another v8 question.

[big col]

Hi everyone, ive been reading this forum for a while now, and i thought id ask my first question. I'm going to bung a 3.9 EFI rover V8 into my MK4 190 LWB Hi Top, and i was wondering if i can change the rear diff ratio? If i can, what would be the best ratio? I'd like it to still be "lively" and relitively fuel efficient, another thing is i've seen some pictures of engine compartments which all seem to have sound proofing on the inner wings and bulk head behind the engine etc,would my van have been fitted with it from the factory or not?Its just that my van hasn't got any and is therefore pretty loud,am i right in thinking that when the V8 goes in i'd have to take the sound proofing out as it would touch the engine anyway?? Or can i put some in with a V8 and if so which type? And how would you overcome any cooling issues? Here's a crazy thought a mid engined V8 tranny. Any answers will be greatly appreciated.

[MrMPuk]

The soundproofing wont fit the new bulkhead anyway.

[Luke]

personally i'd fit the engine then sort the axle once its up and running i'd have thought you want to go lower on the ratio 3.89:1 is the lowest transit axle available

[big col]

that seems to make sense,I'll do that,Cheers

[sidspop]

Manual or auto?

[big col]

Auto! I've read on here that a manual would be a nightmare coz of the clutch linkage, and the gear stick aswell I'd imagine. You'd have to extend the gear lever, unless one off a 110 or 90 land rover would fit, (with mods). It's probably gonna be one of those jobs where you open up a big can of worms. Where theres a will (and there is a will!) theres a way.

[Luke]

what do you do about the 4wd bits transfer box etc surely you need a 2wd box

[big col]

Apparantly you can change a plate on the back of the gearbox for one off of a rover SD1. Hey presto,2WD.

[sidspop]

I would be tempted to change the complete axle.

Ideally you want the same rolling circumference for tyres as RR, but that's probably a bit large. Reason being the engine & box are set up to see a particular diff/wheel/circumference etc. So if you star fannying around with different diffs, it's gonna throw it a little. Not really a great issue, but there's another problem. That being the torque of a 3.9, and depending which diff you go for, it may not last too long. Thats why I asked auto/manual. Autos tend to be a bit more sympathetic than a manual.

Now if you were to change the complete axle, (Volvo 740 built like a shithouse, 500HP no problem) the only things you may have to do are a bit of re-plumbing brakes, maybe new propshaft end, and some wheels to suit, or adaptors, or even shafts redrilled.

So rather than trying to shove a lot of power through a hard to get diff, change the complete axle, and have an axle that's proven, with more ratios available.

Make sense?

[big col]

Makes perfect sense ! I realy was hoping it would be as simple as shoe horning the engine in, fabricating engine/ gearbox mounts, getting a prop that fits,might have to get my calculator out on this one!!!

[carnut1100]

You would almost certainly have to widen a Volvo axle for Transit.
It would give you 5x108 stud pattern too.
If you did use a Volvo axle there is a LSD centre from the USA for about $500 called a Truetrac which goes right in. You would want the high preload one for a Dana 30 from a Jeep, same diff centre.
You can also get Detroit lockers pretty cheap for a Dana 30.

3.89 would be ok if you had a 5 speed, be pretty crap with a 4 speed.
I was running a 4 speed with a 3.50 ratio axle and wanted a higher one for highway....

Another though, can you get a bellhousing or adapter to match a toyota W58 or similar 5 speed to a Rover engine?
If so, then look at a Toyota Hiace, as most of those had a W series box which fits the same bellhousings as a Supra box, is just as tough, has a lower first gear for quick takeoffs ifout of a diesel, and had a column shift.
You can use the cable shifter from a tarago ( I think it is called a Spacewagon over there?) and put it anywhere you want it.
Now, I just happen to have a 2 litre diesel Tarago sitting next to the Tranny with a buggered engine.......might have some fun with that one later!