... smok m if ya got em soon as the Predator power programmer becomes available for our 05 ssr Im putting up the coin and buy IT then just play with the thing yipppeeee skippee
 

·
Senior Privileged Member
Joined
·
4,100 Posts
Mike-em: All your questions have already been answered in a LONG string of earlier posts. Use "4.56" as the search key.


To give you just a QUICK recap here:

1) How do I identify the type of axle assembly installed in my truck? IT's an "8.6". NOT an 8.5 or 9 but an 8.6.

2) What reprogramming of the computer systems is required? (speedo, traction control, etc) You change ONE field in the PCM: the "gear ratio" field. The PCM programming is smart enough to adjust everything base don that alone, INCLUDING shift points. The sole exeption is that you MAY have to manually adjust the speed limiter (changing the gear ratio affects the speed limiter as that programming uses the driveshaft rpm as its trigger).

3) What brand of gears would you recommend and why? Motive Gear, Yukon, or Ruchmond all have their advocates. My installer favored Motive Gear. But, no matter which brand, insists on getting the more expensive version that is QUIETER. If you get the cheaper one, you will regret it.

4) Does Chevrolet offer a factory set of gears? Chevrolet's current offerings stop at 4.11. While 4.11 is ok, the benefit of the 4.56 is almost exactly DOUBLE that of the 4.11 when you put the data into a software modeling program. The 4.56 cuts the 0 to 60 time by 0.8 to 1.0 second depending on options on the vehicle, your driver weight and amount of fuel on board. And, the 4.56 still gives you 40 mph in 1st (after you raise the shift points in the PCM from 5600 to 6000, which gets you another 0.15 second reduction in 0 to 60 time). The 4.56 runs 2198 rpm at 60 mph and 2930 at 80 mph. It feels good. Fuel mileage decreased only 7.4% in VERY precise actual measurements before and after.

5) Can I get the work done at the dealer and maintain the factory warranty? Maybe, but more pertinent questions are:
(a) Can the dealer's tech do a PRECISE job that will give you a QUIET rear end, while working fast to beat the book time and make more money?
(b) If you have ANY problem other than actual rear end gear problem, you can't be denied warranty by Chevrolet just because you chnaged something no the vehicle. The change has to have caused the problem in order to void warranty on whatever damage was done.

6) What installation "lessons learned" can you share? Get the work done by the very best, most experienced technician you can find. The resulting noise level, whether quiet or loud, will depend on (a) qaulity of gears bought and (b) skill and patience of the installer. I paid Reese at MTI Racing to re-do the fine adjustments on mine, as he had once done 80 rear end changes within 3 months while a race team crew leader, and the results were betetr than what the earlier installer had gotten.

Jim G
 

·
Premium Member
Joined
·
3,926 Posts
Please take the time to specify whether the SSR is an auto or 6 speed as it makes a difference to which rear axle you will have.

Auto - 10 bolt - 8.6" ring Gear
6 Speed - 14 bolt - 9.5" ring gear
 

·
Senior Privileged Member
Joined
·
4,100 Posts
2005 SSR speed: You are correct about the difference in size. I am not sure about the bolt count. I have never checked that!

I was talking about the automatic.

The difference in performance is also vivid on the 6-speed, although not quite as strong: about 6/10 quicker to 60 and 6/10 in 1/4 mile. Cheapest ET reduction there is!

Jim G
 

·
Supporting SSR Hobbyist
Joined
·
10,122 Posts
Discussion Starter #10 (Edited)
Thanks 6speed,
I do have an auto and will be sure of the quotes I get.

Thanks Jim,
Through the long and short of it, I have to imagine that if the 22% increase in rpm for 4.56 gears yeilded a ~1.0 sec improvement in 0-60 time with a 7.4% hit on fuel economy, the 10% increase in rpm for 4.10 gears would be half of that......

My rpms between 70 and 75 (seems to be the drive train sweet spot) are about 2250-2300 with the 3.73s. Changing to 4.10s will take me to the 2475-2530 range and the 4.56 will be in the 2750-2815 range. This is where I have to weigh the change in cabin noise into the equation a little. I do love having my bride along and she likes driving the SSR too.

I'll bet the 6 speed operators would really benefit from the 4.56 gear change though. Their cruise rpms are below the useable range......

The jury is still out with me for the automatic. I wanna see what jetcop20 has to say after his change.

Regards,

Mike
 

·
Premium Member
Joined
·
3,926 Posts
The bolt count refers to the amount of bolts holding the rear cover on, ie 10, 12 or 14 bolt rear axles.

The problem is that the 14 bolt axles I have seen GM use in the past have all been 10.5" ring gear in the full floating axles. The axle we have is a semi-floating axle similar in design to the ones used in the SS454 trucks and some Z71's. I just dont know what else uses this 9.5" rear axle?
 

·
Resident Rocket Scientist
Joined
·
11,997 Posts
2005SSR6Speed said:
The bolt count refers to the amount of bolts holding the rear cover on, ie 10, 12 or 14 bolt rear axles.

The problem is that the 14 bolt axles I have seen GM use in the past have all been 10.5" ring gear in the full floating axles. The axle we have is a semi-floating axle similar in design to the ones used in the SS454 trucks and some Z71's. I just dont know what else uses this 9.5" rear axle?
Yukon and similar.
 
