3.91 gears help

[Mr2Hard2See]

Will do buddy

[pnwdan]

Originally Posted by PepeLePew

You're a bad influence (in a good way). I want gears so bad but have been hesitant seeing that others spend about $1,800-$2,000 to have a shop do it. If I your telling me I can get the parts myself and have a local transmission shop do the install for a reasonable price and be out $800 or less, then I am going to have to do this.



I have 2 questions though.



What did you do for speedo calibration and how much did it cost? I see some of the GM gear sets you can buy from dealerships come with free calibration service too. But if you have to pay for the install at the dealership that might not be a good deal after all.



I have a manual and have been hesitant to step up to 3.91s not thinking it was a big enough jump to make it worth it. When I think about 4.11s, I see a mixed bag of people saying they are the way to go on an NA car but they can be noisier and might not be as strong. So I am kinda leaning toward 3.91s and possibly going FI in the future (centri SC).



OP, let us know how it turns out... very interested in your results and first impressions.

I have not calibrated my speedo yet because I am getting ready for a cam install. After the install she goes to the dyno for tune so I'll do it at that time. My radar detector has GPS and I use it to reference for now.

I too have a the manual and I too was hesitant. Seems logically that the 4.10 would be a better choice by the numbers for a NA manual car but I looked at a few personal factors. One, I may go for some boost in the future. I dont want to redo the rear again unless absolutely necessary. Two, the 4.10 sets are weaker and seem to tolerate less abuse. Three, the 4.10 are not GM gears so that factors in as well. When you use these GM gears, reassembly is easy because, like others have stated in these forums, most if not all of the time the diff goes back together without even changing shims. This keeps the potential cost down for install too not to mention the cost of the 4.10 is higher to begin with.

My first impression after install was that my car felt weaker. It feel like it wasn't pulling as hard as it use to. I realized I was wrong because the car isn't weaker. It's working less to do the same task. After having them for a few weeks I can say it's a great mod to have and I can also say that due to the speed limits I drive most, my milage has gone up. I also like to use 6th gear now on the freeway.

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[PepeLePew]

Originally Posted by pnwdan

I have not calibrated my speedo yet because I am getting ready for a cam install. After the install she goes to the dyno for tune so I'll do it at that time. My radar detector has GPS and I use it to reference for now.

I too have a the manual and I too was hesitant. Seems logically that the 4.10 would be a better choice by the numbers for a NA manual car but I looked at a few personal factors. One, I may go for some boost in the future. I dont want to redo the rear again unless absolutely necessary. Two, the 4.10 sets are weaker and seem to tolerate less abuse. Three, the 4.10 are not GM gears so that factors in as well. When you use these GM gears, reassembly is easy because, like others have stated in these forums, most if not all of the time the diff goes back together without even changing shims. This keeps the potential cost down for install too not to mention the cost of the 4.10 is higher to begin with.

My first impression after install was that my car felt weaker. It feel like it wasn't pulling as hard as it use to. I realized I was wrong because the car isn't weaker. It's working less to do the same task. After having them for a few weeks I can say it's a great mod to have and I can also say that due to the speed limits I drive most, my milage has gone up. I also like to use 6th gear now on the freeway.

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Great feedback, thank you sir!

[mbesman]

I'm interested in doing this as well. Question? Tick performance sells the package deal at 450 but I notice others buy a Yukon Kit as well
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Is the kit necessary? All advertising from the all in one kits do not mention a minor install kit is needed.
And, if you have a local shop install, will Chevy dealer recalibrate the speedo and if so about how much is that service?
Thank you

[pnwdan]

Originally Posted by mbesman

I'm interested in doing this as well. Question? Tick performance sells the package deal at 450 but I notice others buy a Yukon Kit as well
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Is the kit necessary? All advertising from the all in one kits do not mention a minor install kit is needed.
And, if you have a local shop install, will Chevy dealer recalibrate the speedo and if so about how much is that service?
Thank you

That kit only comes with a few more pieces that aren't needed. Waste of money really.

The kit also comes with the friction modifier fluid for the diff in that little bottle. If you use royal purple gear lube, its included in the oil. That's what I did.

