[Lumps!] Question about the rear end

Lumps
21

In reply to a message from exer51 sent Wed 29 Nov 2006:

The rear end can take lots, and will last a lot longer if you set
it up to control axle tramp. I put about 750hp/750tq thru mine in
a road racing application and I’ve never even broken a universal.

Quite a bit in the archives on this.

Cheers, Andrew Robertson, New Zealand
Xj s1 454TT, Xj S1 383–
The original message included these comments:

So my question is, how much power can the stock rear end take, and

–
Andrew Robertson
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22

In reply to a message from exer51 sent Wed 29 Nov 2006:

My two driver Jaguars have 383’s with varying HP and transmissions.
300+HP is enough to move the car briskly on the street. The
determination of performance is gearing - the trans chosen makes
much of the performance possible.

700R is a good choice - I just do not like the drop in RPM between
the 1-2 shift. My Series II car has a 383/700R and will stay up
with late model Camaro’s, Mustangs and the such and has four doors
and is comfortable and cheap to own and maintain.

200R is a better choice - good 1st gear ratio and you do not have
the loss of RPM between 1-2 (also lower RPM’s in OD). My Series 1
has a brand new replacement ZZ4/383 with major HP/Torque, headers
etc and will blow the doors off the above cars and hold it’s own
with AMG’s etc. Same cheap to own and maintain quote.

Using a rear end gear ratio for performance means 3.XX or higher
numbers. Combine the heavy Jag car with a 2.88 and you must have a
good trans gears and low end Torque to move these heavy cars.

The rear end will stand up to 500HP (general quotation from Hot Rod
shops). Use quality engine mounts - ask me how I know the
difference? I use only the Suncoast mounts NOW.

Make sure the steering and suspension is operating normally. Use a
new aluminum Camaro radiator and fan(s, good mounts and proper
exhaust. I plan to switch both my carb’d engines to some form of
EFI for smoothness and economy very soon - carbs work but need
fiddling with. Both of cars are California Smog Exempt so no
inspection requirements from my state.–
The original message included these comments:

few grand on a crate. A new built 700R4 is another couple grand.
So my question is, how much power can the stock rear end take, and

–
'71 XJ6 383/200R, '74 XJ6 383/700R, '74 Nova SS Glendora, CA
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23

In reply to a message from Roger Mabry sent Fri 1 Dec 2006:

Vaughn
I posted re the LS based engine trans combos. Lots of good
suggestions here so far…the only thing I suggest you REALLY
need to do is call Andrew. He has SO much info for you to use. He
has already built all of these combos. He knows the advantages and
disadvantages of each AND he isn’t afraid to share this info with
you. Not to many BUSINESS’S on these forums are willing to do that!
Best of luck.
PS If you go gen II small block, I agree with Roger 100% on the
200R4 trans. Much better 1-2 gear ratios and a lower OD gear. I
have the 700R in mine and I am very happy with it but if I were to
do it again…–
Rob Wade
Windsor Ontario, Canada
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24

In reply to a message from exer51 sent Thu 30 Nov 2006:

Hey guys,

I assure you my engine isn’t going anywhere! I am in fact using
two sets of engine adapters… I am using a Suncoast pedestal kit
and a set of Speed and Performance aluminum engine mount relocation
plates. The Suncoast pieces are well constructed and proven and
Speed and Performance parts have a lot of credentials. They are
very stout pieces! They allow me to put the LS1 exactly where the
older style SBC would sit.

For the trans crossmember I had my girfriend’s dad design me a
custom piece for my 4L80E and it is definitely overbuilt.

As far as the LS1/GenIII engines go, I think they are the way of
the future. Lighter, more power and better fuel economy. The
4L60E is a fine unit for more conventional setups and boy I wish I
had those 1st and 4th gear ratios. I am also using a beefier
transmission to reliably support the torque of a forced induction
setup. My shortblock is built to handle about 800hp at the crank
(honed block, forged rods and pistons, 8.5:1 compression ratio, ARP
main and head studs) so I want a transmission that will take some
serious abuse.

Anyway, I wouldn’t worry too much about the rear end itself. Like
it’s been noted already, you may want to brace the rear end unit
against the chasis and perhaps the traveling portion of the
suspension as well. If running a high HP/torque application, you
are going to have more of a challenge getting the power to the
ground (due to compliance in the independent suspension) than you
will making the rear end last.

