Hi all im new to the site so thought i would do the thing and say hello.

Im currently not driving any 4x4 not even a landy!!!

At present im considering building Tomcat.

spec still being worked out.

Any help with regards to diff ratio's etc would be most welcome.

regards

adam

Welcome, I take it you're also a Fiat fan.

Yeah used to like the old 131 dont see much about these days.
Thanks for welcome...

Anyway Gang im needing some advice surely theres a forum or some build thread somewhere of A Tomcat under construction???

What you think of this spec..

Disco 2 Chassis wider axle.
3.1 TD Isuzu unit.
R380 Gearbox.
transfer box unsure Think possibly 1990/92 Range rover classic for viscous coupling.
Diffs 4.1 ratio aval from tomcat motorsport.
or alternative.

regards adam
Anyone want to add any suggestions??
Drive train strong enough for engine torque figures etc??

Well there are a number of ways to look at this and I'm not sure which answer to give.

Some things to consider. You will be looking at about 2000 hours build time for a Tomcat. If that is just weekend and evenings then the build will extend into years. There are a number of 'abandoned projects' for sale; this is both a warning and an advantage. You could use one of these as a starting point, altho' there maybe a lot of work that you wish to 're-do'.

Looking at the spec list you give so far it looks pretty good. You do have to ask yourself what sort of thing do you wish to do in the Tomcat when finished. The Isuzu engine is a good all rounder, but would not really sure any high speed events.

The LT230 transfer box would always be my choice. The VC can work well but are not know for their ruggedness. The R380 is a good choice too. I assume you have factored in a converstion kit to link the Isuzu to the R380.

With regard to the Disco 2 axle the wider track is only of benefit for high speed stability when off road. The internals are also expensive to upgrade and maintain. Additionally the Watts link used to locate the rear axle is great for stability but gdoesn't do much for axle travel. Again it returns to the 'what is your intended use' question. It does affect eh whole build To be honest I would go with a RRC style chassis and axle combination. More availabillity of spares and upgrades.

Hard to say why you opted for the 4.1 diff ratio unless you are considering some fairly big tyres, in which case I would also look at getting a 1.6 ratio LT230 transfer box out of a D110 to maintain a reasonable off road low range. Of course if you go the ZF auto route rather than the R380 then you will be that this problem is somewhat negated.

My most recent experience in this area is with a D-Lander build. It's main donor was a TD5 D90; used engine, axles and suspension. The gearbox was an auto from a Disco2. This was with me for 6 months and has been returned to the owner for final finishing (cockpit interior and winch fitting)

Hopefully that gives you an idea of the scale of the project. All the thought and sketching and planning you do now costs nothing......but as soon as you start building, it can be harder to undo

Diff ratio's where suggested by Paul at Tomcat. and Andy i typed in incorrect ratio> it's meant to be (4.75)
As for Transfer box 4cyl defender (1.38 was suggested for accelration ( Or rrc viscous for reasonable top end and donut ability lol)

Chassis type changed to RRC.
Along with axles easier to pick up and cheap.

Engine choice has been changed.
After checking out conversion kits for isuzu to R380 box
and the cost of buying an engine+wiring loom and the fact that paul would need to modify engine mounts etc and he dont no if it would fit anyway.

Decided

That it would be easier and cheaper just going for a late disco 4.2 v8
and use it as a donor car for engine and loom plus performance wise also.

I can sell off the panels/doors etc + interior and bits i dont need maybe make some cash back.
No mods to 100" chassis as it's designed for the engine anyways and should give better performance power wise at cost of fuel

Im not a big fan of rover V8's (SORRY ALL) or Automatics for that matter.

4x4 is to be 60% on road and 40% off. However a trip down to capetown would be fantastic and defo on the cards.

Build time 18 months max.

Andyb any comments on drive train now? The more input i can get the better!!!

Adam

I'm still intrigued as to why you want such low geared diffs.

A complete donor vehicle is a good idea. That way you will have everything that you need, including all the little bits that you just don't think of at the start As an aside, the D2 steering box is also pretty robust and a favorite amoungst the offroad race community.

As for drive train, I would go for 24 spline with Ashcroft internals. Maybe a pair of 4-pin diffs if you can find them. If you want locked diffs then ARB or Jack Mac are favs. This is a simple and common setup if you want to stay with Rover axles.

Nothing wrong with V8 (look up MegaSquirt and EDIS setup) and auto box. An auto off road is a real no brainer, but you will need to make sure that you have good cooling for the ATF. The original bog brush cooler is a bit pants.

Am I to assume that Tomcat are building the car for you?

If i decide to go for it.

They will be doing chassis prep and attaching the frame work to chassis possibly get powder coating done at same time by there contacts.

Thats why im digging about trying to find suitable engine option.

So that i can take say isuzu engine with converter plate r380 gearbox and lt230 with 1.6 ratio complete to them so they can work out how far back they can move the engine and can fabricate suitable engine etc mounts.
Paul said somthing about moving the unit back about 10" over standard Rrc V8.

The diffs at 4.75 are ashcroft internals or it's the other way around i honestly cant remember got so much different ideas regarding running gear ratio's etc.
Where did i put that asprin.......

regards adam

The rest of the build i will do myself.

Best of luck with it. You'll have to do a 'build thread'

mirafiori said:

Anyway Gang im needing some advice surely theres a forum or some build thread somewhere of A Tomcat under construction???

Click to expand...

Matt Builds A Tomcat

ello andy, hows you and the family ? :hurt::baby:

Hi ya. All cool. I am managing to do night feeds and stay awake at work!! Apparently....it gets easier.

andyb66 said:

Hi ya. All cool. I am managing to do night feeds and stay awake at work!! Apparently....it gets easier.

Click to expand...

when ????

when they go through the night it gets easier so not much longer !

Yeah she is two weeks and a day old now, so hopefully by the end of the month.....or is that too soon??

hard to say mate..first daughter was great after a few days. second was great after a month and ezri grew little red horns for 9 months !

Disco71 said:

ezri grew little red horns for 9 months !

Click to expand...

Cricky I hope not !

andyb66 said:

Cricky I hope not !

Click to expand...

i think the term is 'selective hearing' when they are like that