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-   -   Need Rearend Help (http://www.hotrodders.com/forum/need-rearend-help-92515.html)

HARDEIGHT 06-26-2006 10:05 AM

Need Rearend Help
 
My trans guy tells me I need to be running a 373 or a 410 gear with the setup I plan on running. (700r4 no lockup, 33x21.5 rear tires ,air ride tech 4 link with bags,zz4 crate motor). Rearend is what came stock in the truck (88 c1500 chevy) 273 gear according to the glove box tag.

Talked to a rearend specialist about putting 410 gears in my housing and was told everything needed to be changed inside .The est for that was $1200. If thats the norm thats fine I can bite the bullet and have him do it but I just wanted to know if I have any other options, like getting a used rearend with 410 gears .are they readily available? I would rather keep my old housing for fittment reasons (everything has been mocked up with this housing) tire fittment is a concern.

I know little to nothing about rearends so I hope my questions are making sense.

Any other ideas lets hear em

Thanks Dave

Not A T 25 06-26-2006 10:32 AM

Quote:

Originally Posted by HARDEIGHT
My trans guy tells me I need to be running a 373 or a 410 gear with the setup I plan on running. (700r4 no lockup, 33x21.5 rear tires ,air ride tech 4 link with bags,zz4 crate motor). Rearend is what came stock in the truck (88 c1500 chevy) 273 gear according to the glove box tag.

Talked to a rearend specialist about putting 410 gears in my housing and was told everything needed to be changed inside .The est for that was $1200. If thats the norm thats fine I can bite the bullet and have him do it but I just wanted to know if I have any other options, like getting a used rearend with 410 gears .are they readily available? I would rather keep my old housing for fittment reasons (everything has been mocked up with this housing) tire fittment is a concern.

I know little to nothing about rearends so I hope my questions are making sense.

Any other ideas lets hear em

Thanks Dave

What rearend do you have in the car now 10 bolt 12 bolt front loader? A different rearend might be the way to go depending on your pocket book. I would think changing the rear gears should only require a ring and pinion set bearings shims and the set up cost. To me $1200 sounds like a lot. A good used rear can be had I would think for less than half of that. Just my opinion :)

HARDEIGHT 06-26-2006 10:43 AM

Rear end is a 10 bolt (10 bolts on the cover) .The shop that gave me the est said to run 410 gears I need a posi unit which 'm guessing I dont have and the only thing they could reuse was the housing and poss the axles but I cant remember for sure re the axles.

Thanks Dave

Not A T 25 06-26-2006 11:00 AM

Quote:

Originally Posted by HARDEIGHT
Rear end is a 10 bolt (10 bolts on the cover) .The shop that gave me the est said to run 410 gears I need a posi unit which 'm guessing I dont have and the only thing they could reuse was the housing and poss the axles but I cant remember for sure re the axles.

Thanks Dave

Is your 10 bolt the stock width or has it been cut down you can get a new posi center section for $400 ~ $600 the ring and pinion set around $200 bearing install kit $100 and then the labor for them to do the work? I would think you could use your axles. I have a 10 bolt with 3:73 gears with my 700R4 on back of a Stroked 350 all new except the rear and I added a Powertrax no slip unit to make it a locker all seems to work great

HARDEIGHT 06-26-2006 11:45 AM

The rearend is the stock width. The #s your giving me seem to be close to his throw in a few hundred for lbr and its close to 1200. I dont have any idea what the lbr involved to do this swap should cost though.

If it comes down to getting a used one with the correct gears and having it gone through or just using my existing housing and having the swap done I would rather re use what I have unless I could save 4 or 5 hundred because my exising housing is all blasted and painted already .

dave

Not A T 25 06-26-2006 11:57 AM

Quote:

Originally Posted by HARDEIGHT
The rearend is the stock width. The #s your giving me seem to be close to his throw in a few hundred for lbr and its close to 1200. I dont have any idea what the lbr involved to do this swap should cost though.

If it comes down to getting a used one with the correct gears and having it gone through or just using my existing housing and having the swap done I would rather re use what I have unless I could save 4 or 5 hundred because my exising housing is all blasted and painted already .

dave

Have you considered using 3:73 gears on your open rearend they work fine with my 700R4 :confused: Unless you are wanting the performance of the posi rearend. You could also find a used posi section and just replace yours quite a bit cheaper but used is used and new usually ends up cheaper in the long run. :cool:

HARDEIGHT 06-26-2006 04:48 PM

According to my trans guy 373 is as low as I should go due to the rear tire size , 32" actual height,to get an acceptable rpm at 60 mph in od.Any lower and I would run the risk of overheating the converter.

Its looking like new is the way to go

Thanks Dave

302 Z28 06-26-2006 05:20 PM

Your trans guy is right, that 2:76 rear axle will make that vehicle a pig with a 700R4. I am figuring on 29" tires on my 34 with a 3:70 and a 700R4 for a highway rpm of 2200 to 2500. There are any number of rpm calculators on the net, pick one and figure your rpm at 60 and 70 with different gear ratios and tire sizes.

Vince

Not A T 25 06-26-2006 06:45 PM

Quote:

Originally Posted by HARDEIGHT
According to my trans guy 373 is as low as I should go due to the rear tire size , 32" actual height,to get an acceptable rpm at 60 mph in od.Any lower and I would run the risk of overheating the converter.

Its looking like new is the way to go

Thanks Dave

Why have you chosen to go with no lock up?

HARDEIGHT 06-26-2006 08:16 PM

I was told going with no lockup would be easier in the long run .

This truck will be lucky to see 500 mi a year so a few mpgs are not a concern

DAVE

Not A T 25 06-27-2006 06:04 AM

Quote:

Originally Posted by HARDEIGHT
I was told going with no lockup would be easier in the long run .

This truck will be lucky to see 500 mi a year so a few mpgs are not a concern

DAVE

Not being a trans guy I guess I dont understand how it would be easier I am just going by the 700R4 I just installed in my street rod and I had it built with Hyd lock up and it required no wiring at all just set up of the TV cable which all 700R4 trans have. Good luck with your project :thumbup:

HARDEIGHT 06-27-2006 08:36 AM

Thanks t25 , I know almost nothing when it comes to transmissions and rearends I just do what they tell me .
Thanks again for your input.

Dave

DOUBLEDICK 06-27-2006 09:55 AM

I run a 700r4 in my truck with a gm 10 bolt and a powertrax locker.my valve body locks my converter in OD no electronics also I have the after market valve that lets me keep overdrive through 3/4 throttle.It is well worth it so it doesnt downshift at the slightest touch of the throttle.As far as gear ratios I run 4.56 gears and 31x10.5 tires and am turning 2650rpm at 70 but I pull a trailer so I need the lower gears I would recommend 427 gears with the 32 inch tires and nonlock up converter as trucks are heavy.My 2300 stall converter helps get this 6000lb rig rolling.I run a 500+hp 427 so my trans has the hardened parts inside and I still get 14mpg at 70mph in overdrive and in town it zips along quicker than my buddies 66 Nova with a 350/350 combo. I am quite impressed with the powertrax locker it is quiet,it just goes right in the stock carrier and it is holding up to the punishment of my torque monster 427 big block.

HARDEIGHT 06-27-2006 10:16 AM

thanks double d i'll bring that up to the trans guy


Dave


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