As far as computers go, I would advise getting a whole pullout.
The Camaro Z28/Trans Am automatic trans pullouts are the best
because they come with the computer ready to run. Worst case is
that you will have to buy an aftermarket harness to cut out some of
the extra wiring. I think the intake manifold of the truck GenIII
engines is too high for an XJ6 so you may want to be careful with
those. One more thing… I have been measuring and it looks like
the A/C compressor will fit the XJ6 chasis in its stock location.

I will be updating my page sometime this week so keep an eye out!–
The original message included these comments:

An LS1/2/6 however would be awesome. I was looking around on ebay,
and you can find LS v8s with 4L60 trannys for a reasonable price.
Only question is how easy is the engine going to be to bolt in…
The mounts were changed for the LS engines over the old SBC. I have
kept up with this guys project
Dave's Jaguar XJ6 LS1 Swap
Apparently he just used some mount adapters that bolt to the block
that make it fit the old SBC design. I just dunno if that would be
a good thing though, I mean 2 adapters for the engine mounts…
Sounds like a recipe for the engine just falling out of the car one
day when you’re revving it good.

–
1985 XJ6 LS1 turbo project
Pittsburgh, PA, United States
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25

In reply to a message from DYSmooth sent Mon 4 Dec 2006:

Ahhhhh, you guys are killing me… Ok so I’ve now talked myself
into doing a Gen III/IV swap. It’s a better way to go than with the
old SBC, and I think it’s worth the extra money/trouble. However
this means it’s not going to be happening in the immediate future.
I guess I’m going to talk to my mechanic here soon and just work
with what’s in the car for now.

So you had to do all kinds of insanity to get the 4L80 to fit… I
don’t know if I’ll want to deal with that. I’ve had the 200R
suggested over a 700R a few times. I’ve looked it up and it seems
ok. More overdrive is always a good thing. Does anyone know if that
will easily fit into the Jaguar, and will it hookup to a Gen
III/IV? If not is there anything else that will work with the Jag
and Gen III/IV that is better than a 700r?

I just want to kind of plan out the major pieces that need to be
dealt with so I can figure out the budget, and see when I’ll be
able to get it done. Thanks again for all the info!–
Black On Black 1972 Jaguar XJ6 Powered by A Chevy 350
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26

In reply to a message from exer51 sent Tue 5 Dec 2006:

Hi 51,
With a TH 700 which is better locked up you won’t need no extra
electrical worries and with the Right gear in it should handle
the 500 ponies you may eventually get under the bonnet,.
All the best from Kelpie in Australia…–
The original message included these comments:

suggested over a 700R a few times. I’ve looked it up and it seems
and Gen III/IV that is better than a 700r?
Black On Black 1972 Jaguar XJ6 Powered by A Chevy 350

–
nwf
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27

In reply to a message from exer51 sent Tue 5 Dec 2006:

To be quite honest, the best bang for the buck out there right now
for the XJ6 swap is the LT1. Less adapters, great power, great
fuel economy, and you can snag them for a great price. Two major
obstacles you will face with the LS1/GenIII are the oil pan and the
exhaust. You will probably need custom pieces for both. They�re
out there, you just have to pay up for them.

I would advise not doing the 4L80E swap unless you are going over
600 ft/lbs of torque� it�s just not worth it in my opinion. If
going for an LS1, I would try to get a 1998-2002 Z28/Trans Am
pullout with an auto trans. That 4L60E will be great and the
computer will control everything. I am not sure if you would want
to go from an electronic setup back to a vacuum operated one
(200R4.) I would try to keep it simple� if you don�t, your project
will get complicated very fast.

