Repair-It

kevm14 wrote:So quite a bit of work to make it into something you'd really want to use semi-regularly, but nothing impossible.

I did daily drive that car (even in the winter) for the whole time I had it up until the engine came out. I was younger then, FWIW.

kevm14 wrote: 85 mph Speedo really does suck. You could get a later cluster. Either way, you'll probably end up having to get that Dakota Digital Speedo driver, OR, figure out how to adapt the Speedo cable and VSS to the trans.

JTR use to have those parts. Also, I could adapt the Caprice cluster into the Monte, which would put me in a strange mileage predicament jumping from ~115k to ~170k.

kevm14 wrote:

Adam wrote:Also, backing plate to backing place is 51.5" (1308mm), I think.

I believe it is at the axle face. It will be wider there. But at least you have that number and could measure your Caprice.

Yours is 1566mm, which is 61.65". Even adding a few inches for backing plate to axle face, I think you're still looking at an axle that is like 4" wider. And that's the narrow 91-92/9C1 axle. The B-body is a much larger car.

I could always have the axle shortened, but that sounds like a good way to spend lots of money between the housing and getting new (shorter) axles then a new POSI unit with possibly different gearing. It would probably be cheaper to upgrade the carrier in the stock axle then run it until I start making more than 260hp. Or just run the stock axle and not do a lot of one-wheel burnouts.

Anecdotal experience: a guy I used to work with at Ford had an '88 Monte SS. He swapped in an early '90s 454 with truck oval port heads and a mild cam upgrade. He didn't touch the trans or axle (non-posi). He drove the car for at least two years like that w/o doing burnouts and didn't have a problem. That was probably at the 300hp/400lb-ft level with the cam/intake/headers combo. Doesn't sound like amazing output, but considering that is 50% over stock, it really woke the car up.

Adam wrote:First try at the SPID:

With updates...

D71 - MIRROR O/S LH & RH, REMOTE CONTROL, ELECTRIC, MANUAL FOLDING
FC3 - FLEET INCENTIVE MILKE SQUARE TRANSPORTATION (-TRK G)
FC4 - FLEET INCENTIVE MICHAEL BAKER CORPORATION (U/W-TRK CKMLST)
F41 - SUSPENSION SYSTEM, FRT, RR, FIRM RIDE, HANDLING
K64 - GENERATOR, 78 AMP
QYH - TIRE ALL, P215/65R15/N WOL R/PE ST TL HWY
CORRECTION: 11L - SECONDARY COLOR EXTERIOR, DK WILLOW SAGE MET (95)
79D - TRIM COMBINATION, CLOTH, RUBY RED (D) (93)
79I - INTERIOR TRIM, RUBY RED (93
799 - SEAT BELT COLOR, RUBY RED (93)

Additions/corrections in bold.

F41 is sweet. Also was available on the Caprice. One of the rags famously (and probably more than once) had favorable things to say about an F41 boxy Caprice. I think one of them even compared to like a MB 380SEL.

78 amp alt? Seriously?? One of the many nice things about the 90s B-bodies. All LT1s come with a 140A, which is still decent by 2015 standards (but far from the highest currently available). The 90s basically gives you guaranteed access to the baseline modern requirements which were still a crapshoot in the 80s.

215/65-15s? On an SS??

My 9C1 has 79I and is Ruby Red. How about that.

Adam wrote:JTR use to have those parts. Also, I could adapt the Caprice cluster into the Monte, which would put me in a strange mileage predicament jumping from ~115k to ~170k.

http://www.jagsthatrun.com/Pages/SpeedS ... meter.html

I believe you're dealing with the 40 pulse per driveshaft rev VSS. I don't see any parts for that, for some reason.

Adam wrote:

kevm14 wrote:I could always have the axle shortened, but that sounds like a good way to spend lots of money between the housing and getting new (shorter) axles then a new POSI unit with possibly different gearing. It would probably be cheaper to upgrade the carrier in the stock axle then run it until I start making more than 260hp. Or just run the stock axle and not do a lot of one-wheel burnouts.

Anecdotal experience: a guy I used to work with at Ford had an '88 Monte SS. He swapped in an early '90s 454 with truck oval port heads and a mild cam upgrade. He didn't touch the trans or axle (non-posi). He drove the car for at least two years like that w/o doing burnouts and didn't have a problem. That was probably at the 300hp/400lb-ft level with the cam/intake/headers combo. Doesn't sound like amazing output, but considering that is 50% over stock, it really woke the car up.

So axle/diff strength requirements depend on power/torque, transient spikes, and weight/traction. If you don't increase traction, chances are pretty good that you could put 500 hp into the axle and it would be fine. It's when you start adding traction that weaknesses will be revealed.

Think about it this way: what is the maximum input torque that the axle will ever see? The answer is however much torque is required to break the tires loose. And that number doesn't change if you double, triple or quadruple engine output. And in gears where you DO have traction, you are, by definition, putting less torque into the axle than you were in 1st gear when breaking the tires loose. Rolling burnouts at 80mph don't put any more stress on the axle/diff than a burnout at 10mph. And burnouts aren't really that stressful. Now doing one against the brakes does put more stress on everything, but I can't say off hand how much that really adds.

With no reverse peelouts, no one wheel peels and no neutral drops, I'd imagine that rear would be just fine. Until you start adding traction. And on the street, I doubt you can really add enough to destroy the axle if you follow the rules I just mentioned. Oh, and the formula changes if you have a manual trans and you're banging gears. The shift shock transients can cause issues.

The benefit of the 8.5" is really more just because you won't have to think about the axle as much when hooning around. Also hotrod parts for the 7.5" pale in comparison to the 8.5", I think. I'd be surprised if you could even get a Truetrac for example.

I have seen GN 8.5s for not much money which would bolt in to the Monte (the 80's 442 had the 8.5 also). I would guess that all of those are posi. I would have guessed that about the Monte also, but for the Monte it was optional, not standard. That would have increased grip though, to Kevin's point, and I still didn't hear about Monte's blowing the rear even with posi.

I have this in my Caprice:
http://www.eaton.com/Eaton/ProductsServ ... /index.htm

I stand corrected. They do make it for the 7.5":
http://www.summitracing.com/search/prod ... 4294945459

Best posi ever.

kevm14 wrote: Best posi ever.

Helicopter sound effect not included?

That's not the carrier.

kevm14 wrote:With no reverse peelouts, no one wheel peels and no neutral drops, I'd imagine that rear would be just fine.

Myself and some people I know have broken several 7.5" axles (usually spider gears) from doing all the above.