How To: Dropping the front differental after TB crank (MMP) - Chevy Colorado & GMC Canyon
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post #1 of 318 (permalink) Old 07-08-2007, 09:00 PM Thread Starter
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How To: Dropping the front differental after TB crank (MMP)

Disclaimer: "Please use caution and seek professional assistance when necessary. ColoradoFans.com, myself and all associated members are not responsible for any damages, injuries or other harm which may occur with this modification. This post does not reflect the views of ColoradoFans.com and it's ownership." Before attempting this modification, it is advised to verify your Colorado or Canyon service manual or a certified mechanic, as not all GMT 355's are the same!

A CFans Members Mod Projects/How-To by Coyote



Description:
Reduce the severity of the angle on your CV boots after cranking your torsion bars by lowering the front differential by 1/2". Also allows you to turn your wheel full to one side without causing a metal on metal sound.


Skill Level: Easy

Modified GMT355:
Make: Chevrolet
Model: Colorado LS 4WD
Year: 2005


Theory of Operation:
Lowering your front differential will reduce the angle of your CV boots. This should help prolong the life and reduce the chances of tearing/ripping and expensive repairs.

1. Purchase the appropriate spacer for about 1/2". I used 6x 1/2 flat zinc washers from Menards. SKU 232-1172 A single piece spacer will be easier to install than 6 washers.

2. Loosen the 2 bolts holding the differential to the frame on one side of the vehicle. Make sure you have at least 1/2" between the frame and top of the mounting bracket.

In the picture below one mount is above the cv joint and the other is above the tie rod end boot.



3. Remove one bolt all the way; I chose to do the rear first. After removing place the six washers between the frame and the mounting bracket.



4. Reinsert the bolt through the mounting bracket hole and your spacer. Tighten enough to hold it up and then do the same for the other bolt on the same side. Snug the bolts on with a socket wrench.



5. Repeat steps 2 through 4 on the other side of the vehicle.

6. Torque the bolts to 112 ft/lbs.

CV angle before:


CV angle after:


CV angle after spacers:



After spacers photos:


1" spacers installed



CV angle after spacers



Differential height after spacers



Pinion angle after spacers

'06 Crew Silverado 4.8L 3.73 4WD G80 Granite Blue Metallic

'08 EC 3.7 Auto 3.73 4WD G80 Granite Black Metallic - Traded for 2006 Silvy

'05 EC, I5M, Z71, 4wd 4.10 gears, G80, SB Orange, 1.5" AAL, 1.5" TB lift, Lifted Club #115 - traded for 2008

'76 CJ5, 304 V8, 3spd, rebuild in progress.

AAL Install - CV Stress Relief

RIP Spike 9-25-2007
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post #2 of 318 (permalink) Old 07-09-2007, 01:36 AM
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WOW 1/2" that did make a big improvement!
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post #3 of 318 (permalink) Old 07-09-2007, 09:56 AM
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Awesome write up!

Thanks for the info... Now we just need to have someone start machining some spacers... :)

2004 Colorado Z71 4x4 Extended Cab
H3's w/ Goodyear MT/R 265/75/16
TB Crank
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post #4 of 318 (permalink) Old 07-09-2007, 10:00 AM Thread Starter
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Thanks guys.

We really need someone to make some longer M14x2.0 bolts. I don't think anyone makes one longer then 100mm. If we could get something like 120mm we could drop it even further.

'06 Crew Silverado 4.8L 3.73 4WD G80 Granite Blue Metallic

'08 EC 3.7 Auto 3.73 4WD G80 Granite Black Metallic - Traded for 2006 Silvy

'05 EC, I5M, Z71, 4wd 4.10 gears, G80, SB Orange, 1.5" AAL, 1.5" TB lift, Lifted Club #115 - traded for 2008

'76 CJ5, 304 V8, 3spd, rebuild in progress.

AAL Install - CV Stress Relief

RIP Spike 9-25-2007
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post #5 of 318 (permalink) Old 07-09-2007, 01:08 PM
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Call Maryland Metrics at 410.358.3130 and talk to the sales guys. This is the place I got the 12 bolts for my bodylift. Cost me $20 for all 12 I think.

05 Canyon EC SLE - I5M Z71 GT4
V1 | FRAM Boost+RamAir | LED + HAW Strobes | BFG 33-12.5-15
Rancho | Bubaloo Skidz | MBRP Dumped System
Cat Gut| 3 x Lightforce Blitz | eFan | PCMforless <- very unhappy
1.5" TB/AAL/1" BL | Fold-A-Cover | Line-X OTR | Brake Box
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post #6 of 318 (permalink) Old 07-09-2007, 01:16 PM Thread Starter
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Quote:
Originally Posted by rangerbob
Call Maryland Metrics at 410.358.3130 and talk to the sales guys. This is the place I got the 12 bolts for my bodylift. Cost me $20 for all 12 I think.
I looked at the website yesterday and they didn't have any. I am guessing you have to go to a M16 to get longer than 100mm. I will call them later, thanks.

