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View Full Version : IRS differential covers vrs irs brace


ausie
01-20-2010, 03:52 PM
I am looking into upgrading my IRS differential and gears. I still have the stock aluminum cover and no brace. I would like to know if anybody hear has experience or knowledge of the components I am interested. Comments please.

I have been searching for components and what I found so far:

Differential covers:

LPW Differential Cover and girdle support. Thicker wall construction but looks like a cast piece. Cost is $219.00


FORE billet IRS Cover: This is a very nice piece at $440.00 made from billet aluminum. High strenght CNC component (not cast).
http://www.foreprecisionworks.com/0058-200.html

Rear suspension components:
Kenny Brown hard launch differential cross member support brace and aluminum bushings.

Since most of the mods will require removal of the IRS assembly, I may as well have the gears replaced, new bearings installed, and the differential rebuilt considering the mileage is at 50k.

puzzle13
01-20-2010, 10:13 PM
I had the stock cover with a Steeda Brace and never had any problems except for a small seeping leak due to heat & abuse. When I changed the fluid and resealed the leak no longer existed. Due to the amount of work involved in changing the diff fluid ... you must remove diff from Irs and drain, clean, reseal ... then install & fill, I bought the FORE Billet cover and it is a beautiful piece! Nicely done and has all the ports for a cooler, temp gauge, and drain. I have a cooler installed and a gauge due to my track use. The unit is very strong and is not supposed to leak due to an o-ring for sealing. That is where the accolades stop!!!!!!!!! The cover is very thick & strong, but this causes the fluid to heat up more and it will spit fluid from the vent tube with just normal driving in hot weather. They include a expansion tank to install to help with this problem, but in my humble opinion the expansion tank is too small and you have to vent it somewhere ... they suggest through the gas tank fill area, but what about water & gas that gets in that area possibly getting into the rear diff? I am also having leaking problems with mine and it has not had a lot of use. Granted it was track duty, but no more than 6 days on track and mine is vented into the trunk with an expansion tank a little bigger than theirs and it still spits until you get the fluid level correct. My expansion tank sits just under the trunk lid, so it is at least 1.5 feet above the diff and it still will spit. It is very hard if impossible to check the fluid level with a cooler on due to the arrangement of the ports. I fill mine through the expansion tank. If you are not doing track duty & do not need a cooler, I do not recommend this cover. Stay with stock & put on a brace.

I am looking into upgrading my IRS differential and gears. I still have the stock aluminum cover and no brace. I would like to know if anybody hear has experience or knowledge of the components I am interested. Comments please.

I have been searching for components and what I found so far:

Differential covers:

LPW Differential Cover and girdle support. Thicker wall construction but looks like a cast piece. Cost is $219.00


FORE billet IRS Cover: This is a very nice piece at $440.00 made from billet aluminum. High strenght CNC component (not cast).
http://www.foreprecisionworks.com/0058-200.html

Rear suspension components:
Kenny Brown hard launch differential cross member support brace and aluminum bushings.

Since most of the mods will require removal of the IRS assembly, I may as well have the gears replaced, new bearings installed, and the differential rebuilt considering the mileage is at 50k.

ausie
01-21-2010, 05:43 PM
Thanks for the reply Puzzle13! I read some of your posts in another website (Assuming you used the same name). The part looks beefy but considering the issues many have had with it, the best route for me would be to stick with the stock cover and add the BilletFlow brace.

There are not too many shops in my area that are performance/speed shops that will tackle the rear end, especially with the gears, etc.... If the housing and cover are still in good shape, best to keep the two mating parts and not get aftermarket covers, although the LPW cover seems like a good deal.

Considering the issues I have with the rear end, sometimes the differential slips momentarily and I go no where then all of a sudden it kicks in. Traction-loc needs to be rebuilt. I will take it one step farther, have the differential replaced with a turetrac so I no longer have to worry about clutch packs in the differential as well as eliminate friction modifier.

Now for the gears, may just keep the 3.55's if they are in good shape. I would rather spend the money used for the gear set somewhere else. Would 3.73 make a difference or not. More research is at hand.

STACYSTANGZ
01-22-2010, 10:11 AM
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STACYSTANGZ
01-22-2010, 10:51 AM
First all, the primary function of the cover is for strength...there are a handful of guys out there who have shattered their OEM diff cover WITH a brace. I challenge anybody to break our piece.

