revived V8 Ninety?

[Rocket]

Hi guys

Your advice required.

I have a (factory) 1989 3.5 V8 ninety whose motor is a bit tired and rough and has been for a while. I plan to get it sorted or replaced this year.

While the motor is out I plan to replace the (also knackered) Santana Lightweight LT85 gearbox with an earlier heavy duty LT85 in excellent nick which I already have. While I am at that I want to have a good look at the LT230 transfer box and recondition/replace it if necessary.

Later when my wallet has recovered I will be fitting some 255/85 BF Goodrich mud terrains and a lift kit if necessary.

My question is, as I will ultimately be putting larger diameter wheels on which will raise the gearing should I take the opportunity now of fitting a transfer box with a lower gearing to compensate.

My 90 has always felt overgeared in fifth with 7.50 X 16s but this could be because the motor has been weak (knackered cam I think). Things could be fine with a rejuvenated motor but I thought I would take advice from those who may already have dabbled with such things.

Cheers

Rocket

[Hybrid_From_Hell]

welcome to the forum,

V8 90 (if its a genuine one)............... has a special T Box ratio 1.9 somethingorother :1 .......under the normal 1.2 :1 one.

Normally supplied as std on 205x16s, .............there was a factory option for 7.50 x16s

Having one myself, I was ok until I went bigger than 7.50x16s, .........so if your having probs its prob the engine that is knackered....

When I went to 235x85x16 on a Pulsair V8 this got worse, ..............and then worse still .............with 34x10.50x16 simexes...

By this time I had changed the engine to something more powerfull, but the gearing was too far out really,

I have therefore a program in excel that will work out whats what and where you may end up.

To run it you need :

1 2 3 4 5th gear ratios,

T Box ratio,

and Circumference of tyre,

diff ratio,

this then shows the spped at all sorts of RPM,

I worked out that mine was as std from the factory about 25 mph per 1000 rpm, ie at 4,000 rpm it should be doing 100 mph, the program showed that with the mods I made 150 mph was more likey from the overall gearing , and as such I played about and ended up with 4.11@1s from ashcrofts.

This brought everything back to std, and it now goes like the proverbial....

The real benefit is I have also 'regained' low ratio as std, .........changing T Box ratios has no effect on Low ..............as the ratio for low is the same for all ratios, ..............only the high changes..

Ping me your data 1 2 3 4 5th TBox ratio diifs and circumference etc and I'll run prog and send back to you

ask for options and I'll run them too and you can see the difference, anything over about 28 MPH per 1000 RPM is moving to far

Hope this helps

Nige

[Rocket]

Nige

Wow, thanks just what I need.

I'll dig out the info, although how can I be sure what my present transfer ratio is? It is a genuine factory V8 90 as confirmed by VIN Number. Its actually an ex police vehicle so may have been ordered with 7.50 X 16 s. Would that option have meant it was supplied with different gearing?

Cheers

Rocket

[Hybrid_From_Hell]

Ok

To see which T Box you have and the ratio, if we asuume (dangerous) that it is genuine & Origional, or if ever fixed fixed with the correct parts etc and the ratio not changed, then the number stamped on the back of the Transfer Box casing will give it to us.

Have a rummage underneath the 90, look at the rear face of the T Box and around the edge you'll see a number and letters, write this down and post it back here, I'll look it up in my info and check what (if everything is as it should be) - the ratio is

Nige

[Rocket]

Ok

To see which T Box you have and the ratio, if we asuume (dangerous) that it is genuine & Origional, or if ever fixed fixed with the correct parts etc and the ratio not changed, then the number stamped on the back of the Transfer Box casing will give it to us.

Have a rummage underneath the 90, look at the rear face of the T Box and around the edge you'll see a number and letters, write this down and post it back here, I'll look it up in my info and check what (if everything is as it should be) - the ratio is

Nige

Nige

Here are the other details from spec lists. I'll try and get the T box Serial No tonight

LT 85 Serial No 20C 06615

5 = 0.8:1

4 = 1:1 direct

3 = 1.436:1

2 = 2.12:1

1 = 3.65:1

LT230 Serial No ???????