To answer your question about the install kit, you need it in case different shims are required.

The parts I listed in my post are the minimum requirement.

You will need to get gear lube for the install and for the the fluid change after break in. Royal Purple is around $21 a bottle. Need 2 minimum.

If you have higher milage you may want to replace carrier bearings as well.



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[PepeLePew]

Originally Posted by pnwdan

That kit only comes with a few more pieces that aren't needed. Waste of money really.

The kit also comes with the friction modifier fluid for the diff in that little bottle. If you use royal purple gear lube, its included in the oil. That's what I did.

To answer your question about the install kit, you need it in case different shims are required.

The parts I listed in my post are the minimum requirement.

You will need to get gear lube for the install and for the the fluid change after break in. Royal Purple is around $21 a bottle. Need 2 minimum.

If you have higher milage you may want to replace carrier bearings as well.



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I'm takin notes

[mbesman]

Ok...that helps, thank you..getting on the right track now. Now I found two types of install kits and there is a huge difference in price. I also notice 8.5" and 8.6" with or without IRS in the title. Which one is the right one?

https://www.ebay.com/itm/Yukon-Minor...sAAOSw~vNaxt2h

https://www.ebay.com/itm/Yukon-Gear-...IAAOSwRXJcjMtF

Thanks for all your help guys

[PepeLePew]

Originally Posted by Mr2Hard2See

well guys I just bought all my parts on ebay. My parts total came out to $364.90 for everything above....I'm astatic because I just killed it deal wise. fellas you guys gave me the proper info and I utilized my shopping skills. This has to be the cheapest you can buy all of these brand new parts for.

gear set $271.44 10% discount=$246.54

s1392 rear pinion bearing $41.69 10% discount=$37.52

s1387 pinion inner bearing $55.74 10% discount=$50.17

Yukon Gear Minor install kit on Amazon for $30

Hey MrHard2See - Do you have the link for the Yukon Gear Minor Install kit. When I look it up on amazon its like $137. It is the MK GM8.6IRS. Is that the one you got?

Also, I am kicking myself, when I first opened the links that pnwdan sent, the gears were 230 something, and now they are 280+. It's like amazon knows I'm interested because I clicked the link a few times and they jacked the price up on me. Maybe I'll try to clear my cache.

[pnwdan]

Same link. Gotta wait it out. Goes up and down lol

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[Mr2Hard2See]

Originally Posted by PepeLePew

Hey MrHard2See - Do you have the link for the Yukon Gear Minor Install kit. When I look it up on amazon its like $137. It is the MK GM8.6IRS. Is that the one you got?


Also, I am kicking myself, when I first opened the links that pnwdan sent, the gears were 230 something, and now they are 280+. It's like amazon knows I'm interested because I clicked the link a few times and they jacked the price up on me. Maybe I'll try to clear my cache.

Just as Pnwdan stated it’s the same link. I paid $30 for that part. Now it’s priced at $138 that’s a crazy mark up. Sorry I don’t have a better answer but yes that’s the part I purchased and it arrived today. I guess you’ll have to wait till it drops again

[pnwdan]

Same thing happened after I bought mine. I looked a day later and the price was up. Then a few days later it was back down. Use the PN from the Amazon link to do a search. See if it's cheaper somewhere else otherwise just wait it out and it will go back down. Amazon is a scam that way. Hate that crap


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[CamaroFred]

Originally Posted by PepeLePew

Hey MrHard2See - Do you have the link for the Yukon Gear Minor Install kit. When I look it up on amazon its like $137. It is the MK GM8.6IRS. Is that the one you got?

Also, I am kicking myself, when I first opened the links that pnwdan sent, the gears were 230 something, and now they are 280+. It's like amazon knows I'm interested because I clicked the link a few times and they jacked the price up on me. Maybe I'll try to clear my cache.

Put it on your wish list and perhaps in a day or two they may mail you with a lower price. I've seen that more than once.

[PepeLePew]

Originally Posted by CamaroFred

Put it on your wish list and perhaps in a day or two they may mail you with a lower price. I've seen that more than once.

Great advice. Thanks Fred. I’ll give it a shot.

[pnwdan]

Yes great advice. The app will tell you when it drops.

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