Rear end and big tires - Page 2 - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Transmission - Rearend
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #16 (permalink)  
Old 11-17-2010, 10:19 AM
kleen56's Avatar
Registered User
 
Last photo:
Join Date: Oct 2006
Location: Santa Clarita CA
Posts: 797
Wiki Edits: 0

Thanks: 4
Thanked 5 Times in 5 Posts
Lower gearing always helps with pulling power, but as Cobalt stated, will affect your highway driving by causing the engine rpm to be higher. I'd find out what gearing you actually have before guessing or planning to change gearing. You state the problem is lack of power at 35 mph. The gears may not make a big difference for you and you may want to look at helping the engine perform better. Headers and exhaust always make a big difference as does intake/ carburation. Your already running a Qjet carb which is a good carb so a good intake manifold might help. Have you done a compression check on the engine yet? If exhaust and intake is not enough, a camshaft (RV cam) change is another possibility along with dropping a Big Block in there (joking!). Your stock converter is fine. A stall converter will only help you launch off the line and not at 35 mph pulling something.

Last edited by kleen56; 11-17-2010 at 10:27 AM.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #17 (permalink)  
Old 11-17-2010, 10:45 AM
Mertz's Avatar
Member
 
Join Date: Jun 2002
Location: Reardan, WA
Posts: 655
Wiki Edits: 0

Thanks: 1
Thanked 2 Times in 2 Posts
I already have ceramic headers and a performer intake with K&N top air cleaner. I haven't done a compression check but everything indicates that that shouldn't be a problem. It doesn't use any oil and it has a strong sound with the proflow mufflers and dual exhaust. Never has a starting problem even with the choke disconnected. Plugs and spiral core wires are new and shielded from header heat. It is fast above 50mph.

I also replaced the stamped rockers with roller tip to make sure I have equal length 1.5 rockers. I got new push rods to get the geometry right in the middle of the valve. They are adjusted with zreo lash than 1/2 turn if I remember right. If not 1/2 than 3/4. Ignition and timing are right on. I am using ported vacuum now instead of manifold because the new carb ran better that way. I can try going back to manifold.
Reply With Quote Quick reply to this message
  #18 (permalink)  
Old 11-17-2010, 10:51 AM
kleen56's Avatar
Registered User
 
Last photo:
Join Date: Oct 2006
Location: Santa Clarita CA
Posts: 797
Wiki Edits: 0

Thanks: 4
Thanked 5 Times in 5 Posts
I'm just curious why you lack power at the 35 mph range and not 50 and above? Maybe you have high gearing in the rearend and all your power is on top end. Then lower gears will definitely make a huge difference and wake up your low end pulling power. Now I'm curious what gearing is in there! LOL...
Reply With Quote Quick reply to this message
  #19 (permalink)  
Old 11-17-2010, 11:47 AM
Mertz's Avatar
Member
 
Join Date: Jun 2002
Location: Reardan, WA
Posts: 655
Wiki Edits: 0

Thanks: 1
Thanked 2 Times in 2 Posts
I will let you know as soon as I find out (this weeekend). I was having the 35 mph power problem when dailing in my Qjet. It has gotten somewhat better using Cliff's quad instead of mine but I don't think that is the problem.
Reply With Quote Quick reply to this message
  #20 (permalink)  
Old 11-17-2010, 08:43 PM
fast68's Avatar
likes chevy trucks & boobies
 
Last photo:
Join Date: Oct 2005
Location: IL
Posts: 1,970
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
410 or 457 were the most common ratios in the HO52 rear

the dana 60 rear that sometimes were under these trucks were mostly 4.10

but some were 4.57 or 4.56

and most were 4.10

can pull a house with these but horrible RPM on highway,.

will be screaming engine at 55 or 65

these were heavy strong workhorse trucks and not traveling trucks made for highway mileage

the sticker in the glovebox is called the SPID label and it should list the axle ratio

but not always does it

look for G codes

such as GT4 or GU6

there are axle related codes

i can give you full listing of axle ratios of both axles they put under these trucks if you really need, i have a red book for the trucks 72 older it lists every single RPO code, and ratio and combination for these trucks these years, and it lists year by year and model by model etc.


if you need info like this then PM or email me
Reply With Quote Quick reply to this message
  #21 (permalink)  
Old 11-18-2010, 05:46 PM
prostreet6t9's Avatar
Differential/Driveline
 
Last photo:
Join Date: Sep 2008
Location: oregon
Age: 50
Posts: 1,715
Wiki Edits: 0

Thanks: 5
Thanked 38 Times in 35 Posts
1972 C20 Truck Chassis w/ Leaf Springs

603322-1 Standard 4.10

603322-2 Powr-Lok 4.10

603322-3 Standard 4.56

603322-4 Powr-Lok 4.56

603322-5 Standard 3.54

603322-6 Powr-Lok 3.54
Reply With Quote Quick reply to this message
  #22 (permalink)  
Old 11-18-2010, 05:47 PM
prostreet6t9's Avatar
Differential/Driveline
 
Last photo:
Join Date: Sep 2008
Location: oregon
Age: 50
Posts: 1,715
Wiki Edits: 0

Thanks: 5
Thanked 38 Times in 35 Posts
1972 C20 Truck Chassis w/ Coil Springs

603321-1 Standard 3.54

603321-2 Powr-Lok 3.54

603321-5 Standard 4.10

603321-6 Powr-Lok 4.10

603321-7 Standard 4.56

603321-8 Powr-Lok 4.56
Reply With Quote Quick reply to this message
  #23 (permalink)  
Old 11-21-2010, 01:38 PM
Mertz's Avatar
Member
 
Join Date: Jun 2002
Location: Reardan, WA
Posts: 655
Wiki Edits: 0

Thanks: 1
Thanked 2 Times in 2 Posts
Here is what I found on the diff These numbers were upside down and read C-30255 The only G codes in the glove box are G70 and G50 for leaf springs. I did find a tag that read 41.10. Before I checked the numbers I put the rear end in the air and spun the tires to try to count drive shaft revs. If I spin the left tire forward the right tires spins backwards and visa versa. The problem is that the drive shaft does not continually spin like it is only catching part of the time. There are 10 bolts on the cover and appears to be a Dana 60 although I found other sites that say it could or should be a GM 8.875. (A little more web surfing and I am pretty sure it is a Dana 60. It has the 60 at the bottom. I could read the 0 but was not sure about the 6) I am going back under to see if I can find numbers on the tube.

