Just a few questions

[samcrf450]

What rear ends are you guys running in your trucks? I have a 10 bolt that fits but should I go with a ford 9" due to the C-clips on the 10 bolt? I am going to be putting a parallel 4 link system in it with coil over shocks. I thought I had to have a 9" for that but I went to a shop up here that had a bar going from the front left mounting point to the right rear of the 4 link instead of welding a pan hard to the axle housing.

Also what brand are the poly gas tanks that I keep seeing? I can't decide between aluminum and poly.

[dwcsr]

Depending on what your driving habit is going to be and what HP you have a 10 bolt could be fine. For street a 9" is overkill. It gets worse mileage that a 10 bolt even with the same gearing. You can save the money and redo the 10 bolt carrier and gears it would be plenty strong enough. I have a 12 bolt truck rear because thats what I had available and I have no worries about it standing up to the 550 hp BBC.

9" ford rears are not any stroner than a 12 bolt car rears. The reason for use of a 9" is if your racing and need to change gearing quicky you can. Now because of the popularity of them they are hard to find but you can get just about any ratio you want. If your worried about C clips you can get C clip eliminators.

I know somebody will chime in and say I blew up 22 12 bolts before they got a 9" but thats not the norm.

[55ChevyPU]

from my understanding chevy 10 bolts are much more prone to warping if you weld on them compared to a ford 9". I have a chevy 10 bolt in my truck right now.

[trkklr77]

Originally Posted by dwcsr

Depending on what your driving habit is going to be and what HP you have a 10 bolt could be fine. For street a 9" is overkill. It gets worse mileage that a 10 bolt even with the same gearing. You can save the money and redo the 10 bolt carrier and gears it would be plenty strong enough. I have a 12 bolt truck rear because thats what I had available and I have no worries about it standing up to the 550 hp BBC.

9" ford rears are not any stroner than a 12 bolt car rears. The reason for use of a 9" is if your racing and need to change gearing quicky you can. Now because of the popularity of them they are hard to find but you can get just about any ratio you want. If your worried about C clips you can get C clip eliminators.

I know somebody will chime in and say I blew up 22 12 bolts before they got a 9" but thats not the norm.

im sorry but WTF!?!?! how is a 9" going to cuase you to get worse mpg!?!??!


why are you trying to get rid of the c clips? are you worried about them failing, they dont hold any load and can only come out if you shrapnel the cross pin. the c clip makes them more of a pain to swap axles shafts, repair end seals, add disc brakes, any thing where a shaft would need to be pulled but in no other way affect the strength of the axle.

as far as axle warping, how you guys are warping an entire housing is beyond me, it takes a huge amount of heat and wire to warp and axle. if you were to just run a giagantic bead across the top of the axle from one end to the other non stop i could see it but just welding a bag mount or some new perches shouldnt do anything.

a 9" would be a great axle to put in if you are running a big traction tire and high hp/trq, a 10/12b should be fine for a long time.

[55ChevyPU]

Originally Posted by trkklr77

im sorry but WTF!?!?! how is a 9" going to cuase you to get worse mpg!?!??!


why are you trying to get rid of the c clips? are you worried about them failing, they dont hold any load and can only come out if you shrapnel the cross pin. the c clip makes them more of a pain to swap axles shafts, repair end seals, add disc brakes, any thing where a shaft would need to be pulled but in no other way affect the strength of the axle.

as far as axle warping, how you guys are warping an entire housing is beyond me, it takes a huge amount of heat and wire to warp and axle. if you were to just run a giagantic bead across the top of the axle from one end to the other non stop i could see it but just welding a bag mount or some new perches shouldnt do anything.

a 9" would be a great axle to put in if you are running a big traction tire and high hp/trq, a 10/12b should be fine for a long time.

hrmm think so ?

[dwcsr]

I was told by the guy that narrowed mine that they all warp when you weld on them. It has nothing to do with the case and carrier but the tubes. My 12 truck axle which has thicker tubes that the normal 9" warpped a full 1/2" from welding on the air bag perches. What he said was that do all your welding then get it straightened or the new ends put on if your narrowing. I do agree that the 10 bolt would be more likey to move more but how do you really know if you don't use the housing end jig to check it.

[55ChevyPU]

honestly the leading problem is probably the fact that most people you go to dont take their time and try to rush it using to high a voltage and generating way to much heat. Id say regardless of what you decide to do just make sure you go to someone you know is going to take their time and do a good job.

[CAL 58 GMC]

Originally Posted by 55ChevyPU

honestly the leading problem is probably the fact that most people you go to dont take their time and try to rush it using to high a voltage and generating way to much heat. Id say regardless of what you decide to do just make sure you go to someone you know is going to take their time and do a good job.

55Chevy is right. It's the amount of heat that warps the metal. A tig welder would be the best choice of welding due to the fact you can control the heat much better. If you take it to a good welder they should be able to keep it from warping.

[5Mike7]

The 9inch has more rotational drag than a 12bolt, and others, but I'm not sure how much that would translate into HP loss and MPG loss, but there would be some.

There are C-clip eliminator sets, unsure of price or if compatibility with your rear you have.

I've never warped a rear by welding perches on, and I use my mig, and no fixtures.

I could see if you shortened one and got in a hurry you could warp'em quickly, especially if not using a jig to keep it set and if you didn't tack and weld it properly.

All that aside in my '57 I runa truck 12 bolt from an early 60's GMC and in my '59 I run a Dana44 from another early GMC.

On he 12 bolt I had to cut off the coil spring stuff and put on perches, on the Dana I had to move the perches about an inch each as I recall.