'06 Crew Silverado 4.8L 3.73 4WD G80 Granite Blue Metallic

'08 EC 3.7 Auto 3.73 4WD G80 Granite Black Metallic - Traded for 2006 Silvy

'05 EC, I5M, Z71, 4wd 4.10 gears, G80, SB Orange, 1.5" AAL, 1.5" TB lift, Lifted Club #115 - traded for 2008

'76 CJ5, 304 V8, 3spd, rebuild in progress.

AAL Install - CV Stress Relief

RIP Spike 9-25-2007
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post #7 of 318 (permalink) Old 07-09-2007, 01:34 PM
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Quote:
Originally Posted by coyote
Quote:
Originally Posted by rangerbob
Call Maryland Metrics at 410.358.3130 and talk to the sales guys. This is the place I got the 12 bolts for my bodylift. Cost me $20 for all 12 I think.
I looked at the website yesterday and they didn't have any. I am guessing you have to go to a M16 to get longer than 100mm. I will call them later, thanks.
Their website is difficult to navigate. Just call them up - it's super easy.

05 Canyon EC SLE - I5M Z71 GT4
V1 | FRAM Boost+RamAir | LED + HAW Strobes | BFG 33-12.5-15
Rancho | Bubaloo Skidz | MBRP Dumped System
Cat Gut| 3 x Lightforce Blitz | eFan | PCMforless <- very unhappy
1.5" TB/AAL/1" BL | Fold-A-Cover | Line-X OTR | Brake Box
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post #8 of 318 (permalink) Old 07-09-2007, 06:13 PM
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From what I understand, the existing bolts work fine with a 1/2" drop?

This seems like a pretty promising modification -- be sure to post here if someone has a one piece washer made up for this. I'd be interested in purchasing a set; however, I'll be gone from my truck for a couple months in less than two weeks, so I don't have the time to do this mod before I get back.

Oh yea, and for anyone with bubbalo's skid plates, will this affect their mounting? (I'm considering buy a set)

'06 Z-71 Crew Cab -- Sold.

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post #9 of 318 (permalink) Old 07-09-2007, 11:26 PM Thread Starter
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Yup stock bolts were good for 1/2"

'06 Crew Silverado 4.8L 3.73 4WD G80 Granite Blue Metallic

'08 EC 3.7 Auto 3.73 4WD G80 Granite Black Metallic - Traded for 2006 Silvy

'05 EC, I5M, Z71, 4wd 4.10 gears, G80, SB Orange, 1.5" AAL, 1.5" TB lift, Lifted Club #115 - traded for 2008

'76 CJ5, 304 V8, 3spd, rebuild in progress.

AAL Install - CV Stress Relief

RIP Spike 9-25-2007
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post #10 of 318 (permalink) Old 07-10-2007, 10:32 AM
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I'll check the skid plate mounting when I do this this weekend.

05 Canyon EC SLE - I5M Z71 GT4
V1 | FRAM Boost+RamAir | LED + HAW Strobes | BFG 33-12.5-15
Rancho | Bubaloo Skidz | MBRP Dumped System
Cat Gut| 3 x Lightforce Blitz | eFan | PCMforless <- very unhappy
1.5" TB/AAL/1" BL | Fold-A-Cover | Line-X OTR | Brake Box
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post #11 of 318 (permalink) Old 07-10-2007, 10:36 AM Thread Starter
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Quote:
Originally Posted by rangerbob
I'll check the skid plate mounting when I do this this weekend.
Thanks.

'06 Crew Silverado 4.8L 3.73 4WD G80 Granite Blue Metallic

'08 EC 3.7 Auto 3.73 4WD G80 Granite Black Metallic - Traded for 2006 Silvy

'05 EC, I5M, Z71, 4wd 4.10 gears, G80, SB Orange, 1.5" AAL, 1.5" TB lift, Lifted Club #115 - traded for 2008

'76 CJ5, 304 V8, 3spd, rebuild in progress.

AAL Install - CV Stress Relief

RIP Spike 9-25-2007
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post #12 of 318 (permalink) Old 07-10-2007, 11:41 AM
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Sweet. I usually do all my car stuff by a friend and he also just got a bridgeport last week.

How much thread did the bolts have left with the spacer?

2004 GMC Canyon SLE Ext Cab Z71 4x4

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post #13 of 318 (permalink) Old 07-10-2007, 11:44 AM
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Coyote - I'm going to machine 24 donut type steel spacers, dia. = 1.500" X thickness 0.500" with a 0.500" center hole.
I will have them ready for shipping by Friday. Yours are free!
I will make a thread in the FS section with price and shipping details.
What other thickness sizes do you recommend?
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post #14 of 318 (permalink) Old 07-10-2007, 11:46 AM Thread Starter
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Quote:
Originally Posted by BahamaTodd
Sweet. I usually do all my car stuff by a friend and he also just got a bridgeport last week.