The engine does not rev very high at highway speeds. I have had it to 85 with no problems and it could have gone more. It is weak at 35 mph.

Is this a limited slip differential? Could there be something wrong with it that is allowing it to slip when it shouldn't. I have never been able to burn the tires.

Where would I find the numbers you list? The ones I found are on the passenger side of the diff housing on top and are upside down.

This truck is pretty much stock except what I did to it. It shows 152,000 miles and I believe that is original. I don't think there has ever been a rear end swap or gear change. If it had I would guess the tag would be missing.

Last edited by Mertz; 11-21-2010 at 01:58 PM.
Reply With Quote Quick reply to this message
  #24 (permalink)  
Old 11-25-2010, 12:25 PM
Mertz's Avatar
Member
 
Join Date: Jun 2002
Location: Reardan, WA
Posts: 655
Wiki Edits: 0

Thanks: 1
Thanked 2 Times in 2 Posts
As a little turkey day fun I went out and played with my truck. I should mention it is snowing and about 13 degrees. I jacked up the rear and did the tire rotation check and got a little over 4 turns on the drive shaft with 2 turns on the wheel. That would mean the tag is correct and I have 4.10 gears. Now what? My transmission guy said there is probably nothing wrong with the torque converter. I did read somewhere that if the stator is allowed to spin backwards it will have no low end but scream on the high end which is just what mine is doing. I did one other thing and that was to put a clamp on the PCV hose on the carb. It was somewhat loose. It seemed to run a little stronger. It also seemed to run a little stronger when I pinched the hose. No change on the vacuum gauge which is at 16 at idle which is about 2 low from what I have in the summer. I think it is running pretty good because I don't have a choke connected and it started after a little cranking to get gas to the carb.

BTW I also checked for voltage at the coil and got battery voltage (12.43v) with ignition off and alternator voltage with it running (14.21v)

Last edited by Mertz; 11-25-2010 at 12:32 PM.
Reply With Quote Quick reply to this message
  #25 (permalink)  
Old 11-25-2010, 02:58 PM
akhappyjack's Avatar
Registered User
 
Join Date: Sep 2007
Location: Fairbanks Ak
Posts: 16
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Big rear Big tires

lack of power @35 does it struggle to get to 85? or just flatten's out at 35 and starts to pull above 40-45
Reply With Quote Quick reply to this message
  #26 (permalink)  
Old 11-25-2010, 06:37 PM
Mertz's Avatar
Member
 
Join Date: Jun 2002
Location: Reardan, WA
Posts: 655
Wiki Edits: 0

Thanks: 1
Thanked 2 Times in 2 Posts
Once it gets above 35 or 45 it takes off like a rocket. I have no trouble getting from 50 to 85 and it does not over rev. it is very sluggish from zero to 45.
Reply With Quote Quick reply to this message
  #27 (permalink)  
Old 12-11-2010, 10:22 AM
bosco200's Avatar
Registered User
 
Last photo:
Join Date: May 2009
Location: Ste. Genevieve
Posts: 89
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
My 72 C20 has 4.57's and it starts screaming at 50mph and starts suckin down gas like crazy...but im gunna throw a 350 motor and T56 tranny in there...has a 250 straight 6 with a 4 speed manual now.
Reply With Quote Quick reply to this message
  #28 (permalink)  
Old 12-11-2010, 11:05 AM
matts37chev's Avatar
I don't understand?
 

Last journal entry: this is only a test
Last photo:
Join Date: Jan 2009
Location: Shelton,Wa.
Age: 44
Posts: 2,420
Wiki Edits: 0

Thanks: 0
Thanked 5 Times in 4 Posts
i would try the tire front to rear swap, just to see what it does.
its fast, easy and free
Reply With Quote Quick reply to this message
  #29 (permalink)  
Old 12-11-2010, 09:44 PM
Mertz's Avatar
Member
 
Join Date: Jun 2002
Location: Reardan, WA
Posts: 655
Wiki Edits: 0

Thanks: 1
Thanked 2 Times in 2 Posts
After some more research I find that the stock tires and the ones I have on now are the same diameter so I am using the 4.10 rear end as designed. The change from front to back will help. Right now the truck is in the shop with about 4' of snow in front of the door so it won't be going anywhere soon. I still think that with the 4.10s I could have a weak engine and still burn rubber.
Reply With Quote Quick reply to this message

Recent Transmission - Rearend posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Mazda Pickup Truck 1990, model B2200 rear end awbazar Transmission - Rearend 4 12-17-2009 05:15 AM
this is a saver.... GM build codes TooMany2count General Rodding Tech 24 11-23-2009 09:36 AM
Rear End vibration driving me insane 973kgt Transmission - Rearend 41 11-13-2008 11:01 PM
will a '69 Chevelle rear end fit into a '70 Chevelle? SMO'KUM UP Introduce Yourself 2 09-17-2007 07:15 AM
Rear end no oil, big mistake. anyoldchevy Transmission - Rearend 14 06-23-2007 09:28 PM


All times are GMT -6. The time now is 01:26 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.