I see SLP has there posi units for $99. How much better are they than the stock ones? I am thinking about this instead of getting a 9-inch rear, but I am worried about breaking my rear end. DO you think this will hold up to my power with the slp posi and 3.73 gears???

 

ttt

 

the slp take off unit is better than the stock rear end.. alot better traction.. it will handle 3.73 gears just fine.. if your intrested in have one that im selling.. nothing wrong with it, new bearings.. drove about 10 miles with it in..

 

i'm interested...

will richmond gears that came for the stock 89 RS rear fit or will i need new ones. I have a friend who wants to buy these from me really bad, so doesn't matter much.

 

if the gears were purchased for your stock setup then they will not fit (2.73 being stock gear ratio), the stock carrier is a 2-series while the SLP take off is a 3-series carrier.

 

unit needs series 3 gears .. 3.23 or higher.. email me if you intrested..

 

yeah, let me call my friend , he offered me 150 for my ring and pinion (still in the box) yesterday, so i'll see if he will take me up on that.

 

The SLP posi is nice. From what I saw, you do not need to go 9-inch yet. We have options. If you're on a budget and not planning any major mods, get the SLP posi. Give regards from The Rearman too! We do a lot of buying and selling with SLP.

 

Ok, my engine builder told me if I got traction at the dragstrip, the 10 bolt would break. I don't want to worry about this when I am a good hour and a half from home!! But if you think it will hold up, I want to take your word.

 

Would you mind emailing me your request with phone number? It is important to know what you have and what you want for an end result.

A 10-bolt rear can hold up if you have a good one. For example, the stock 10-bolt is only 7.5 inches and has GM parts. We make an aftermarket rear 8.5 inches with all aftermarket parts which can hold up. That means stronger housing (7.5 to 8.5), stronger axles, stronger posi unit, stronger gears, and Timken bearings & seals. I don't know exactly what you have, but our 10-bolt can do it. For those who need convincing, look at some customer brag pages on our web site www.rearman.com . My friends reside on www.iroc-zpost.com . Webmasters Al Hurst and Sandy Mandel have no complaints! We have 9-second F-body customers, and amazingly not all use 9-inch rears...

 

yeah, I really don't want to spend alot for the rear end. If i have to spend more than $200 not including ring and pinion, I am just going to have my engine builder custom make me a 9inch rear. He can do it for around $800-1000. What do you think i should do?

 

It'll hold up to an engine with those heads, no offense but I find it hard to believe it'll put out 450 hp.
If it does Why put in a slp unit in it? they take these out because they add power to the car. The slp zexel torsen TAKEOUT is not rated for that much power. SLP replaces the factory installed zexel with a heavy duty zexel that costs a little more than the average limited slip. The Zexel Torsen design was intended more for road use not all out drag racing. I was going to get one also but changed my mind. I would go with a 9 inch, the 8.5 would work just as well and keep it all GM.

 

A few years ago I was searching to see if anyone marketed a rear end between the 7.5" and 9"/12 bolt. The GM/SLP Dana 44 was the only one that came up and was (and still is) well overpriced. For the Dana 44 price a basically full race aftermarket 9" can be purchased. I have quoted the e-mail that you actually sent me Yvonne. I am glad I kept it, and even happier that it has your name on it.

"Art said it will be cheaper for the 9" than the 12-bolt rear. Any others
will break.

Ford 9-inch rear $2150 plus shipping
12-bolt rear $3000 plus shipping

It includes:

1) Moser high-strength axles, new
2) high-strength posi unit, new
3) bearings and seals new
4) housing checked for straightness and integrity (guaranteed)
5) housing sandblasted
6) housing painted with enamel
7) complete (backing plate to backing plate)
8) gear ratio of your choice
9) ready to bolt in

If it sounds steep, don't fret. The rear is durable and correct. It beats
replacing it often and/or having an accident.

If interested, please send phone number and address for Art to close the
deal.

