When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
When are you guys back in CA - this can only be done in-person, right?
For now yes, we are only doing it person - CA #2 date is TBD, It's going to be at the same place - Star Motor Werks in Costa Mesa. You can contact Chris Mattox over there if you have any questions about how the last one went.
I have graphed axle torque on a speed graph (I did not include 7th gear) for 3 options with a typical bolt-on 450whp car, one is 2.82 vs 3.06 with both redline at 7000rpm, one with 2.82 at 7000rpm vs 3.06 at 7750rpm and a third with 2.82 and 3.06 both redline at 7750rpm.
2.82 and 3.06 both with 7000rpm redline
2.82 and 3.06 both with 7750rpm redline
2.82 with 7000rpm redline and 3.06 with 7750rpm redline
Theoretical top speed between the two gear sets (making some assumptions about tire size) but just so you get the idea... go with the 3.06's and you'll loose a little theoretical top end - but probably won't be a meaningful loss. It also shows the change in the mph range per gear.
Gears 1 through 6 showing Axle torque graphed by speed. The dashed lines are the 3.06 gear and the solid lines are the 2.82. The higher the line is up the graph, the higher the axle torque at any given speed per gear. Axle torque in this graph is wheel torque multiplied by the individual gear ratio and then multiplied by the axle ratio. This would be the effective acceleration potential taking grip and aero out of the equation, the mathematical way to determine which gearing setup or powerband change will be faster at a given speed. The other thing to consider and visualize is that a car's torque curve is a good representation of it's accleration g's. A car with a flat torque curve will maintain g-force through that gear, while a car with a falling torque curve will lose g's through the rpm range. You can see this represented where the 2.82 gear actually have an acceleration advantage over the 3.06 gears at certain speeds because at higher rpm the torque is falling faster than the gearing can keep up with, so the longer gear will be at a lower rpm at the same speed (in the same gear) however as the torque is falling it ends up making less axle torque at 7500rpm than the longer gearset at 6700rpm at the same speed (as an example).
This graph is what you use to determine how rpm, powerband, and gearing can be help or hurt a car depending on its uses.
Awesome, thanks for the explanation. If it’s not too much work, could you please make a graph showing 2.82 vs 3.23?
Here you go, should also mention that the speeds are based on factory 19" tire size circumerence for a 255/30/19
So in this example you see that at 60mph/100kph the 2.82 has an advantage being in 2nd gear still with higher axle torque vs the 3.23 which has to be in 3rd gear at that speed, so it will be playing catch up. This car would be better off moving the torque curve to the right to take advantage of higher redline and shorter gearing. For road course use the shorter final drive will always be an advantage with this powerband, but otherwise it is a toss-up, again depending on application
Only you would question a Forum Sponsor/Vendor in such a condescending manner... I bet you're parents are real proud of the ****ing douche they raised. But if they're from Ontario too, it's par for course.
i don't see how this was what you say it was. he was asking a direct question looking for a direct answer. i personally felt this was a direct question with no harshness about it.
Shorter gearing is compensation for lack of power.
on a side note.why is everyone so proud of replacing the bearings in their diff? I feel like this is totally unnecessary. These bearings never fail. The only reason to replace them is because you don't have the tools to properly remove them. I've seen like 3 diff failures on benz cars over the last 15yrs. 1 had 200k and original fluid (likely very little by that time) and 2 that picked up plastic bags that got sucked into the pinion seal and caused fluid leakage to the point of failure. But replace away, just like people replacing ignition coils that work just fine too and don't really fail either unless you don't change your spark plugs when you should.
Last edited by roadtalontsi; Aug 6, 2020 at 10:32 PM.
[QUOTE=CelicasaurQuote:
Originally Posted by [b]E63007
Celicasaur,
I'm not sure. I understand when you say the bigger Gear needed to be honed inside the Chrysler Diff?? Had not the bigger gear come from the Chrysler Diff in the first place???
So Again, did you take the Ring & Pinion from the Chrysler SRT8 and swap into the AMG Diff? Please read my previous post and answer accordingly so we can all be certain of how to go about making the plunge to make this conversion.
Celicasaur Posts:
Sorry replying so late to you.
Ok so I had the diffs removed out of both casings because i needed to mate the AMG lsd to the Chrysler ring n pinion...which then meant homing them both as one unit into the Chrysler casing. I hope that helps to clear things up. You do however need to use the AMG flange which connects the diff to the propshaft.
Here's a quote of mine from the OP:
"After the shop had done the work (new bearings installed of course), it was time to finally fit the 3.06 ring gear and LSD into the Chrysler casing which now has the AMG propshaft flange."
Celiacsaur,
How on earth did you mount the Chrysler Diff to the Mercedes Subframe Front Crossmember? The AMG Diff mounts to that Crossmember with 4 bolts into the front side of the Diff which has 4 respective eared protrusions frontside that are drilled to receive those 4 bolts. That front Crossmember is attached to the Subframe via 2 Bushings bolted R&L to the Subframe. The AMG Diff is connected to the rear via 2 Bushings bolted to the rear Crossmember that is not removable as the front one is.
oops the pic didn't paste! But hopefully you get my drift. It appears the SRT8 Chrysler Diff just does NOT have the same mounting points?? As such, how did you manage this??? I actually bought and received an SRT8 3.06 differential, but it's still in the wooden box it shipped in until I can find a solution to this dilemma, to change gears first and then cross fingers in hopes that someone can reprogram the TCU via mail/return, or do same and wait weeks/months until whenever Eurocharged "Dave et als" comes to Miami and then haul my E63 down there and hopefully drive away??