[samcrf450]

Thanks you guys this is a great site. I will probably just put the 10 bolt in because I have it and it is the right width. The c-clip eliminators are about 150 and then you have to buy new axles. If I did that I might as well put a 9" in.

Also who is using one of the plastic gas tanks? Where are you buying them from?

I will try and post some pics of the progress. I just put in the TCI mustang II and am in the progress of putting the motor mounts in. I just set the cab back on it and the thing looks bad. Still dont have the rear set up but I need to save a little money to get the 4 bar system from TCI. I love these trucks.

[55ChevyPU]

I have a jaz fuel cell relocated in the back, works good.

[trkklr77]

Originally Posted by 5Mike7

The 9inch has more rotational drag than a 12bolt, and others, but I'm not sure how much that would translate into HP loss and MPG loss, but there would be some.
.

the 9" has 1 addition bearing that supports the snout on a 9" pinion gear. other than that how can it have more rotaional drag. all diffs have about the same amount of preload on the carrier bearings and the shaft bearings at the wheel are about the same size.

the strength and after market far out ways that of any 10/12b.

[5Mike7]

Originally Posted by trkklr77

the 9" has 1 addition bearing that supports the snout on a 9" pinion gear. other than that how can it have more rotaional drag. all diffs have about the same amount of preload on the carrier bearings and the shaft bearings at the wheel are about the same size.

the strength and after market far out ways that of any 10/12b.

From the article posted above:

Like the 12-bolt, the 9-inch pinion gear is shimmed to achieve the proper pinion depth with a small pinion shaft diameter of 1.313 inches. Another difference between the two rearends is that the 9-inch locates its pinion gear lower on the ring gear to improve tooth contact. This strengthens the rearend assembly but at the cost of approximately 2 to 3 percent loss of power to drive the gears compared to a 12-bolt. Of course, the sizes of the gears, cases, and bearings are relevant to strength, so you have to give the strength comparison to the 9-inch with its 0.125-inch larger ring-gear diameter and internal pinion support.

[smr72chevy]

you can get the poly gas tank at www.outbacktruckparts.com or www.classicperform.com for around 200.00

[Daniel U]

[QUOTE=samcrf450;1894954]What rear ends are you guys running in your trucks? I have a 10 bolt that fits but should I go with a ford 9" due to the C-clips on the 10 bolt? I am going to be putting a parallel 4 link system in it with coil over shocks. I thought I had to have a 9" for that but I went to a shop up here that had a bar going from the front left mounting point to the right rear of the 4 link instead of welding a pan hard to the axle housing.
QUOTE] I'm going with the TCI front end as well. You can see my 10 bolt on my 54 build thread link. Daniel U

[samcrf450]

55chevypu that is a nice tank set up. My only concern is that I will have the new cross member for the shocks due to the 4 bar link and it is boxed I believe so I will not have access to bolt to it. Is that the 16 gallon tank? Where did you buy it from and do you have the part #?

[entourageguy]

Originally Posted by samcrf450

55chevypu that is a nice tank set up. My only concern is that I will have the new cross member for the shocks due to the 4 bar link and it is boxed I believe so I will not have access to bolt to it. Is that the 16 gallon tank? Where did you buy it from and do you have the part #?

Link to old thread about gas tanks...

http://67-72chevytrucks.com/vboard/s...d.php?t=196350

I used the same Jaz 16 gal tank as 55chevpu. I moved the rear cross member back 4.5" to clear the bed cross member as well as move the flip up filler closer to the rear as well. This also gave me xtra room for the four bar and clearance for the bag and shock mounts.

Brian ...

[dwcsr]

this is a good article on 12 bolt vs 9"

http://www.chevyhiperformance.com/te...nd_comparison/

[CAL 58 GMC]

Originally Posted by dwcsr

this is a good article on 12 bolt vs 9"

http://www.chevyhiperformance.com/te...nd_comparison/

That's a good artical. It looks like 5Mike7 was right about the loss of power to drive the gears with a 9 inch.

[dwcsr]

I don't think that is in the miles per gallon area. What I got from the comparison was that if you need to reay bang the rear end on a daily basis and can afford an aftermarket 9" you would be better off. But for what most of us do, which is crusing and the occassional traffic light burn thru you could save a few hundred and spend it on other things... like beer or chrome stuff or beer or more beer.

The 12 bolt took the pounding from the 427 435 and 454 450 so I think its a good choice for a street truck or car at a cheaper price.

[trkklr77]

2-3% hp loss from the extra tooth contact is a price im willing to pay. you are correct though, they do take more power to run. a 500hp motor already loses 20% +/- throught the tranny, 400 rwhp , minus another 3% is 12 more hp out the door.

[pgf545]

Actually a 12 bolt should be strong enough for any street driven car. My brother runs a 12 bolt in his race car and has not really had any problems with it. It is a small block making about 800hp and runs in the mid to high 10s in a 3000lb Nova. We have had this car like this for about 10 years now and I think he has only put a set of gears in it once, but it didn't blow up...he was doing a regular check up and he found a couple of teeth cracked. It launches really hard so that isn't to bad service.

Bernie

[72dually]

Whichever choice you decide on, consider that the older, (73-6 or so) lincoln disc brake rears have the 5 on 5 pattern and with minimal work, i.e. spring perch removal and replacement are a great choice for the 67-72 trucks. California and Arizona boneyards usually charge around a buck fifty for the complete rear. Most of them will have 2.75 gear, but sometimes you'll get lucky and find a 3.0, and if your really lucky you'll find a posi, but thats pretty rare. Another alternative is the seville disc brake rear, its a 10 bolt. Both rears work, and are plentiful