Anyone have a Jaguar IRS write up?

Hasbeen · Postby **Hasbeen** » 27 Oct 2011 04:03

I have resisted saying it for a while, but I can't resist any more.

The E type handled like a heap of horse manure, & it was blamed on that rear end. On the track my cart sprung Morgan ran rings around them. This was in improved production racing, where modifications were limited, I gather they were not so bad after thousands were spent on improving them.

In my experience it has to be a very good independent rear end to equal most solid ones, with just a little tweaking. I would believe most home modified independent rear ends, in a 7 would struggle to be any better than a mildly tweaked standard unit.

A panhard rod, & straight trailing arms, & adjustable coil overs should do it, & so much easier.

It is not by accident that Oz V8 "super cars", have been replacing the original independent rear ends, with a "propper" diff for years.

Hasbeen

FI Spyder · Postby **FI Spyder** » 27 Oct 2011 14:36

I second Hasbeen's view. Contrary to popular belief solid rear axles are much easier to make better than independent ones. The advantages of independent exist mostly on paper. They're more for show than go. Not that it can't be done. Much money and expertise have to be spent on independent rear suspensions to make them better for racing.

- - - - TR7 Spider - - - - - - - - 1978 Spitfire - - - - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - - Yellow TCT

Beans · Postby **Beans** » 27 Oct 2011 18:44

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by FI Spyder

I second Hasbeen's view ... <hr height="1" noshade id="quote"></blockquote id="quote">
Me too.

I think it's a lot of work for something that won't add anything to the handling of the car.
Unless you are doing it just for the fun of it of course [;)]

<center>

1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)
[url="http://www.tr7beans.blogspot.com/"]My Weblog[/url]</center>

mb4tim · Postby **mb4tim** » 28 Oct 2011 12:08

just one thing to remember... When it's all done and cleaned up, it's a sexy bit of machinery that you just don't see every day.

-Tim
http://www.morSpeedPerformance.com

Beans · Postby **Beans** » 28 Oct 2011 13:30

That's one of the problems, I don't live under my car's every day [:D]

<center>

1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)
[url="http://www.tr7beans.blogspot.com/"]My Weblog[/url]</center>

Hasbeen · Postby **Hasbeen** » 28 Oct 2011 13:35

Of course not TIM, you have to put the thing on a hoist, jack the back up, & pull the wheels off it, or run over someone, before anyone will see it. [:D] That is nothing against doing it, if that is what you want.

Our local TRS, the top tarmac rally people in Oz built a rather exotic one, which they offered for sale for a little while, then dropped, so I assumed it did not do much for lap times. They continue with extensively different front ends, & their performances suggest these really do work.

Of course everyone wants something a little different from their car. I have always only been interested in things that made the car quicker, but I have just spent a small fortune on making my 7 slower. However my air conditioning, which will rob some power, will mean I can enjoy the car through our hot summer. [8D] How our requirements change as we age.

I will also enjoy following this project if ignitiommodule goes ahead with it, & wish him every success.

Hasbeen

grndsm · Postby **grndsm** » 28 Oct 2011 14:00

Hasbeen, I love your stories of racing "back in the day"! But I have to disagree that IRS is not as good as solid axle for anything but drag racing.

There are some instances where solid axle will be better developed and have more options to select. Combine this with some old school mechanics who are just more used to it, so they go with what is more familiar.

I know that most cars do not need much camber in the rear, did you ever see what it takes to get any negative camber from a solid axle? And then, there is that entire thing about hitting bumps and affecting the other side...

Yes there have been some horrendous rear IRS in the past, but let's not comdem the entire type of suspension!

Having said that, 99% present of cars on the street do not really need IRS

Originally, I was going to install '94 Miata IRS on my TR7, it is a very nicely packaged, light unit, with seemingly unlimited aftermarket support. But I eventually came to a conclusion that it will not able to handle my Mitsu engine (400-600hp). I will probably go with a Mustang solid axle... But I would recommend a Miata rear end for anyone with under 300 hp (or so).

Leon
'94 Eagle Talon AWD Turbo 613whp <powered by Mitsu 4G63T
'80 TR7 Spyder GS-T <undergoing Mitsu 4G63T transplant

http://www.cardomain.com/ride/2472999

Hasbeen · Postby **Hasbeen** » 28 Oct 2011 15:40

Leon I don't have anything against IRS, all the Brabhams & Lotus I raced had IRS, as does our Toyota Cressida, on which I have put most of its 377,000 kilometers. That is a good IRS, except when you start to tow with the thing.