How much thread did the bolts have left with the spacer?
Don't know measurement wise, but in the picture for step 4 the rear bolt with washers already has a couple turns to just hold it up. So whatever is left showing and the couple turns. I am guessing there isn't much room after the 1/2".

'06 Crew Silverado 4.8L 3.73 4WD G80 Granite Blue Metallic

'08 EC 3.7 Auto 3.73 4WD G80 Granite Black Metallic - Traded for 2006 Silvy

'05 EC, I5M, Z71, 4wd 4.10 gears, G80, SB Orange, 1.5" AAL, 1.5" TB lift, Lifted Club #115 - traded for 2008

'76 CJ5, 304 V8, 3spd, rebuild in progress.

AAL Install - CV Stress Relief

RIP Spike 9-25-2007
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post #15 of 318 (permalink) Old 07-10-2007, 11:51 AM Thread Starter
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Quote:
Originally Posted by supermodulation
Coyote - I'm going to machine 24 donut type steel spacers, dia. = 1.500" X thickness 0.500" with a 0.500" center hole.
I will have them ready for shipping by Friday. Yours are free!
I will make a thread in the FS section with price and shipping details.
What other thickness sizes do you recommend?
Thanks, I will not recommend any other sizes unless we find longer bolts. I would recommend 3/4" or 1" if longer bolts can be found. It just really depends if you are doing this for show or offroading use. For show you could go further to help keep the CV's as straight as possible, but if you are going off roading you may not want to drop it as far since you are exposing more of the front diff. Anyone else is free to add their opinion.

Also make sure to check the bolt torque after a few hundred miles to make sure everything is holding tight.

'06 Crew Silverado 4.8L 3.73 4WD G80 Granite Blue Metallic

'08 EC 3.7 Auto 3.73 4WD G80 Granite Black Metallic - Traded for 2006 Silvy

'05 EC, I5M, Z71, 4wd 4.10 gears, G80, SB Orange, 1.5" AAL, 1.5" TB lift, Lifted Club #115 - traded for 2008

'76 CJ5, 304 V8, 3spd, rebuild in progress.

AAL Install - CV Stress Relief

RIP Spike 9-25-2007
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post #16 of 318 (permalink) Old 07-10-2007, 01:45 PM
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I stopped by my local GMC dealer at lunch to compare a stock 4x4 Z71 to ours.
The stock CV is straight horizontal.


Stock 4x4 Z71:




This is my CV joint:

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post #17 of 318 (permalink) Old 07-10-2007, 01:55 PM Thread Starter
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Horizontal would be best, but at this point I don't know if we can achieve that.

Bad news. Maryland Metrics doesn't have a source and said they would most likely have to be custom machined.

The only other option it to have someone make a custom drop bracket for some standard sizes like .5", 1", 1.5" and 2". I was already thinking about doing this. Another variation would be to create a bracket extension that can be bolted or welded to the stock bracket. Lets hear some ideas guys.

I think the last idea is the easiest and most promising. Maybe some two pieces of angle iron welded together?

'06 Crew Silverado 4.8L 3.73 4WD G80 Granite Blue Metallic

'08 EC 3.7 Auto 3.73 4WD G80 Granite Black Metallic - Traded for 2006 Silvy

'05 EC, I5M, Z71, 4wd 4.10 gears, G80, SB Orange, 1.5" AAL, 1.5" TB lift, Lifted Club #115 - traded for 2008

'76 CJ5, 304 V8, 3spd, rebuild in progress.

AAL Install - CV Stress Relief

RIP Spike 9-25-2007
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post #18 of 318 (permalink) Old 07-10-2007, 01:58 PM
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Here's a shot of my front diff with my skid plate. There's about an inch of clearance under the diff, but the nut and bolt for the plate's mounting bracket may cause some interference. Ill have to take a look again later to confirm.


2004 GMC Canyon SLE Ext Cab Z71 4x4

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post #19 of 318 (permalink) Old 07-10-2007, 02:42 PM
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I think once I add the 0.500" spacer I will be near stock.

I'll ask my guy if we can get a M14 bolt about 120mm in length.
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post #20 of 318 (permalink) Old 07-10-2007, 02:45 PM
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Do you know how long the stock bolt is?

05 Canyon EC SLE - I5M Z71 GT4
V1 | FRAM Boost+RamAir | LED + HAW Strobes | BFG 33-12.5-15
Rancho | Bubaloo Skidz | MBRP Dumped System
Cat Gut| 3 x Lightforce Blitz | eFan | PCMforless <- very unhappy
1.5" TB/AAL/1" BL | Fold-A-Cover | Line-X OTR | Brake Box
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