Hi = 1.22:1

Lo = 3.32:1

Differential ratios assuming again that they are standard, but axle serial numbers might help

Front 3.54:1? Axle S No 22L 26780C

Rear 3.54:1? Axle S No 23S 066470

255 X 85 X 16 Tyre circumference = 103.874”

7.50 X 16 Tyre circumference = 97.402”

This is calculated using actual tyre diameter not rolling diameter which will be slightly less as the tyre will be squashed on the road reducing its effective diameter. I guess this actual figure can only really be measured on the vehicle, but of course is the one which is most accurate!

[Rocket]

Nige

Found it at last!!!!!!

The Transfer box serial no is 29D 110026C

Also found my transmission brake seized on so it was worthwhile getting under Gromit after all.

Cheers Roy

[Hybrid_From_Hell]

29D is a PROPER V8 90 T Box ratios which are 1.192

So, would you like me to run both this (std) and say 7.50 x 16s and post charts, or any other combos, prob later tonight

Nige

[LR90]

'bout 27mph/1000rpm in hi 5th on 750x16s

That's pretty hi geared!

FWIW mine's ok with the TDi at a little over 22mph/1000 on the Simex which isn't far of a stock 90 with a 1.4 lt230 and 7.50s (ie still higher geared than a stock 90 ex factory on 205s!)

Good choice of transfer box though

[Hybrid_From_Hell]

Here you go, this shows 1 2 3 4 5 with 3.54, 1.192 and tyres at103.8 inches less 5% for approx rolling difference.

Your doing on paper 111 MPH at 4000 RPM in top which is 27.75 MPH, tad on the high side (25 MPH is best) esp when we have the aerodynamics of a small house

Below is the same data but with your 7.50 tyres again less 5% :

this is really close to the 25 MPH per 1000 RPM....

Hope this helps

have a lookie., let me know what you want to do next ?

Nige

[Rocket]

Hi Nige

Many thanks that is an enormous help.

OK, to get the gearing to give me 25ish mph per 1000 rpm in top using 255/85s what can I conveniently change. I know you changed your diffs but as far as I am aware mine are OK so I only want to play with the Lt 85 or the transfer box. What does your program give if I say use a 1.22:1 transfer gear or even 1.41:1 (if these things actually exist) and if the figures look reasonable what vehicle would these transfer boxes be fitted to originally?

cheers

[Rocket]

'bout 27mph/1000rpm in hi 5th on 750x16s

That's pretty hi geared!

FWIW mine's ok with the TDi at a little over 22mph/1000 on the Simex which isn't far of a stock 90 with a 1.4 lt230 and 7.50s (ie still higher geared than a stock 90 ex factory on 205s!)

Good choice of transfer box though

Trev

What size are your simex's?

[Hybrid_From_Hell]

Hi Nige

Many thanks that is an enormous help.

OK, to get the gearing to give me 25ish mph per 1000 rpm in top using 255/85s what can I conveniently change. I know you changed your diffs but as far as I am aware mine are OK so I only want to play with the Lt 85 or the transfer box. What does your program give if I say use a 1.22:1 transfer gear or even 1.41:1 (if these things actually exist) and if the figures look reasonable what vehicle would these transfer boxes be fitted to originally?

cheers

Ok

Change the T Box Ratios :

A 1.410 : 1 4000 RPM = 94 MPH

A 1.667 : 1 4000 RPM 79 MPH (0 - 60 will be good )

A 1.2211 : 1 4000 RPM 108 MPH

Keep what you have now, change to 4.7 diffs. 4000 RPM = 87 MPH (std LR)

Keep what you have now, change to 4.11 diffs. 4000 RPM = 95 MPH (ashcroft)

Keep what you have now, change to 4.2 diffs. 4000 RPM = 93 MPH (Kam)

Keep what you have now, change to 3.8 diffs. 4000 RPM = 103 MPH (Kam)

I look at 1.2211 : 1 or 1.410 : 1, or kam 3.8 : 1 Diffs

bear in mind any future plans of changes ie tyres, engines etc....

