Speed up a 969?

[kw573]

I have a Diamond T 969 that I'm repairing. Currently doing a major open cab rebuild due to rust and other abuse. As I wish to rally this vehicle at every opportunity, I am looking to fit a Japanese diesel and gearbox and up the overdrive or diff ratios. Has anyone found a way to up the diff ratios by 20-30%? Are there different ratio bullgear/pinions available (and helical cut as well) that can be purchased and pretty much bolt straight in? Has anyone tried to have gears made? I'm looking to cruise comfortably at 80kph (50mph). I've never done this before and don't know what's available. Help and advice would be greatly appreciated. Sam.

[Captain Crank]

Sam,

These trucks weren't designed to go fast, stopping is the biggest safety factor.

There's also handling and steering.

Don't butcher it up! You are defeating the whole purpose. (and gonna spend a ton of money)

Keep the original power plant and drive line.

The easiest and most economical way to get a few extra mph is to put larger tires on. It will still look original too.

Also, check your laws down there. The UK requires air brakes to be updated to double circuit for use on the roads.

Cheers,

CC

[Jeff Jensen]

Hi Sam
I have seen pictures of these trucks with super singles, If I find it I will post it.
I have a 969 and drove it around 750 miles one way (41-1/2 mph) 2300 rpm's with 900-20 tires, Truck weighs 22,000 lbs , 6 mpg. I am going to put 11:00-20 NDCC on mine because they are easy to find and much cheaper than buying 10 new 9:00-20's, Do not run 9:00-20 8 plys off 2-1/2 ton 6x6's on the front of this truck they are to light, need to be 10 ply or more.
Keep the gearing original because if something breaks parts can be found and there are no taller gears to put in place, the transmission is all ready 0.768 to 1 overdrive.
The Hercules RXC 529 cubic inch engine is 131.5 HP. torque is 396 foot pounds at 1000 rpm's, You can still today buy a brand new RXC for $2600.00
Some of the guys in Europe have put Cummins diesels in place. I do not know much about Japanese diesel and gear boxes , There is none here in the states that large and you are going to match or have more torque than stated above.
Just remember these trucks are highly collectible and hold a value when original .
Can you post some pictures of what you have.
Jeff

[40 Chevy]

I concur with what Jeff and Captin Crank have stated, especially on the tire issues that Jeff brought up.
If you are going to play with the BIG toys, they should be maintained and operated as orginally designed, for your enjoyment and safety and those of your fellow vehicle operators.

John Gott

[kw573]

Thanks heaps for your comments lads. Clearly, I still have heaps of homework to do.
I didn't consider the tyre sizes option much due to appearance, however, as I have a M1A1 heavy wrecker paddock truck with good tyres, it'll be very easy to test out.
Brakes-wise, yes I do need to check local laws. However, as they seem to stop on a dime I didn't forsee problems there.
I certainly won't be butchering anything on what is a fairly good rolling chassis with a blown engine. Photos to come when I work out how! Really, I couldn't afford to rally this truck much at all at 6 mpg. It's about 200 miles to my local city where most of the action is. 750miles! Well done. I'm impressed!
The diesel I'm wanting to use is an Isuzu 6BG1(out of a 13ton gross truck) which revs to 3300. I'll get the torque/power specs when I go home. However, overdrive boxes (21%) for them are scarce. Still looking/thinking. I calculate 53-55mph with this setup. I really am not looking forward to long-haul trucks bearing down on me at 40kph below the speed limit out on the highway.
I'll get some info and pics. Have a nice day. Sam

[Jeff Jensen]

Found it

[kw573]

Wow, that looks real cool!! I presume that they are 11.00 - 20 tyres, but what would the rims be off? Does the offset on the rears put an uneven load on the bearings compared to duals? I suppose that it couldn't have been a real problem since it was done at times evidently.
More pics another day. Thanks for the picture. Sam,

[Jeff Gordon]

Hi Sam.
I recon the fact that the Isuzu does 3300 RPM the truck would do 50 MPH using the same gearbox.
The situation here in Australia is much differant to you guys in the States.
Our fuel prices are almost double yours.
We have long distance between towns and poor roads between them. We don't have an interstate and an old highway for slower vehicles. Between where Sam lives and the big smoke is mostly single lane each way and the only road with few places to overtake. It is the main Highway. I would never drive my Diamond T along it for any distance as you hold up too many trucks.
Queensland summer tempretures can get to 42 deg C and 99% humidity in the shade. HXC have over heating and head gaskets problems.
Second hand Japanese Diesels are a dime a dozen and Herc's are rocking horse poo.
I would rather see a Diamond T with a Diesel at a show than not seeing one because it is in the shed and you cant aford to use it.
Original breaks are legal in Oz and are fine.
Super singals would be good with 1200/20 on the beach because duels are useless in soft sand.

You do what you want Sam.
Cheers
Jeff

[kw573]

Hi Jeff,
Thanks for the clarifications. Isuzu-wise, I have mucked abouts putting different brand engines and gearboxes together before and I ain't goin' there again!!! What a nightmare. So, the Isuzu keeps an isuzu gearbox. the trick is finding one with a suitable overdrive. They are available in .78 (BG6P) or .74 (BG6U). Both are scarce and expensive. I continue to search.

Drivers seat base, rust removed. Ready for some bog and paint

Drivers seat base.JPG (155.82 KiB) Viewed 4952 times

This base has had the bottom 3" of rust replaced.

It started on this today. It's 3mm plate.

Drivers seat.JPG (193.86 KiB) Viewed 4947 times

I began work on this today. It's 3mm plate. Easy to weld but hard to shape.

Pressed floor panel.JPG (150.59 KiB) Viewed 4922 times

I thought for a long time before deciding to have a go at pressing these floor panels. Most don't seem to worry about it. It took over a week to make the press plates! Photos to follow. They are 1.6mm (16g) sheet and took multipule goes with a 60ton press. I have some softer sheet on order and have been told of a 100 ton press nearby. So maybe the next ones will be even better. These are not real bad at all!
Have a nice day. Sam.

[Jeff Jensen]

Hi Sam
Very nice job.
Yes it can be a nightmare fitting some engines and transmissions unless they have SAE bell housings, then once you find what you want can the original P.T.O. be used.
Some day I will start on my 969, I also have a 981 about 3/4 tore apart.
I think them tires are at least 12:20-20 or larger, I have seen this picture some where else and clearer. The front wheel looks very familiar like on a 5 ton 6x6 and it is off set to be inline with the rear.
The rear looks to have singles but a standard wheel but has to be wider to put 12:00 tires on like the wheel on your Ward.
I have to plow the drive at the shop today, I will stand a 11:00-20 next to it and take a picture.

The other Jeff

[Jeff Jensen]

Here's an 1100 next to my Diamond with 900's on it. There's ice all around so the 1100 appears a bit taller because of that.

[kw573]

Wow! There is a bit of difference there!!! I also notice that there is plenty of room between the two rear axles. I will certainly be having a closer look at this possibility. Thanks for going to the trouble of setting up that pic.
I have recieved a sheet of the more malleable 'bright form' steel to try pressing the drivers side floor panels. More to come. Could you post a couple of pics of your 969? I always like to see anothers' pride/project. Thanks, Sam.

[cessna]

I second that request Jeff! By the way, nice towbar!
Brian

[Captain Crank]

[Jeff Jensen]

Thanks for posting the pictures captain.
As you guys can see I us my trucks, This one has payed for its self many times.
Jeff