If I were to do it again, I would probably do an LT1/4L60E swap.
If that wasn�t fast enough, I would spend $4k on a supercharger kit
that would have me burning rubber in 3 gears!–
The original message included these comments:

Ahhhhh, you guys are killing me… Ok so I’ve now talked myself
into doing a Gen III/IV swap. It’s a better way to go than with the
old SBC, and I think it’s worth the extra money/trouble. However
this means it’s not going to be happening in the immediate future.
I guess I’m going to talk to my mechanic here soon and just work
with what’s in the car for now.
So you had to do all kinds of insanity to get the 4L80 to fit… I
don’t know if I’ll want to deal with that. I’ve had the 200R
suggested over a 700R a few times. I’ve looked it up and it seems
ok. More overdrive is always a good thing. Does anyone know if that
will easily fit into the Jaguar, and will it hookup to a Gen

–
1985 XJ6 LS1 turbo project
Pittsburgh, PA, United States
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28

In reply to a message from kelpie sent Tue 5 Dec 2006:

HI People,
My info is that the TH 200 needs a Lot of improvement before any
REAL power should be put into it.With my TH700 there is NO kind
of computer or Vacuum devices and my builder/Installer has put
an On/Off switch to contol the solenoid.The only minor problem
I had was that he tapped the power for the switch from the
cigarette lighter which did nothing to improve the operations etc…
One last suggestion…Many good motors I have seen have been
junked because of a cracked head or blown piston etc.,and sometimes
the block and crank are re-usable.[I use a 305 iron crank in my 350
for acceleration even after 97000 miles as fitted and re-balanced I
have had no engine problems in my 3 speed 1978 Daimler… I read
once that there are about 30 good combos to build a S B Chevy motor
and the Choice can be yours.If you don’t want the hassle
and a crate motor is THE priority Then the proven stayer in the
race is the ZZ383/425 Bhp with lots of torque to do do any normal
job.I usually go to what I Know…End of story… Kelpie In OZ…–
The original message included these comments:

suggested over a 700R a few times. I’ve looked it up and it seems
Black On Black 1972 Jaguar XJ6 Powered by A Chevy 350

–
nwf
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29

In reply to a message from DYSmooth sent Tue 5 Dec 2006:

So you wouldn’t go for the extra trouble of the LS1 if you started
over? Custom exhaust wouldn’t be too bad. The oil pan however…
You got your setup figured out, correct? What did you do to fix the
problem? Seems to me if I went with a 4L60 and a Gen III/IV things
wouldn’t be too tough assuming the oil pan isn’t terribly hard to
deal with.

More expensive, yes. Awesome, yes. I was raised a Ford/Mopar fan
but the LSx V8s have damn near turned me into a Chevy boy these
last few years. They really are great engines. I’m not just
thinking about this from the initial cost for performance. I think
an LSx engine would be a lot easier to live with once the initial
hassle was taken care of. An LT1 would offer most of the same
benefits for a fair amount less, but the LSx engines are just a bit
better all across the board.

Besides, since it’ll be put off for the LSx engine maybe I’ll be
lucky and someone will release a kit for it before I get around to
it! I think the first person to come out with a proper be-all-end-
all kit for an LSx engine would make a KILLING. I mean if someone
made a custom oil pan, proper mounts, and a piece that makes the
exhaust easy I think they’d start flying off the shelves.–
The original message included these comments:

obstacles you will face with the LS1/GenIII are the oil pan and the
exhaust. You will probably need custom pieces for both. They�re
If I were to do it again, I would probably do an LT1/4L60E swap.

–
Black On Black 1972 Jaguar XJ6 Powered by A Chevy 350
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30

In reply to a message from exer51 sent Tue 5 Dec 2006:

Your 4L60E is the electronically controlled version of the 700R so
those two transmissions are a wash with each other. Both will
handle good power levels. If you go LT1 DO NOT be scared of the
200R (bowtie overdrives .com) Just ask Roger Mabry. He got his from
them and LOVES that trans. They will handle as much power as the
700/4L60’s when built equally. The 700 has a large RPM drop between
1-2 gear, that is annoying to say the least. Go to any performance
sight where 700R’s or 4L60E’s are in these cars (Third gen .org,
camaro forums etc) and you’ll read alot from people complaining
about the 1-2 shift. You have to buy a trans, so buy the right one
the first time. Personally I would go with the little extra
aggravation and cost of the LSx combo’s.–
Rob Wade
Windsor Ontario, Canada
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31

In reply to a message from exer51 sent Tue 5 Dec 2006:

Sorry, can’t edit posts here…one more thing. The 4L80E is one
HEAVY a-- transmission. Its a T400 (strong) with overdrive and it
ways ALOT more than the 700, 200 and 4L60E’s.–
Rob Wade
Windsor Ontario, Canada
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32

In reply to a message from Rob Wade sent Wed 6 Dec 2006:

