Thread: years of IRS?

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hello i was interested in maybe putting irs under a project that i'm planning but i'm not sure what all has irs and what years they had it. i've seen things about the t-bird, vette, and jag and i would like to know what years they came with irs and if maybe some other cars had them that would be usable that i haven't mentioned...thanks a lot

Jeremy

Corvette's have had it since 1963. Truimph used them in their TR4's in the early 60's, so they have been around in one format or another for a long time. My 34 Plymouth street rod has a 81 Vette IRS in it. Expensive to acquire and to install and maintain. Would have preferred a standard axle setup, as ride is not the best especially in a car that would be heavier than the donor car.

The Jag XJS has a beautiful IRS and a Powerlock Diff. They give a great ride and are prety bullet proof. Over here in the UK they are a better choice than solid axles and it was first choice for my '56 F100. The only downside is that the discs are inboard and in some cases they can be difficult to get at for service. They also run four coilovers.
Regards from the UK, Rick

The hot rod standards that I have seen most used are first of all, the Jag then next is the 'vette. Both are excellant choices.

The T-Birds are based on Ford's 8.8 differential that is used in almost everything from a Mustang to Lincoln and F150s. I've only seen a couple of the T-Birds modified for street rod use, but there are plenty of rear ends around, cheap (well, within reason) with parts that are easily found at any NAPA. My experience with the T-Bird has been mixed. My '94 had seal problems forever and the dealer warranty was "evergreen" in that I never let him let it run out. The '97 was a Equalock, with disc brakes and trouble free. Unfortunately, stock, they aren't too pretty and dress up parts may not be easily available(yet) plus they are w-i-d-e.

Most other IRS from 4 and V6 imports will never hold up under American V8 horsepower.

Early model (pre '84) Vette rears are not great performers on the track due to their predisposed high center of roll. Stock Jag rears are not that well suited for high HP applications either, and in general lack stiffness at the differential housing and especially at the wheels. There are companies who make Watts type linkages etc to remedy this situation.

Heidts makes a IRS that uses the best features of both types of rears. It is based upon the Ford 9" but uses hefty corvette style 1350 half shafts and uprights and bearings and the wheels. They have heavy duty support arms at the pinion and beafy control arms and trailing arms to stabilize the wheels.

Kitz

Kitz,
You are so correct but they are sure pretty with a bit of dress up and in a street rod, many times that is all that counts.Most cars don't have excessive Hp (>350/400max) and the diffs will last a very long time.

The Jag IRS I am using is from an XJS V12 and also get used in racing.

My friend has a IRS setup out of a 80ish T-bird with disc brakes. He'll probably take $100 for it if you pick it up. It's in Delaware.

I purchased a Jag irs because it was supposed to have a Dana 44 center section,which in 4x4's I've never had a problem. I can't say the same for the 8.8 differential. If I had the bucks,I'd probably get the 9in. center section,but I don't plan on finding one for a 150 bucks like the Jag. It's all a matter of choice and economics, good luck with whatever you use. Hank

Originally Posted by halftanked

I purchased a Jag irs because it was supposed to have a Dana 44 center section,which in 4x4's I've never had a problem. I can't say the same for the 8.8 differential. If I had the bucks,I'd probably get the 9in. center section,but I don't plan on finding one for a 150 bucks like the Jag. It's all a matter of choice and economics, good luck with whatever you use. Hank

Occasionally you can buy an entire old Torino or even a Town Car with a 9" for $150. I purchased a Torino a few years ago, drove it 10K miles as my winter beater, then removed the 351W, the FMX and the 9". The 351 was rebuilt and went into a rod, the FMX was scrapped and the diff sold for $250 and a junky picked up the rest of the hulk free.

I have a feeling that the Jag may end up costing a fair amount before you are done with it - but still, in the end would be my choice though .