: Newbie with a towing pkg question



4cammer
02-22-09, 02:12 AM
I asked a guy selling his '94 fwb if his car had the towing package. He said he didn't know and asked me how would he determine if he did or didn't have it. So now I'm asking the same question here.

Thanks,

Skip

sven914
02-22-09, 02:39 AM
On the trunk lid there should be a white label with about a thousand 3-letter codes. Look through the codes for the code "V4P", which signifies the 7,000lb trailer towing package.

4cammer
02-22-09, 02:42 AM
Thanks for the help.

I'll tell him and I'm glad I know where to look now.

Aron9000
02-22-09, 03:06 AM
Please correct me if I am wrong on this. The V4P tow package got you:

3.42 rear gears, still open diff
heavy duty cooling
mechanical cooling fan
trans cooler
stiffer suspension

I think you could tow pretty well with a standard FWB, but anything over 4000-5000lbs would be pushing it. If you're going to tow that much, I think a 3/4 ton truck would be a better bet.

csbuckn
02-22-09, 09:20 PM
3 quick questions for this thread
Was this tow package only available from 90 up? Is the V4P code the same for all years? The tow package had posi?

sven914
02-22-09, 10:23 PM
I believe this package was only available from 93-96.

ssstealth
02-22-09, 10:50 PM
A standardbrugham iratd fortowing up to 5000 pounds. The 7000 pound V4P package is easily spotted under the hood by the mechanical belt driven fan and huge off center shroud.

jey
02-23-09, 06:04 PM
And no Posi with the V4P package, only the standard throttle-killing traction control.

csbuckn
02-23-09, 09:02 PM
So what posi would fit behind the 90 brougham? I thought the 91/92 broughams with the tow package had posi. Is there a caprice that would bolt up with no mods?

dirt_cheap_fleetwood
02-23-09, 11:59 PM
Yeah, does my new '90 350 Brougham have a posi or is it open?

Aron9000
02-24-09, 12:06 AM
Yeah, does my new '90 350 Brougham have a posi or is it open?

My 1991 350 does not have it. And my car has just about every other option, D'Elegance, sunroof, wire wheels, cd player.

csbuckn
02-24-09, 09:30 AM
So, after looking at the service manuals for 90 and 91/92 broughams. In 91/92, there was an option for limited slip with 3.73 gears without ABS. It was only available with the 350. There was an option for 3.73 gears without limited slip also, only with the 350. Then both motors also came with the standard rear axle option with 3.08 gear too. To tell what you have, its says the code is stamped on the right axle tube on the front side or stamped on a metal tag on the carrier cover. Its the first 3 digits out of 8.

4MF = 8.5" gear size, 3.08 gears, standard axle
4ML = 9.5" gear size, 3.73 gears, standard axle
4MM = 9.5" gear size, 3.73 gears, limited slip
these code should be on the inside trunk lid too, right?

1990 was semi floating hypoid only, I'm guessing that means standard axle. It doesnt list the gear ratio that I can see. So whats the difference between limited slip and posi?

dirt_cheap_fleetwood
02-24-09, 12:34 PM
Limited slip and posi are similar but different. Limited slip is between a posi and an open rear end. Limited slip is just a few gear and oil changes to allow less slip through friction. It will allow a little bit of slip and will let you have better traction but if you get completely stuck it will only spin one tire. A posi, on the other hand, has the ability to completely lock the rear axle. Posi is usually a mechanical system in the differential with some sort of clutch that engages and disengages the locking mechanism.

75sled
02-24-09, 02:03 PM
I always heard that a limited slip would lock with heat...such as spinning while stuck so that eventually both tires were being driven. Is this all wrong?

jayoldschool
02-24-09, 03:33 PM
A couple pieces of info to add here. "Limited Slip" is the technical term for a differential that has a feature to direct power to a slipping wheel. There have been many ways to achieve this. Auburn use cone friction, Eaton uses clutches, mechanical locks, and even air or electric. "Posi" is short for "positraction", and that is simply a marketing name from back in the day for limited slip. Every manufacturer had their own name for a limited slip option. I won't bore you with all the different terms, but there are good ones from Pontiac and Chrysler.

On most GM cars/trucks, look for option code G80 on the SPID sticker. No G80, no posi ;)

jey
02-25-09, 05:37 PM
In 91/92, there was an option for limited slip with 3.73 gears without ABS. It was only available with the 350.

I believe that option was only available for livery vehicles or vehicles that were to be converted to limos.



A couple pieces of info to add here. "Limited Slip" is the technical term for a differential that has a feature to direct power to a slipping wheel. There have been many ways to achieve this. Auburn use cone friction, Eaton uses clutches, mechanical locks, and even air or electric.

Or viscous fluids:


Limited slip is just a few gear and oil changes to allow less slip through friction.

All are limited slips differentials - viscous coupling, posi, mechanical, etc. Posi just one form of limited slip.



I always heard that a limited slip would lock with heat...such as spinning while stuck so that eventually both tires were being driven. Is this all wrong?

In theory it works as you described. It appears you are describing a viscous coupling system, where the fluids heat up as the speed differential is sufficiently large, causing the fluid to get viscous. However, also consider that you are relying on the gooey-ness of a fluid to transfer energy to the other wheel that is not stuck. There are definitely limits to how much power can eventually be transferred, and of course it depends on things like the condition of the fluid, and even the age/wear-tear of the coupling mechanism.

csbuckn
02-27-09, 12:29 AM
So which one is a good bolt on performance rear end and what car do I get it from?

ssstealth
02-27-09, 05:03 AM
I use the Eaton posi system. It is easily rebuildable, quiet, and works well. I have had it on now for over 140,000 miles with no problems. It also works very well with the traction control system.

jayoldschool
02-27-09, 12:22 PM
Or viscous fluids:

You can't just add a friction modifier or a higher viscosity oil to an open rear end to make it limited slip.

jey
02-27-09, 01:45 PM
You can't just add a friction modifier or a higher viscosity oil to an open rear end to make it limited slip.

Right, there has to be a whole series of plates in the differential to create the heat that makes the oil more viscous.