Thanks again for contacting Art Houser's Rear End Service and High
Performance Parts.
Yvonne Keller
houser@rearman.com"


Now, I disagree with the e-mail and tend to agree more with your current statement. Most people do not need an aftermarket 9", or even a stock 31 spline 9" for that. But many people are heavily taxing their 7.5" rear end, often to the point it explodes once every year or two. This makes for a big market for rear ends that are beyond the stock 7.5" axle and below the 33 spline 9". I think many people would have a long and happy life with a nearly stock 8.5" ten bolt. But after searching around I found nobody was willing or able to fill that market. The Dana 44 was an attempt but at $1900-$2300 it is a waste of time, might as well get the overkill 9". If your company has added to its product line a more affordable rear end for heavy street use then say so. There is a long and distinguished list of users here that are dying to get away from the 7.5" axle. Look at how many people are getting raped over 9 bolt parts to try to get something above the 7.5" axle without breaking their budget on a $2200 rear end.

 

Dr Pepper - Some of what I said was uncalled for (just like some of what you said) and I apologize for that. I am only trying to provide an option to people that can't afford (or don't need) a 9 incher (like myself). If there was money to be made by selling 9 bolt parts, lots of places would be selling them, but almost no place does. Oh and that is my name by the way and since I run this from home, I always use a PO Box as you yourself indicated the types of people on the internet.

Miles

PS I am not (and never will) tell someone they should build a 9 bolt instead of something else. I will only try to provide accurate information so whoever can make an informed decision.

 

There are ways to add a torque arm to a rear end with a cast iron center. I don't favor them as well as the 9" arrangement or a recast 10/12 bolt but it works. The idea is instead of using all custom/aftermarket parts to produce a killer rear end make a tough rear end using common factory parts. I can't count how many posi 3.23 8.5" axles I have seen under TA's in the junkyard. If they had the proper mounts for a 3rd gen they would be worth a little more than the $60 junkyard price. Probably more like $500 in 100k mile condition. I don't know what the 2nd gen axle width is but with all the people running 4th gen axles or 4th gen wheels with spacers I don't think it would be a major issue.

Ignorant bliss? Seems you are trying your best to pick a fight. It is statements like that which push me away from this board. Perhaps you got upset because I commented that the 9 bolt parts are excessively priced. That has always been true, long before you decided to try to tap the market. $300 for a gear set is rape, and as I recall SLP was getting $300 or $400 for a 3.45 gear set. SLP makes it a habit to overcharge, at least you have an excuse that they are hard to get parts. I suspect you are ordering your parts directly from the land down under. You probably get your share of the pie on them but I would say they cost you more than a quality set of gears for a 9". I was not trying to put down what you are doing with 9 bolts. But it does make a statement on how desperate people are for a good rear end. The 4 pinion arrangement with cones may make a stronger posi, but 7.75" gears will only take so much abuse. Then you still have the small case to deflect the gears and axles under load. I have seen these rear ends missing ring gear teeth just like the 7.5" axle. Do you really care when you are coasting half track which part it was that let go? You point out it handles your big block. Lets step aside from the big block worship. The best time I have seen you post has not hit the 11 sec range yet. One 9 bolt making it to 12 flat doesn't qualify it as a reasonable step up from a 7.5" axle. Some of the people here are able to run 11's to sometimes high 10's without an armload of cash. Is a 9 bolt a good option then? Given my experience with them and their obviously small case and gear set I say no. It is still unreliable and will fail in short time. The difference is now when you blow a gear set its a few weeks later for twice the cost you get new ones. I don't think you have changed the face of the 9 bolt world. If someone can dig one up in good condition with a good ratio then run it. For a couple hundred dollars it is a small step up, well worth the price. It is still too expensive to service and too weak to handle a mean car. For 1/2 of a 9" ($1000-$1200) it is simply a waste of money. You are better off trying to jazz up the 7.5" axle, costs less initially and cheaper to service when it does bust. With a little luck you can find a used 9" or 12 bolt for $1000-$1200. A few machine shops will build stock 28 spline 9" axles for $800-$1000. I was hoping to establish something that more than a couple of people in a small town can enjoy. But if they want to make their living off of selling a few killer rear ends to those who can afford it then so be it. That is the route most shops take. Maybe in the last couple of years they have decided there is money to be made in a budget rear end. He no doubt made mention of a performance 8.5" axle, maybe this is it. If that is true then it should be known so people can go that route if they choose. If they have come up with another $2000 alternative then let it be known but don't expect a crowd.

