'70 Dart 392 Project; what direction?

[208Dart]

Tiny bit more progress.
Got minitub about 50% done. Never done this before but working through it
I’ve got the old wheel tubs all cleaned up and spot welds drilled. I still need to cut my trunk hinges to allow me to place the tubs where they need to be. Might need an extra set of hands to help me mark them.

Also got the mini starter from Mancini. Seems like everyone was correct! From what I can tell it’s almost identical to the dodge 5.7/manual trans starter but upper hole is not threaded. however it still does not fit without some grinding. I milled my block/transmission brass with a 3/8” ballmill. Got that done as well but didn’t snap a picture of it installed.

Mike

 

[erict]

Nice, moving along. I’m about to do the mini tub for the first time too, so watching close. Did you use a cut off wheel or body saw?

 

[208Dart]

Nice, moving along. I’m about to do the mini tub for the first time too, so watching close. Did you use a cut off wheel or body saw?

I used a pneumatic “hacksaw” I bought from harbor freight. Worked great! Also bought an pneumatic punch and flange tool for my filler panels. Bought some 18 gauge stainless that I’ll be using. Will give more tips/mistakes when I’m done!

Mike

 

[208Dart]

Not quite the work of art a lot of guys show but almost got the minitub done. Drivers side is all done, passenger needs a patch at back of tub and some finish welding. Hope to finish this up tomorrow and then I’ll be away for awhile. Next up is sub frame connectors and spring relocate then undercoating…
FYI I was told after the fact that stainless was a bad idea with my 25/75 CO2/Argon gas and standard mig wire. I did a few test spot welds and couldn’t break a spot weld with a 5# sledge so I proceeded. Obviously won’t be as corrosion resistant but the factory metal isn’t anyways…. No regrets there.

Mike

 

[208Dart]

Btw I’m very surprised at how mild the factory frame is. I was compressing the sidewalls with a snug vicegrip! Definitely not like the pickup frames I’ve dealt with!

Mike

 

[TT5.9mag]

I’d say your work looks nice. Little welding, some seam sealer and paint. It’ll look great.

 

[208Dart]

Got everything all buttoned up except for rewelding the trunk braces. Turned out very functional if not attractive lol looking forward to starting/finishing the underside welding so I can mount my springs and build my 8 3/4.

Does anyone know if a pinion snubber is beneficial with the hotchkis springs? I’ve read they aren’t purposeful with caltracs….?

Mike

 

[racerjoe]

Got everything all buttoned up except for rewelding the trunk braces. Turned out very functional if not attractive lol looking forward to starting/finishing the underside welding so I can mount my springs and build my 8 3/4.

Does anyone know if a pinion snubber is beneficial with the hotchkis springs? I’ve read they aren’t purposeful with caltracs….?

Mike

You don't need a pinion snubber with Caltracs because the bars prevent axle windup. I run the Hotchkis springs and didn't have a pinion snubber for a while, but put one on to help prevent axle wind up. I do feel like it was beneficial. Depending on how you drive your car, you may be OK without one, but I do a fair amount of hard standing starts at the autocross and at Moparty when I drag race and speed stop. I've also modified my pinion snubber so there's only about 3/4-1" of clearance before it contacts the floor.

 

[racerjoe]

Not quite the work of art a lot of guys show but almost got the minitub done. Drivers side is all done, passenger needs a patch at back of tub and some finish welding. Hope to finish this up tomorrow and then I’ll be away for awhile. Next up is sub frame connectors and spring relocate then undercoating…
FYI I was told after the fact that stainless was a bad idea with my 25/75 CO2/Argon gas and standard mig wire. I did a few test spot welds and couldn’t break a spot weld with a 5# sledge so I proceeded. Obviously won’t be as corrosion resistant but the factory metal isn’t anyways…. No regrets there.

Mike

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I assume you are relocating the springs inboard?

