The Mule rides again (sort of) - pics.

Real tech discussion on design, fabrication, testing, development of custom or adapted parts for Pontiac Fieros. Not questions about the power a CAI will give.

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The Dark Side of Will
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Re: The Mule rides again (sort of) - pics.

Post by The Dark Side of Will »

Shaun41178(2) wrote:When do you get back? Been thinking of getting a 3.94 getrag and I need someone to swap the bellhousings and take the proper measurements if you would be up for that
Do you already have the gears or the donor trans?

Judging by the way the shorter 2nd and 4th really work The Mule up, I expect the 3.94 will be pretty nuts across the board. However, with that much gear, turning to 7 makes it much more usable. Do the 3900's do that with minor mods? Do they need ARP rod bolts?
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Re: The Mule rides again (sort of) - pics.

Post by Shaun41178(2) »

I still have to get a trans but they are still on eBay for 400 shipped. The bellhousing needs swapped but I think I read where some measurements need verified when pulling apart to change bellhousings.

I'll have to check but I think gm limited the 3900 to 6500 from the factory. It can do 7k with a valvespring swap. The rods don't need bolts to spin that high but I have them anyways. 3900 has forged crank and rods from factory.
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Re: The Mule rides again (sort of) - pics.

Post by The Dark Side of Will »

Just need to verify that the diff tapered roller bearings are shimmed for correct pre-load when swapping either case half or the diff carrier.

There were a couple of different ratio combos used with the 3.94 final... Are you looking for the 0.81 fifth to slaughter Evos on the highway?
I don't think GM ever built the 3.79 first with the 3.94 final domestically, but international market minivans had it, and I've seen a transmission come back from a rebuilding factory with that combo.

Edit: The HTOB bellhousing uses a different reverse shift rail than the mechanical throw out transmissions... It's hardly any extra effort to change, but is a difference between the two setups.
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Re: The Mule rides again (sort of) - pics.

Post by Shaun41178(2) »

The International gearset ratios is what I think the eBay ones have. I figure with it apart it could be verified. Not sure if the international has the .81 5th or not off the top of my head. Imainly want to do the swap for the better 4th gear
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Re: The Mule rides again (sort of) - pics.

Post by The Dark Side of Will »

Forged rods? I thought GM put PM rods into everything nowadays.

You'll definitely want to stay away from the 3.79 first. The 2.19 second vs. the 2.05 second is more a matter of preference of a little more in-gear acceleration vs. a little higher speed in gear. 2.19 x 3.94 with a 24.7" tire doesn't even crack 60 at 7000, which is getting kinda short.

OTOH, third hits 107 at 7k. With my front end higher than stock on the anti-dive blocks, my headlight doors pop. With the 3.94 and my new tire size, that will come down to 94 mph.

The real beef is 4th as you know. 0.94 * 3.61 = 3.39 overall, while 1.03 * 3.94 = 4.06 overall, which is almost 20% more aggressive. Speed in gear drops from 157 to 131 with just that change, then down to 126 with my new tire size. Top end punch will be nuts when I get the car on the road with my new trans.

If you plan to run beyond 125 or so, consider the 0.81 5th... but that will be something like 3300 RPM at 80.

That question is why I'm planning a 6 speed swap. I can have a 0.81 fifth with 3.91 final AND a 0.62 sixth to cruise like an Isuzu.

Are you going to need me to provide a bellhousing?
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Re: The Mule rides again (sort of) - pics.

Post by Shaun41178(2) »

Yea pm rods. I think I remember reading pm rods are stronger than the old gm forged rods, so I just consider them a forging.

I'm not too worried about first or second. I do most of my racing from a roll in third anyways. I have a bellhousing already. We traded a few years ago straight up internal slave for external.

Its possible to just swap the final drive right?
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Re: The Mule rides again (sort of) - pics.

Post by The Dark Side of Will »

I thought I remembered that I'd sent you a bellhousing.

Yes, the FD can be swapped by itself, but it involves disassembling the output cluster.

However, as I mentioned, a 1.03 4th really wakes the car up for highway rolls.
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Re: The Mule rides again (sort of) - pics.

Post by ericjon262 »

The Dark Side of Will wrote:Of course after I made my last post I went and looked... I was a bit surprised to see how cheap they are.

Doesn't a *LOT* of grease end up between the cones and wasted?