I'm confused man....truth me told, i'm pretty sure i've got an old AMG diff casing and 2.82 gears with chrysler open diff with copious amounts of rust sitting in a dark corner of my garden right now. Maybe I had a different type of casing from the SRT8? I think mine came off a 300C Hemi.
It's a little cloudy for me to remember, but if I wrote this in my original post, I wouldn't have mixed up the info. Also worth noting is the fact that I had to have the propshaft flange removed from the AMG casing, which presumably would have been to mount onto the chrysler unit. I'm sure I also posted as many part numbers as I could...
Can you let me know what year your E63 is so I can determine if the Chrysler Diff you used actually fits on the differential Crossmember of the E63? Also, who did you get to tune your TCU?
Can you let me know what year your E63 is so I can determine if the Chrysler Diff you used actually fits on the differential Crossmember of the E63? Also, who did you get to tune your TCU?
Hey man, it was a 2010 model with the square-ish headlights
Some guy tuned it via a friend of mine. It was a long process, but thankfully you guys have Eurocharged offering this service now 😀
anyway i can get that graph on a 2.24 and 2.47 with an 8000rpm shift point?
Not without a dyno graph. But you're going the wrong way, you want to go with a shorter final drive the higher your redline is provided your torque isnt dropping, otherwise you don't get any benefit
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
Originally Posted by blurred
Not without a dyno graph. But you're going the wrong way, you want to go with a shorter final drive the higher your redline is provided your torque isnt dropping, otherwise you don't get any benefit
He’s supercharged so probably needs higher gearing to hook
He’s supercharged so probably needs higher gearing to hook
going to a substantially taller final drive will negate the additional power almost to the point that a stock car with shorter gearing will be faster. It only starts making sense if he is making, lets say 410wtq flat to 8000rpm, then the taller final drive will make more axle torque after about 6000rpm in each gear vs the typical 450whp bolt on car with falling torque after 5000rpm.
OK Guys, I finally bit the bullet and went ahead with the 3.06 Gear swap from a 2009 SRT8. I brought both cases, after removing the differentials, to a local shop and had them remove both Pinions. I tried and failed miserably after having destroyed a Dead Weight Hammer, a 4x4 block of wood used with a 10lBFH! etc!! When I went to the shop to pick up the case and the gears the guy told me he was amazed at how good shape the gears were and showed me just how "shiny" the Pinion was, which was evidence of its having been broken in very well, as well as how smooth and unblemished the Races and bearings were!! I said that I had new ones but he insisted not to even bother! In fact, after further dis
cussion, he said that if I gave him a hand, he would swap over the Races for me and set the Pinion!!! After 10 minutes, "we" were done!! All he needed me for was to hold the Pinion in place as he tapped in the bearing as tight as he could manually with a punch. Afterwards, he showed how smoothly it turned but I was definitely concerned about the proximity to the Ring Gear the Pinion would be as well as Backlash. He told me that since the Races fit perfectly, it was likely the same spacer he used on the Pinion would be OK. Further, there was no Crush Washer interestingly, neither on the SRT8 nor the E63!! He instructed me to go home and tighten it down with just the Flange on to see if it all lined up properly. So I ended going back to first tighten down the Flange, first by giving it a few whacks with the nearly destroyed dead weight hammer to seat it, then I took my trusty DeWalt Impact Driver to it carefully watching the flange get drawn to the Bearing. I might mention that in order to keep the flange/Pinion from spinning, I used old bolts from the Rubber Discs, the same that go through the flanges holes obviously only doubling up on Nuts, one drawn in as far as it would go, and then set that in one of the flanges holes with a washer and used another nut on the underside to keep the bolts protruding above the flange such that I could use a lever to keep the flange/Pinion from spinning while I tightened down the nut. So when it touched it, I let off and checked. Still fairly free-spinning...so I ended up using only a few 20 degree turns to get it tight to were there was a bit of "resistance". When I looked at the Nut, there is a mark on it that aligns to where the first threads are. So I noticed that the Nut I removed showed that in order to be in the same depth as the original was, I needed to make another 1/8th turn and I was done!!
So then I went ahead and installed the LSD using the same CirClips and their respective sides as they are both different widths. I set the first Race in the side opposite the Ring Gear first along with the CirClip and used a punch and light hammer to tap it into its notch. then I flipped over the Diff gently so that the LSD was seated in the race just installed and then proceeded to install both the Race by tapping it with the punch as well as the CirClip. This required a bit more effort as it was a very tight fit. When finished I used some gear paste to see if all was centered and then took it back to the shop and had my guy inspect it. He said it was great with hardly any backlash. He actually mentioned that there was more backlash on racing cars!! So all that's left is to install it in with my entirely newly refurbished subframe,new shocks, airsprings bolts bushings etc and hope and prey that my contact can change the gearing via the OBD port to effect both the TCU and ECU! Have a Merry Christmas!!!
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
Nice update. Please report back on the TCU tuning as that’s the only thing keeping me from doing the same. Are you in the US, and are you having EC do it?
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