 

[208Dart]

You don't need a pinion snubber with Caltracs because the bars prevent axle windup. I run the Hotchkis springs and didn't have a pinion snubber for a while, but put one on to help prevent axle wind up. I do feel like it was beneficial. Depending on how you drive your car, you may be OK without one, but I do a fair amount of hard standing starts at the autocross and at Moparty when I drag race and speed stop. I've also modified my pinion snubber so there's only about 3/4-1" of clearance before it contacts the floor.

Perfect answer thank you. I’ll be on the lookout for one for the 8 3/4 build.
Car will be a toy/fair weather driver. Doubt I’ll hit any track more than 4-5X in the life of the car but I’d like to give these 315 series tires every advantage they can get on the street.

Yes I have RMS spring relocate brackets to bring the springs inline with the frame rails.

Looks like I’ll roughly have 2” of width clearance for the tires in the wheel wells. I’m assuming I should place them in the center? Handling logic tells me the wider the better but I’m unsure of how much sidewall flex I’ll have with these.

Mike

 

[racerjoe]

Perfect answer thank you. I’ll be on the lookout for one for the 8 3/4 build.
Car will be a toy/fair weather driver. Doubt I’ll hit any track more than 4-5X in the life of the car but I’d like to give these 315 series tires every advantage they can get on the street.

Yes I have RMS spring relocate brackets to bring the springs inline with the frame rails.

Looks like I’ll roughly have 2” of width clearance for the tires in the wheel wells. I’m assuming I should place them in the center? Handling logic tells me the wider the better but I’m unsure of how much sidewall flex I’ll have with these.

Mike

I've seen the relocation brackets centered, and offset to one side by leaving one side of the frame rail in tact. Obviously if you offset them, you will have to deal with the offset on the rear rail, which may require additional fabrication beyond just drilling a hole and welding a sleeve into the rail.

 

[208Dart]

I've seen the relocation brackets centered, and offset to one side by leaving one side of the frame rail in tact. Obviously if you offset them, you will have to deal with the offset on the rear rail, which may require additional fabrication beyond just drilling a hole and welding a sleeve into the rail.

Sorry I was asking about tire placement in regards to how narrow I cut my axle housing not in relation to where I relocate my leaf springs. Do I center my rubber in the wheel well or do I push it out as wide as possible?

I’m not too worried about cutting into the frame rails. The factory frame steel seems fairly flimsy and the RMS brackets should give it some extra support, though I may weld an additional side plate to mimic how USCT has their design.

Mike

 

[208Dart]

Finally about got this knocked out. Need to fab and reweld truck support brackets but I’ve got the leaf springs relocated and hotchkis springs “bolted in”. Based off my earlier mockup pics I’m going 1” lower and 1” rearward for axle location for now. Also these springs should drop me down an additional inch so it’ll hopefully put the stance where I want it!
Had to turn a .665” OD pilot to fit a 1 1/8” hole saw to fit the existing shackle bolt holes in the frame. Worked great! If anyone wants it let me know and I’ll send it to ya. I don’t plan on needing it again and can always make another one.

I’ve got the undercoating cleaned off for the subframe connectors. Should have those knocked out by weeks end hopefully.

Mike

 

[208Dart]

Got a little bit of a decision to make on the rearend... I've got an 8 3/4 housing here and a 741 case/open with 3:23 gears. Pricing everything out on Doctor Diff's website and I think I'm around $1600 for axles/rebuild kits/bearings/suregrip/brake kit...etc I've emailed Cass a few times, but they're closed for the next week. When I asked for advice on rebuilding my centersection he just sent me the 489 Modular Iron case he offers.

That got me thinking. Just last night I've found 2 different Dana60 truck rearends. One is a Powerlok with 3:54 gears/drum brakes. Older 5x5.5 Bolt pattern.
The other is a newer 2000 Ram 2500 axle with disc brake setup. Gearset unknown, seller says it was recently rebuilt but someone did it wrong so it needs a new gear set and claims it is a limited slip as well.

Both sellers claim they're true D60's and not the D61 or D60HD. So hopefully we'd be good to go there.