I could post up the full data sheets , have a think let me know, if you wnat options alternatives run Post up what you wnat

If you wnat to have a more "final scrunt" Post what combo....

Nige

[LR90]

The Simex are 35" and great. I'd like to run 255/85s as road tyre sbut it woudl probably be a tad undergeared.

[Rocket]

Hi Nige

Thanks

Could you please post up the tables for the 1.22:1 and the 1.4:1 transfer boxes with both tyre sizes.

On the face of it the 1.22:1 doesn't look low enough and the 1.4:1 looks too low, although as LR90 pointed out it allows more radical wheel sizes but there must be many more complications with even larger wheels e.g. extra lift, castor correction. etc I'd like to keep things relatively straightforward if possible.

By going to a 1.4:1 transfer box things would be very revvy and thirsty if I ever used the 7.50 X 16s again but I suppose I have got to decide what will work for me and stick with it.

Cheers

[darthdicky]

By going to a 1.4:1 transfer box things would be very revvy and thirsty if I ever used the 7.50 X 16s again but I suppose I have got to decide what will work for me and stick with it.

Most standard 90's run 1.41:1 transfer boxes and 7.50 or 235/85 tyres (same size almost), and I wouldn't say they're particularly revvy even on the motorway. TDi's only rev to 4000 or so anyway.

If running larger 255/85 tyres I'd guess that 70mph would be about 2500rpm with a 1.4 transfer box, which I'd say is about right?

Richard

[Hybrid_From_Hell]

If running larger 255/85 tyres I'd guess that 70mph would be about 2500rpm with a 1.4 transfer box, which I'd say is about right?

Richard

er, then you would guess wrong ..............

1.2211:1 Box..............

1.410:1 Box

Hope this helps, have a think ask if you need other options run, happy thinkuing

Nige

[LR90]

Note also with the 1.4 transfer box Low 3rd is now higher that Hi 1st and it won't take Mr Ashcroft crawler gears if you choose that route later.

[Hybrid_From_Hell]

Note also with the 1.4 transfer box Low 3rd is now higher that Hi 1st and it won't take Mr Ashcroft crawler gears if you choose that route later.

Trev is absolutely 100% right here, and more neds to be thought through re the Low Box if you plan to use it off road ..................

The fact your Low won't be so much / any more .....by the fact that only the High range changes all Low Gears are the same ratio is importnant for hill desents off road....

To give you a better understanding.............. heres my "Chosen" Route

1.19 : 1 V8 T Box,

34 inch simex,

LT85 Primary difs changed to

4.11:1s from Dave at Ashcroft (yummmmm !)

.................means both high and low are returned to B Close to std.......... B)

Have a good think, ...............you only want to do this once !

[simonr]

I would consider a 1.6:1 transfer box.

I also have a V8 90 - G reg.

I changed mine from 1.2 to 1.4 when I put 35" tyres on - but it still struggles to get up to 70 and the engine is barely red-lineing.

I wish now I'd gone for 1.6:1!

Si

[Rocket]

Trev is absolutely 100% right here, and more neds to be thought through re the Low Box if you plan to use it off road ..................

The fact your Low won't be so much / any more .....by the fact that only the High range changes all Low Gears are the same ratio is importnant for hill desents off road....

To give you a better understanding.............. heres my "Chosen" Route

1.19 : 1 V8 T Box,

34 inch simex,

LT85 Primary difs changed to

4.11:1s from Dave at Ashcroft (yummmmm !)

.................means both high and low are returned to B Close to std.......... B)

Have a good think, ...............you only want to do this once !

Simonr

I'm afraid I don't understand, are you saying it feels overgeared as it struggles to get to 70?

Do you really mean 1.6:1? thats geared very low and according to Nige's table would make your low ratios practically useless.