It was just that the E type rear end was considered a pretty lousy one in its day that made me post.

If you people have found how to make them work, with your experience with rodding that's fine, but with the particularly short wheel base of our favourite cars, I think it makes it harder to get one to work well.

Hasbeen

trekcarbonboy · Postby **trekcarbonboy** » 28 Oct 2011 16:39

I really don't know much about the performance side of this topic but it sure looks like it would add alot of unnecessary weight to the car.

Craig '75 2.0 FHC

ignitionmodule · Postby **ignitionmodule** » 03 Nov 2011 16:37

I do appreciate all the input into this - I had to turn down the last car I looked at, too rough for my needs.

What I'm building is a TR7 with the aluminum Chevy LS engine. Power to weight on the Buick V6 just wasn't quite enough for me.

I had looked to the Jag IRS as a solution because I've rebuilt a few of them over the years and it seems to solve my need to accomodate extra horsepower, get a limited slip under the car and add rear disc brakes with a working parking brake. The LSD XJS rear ends are easy to find over here even though it would not be my preferred model due to the extra modification but even in the street rod community it seems to be the desired choice over some of the "racing" IRS units available.

I don't mind doing something easier, just considering what's available. Still, it should be simpler than the last car I rebuilt...
www.12claws.com

Hasbeen · Postby **Hasbeen** » 04 Nov 2011 03:36

Ignitionmodule, I see your point.

Here in Oz we tend to stay with the solid axle for high powered competition cars, because there are many strong units that are easy to fit, which come with good disc brake set ups, & an LSD that can handle the job.

We have a locally built Nissan unit that only requires the mounting brackets to be changed to fit.

The Nissan unit is the same diff as used in the high performance Holdens. The Holden unit is a little longer, & requires shortening unless you are going for wide arches. It does have a wide range of ratios available, & is the one used in our V8s racing at Bathurst.

I don't know where you are, but this Holden went to the US as the last Pontiac GTO, & to England as the Vauxhall Monaro, or HSV 4 door sedan.

Might be worth a look for you. They are strong enough that my son has not been able to break one, after destroying a number of original TR8 diffs, at about 1 every 500 miles.

Hasbeen

ignitionmodule · Postby **ignitionmodule** » 09 Nov 2011 11:04

Thanks - I'm in the US. Those GTO's are a bit rare but I'll look into it as an option.

Cobber · Postby **Cobber** » 09 Nov 2011 13:10

The GTO diff mentioned by Hasbeen is the IRS version of the Aussie made Borg Warner diff (if my memory serves me correct Designated M80)
The solid rear is the M78 you'll find M78's in GM F body Camaros and Firebirds 1985-90? I believe they are commonly referred to as 9 bolts in the US.
So I sure you should find one of those easy enough, they should be stacked 10 deep at the garbage tip!

For our mates in the UK these found their way into Jensen-Healeys, Some Morgan Plus 8s and some Vauxhalls, although I don't know which one's
There were limited numbers of Aussie made 70's Chrysler Valiants, Chrysler by Chryslers and 70's Ford Falcons, Futuras, Fairmonts Sold into the UK and I believe the Sth African market too.
Aussie 80's Ford LTDs were sold into the UK as was the Aussie made Lonsdale (Mitisbishi Sigma here in OZ)

Borg Warner Aust got taken over by BTR who in turn got taken over by Ion who quickly went broke and the plant got taken over by Spicer (part of Dana)
They are still in production.
You may well find these diffs in other cars over there as well but I don't know which, so I guess you could look for M78 under Dana, Spicer, BTR or Borg Warner brand names

The good thing about these axles is the diff housing is cast steel (not iron) so it can be welded to which makes modifying them easier.
Ratios available:
2.77
2.92
3.08
3.23
3.45
3.73
3.91
4.10
5.13

There are 3 types of Slip Resistant Differential (LSD) center:
Speed Sensitive : Hydratrak SRD
Torque Sensitive : Separated Cone SRD or Integral Cone SRD


80'Triumph TR7, , 73'Land Rover (Ford 351. V8),
'89 Ford Fairlane
85'Alfa 90, 69'Ford F250.
76' Ford F100

Anonymous

Anyone have a Jaguar IRS write up?

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