Since the work for narrowing the 8 3/4 and the Dana 60 is the same, I'm leaning towards a D60 swap. The drum brake D60 I can buy for $500 (doesn't need gears) and the Disc brake D60 I can buy for $350 (needs gears but has discs already). I'm unsure if I can reuse the calipers and mounting hardware on the Disc brake housing if I narrow and buy 5x4.5 rotors.

Any advice would be appreciated!

 

[208Dart]

Pics of each rearend. @DionR Both of these are close to you. One is in Cheney the Other is Post Falls.

 

[408 swinger]

I know what I would be doing.... Buying those 60s! People don't give the 8 3/4 enough credit. With street tires, you'd probably never break it. But those 60s for sale are awfully cheap insurance.

 

[DionR]

Got a little bit of a decision to make on the rearend... I've got an 8 3/4 housing here and a 741 case/open with 3:23 gears. Pricing everything out on Doctor Diff's website and I think I'm around $1600 for axles/rebuild kits/bearings/suregrip/brake kit...etc I've emailed Cass a few times, but they're closed for the next week. When I asked for advice on rebuilding my centersection he just sent me the 489 Modular Iron case he offers.

That got me thinking. Just last night I've found 2 different Dana60 truck rearends. One is a Powerlok with 3:54 gears/drum brakes. Older 5x5.5 Bolt pattern.
The other is a newer 2000 Ram 2500 axle with disc brake setup. Gearset unknown, seller says it was recently rebuilt but someone did it wrong so it needs a new gear set and claims it is a limited slip as well.

Both sellers claim they're true D60's and not the D61 or D60HD. So hopefully we'd be good to go there.

Since the work for narrowing the 8 3/4 and the Dana 60 is the same, I'm leaning towards a D60 swap. The drum brake D60 I can buy for $500 (doesn't need gears) and the Disc brake D60 I can buy for $350 (needs gears but has discs already). I'm unsure if I can reuse the calipers and mounting hardware on the Disc brake housing if I narrow and buy 5x4.5 rotors.

Any advice would be appreciated!

I've got a buddy that just put a Dana60 under his Dart. Started with a truck axle he got out of the wrecking yard and cut it down using 8.75 housing ends and axles from Dr Diff. I think he was $500-600 into the whole thing. But I think he was only $150 or less into the axle, not $500, and he put stock drums on it.

My bet is the disk brakes on the later one will be useless to you. Unless you want to redrill the rotors or something. I doubt you can find an off the shelf rotor that will match up but with the 5x4.5 bolt pattern, I could be wrong though. So you are probably in for a brake kit either way.

I don't know about the later axle, but I've always heard that doing gears in a Dana 60 is a bear. You have to have a case spreader to get the carrier out and back in. Never messed with one, but doesn't sound like fun.

Because of that, I would lean towards the older axle assuming the gears are already what you want. After buying new gears and getting them installed, I can't imagine the newer axle being cost effective. On the other hand, if you are set on dis brakes and are going to change the ratio anyway (not saying you are, just as a thought), the cheapest one you can get will be the best since you are tossing the brakes on both and have to buy gears and get them setup either way.

On a side note, the 8.75" case isn't hard to rebuild. Not much too it, biggest trick is getting the pinion depth right and if you are just swapping the bearings and re-using the current pinion, shouldn't be anything more than matching or re-using the shims it has on it now.

Another option you might look at is narrowing an 8.8 out of an Explorer. Not my favorite option, but the 8.8 is probably the direction I will go when I do my G3/T56 swap and upgrade to 3.55 gears.

 

[DionR]

Pics of each rearend. @DionR Both of these are close to you. One is in Cheney the Other is Post Falls.

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Willing to help any way I can.

 

[DionR]

I'm unsure if I can reuse the calipers and mounting hardware on the Disc brake housing if I narrow and buy 5x4.5 rotors.

Nothing exhaustive, but did a little looking around to see if I could figure out some 5x4.5 rotors. Started with the parking brake shoe and they appear to be used on a fair number of rigs, unfortunately they are either Chevy's, more Rams or a Ford trucks. This leaves zero options for a 5x4.5 bolt pattern.