Nige

You are absolutely right about the gearing, in that it keeps all the ratios functioning as they should, but how much are the dif gears to change and if I go to 34" Simex's (Which I very much like the idea of!!) how much will I have to lift the suspension and does this now involve castor correction etc. Also If I have to strip the difs I know I won't be able to resist the lure of lockers of some sort and then theres the drum braked rear axle to think about changing and, and, and.............................................................................

.....

Perhaps I better just get one thats already modified! but then Gromit and me have been through a lot together so I'll have to persevere.

[LR90]

Simonr is correct, wtih big tyres and stock diff ratios a 1.67 is ideal (but only low 1st is lower than any of the hi gears!). I ran this for a while and road gearing is fine.

Like Nige I've gone for 1.192 now though and non standard diff ratios (which is beginning to look expensive) but it gives me good road gearing (like the 1.67) but with a nice spread of Low gears.

[Bull Bar Cowboy]

Its probably going to come down to the overall condition of your engine in terms of power / torque etc ……………. big problem with the V8’s is the top end can have loads of wear, bringing the power down considerably and the engine will still sound absolutely fine.

I run a V8 3.5 EFI 90 truck cab and the engine is doing a tad under 200 ponies. When I fitted the rebuilt motor I also fitted a LT77S V8 Gearbox and 1.222 transfer box. However, on 235/85’s (Bronco Grizzly, so probably 32.5’s) it was over geared (@ 28.5 mph /1000 rpm), but not undriveable. I did about 32K with this configuration, the downside being continual gear changes on fast A roads and long motorway hills.

Recently I have changed the Transfer box to 1.410 and for me the gearing is just about right, in fact I will also be changing tyres soon to 285/75’s and cannot see any problems looming. I suppose the nicest way of putting it is that I am not renowned for being the slowest driver on the roads .

Ian

[Rocket]

Well Guys

It looks like the consensus is stick with the present set up as far as gearbox and transfer box go. This allows me to proceed with rebuilding the motor and get everything sorted in the gearboxes without making any changes. Then go for the dif ratio change when I fit the bigger wheels. Ashcroft are quoting £195 per dif for the 4.11:1 crown wheel and pinion which isn't too bad but I just know it won't stop there.

Thanks again

This has also shown me where to post. I got very little response to this question on the defender forum but I am sure the same people read it.

[Hybrid_From_Hell]

I would consider a 1.6:1 transfer box.

I also have a V8 90 - G reg.

I changed mine from 1.2 to 1.4 when I put 35" tyres on - but it still struggles to get up to 70 and the engine is barely red-lineing.

I wish now I'd gone for 1.6:1!

Si

Fit an Eales 4.5V8.......................and job done

Also places you on '1st name terms' with all petrol stations within 25 miles radius of "Home"

Oh and rocket.

I saw this post early on in the day when I logged on, and hence I replied as I has some info for you....

I then saw you post in defender forum but had already replied...so I used this post

I as do many do go to defender forum so you would have had a reply even if not poted in international.....

Anyway, have a think, if you wnat some more "Possibilities run" post up and I'll run them..

Nige

Nige

[will_warne]

Rocket, I've been watching this thread progress and I thought I'd add my 2p worth. I ran for about 3 years a tuned Tdi then TGV engined 90 with an R380 and 1.41 LT230 with 255x85s (as a road tyre) and it was superb. It was reasonably lively and pulled well on the motorway and A roads. Low was a little high but you learn to drive round it. However, both on and off road were a bit of a struggle on 35" Simex...

I now run the vehicle with a ZF 4 speed auto box and 1.66 transfer box and 3.54 diffs with 35" Simex perminantly. This gives me a very nice on road ratio, plenty of legs off road, the naturally strongest ring and pinion setup which makes getting hold of spares a breaze, a good hill climbing ratio (2nd low). To sort out the overgearing in low range I've also just got an underdrive. That gives me engine breaking and low speed control, plus, if you put the transfer box into high and engage it you get a 35% reduction on low range; ideal for really nasty hill climbs. This isn't a cheap solution but, having looked at all the transmission options, this is the one that I liked best overall. If I were you I'd pop in a 1.41 transfer box and see how you get on.