Hi People,
WHAT is it about this pedantic problem about 1 to 2 change on
any of the 4 speed TH’s??
Did ANYBODY research the Stall speed of the convertor in
realistic comparison to the Torque spread of the motor supplied and
the diff ratio which has the Final say in the matter.Seeing that
2/3/4/speed G.M. Auto gearboxs have been fitted behind Chev motors
for decades now and the variables are readily available for ALL to
see if needed.We all without exception are indecisive on some
matters and the great amount amount of possibities does blur one’s
judgement.
On my 1974 Daimler which has a 3.54 six cyl diff 1st gear is
rarely used for more than a few seconds and the 4th gear in the TH
700 is excellent on the open road…I for one have got what I have
always believed to be the perfect combo and if I ever haul a C/Van
the 1st gear will earn it’s keep…
Each to their own and after all it is your money…Whatever you
decide Good luck & don’t do it twice…All the Very best.Kelpie in OZ–
The original message included these comments:

700/4L60’s when built equally. The 700 has a large RPM drop between
1-2 gear, that is annoying to say the least. Go to any performance
Rob Wade

–
nwf
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33

And parasitic, too. …just like the old 400.

Doug Dwyer
Longview Washington USA
1995 XJR
1988 XJS V12 Coupe

Sorry, can’t edit posts here…one more thing. The 4L80E is one
HEAVY a-- transmission.

//please trim quoted text to context onlyFrom: “Rob Wade” robsxjs@hotmail.com

34

In reply to a message from Rob Wade sent Wed 6 Dec 2006:

Hi Rob,
The TH400 G/box in any form is costly to run at at least 1 or
more mpg in theory…BUT…what price comes for the relability
that it’s reputation is based on.No grey area on this one.
All the best from Kelpie in OZ…–
The original message included these comments:

HEAVY a-- transmission. Its a T400 (strong) with overdrive and it
ways ALOT more than the 700, 200 and 4L60E’s.
Rob Wade

–
nwf
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35

In reply to a message from exer51 sent Tue 5 Dec 2006:

Well, it all depends on what your goals are. If you want to get
your Jag on the road and start enjoying it at an affordable price,
I�d go for the LT1 swap. If you want a unique but long drawn out
project with lots of issues to resolve and money to spend, go for
the LSx swap. I have driven stock LT1 cars and LS1 cars and
they�re tough to tell apart performance wise. If you need more
power, get a Vortec supercharger kit� I bet the only problem you
have with the 1-2 shift is going to be traction! :o)

I think there is some potential for an LS1 kit, but it will not
give you the bang for the buck that an LT1 kit does. By shape, the
LS1 will let you move it farther back into the Jag engine bay,
perhaps giving your oil pan additional room, letting you use a
stock oil pan. The problem is that when you move the engine back,
you will be creating interference with the A/C compressor. The
exhaust is still going to be an issue� every stock manifold I have
found interferes with the narrow engine bay.

Want to have something different? Start measuring the GM 4.2L
straight sixes! I had a junk one sitting in my shop and it was
really teasing me� I�m too far into my LS1 swap now to turn back.–
The original message included these comments:

So you wouldn’t go for the extra trouble of the LS1 if you started
over? Custom exhaust wouldn’t be too bad. The oil pan however…
You got your setup figured out, correct? What did you do to fix the
problem? Seems to me if I went with a 4L60 and a Gen III/IV things
wouldn’t be too tough assuming the oil pan isn’t terribly hard to
deal with.
Besides, since it’ll be put off for the LSx engine maybe I’ll be
lucky and someone will release a kit for it before I get around to
it! I think the first person to come out with a proper be-all-end-
all kit for an LSx engine would make a KILLING. I mean if someone
made a custom oil pan, proper mounts, and a piece that makes the

–
1985 XJ6 LS1 turbo project
Pittsburgh, PA, United States
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36

In reply to a message from DYSmooth sent Wed 6 Dec 2006:

Seconded!

The LS1 is a very interesting engine. Does it really need the 4L80?
why not use a 4L60?

The LS1 pan is aluminum, I think and as such sectioning is a more
difficult project than a tin LT1 pan, right?

My 83XJ6 is lumped with a 94 Cadillac LT1 and 4l60e. Smooth, quiet,
fast and economical. It is a great combination. I have to maintain
it, but the car is 23 years old and the engine trans is 12 years
old, so what do I expect?