I'm painting Corvette rotors this weekend.
I had a design ready to use 4th gen F-body (F4?) or C5 calipers on Fiero spindles with the 12" 4th gen F-body rotors. I drew them up in OnShape, then spaced the calipers out another 3/8" to fit the 12.75" C5 rotors. I'll have Corvette wheels *AND* brakes on the front end.
Tomorrow I'll order hub centric rings from the same outfit that made my adapters. For the record they are for a 57.1mm wheel pilot journal and a 70.3mm wheel pilot bore. I'll order them with a little extra length to make sure they locate both the brakes and the wheels.

some notes on the calipers. the calipers, are very similar, but I can say for sure the mounting brackets are different, F4 brackets use M12x1.75 bolts to mount the caliper, C5 uses M14 bolts, the spacing however, is the same, right at 5" IIRC. then the pads, the C5 pads will not fit in the F4 brackets, they could probably be made to fit with a flat file and ten minutes though.

have you driven the car with the vette wheels on the back yet? any rubbing? I'm about to order new wheels and tires, and was looking at some 18x9's, but if I can squeeze 18x9.5, why the hell not.
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Re: The Mule rides again (sort of) - pics.

Post by The Dark Side of Will »

ericjon262 wrote: some notes on the calipers. the calipers, are very similar, but I can say for sure the mounting brackets are different, F4 brackets use M12x1.75 bolts to mount the caliper, C5 uses M14 bolts, the spacing however, is the same, right at 5" IIRC. then the pads, the C5 pads will not fit in the F4 brackets, they could probably be made to fit with a flat file and ten minutes though.

have you driven the car with the vette wheels on the back yet? any rubbing? I'm about to order new wheels and tires, and was looking at some 18x9's, but if I can squeeze 18x9.5, why the hell not.
The pics I posted were with the spring removed and the wheel raised all the way to metal to metal contact via a jack... and there was still plenty of clearance. I don't see any chance of problems at any reasonable ride height.

They are the stock 18x9.5 C5 base model rear wheels with 1" thick adapters.

Interesting detail on the calipers. I discovered back in '03ish that 4th Gen F-body calipers & rotors would bolt up to W-body knuckles resulting in a cheap brake upgrade that fit under 16" wheels. The W-body calipers use 14mm bolts as well, so there had to be concentricity spacers to use the 12mm F-body bolts.

I'd read that the Corvette and F-body calipers were dimensionally identical except that the 'Vette units were pressure cast vice gravity cast. I had not read about the difference in bolt sizes, but it's not surprising. I'll leave enough meat in the adapter brackets to be sure they can be used with either 12mm or 14mm bolts.
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Re: The Mule rides again (sort of) - pics.

Post by ericjon262 »

I got a set of C5 caliper brackets in today, and there are more differences than just the bolt size. the bolt spacing for the bracket to knuckle is the same, I haven't yet checked bracket to caliper. the big difference is that the caliper to knuckle bolts are radially further away compared to the F-body. I haven't taken any measurements yet, but it appears to be at least 0.25", clearly noticeable by eyeball.tomorrow morning when I get off work, I'll try and test fit the caliper in the bracket.
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Re: The Mule rides again (sort of) - pics.

Post by ericjon262 »

F-body on the left, C5 on the right.

img_20170413_193118 (1).jpg
img_20170413_193118 (1).jpg (205.79 KiB) Viewed 1902 times
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Re: The Mule rides again (sort of) - pics.

Post by The Dark Side of Will »

That's what lets the C5 Calipers with C5 rotors bolt up to 4th Gen Fbody knuckles.

IOW, the same adapter brackets that mount the F4 calipers to work with 12" F4 rotors will also mount C5 calipers to work with 12.75" C5 rotors.

ETA: Nvm, I was looking at them backwards and it was too early in the morning.

C5 brakes on F4 knuckles require somewhat fancy adapters.
Yes, the two brake setups will require different adapters and the difference will apparently be more than just the difference in rotor radius.
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Re: The Mule rides again (sort of) - pics.

Post by ericjon262 »

I test fit the F$ caliper in the C5 bracket today, fits just fine. so the calipers themselves are the same, except for maybe a slightly different line or bleeder placement.
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Re: The Mule rides again (sort of) - pics.

Post by ericjon262 »

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Re: The Mule rides again (sort of) - pics.

Post by The Dark Side of Will »

Being on the same side of the planet made it easier to measure for the oil cooler than it has been. I was just being lazy until now.
There's over 30" of distance from the inner face of the right cradle rail to the point at which the connection to the Northstar thermostat inlet needs to turn upward. That being verified, I requested a quote for a 3" cooler with 18" core (the longest they make), 3/4" NPT oil connections, a 1.25" water connection on one end and a 1.5" connection on the other end. They have a 50/50 chance of getting the orientation of the drain fitting correct, so I'll let them pick that first because I couldn't concisely state where I wanted it, beyond 90 degrees from the oil fittings.

The different water connection diameters are to connect to the Fiero coolant pipe (1.25") on one end and the Northstar thermostat inlet (1.5") on the other without using any reducer pipe or hose couplers.