B

·
Guest
Joined
·
0 Posts
4.10 gears

I have just had the 4.10 gears installed in my :ssr . I am not sure if I let the tech flash my vcm with the gear change, is that going to affect my tuning and gear shift points already programed in by Ed Wright? I guess I will call Ed to get him to change it if no one knows. Right now I just have to turn the traction control off.
The :ssr does move much better now...... and no rear end noise. I used GM gears. A cost of $950 for everything, parts and labor. :thumbs :)

Hood gets delivered tomorow 9-27, be on for the saturday cruise.
See some of you at Decatur October 1st. :seeya
 

·
Senior Privileged Member
Joined
·
4,100 Posts
BobA: The fields in the PCM are INDIVIDUALLY programmable, so I would normally say your tech would not disturb your other programming if he sticks to the agenda, EXCEPT that changing the rear axle ratio does automatically change shift points as well!

The idea was to help folks who are changing their gearing to not have to individually adjust their 2-D shift point graphs (because it's cumbersome). However, since your custom tune almost certainly included adjusting shift points, it will need correction again after the rear axle ratio field is adjusted.

2005SSR6speed and hdflstf: The rear axle on the SSR is technically an "8.6 inch" axle. THis distinction was probably made by GM to avoid confusion with their other axles which are similar in dimension but which are both very different from this one.

Jim G
 

·
Premium Member
Joined
·
3,926 Posts
JimG - I am confused by your last post on the 8.6" axle.

2005SSR6speed and hdflstf: The rear axle on the SSR is technically an "8.6 inch" axle. THis distinction was probably made by GM to avoid confusion with their other axles which are similar in dimension but which are both very different from this one.


The 8.6" and 9.5" refers to the size of the ring gear within the axle housing. The axles themselves are refered to c-clip and then a spline count. You can replace the axels with forged ones and install c-clip eliminators. There are 2 distinct different axles under the 05 and newer SSR, one is the 8.6" which is under the Automatic and a 9.5" which is under the 6 Speed. The 10 bolt rear axle (8.6" ring gear) is used in everything from the old camaros to the current trailblazer. Bend over and look at the bolt count on the rear cover and talk to a tech at a ring and pinion shop.


motordoctor - The only reprograming needed for the 6 speed SSR is the gear ratio so the speedometer is correct.
 

·
Registered
Joined
·
63 Posts
I would recommend that you do not use the c clip eliminator's. I replaced the axles in my street rod [Chevy 10 bolt] because of bad bearings. I wanted to use the eliminator package.. The manufacturer told me they were for straight line drag racing and would not last on the street under side load conditions. I went with new c clip axles. The eliminators are aluminum and they said the aluminum will not hold under side load stress. Guess they know more then I do so I took their advise. Motordoctor.

How does the 4.10 effect performance and other factors. Does it make it really more street friendly. I remember from the old days that the 4./56 really made the engine sing but with the overdrive trans is should be livable but what about performance vs. mileage and reliability.
 

·
Senior Privileged Member
Joined
·
4,100 Posts
2005SSR6Speed said:
JimG - I am confused by your last post on the 8.6" axel.

2005SSR6speed and hdflstf: The rear axle on the SSR is technically an "8.6 inch" axle. THis distinction was probably made by GM to avoid confusion with their other axles which are similar in dimension but which are both very different from this one.


The 8.6" and 9.5" refers to the size of the ring gear within the axel housing. The axels themselves are refered to c-clip and then a spline count. You can replace the axels with forged ones and install c-clip eliminators. There are 2 distinct different axels under the 05 and newer SSR, one is the 8.6" which is under the Automatic and a 9.5" which is under the 6 Speed. The 10 bolt rear axel (8.6" ring gear) is used in everything from the old camaros to the current trailblazer. Bend over and look at the bolt count on the rear cover and talk to a tech at a ring and pinion shop.


motordoctor - The only reprograming needed for the 6 speed SSR is the gear ratio so the speedometer is correct.
2005SSR6speed:

1. I was trying to caution people to NOT equate the 8.6 with a similar SOUNDING 8.5. Some ring/pinion catalog pages do not show the 8.6 parts.

2. Changing the raer axle ratio in the PCM AUTOMATICALLY also changes the 2-dimensional gear shifting tables, NOT just the speedometer reading! If the shifting has been separately re-programmed by a tuner, that re-programming will be affected.

Jim G
 

·
Senior Privileged Member
Joined
·
4,100 Posts
Motordoctor: I am sorry but I have typed in all that information on fuel mileage effect and rpm changes at least several times alreayd during the past few months, and I simply don't have time to do it again! :)

You have two choices:

1. Use the search button and key words "4.56", "gearing", and "mileage"

and / or

2. Buy a subscription to my e-book, which repeats the information but in even greater detail for the masochists among you. :)

In really brief summary, actual careful instrumented testing established that the 4.56 ratio uses only 7.5% more fule than the stock 3.73. The effect of the 4.11 versus the 4.56 is almost precisely 1/2. The 4.56 gearing results in only 2930 rpm at EIGHTY mph. Use math to figure rpm at other speeds!

With the 6-speed, the rpm varies between the 05 SSR and the 06 SSR because the INTERNAL gearbox ratios on the Tremec are different for the 2 years. Converting to 4.56 with either one gets you nowhere even remotely close to "high" rpm! In fact, the rpm are still too low for a 6500 rpm engine! See my book for the details.

Jim G
 

·
Registered
Joined
·
269 Posts
I got a quote

to change to 4:56 and possibly use an Auburn unit. $600.00. This shop has been setting up diffs for 25 years. Sounds reasonable to me.

Scott
 
1 - 20 of 29 Posts
Top