GM High performance magazine wrote a series of articles on
improving the LT1. I learned a lot there. Presently, they are
publishing a series of articles on the LS1. Very interesting!

One project was an LS1 in a Solstice, I think!

Andrew at Jaguar Specialties has a ‘‘kit’’, I think!

Carl Hutchins, Jr.–
The original message included these comments:

Well, it all depends on what your goals are. If you want to get
your Jag on the road and start enjoying it at an affordable price,
I�d go for the LT1 swap. If you want a unique but long drawn out
project with lots of issues to resolve and money to spend, go for
the LSx swap. I have driven stock LT1 cars and LS1 cars and

Besides, since it’ll be put off for the LSx engine maybe I’ll be
lucky and someone will release a kit for it before I get around to
it! I think the first person to come out with a proper be-all-end-
all kit for an LSx engine would make a KILLING. I mean if someone

–
Carl Hutchins
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37

I have 2 lt1’s. one is putting down 406 hp to the rear wheels on pump gas in
my 85 XJ6. smooth economicala d reliable. Ive been running it 6years and
have only changed the coil! It has about 150,000 miles on it. Just for the
fun of it I built a new LT1 hoping for 600 hp naturally asperated. I’m
hoping to swap them over Christmas break. My 4l60e has been used and abused
severly. The tail shaft leaks due to a unballanced drive shaft. I will be
fixing those issues when the engine swap takes place. The lt1 4l60e combo
can’t be beat!

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38

In reply to a message from cadjag sent Wed 6 Dec 2006:

HI Carl,
I read in a CHPP Book where G.M. Had a Carbureted manifold for
The later LS Motors.It shows the photos of the parts and factory
numbers.
IF any body wanted to repower a non pollution car they can have
the old style carbs of available choice without the costs of the
computers and more electricks etc.,
Where there is a will there is a want…All the best…Kelpie…–
The original message included these comments:

The LS1 is a very interesting engine. Does it really need the 4L80?
publishing a series of articles on the LS1. Very interesting!
Carl Hutchins, Jr.

–
nwf
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39

In reply to a message from Gary Etsell sent Wed 6 Dec 2006:

Hi Gary E.
If you go for the 600 BHP in your project motor I would like to
Know All the details of the proposed Camshaft and Kit that is on
the menu.I presume that .7’’ has been considered for valve lift?
Sounds Great and Good Luck from Kelpie in Australia…–
The original message included these comments:

I have 2 lt1’s. one is putting down 406 hp to the rear wheels on pump gas in
fun of it I built a new LT1 hoping for 600 hp naturally asperated. I’m

–
nwf
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40

In reply to a message from kelpie sent Wed 6 Dec 2006:

Trans Type First Second Third Fourth Fifth
ALLISON 1000 3.10 1.81 1.41 1.00 0.71
POWERGLIDE 1.82 1.00 - - -
POWERGLIDE 1.76 1.00 - - -
Turbo 4L60 3.06 1.62 1.00 0.70 -
Turbo 4L60E 3.06 1.62 1.00 0.70 -
Turbo 4L80 2.48 1.48 1.00 0.75 -
Turbo 4L80E 2.48 1.48 1.00 0.75 -
Turbo 350 2.52 1.52 1.00 - -
Turbo 400 2.48 1.48 1.00 - -
Turbo 200-R4 2.74 1.57 1.00 0.67 -
Turbo 700-R4 3.06 1.62 1.00 0.70 -

Here are the gear ratio’s on all GM rear drive transmissions. As
you can see, there is a substantial difference in the 1-2 shift on
the 700R(4L60E) and 200R transmissions. In a jag with a little more
gear than a 2:88 it isn’t such a big deal but pull your 4000lb jag
with a 2:88 and that 1-2 rpm drop is very noticeable. If your a
performance orientated kind of guy, its downright annoying! I even
run a 2800 stall lock-up converter in my xjs and it does help
somewhat, BUT at the sacrifice of some around town fuel economy.
Now, I would LUUUUUUUUUUUV to find a 3:07 posi to put in my combo.
Don’t get me wrong, I am very happy with my current TPI/700R4/2:88
combo BUT I would do the car differently IF this drivetrain weren’t
in the car when I bought it AND I was starting fresh.–
Rob Wade
Windsor Ontario, Canada
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