There is the possibility that the width and diameter of the shoe is the same as other options, but there wasn't any data to use. So kind of dead ended there.

Best I can tell, those disk brakes won't be useful to you.

 

[208Dart]

Nothing exhaustive, but did a little looking around to see if I could figure out some 5x4.5 rotors. Started with the parking brake shoe and they appear to be used on a fair number of rigs, unfortunately they are either Chevy's, more Rams or a Ford trucks. This leaves zero options for a 5x4.5 bolt pattern.

There is the possibility that the width and diameter of the shoe is the same as other options, but there wasn't any data to use. So kind of dead ended there.

Best I can tell, those disk brakes won't be useful to you.

Really appreciate the legwork on that and confirms what I was suspicious of. At first glance it seems like a great idea, but likely not compatible with my setup. I think the D60 with 3.54's and powerlock is from a 70's vehicle, I'd be going through it anyways with new carrier bearings/races plus pinion seal+bearing. Looks like amazone has a cheap case spreader for $118. I'm sure with the right tools it wouldn't be a problem. I did a ring/pinion gear swap on my 2010 cummins front axle this last year and it wasn't a bad job. I think this will be easier on a bench instead of underneath the truck!

As always thanks for the input Dion! Seems like you're always willing to contribute and it's appreciated.

Mike

 

[208Dart]

Well took a little afternoon trip and snagged that D60/3.54/Powerlok rearend. Got it for $450. Confirmed 3” axle tubes and popped the diff cover and it’s greasy but everything looks solid and turns smoothly. Not a rusted/pitted as the pic makes it look.
Seller actually owns a business building off-road Dana axles and said he doesn’t need a case spreader on these typically but if you use one to use a dial indicator and spread no more than .010-.015” which makes sense why he can usually get them out with two pry bars.

Will likely order the rearend components next week when Cass gets back from a show.

Mike

 

[408 swinger]

I would just leave the gears in it and build from there.

 

[208Dart]

I would just leave the gears in it and build from there.

It’s a good suggestion. Only thing I don’t like about that is no pinion bearing replacement. I don’t like leaking pinions and often even if you replace the pinion seal they will leak again shortly if the bearing is worn. Unsure what I’ll do though at the moment.

Mike

 

[208Dart]

Few more progress pics. Got my sub frame connectors welded in. Not a terrible job, just long with the short weld runs. Not fun without a lift and sparks coming down on you all the time

Also got the Dana60 tore down. No case spreader needed, slight equal pressure on either side with prybars and it popped out easy. I had to dang near melt the drums to get them off the axle ends though. Thank god for torches!

Also was mildly apprehensive on what I’d find the spline count of the axles were. In searching on this year axle number t seems that they received a an oddball 17 spline axle, a 29 spline axle, and 30 spline axles in various configurations. Was excited to pop and axle out and counted 30 splines. This means I can just get a clutch rebuild kit for the powrlok and won’t have to change side gears.

Have talked with Cass at Dr. Diff a little bit…. Still need some questions answered.

Is it better to run equal length axles/tubes on this setup or am I better off mimicking the factory mopar 1 3/16” pinion offset? I guess factory Dana 60 cars had this offset, but since no A body’s came with a Dana 60, is it still applicable?

Also, what size brake lines should I run? Going to be bending up my own. Will visit the brake forum.
Also trying to decide on power brakes or not. Have read mixed reviews on the manual/4 wheel discs. A smaller 15/16 bore Master cylinder seems to be recommended but haven’t heard anyone really praise their manual 4 wheel disc setup.

Mike

 

[DionR]

Have read mixed reviews on the manual/4 wheel discs. A smaller 15/16 bore Master cylinder seems to be recommended but haven’t heard anyone really praise their manual 4 wheel disc setup.

I run C5 calipers on 13" Cobra rotors on the front and the Jeep GC rear brakes with a 1 1/32" master cylinder without power assist. The brake pedal is stiff but it stops well enough.

Kind of feels like pedal effort is a personal opinion so I can't give a recommendation. I know I like mine but I am also working on swapping even bigger brakes on the front so never enough, right?