I also test fit the C5 ZO6 rear wheel. It needs about 1/8" more spacer than the base C5 rear wheels in order to clear the strut. That means it has about the same offset as the base wheels. I'll have to move it inboard about 1/2" in order to get the outer lip at the same location as the outer lip for the C5 wheels currently is. That will move the inner lip in 1/2" relative to where it is now. Since I can move the strut inboard at least 1", I should ultimately be able to fit an 18x11 on the rear.

ETA: The Accusump I bought years ago which has been sitting in my dad's garage since came with mounting clamps from Five Star Clamps in Crest Hill, Illinois. Their page for additional mounting products is here:
http://www.normaamericasds.com/brand/fi ... /Retaining Products
http://www.normaamericasds.com/sites/de ... 0Clamp.pdf
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Re: The Mule rides again (sort of) - pics.

Post by The Dark Side of Will »

Hmmm.... What are these?

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Re: The Mule rides again (sort of) - pics.

Post by The Dark Side of Will »

The C5 ZO6 wheel has 11 13/32 outside width with 8 1/32 outside backspacing
Therefor the offset is <scribble> 2 21/64 or 59.13mm. If I squint a little bit, that looks like the 58mm spec I've seen on the interwebnets.
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Re: The Mule rides again (sort of) - pics.

Post by The Dark Side of Will »

The Dark Side of Will wrote:The C5 ZO6 wheel has 11 13/32 outside width with 8 1/32 outside backspacing
Therefor the offset is <scribble> 2 21/64 or 59.13mm. If I squint a little bit, that looks like the 58mm spec I've seen on the interwebnets.
The base C5 wheel measures 10 1/16 outside width and 7 7/16 outside backspacing. That is to the "face" on each side, just radially in from the lip representing the extreme dimension. I had to use that measurement because both of my base C5 wheels currently have tires on them.

That calculates to 2 13/32 or 61.12mm of offset.

That's weird because most of the internet says 65mm, while Skulte--who ought to F#$%ing know--says 63mm. ( http://www.skulte.com/adapterfaq.html ). With the result being off by either 2 or 4 mm, that means a measurement was off by 4 or 8mm.
However, Skulte's main site is down, so they may be out of business.

The outer lip on these wheels is oddly profiled and may have skewed my measurement. I can believe the geometry of the puts my width measurement high by as much as 4mm, which would then put my offset calculated from measurements at 63mm.
I can't believe that the lip geometry makes my overall width measurement 8mm high, which would be what was required to put my calculated offset 4mm high.

But if 63mm is the right number, then most sources on the internet are wrong. This wouldn't be the first time--not even the first time in this thread!--but would be mildly surprising.
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Re: The Mule rides again (sort of) - pics.

Post by The Dark Side of Will »

The Dark Side of Will wrote:
ETA: The Accusump I bought years ago which has been sitting in my dad's garage since came with mounting clamps from Five Star Clamps in Crest Hill, Illinois. Their page for additional mounting products is here:
http://www.normaamericasds.com/brand/fi ... /Retaining Products
http://www.normaamericasds.com/sites/de ... 0Clamp.pdf
Well, these idiots told me that the 3" clamp with nylock nut isn't popular with their distributors and asked me to pick something else.

At least Canton has a version of their product that's usable:
https://www.cantonracingproducts.com/cg ... key=24-240

Kinsler has a similar clamp:
http://kinsler.com/Shop/product/mount-b ... ing-holes/
Although it's not clear what size it is and they want WAAAAAAAYYYYYY too much money for it anyway.

Paydirt! Jegs to the rescue:
http://www.jegs.com/i/JEGS-Performance- ... 1/10002/-1
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Re: The Mule rides again (sort of) - pics.

Post by The Dark Side of Will »

I bought some fender washers from McMaster-Carr and bolted up the C5 ZO6 wheel.
I used stacks of three totaling 0.180" to space the wheel out enough to clear the strut.

The base C5 outer lip position was just a hair under 2 1/8".
The C5 ZO6 outer lip position was just a hair under 2 7/16".

This means the ZO6 wheel sticks out 5/16" further with 3/16" of extra spacer. This means that with the same spacer thickness, the ZO6 wheel would only stick out 1/8" more than the base C5 wheel. However, the base c5 wheel has that weird lip profile I discussed above. In light of that, in terms of tire fitment, the difference is probably 3/16" or 1/4".

EDIT: I can't do simple math. The C5 ZO6 outer lip with 3/4" spacers would be in the same position as the base C5 lip with 1" spacers. Fortunately, 3/4" is still a workable adapter thickness. I'm tempted to order one 3/4" thick so it will be ready for test fitting when I get my struts modified.


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