Just for the record, Michael (aka puzzle13) told me that he was discharging fluid with his OEM cover. I agree, our cover made his problem worse since our cover has more mass and less surface area...which is opposite of how you would design a heat sink...but this is the price you pay for the added strength. Michael runs his car on the track...and a catch can was collecting two ounces of fluid per track session in the middle of the summer with no differential cooler. He is using his own expansion tank that feed and drains from the side, so it accumulates some amount of fluid in the tank that never gets returned...and sloshes around in his tank until it gets returned. Our expansion tank will hold 8.5 ounces and feeds/returns from the bottom, so all the fluid always flows back to the axle housing on cool down.

He has since installed a diff cooler, and I apologize that I don't have a lot of choices of where I can put the ports. I've done the best I can do here and am not making any changes. Likewise, I really don't have room to put a dipstick, and I'm not going to run up the cost another $100 to put in a proper sight gauge.

If I remember correctly, his cover has been installed and removed several times which could have damaged the o-ring...we have a replacement o-ring if you need one.

I don't agree that an expansion tank is not for street cars. It is OEM on the new GT500. Ours mounts behind the trim panels in the trunk, so it is completely unseen once installed.

Michael, I'm sorry that you've had problems, but even after six months, my offer is still on the table to return the cover for a refund.

Justin Fore

puzzle13
01-22-2010, 03:15 PM
Stacy,

My cover has only been installed one time and never removed. It was done to all the specs that Justin specified to the guys at Pro Dyno. My stock cover was in fact spitting a little bit of fluid, but very little especially compared to the Fore cover. Yes, I doubt that this cover will ever break and that is one reason why it is still on the car! All I know is that with a cooler this cover still makes the diff fluid run around 220 degrees if the ambient temperatures are above 85 degrees. As to the offer for a refund ... this is the first I have ever heard of it. I have not given up on the cover ... I hope to find out why it is leaking soon. The car has been on jack stands for 2 months and the diff continues to leak. I just have not had the time to get around to it. Concerning the expansion tank ... my comments were my opinion on whether I would want to have an expansion tank on a car that is only driven on the street. My original cover only spit after a weekend at the track, but I honestly believe that any driving for more than 30-40 minutes in hot summer weather would cause the Fore cover to spit. My recommendation was for somebody that said his car was only a street car with very limited time at the drag strip.

First all, the primary function of the cover is for strength...there are a handful of guys out there who have shattered their OEM diff cover WITH a brace. I challenge anybody to b

reak our piece.

Just for the record, Michael (aka puzzle13) told me that he was discharging fluid with his OEM cover. I agree, our cover made his problem worse since our cover has more mass and less surface area...which is opposite of how you would design a heat sink...but this is the price you pay for the added strength. Michael runs his car on the track...and a catch can was collecting two ounces of fluid per track session in the middle of the summer with no differential cooler. He is using his own expansion tank that feed and drains from the side, so it accumulates some amount of fluid in the tank that never gets returned...and sloshes around in his tank until it gets returned. Our expansion tank will hold 8.5 ounces and feeds/returns from the bottom, so all the fluid always flows back to the axle housing on cool down.

He has since installed a diff cooler, and I apologize that I don't have a lot of choices of where I can put the ports. I've done the best I can do here and am not making any changes. Likewise, I really don't have room to put a dipstick, and I'm not going to run up the cost another $100 to put in a proper sight gauge.

If I remember correctly, his cover has been installed and removed several times which could have damaged the o-ring...we have a replacement o-ring if you need one.

I don't agree that an expansion tank is not for street cars. It is OEM on the new GT500. Ours mounts behind the trim panels in the trunk, so it is completely unseen once installed.

Michael, I'm sorry that you've had problems, but even after six months, my offer is still on the table to return the cover for a refund.