And as a side note, I have been communicating with people across the internet for more than 15 years now. In that time I have talked to countless people. Some of those people are the closest of my friends. Some I would probably shoot on sight. Most of my e-mail addresses provide enough personal information that someone could drive up to my front door or walk in to my office. Would you disclose that much information about yourself to everyone in the world? I noticed you use a PO Box for your orders and have them sent to a fake name. So this has probably crossed your mind, a wise decision.

 

I'm not interested really in 9-bolts or 12's. I am just wondering if the SLP Posi unit with 4.10 gears (I am trading my friend ) will hold up to the power of my engine. My engine builder found out the HP for my car using desktop dyno with HP being 410 and 350 ft/pounds of torque. Which is a little under what we were expecting, but still enough (for now)

If this will brake, I will just have the guy build me a 9-inch rear end. For $1000, thats cheap for what Im getting. And then gear changes would be easier cause he said 4.56 gears would be best for my car.

So will the 7.5 hold up or should I get the 9-inch?

 

With 4.10 and above gears I don't think it will hold. Those gears are going to give you a high torque multiplication at the rear axles. This torque will be seen by every part of your rear end. Your new torque expectation sounds a little low, most 350's of that category pull about 370-390ft-lbs. Even at 350ft-lbs are you exceeding the factory rating for the axle. There is a little give-or-take due to drivetrain losses. Torque spent driving a water pump is of no concern to the rear axle. A few years ago I dug up a rating for the 7.5" axle of 3700 ft-lbs at the axles. This means with 4.10 gears you can have no more than 900ft-lbs going in to your rear axle. With a 700R4 that means no more than 300ft-lbs after transmission/accessory losses. This is real borderline if the engine produces 350ft-lbs on a dyno. I am not convinced your engine needs 4.10 or 4.56 gears. You may be better off with the 3.73's or even 3.42's, for durability and performance. I have found this 3700ft-lb rating to be a good rule of thumb. Seems when a car has rear end trouble it has been exceeded, but when it hasn't been the rear end usually holds. There are always exceptions and a dozen smaller factors but it seems to work well as a predictor. This naturally doesn't account for smashing the gears on a shift or launching at high RPM. Wish I had a rating on a 9 bolt, but I would say it isn't that much better. If it is a pure race car (4.56 gears, 11.5CR, apparently high RPM cam, sure sounds like it) I would run it till the rear end barfs. But since you seem concerned about relying on it with real low gearing you probably should go to the 9". $1000 is cheaper than you will find it elsewhere and about right for a regular old machine shop just building another custom rear end. Then your rear end worries are over, even if you decide to add to your engine.

Saw you are running a TH-350 after post. That will help out matters a little. You don't have that low 1st gear to tear things up with. Going back to the 3700ft-lb rating that gives you 358ft-lbs in to the transmission after losses. Enough that you should have it covered. In that case I would run it till it blows. Chances are you are fine. Now if you had a 383 or 400, different story.

 

yeah, my friend talked me out of 4.10s so I will run 3.73 with the SLP. Hey $100 if it blows, FOrd 9-inch time. Thanks for responding with that information about the rears.

 

will this fit in a 1986 tpi trans am

 

the slp unit will fit in any 10bolt 7.5 inch..

 

on the slp website is says something about 88 and up and 28 spline axles??

 

yes that is correct must be 28 slpine..