Justin Fore

puzzle13
01-22-2010, 03:23 PM
Ausie,

You don't need to install a TruTrac unless you want to spend the money. I considered the same thing, but after talking to a company out of Florida that sells all of the TruTrac, etc. and rebuilds the stock ones I changed my mind. I instead just had a new clutch pack installed, but used the carbon fiber kit that is for the GT500. These handle the heat better and are supposed to last longer. Mine were changed at around 18,000 miles. I also installed the 3.73 gears. My opinion on that is ... for a street car, if you do a lot of highway cruising and are concerned about gas mpg ... don't. It definitely changes your shift points and will give you some extra punch out of the hole, but I did mine due to track duty. As to the brace for the back ... I am not familiar with the other one you specified, just be careful about fitment prior to ordering. There was another type out there that had to be modified to fit as it was mainly for a solid axle car. In that case, fitment, the Fore differential does fit wonderfully. The Steeda brace works well with the stock cover and does cost a little less than the billet one and you can't see either one unless you are under the car.
Thanks for the reply Puzzle13! I read some of your posts in another website (Assuming you used the same name). The part looks beefy but considering the issues many have had with it, the best route for me would be to stick with the stock cover and add the BilletFlow brace.

There are not too many shops in my area that are performance/speed shops that will tackle the rear end, especially with the gears, etc.... If the housing and cover are still in good shape, best to keep the two mating parts and not get aftermarket covers, although the LPW cover seems like a good deal.

Considering the issues I have with the rear end, sometimes the differential slips momentarily and I go no where then all of a sudden it kicks in. Traction-loc needs to be rebuilt. I will take it one step farther, have the differential replaced with a turetrac so I no longer have to worry about clutch packs in the differential as well as eliminate friction modifier.

Now for the gears, may just keep the 3.55's if they are in good shape. I would rather spend the money used for the gear set somewhere else. Would 3.73 make a difference or not. More research is at hand.

ausie
01-22-2010, 05:30 PM
I appreciate the input from everyone. Thank you. :thumbsup:

Just one point, I do like the FORE cover and I am sure it is a well engineered part. I was happy to see some more products available for the 03/04 terminators. What inspires me about the FORE differential cover is the strengh of the part. I would prefer a CNC machined part made from a quality Alloy that you may not get from an aluminum casting.

I know that the differential housing can be destroyed easily and not just the cover. I have seen countless pictures of blown rear ends of the production cars which is the one reason why Ford delayed deployment of the IRS in the mustang due to the same issue during development. The differential brace is just an afterthought and probably does not fully displace all of the forces exerted on the differential cover. Since it is a cast part, there could be some unseen flaws in the casting and with time those forces continue to weaken the part even more until fracture. Another issue with the IRS differential housing is that it will not hold up well to change in load when replacing the rear gear.

My desire is longevity and a component that will endure and perform the task it was design for. I have found differential housings that were made from cast iron with an aluminum cover but the cost is too high for my budget.

I would prefer to use a different differential other than the trac-loc setup I now have. It still works fine even with the clutch slip but there are better differentials on the market. The truetrac seems to have the drive characteristics I am interested in based on many reviews I have read. No I do not run opentrack events but I drive on backroads that are demanding. As for the heat and overflow of the diff fluids, using the truetrac should reduce operating temperatures as well as eliminate the requirement for friction modifyers which add to the heat as well as having the cost of disc replacements when they wear out.

The cooler option is a great idea but I will not require it (having that as an option is with the ports in place also makes the FORE part desireable) As for an expansion tank, perhaps one with a suitable foam breather to prevent dirt and moisture from contaminating the fluid as well as allow for vapor emmission to reduce pressure buildup from the heat. Not sure what would be sanctioned by the SCCA, IROC or whatever governing association for track use, but on the street there probably is not much regulation requirements to pass other than CARB. Most SRA's have a vent tube that will dump fluids out if they expand beyond the capacity of the differential case.

I still have interest in the FORE cover, but it is a bit high in cost for my current budget. Something to consider. As for the gears, I will keep the 3.55's and only replace the differential. I will try to decide by next week. I have seen a few places to purchase the FORE cover as well as all the other parts. I have ideas where to get expansion tanks and such as I have found many doing research looking for that perfect setup to replace the PCV system with breathers and catchcans used in racing applications.

I am still doing some research on the topic so the more information I can gather the better my decision will be.

ausie
01-22-2010, 05:35 PM
Stacy,

The expansion tank you mentioned, is that included in the cost of the cover or is it an additional cost? I have only seen listings for the cover itself and not sure if the listing has been updated.

Thank you

Eric