1999 Disco I 300TDi: Fixes, Mods, & Trips

[Ray_G]

Appreciate the comments on Coyote, everytime I drive that truck I smile-it actually has been nice having to leave her behind while I'm overseas b/c when I go back I fall in love with her again. Getting th kiddos out early is awesome, as you saw I did it with mine and now it is second nature to them-keep taking those pics, the scenery alone is nice to look at when it was 120 here in the city!

Good thoughts on the LT230 idea, I may tuck that away for any future Tdi build in my future-finding those 1.4s can be tough though since the Defender guys hoarde them. Totally understand on the ZF over R380, ironically my wife prefers the 5 speed but that's b/c she is also known as 'skinny pedal' at times because of her penchant to wring vehicles out so the manual gives her the chance to get whatever performance she can from the truck. I have been incredibly impressed with the R380 in 1st or 2nd, TC in low/locked, and just crawling with good tires in mine-hence why I'd love to see it in a diesel vice gas.

Have fun camping!
r-
Ray

 

[NW40]

It’s been 5 months since my last update…so much for posting a thread every week on the build progress! Ha! Maybe the key is keeping things short and sweet, so I’ll just leave this photo here of two 5-gallon buckets in my back seat. Scored a sweet deal on what’s inside, and I’m excited. Would’ve installed them today, but hurt my shoulder over the weekend, so maybe next week.

 

[Ray_G]

Do the buckets need air lines to activate, or are the mechanically driven?

Regardless I'm jealous and looking forward to seeing where you are going-I am seriously thinking about ARBs upon return to Coyote full time.

 

[ZG]

Everybody recognizes what those buckets are for....but the ones I prefer are typically green!

 

[NW40]

Spot on, guys. Only a 4x4 community would get excited about 5-gallon buckets!

These contain Truetracs with Ashcroft 4.12s, all at a price I couldn't refuse. Supposedly only 500 miles on them before the guy rolled his Disco and threw in the towel. I'm almost more excited about the gearing than the Truetracs, though I'm looking forward to the additional traction and have run into several situations where it would've come in handy. But regarding gearing, with my 245/75s, currently 3.54 gearing, the Tdi with auto box, and loaded up for a trip, I slow to a 35mph crawl climbing the local mountain pass. Even some freeway grades in town bring me down to 50 while everyone else cruises along at 60-70. So these 4.12's should do the trick in restoring some hill climb performance. Just hoping that the 4.12's don't swing me too far in the other direction and limit my top end speed too much in the flats. If so, I'll just have to go up in tire size next time I'm due for tires! Curious what this gearing will do to my fuel mileage, too.

And Ray, I definitely agree that ARBs or similar air or E-locker would be ideal and, in my opinion, a better solution compared to the Truetrac LSDs. Go in that direction if you can. I just couldn't swing the higher cost of the lockers plus the added cost of HD axles that I hear are necessary with true lockers. Especially when this setup presented itself to me at less than the cost of the gears alone.

 

[ZG]

Honestly...they might. I have 4.11s in mine with 33s, and rpms are a bit too high for the highway cruising. Not unbearable, just not where I'd like. And that's almost 3" more than yours.

 

[NW40]

That's a good reference point for me, ZG. What engine/gearbox are you running?

 

[ZG]

300tdi R380 1.2r LT230

 

[XJLI]

Thats gonna be way too much gear for 31s.

Time for a lift and larger rubber!

 

[NW40]

Sounds like I'll be limited on the top end. I'll be sure to post my experience. Not sure how the gear ratios differ between the R380 and diesel-spec ZF; might be in my favor, I don't know, but not enough to make up for the 4.12. Hmmm, might run the gears anyway for a while to get a feel for it, and either swap the gears out down the road for something more conservative, or go to a larger tire. Pretty sure I won't want to go over 32", though. Decisions, decisions....

Anyone want to swap your 3.9's for my 4.12's?

 

[Ray_G]

And Ray, I definitely agree that ARBs or similar air or E-locker would be ideal and, in my opinion, a better solution compared to the Truetrac LSDs. Go in that direction if you can. I just couldn't swing the higher cost of the lockers plus the added cost of HD axles that I hear are necessary with true lockers. Especially when this setup presented itself to me at less than the cost of the gears alone.

Twin TT's will be a sweet setup, my truck runs a TT in the back and a 4 pin open dif in the front and with the 5 speed in 4 low locked it does very, very well.

The gearing, as others have alluded, may be an issue though. I have 4.11's in my setup on 255/85's (33's) and it runs pretty good with a V8 and the 5 speed. It runs better than when I had 245's or 235's to be honest-but I do worry with the 300TDi you may not have the juice to push the 255's quite as easily though with a rover lets be honest, HP is a very relative thing!
r-
Ray

 

[NW40]

I’ve been running a variety of gear/tire/transmission combos with Ashcroft’s gearing calculator, and the 4.12s and 245/75s combo doesn't seem too outrageous for my 300Tdi and ZF auto, especially when compared to the RPMs that the Rover engineers designed to.

To summarize all the data I've been looking at, here's a table:

So, compared to my current gearing and tires (which results in under-gearing), the 4.12s are raising my engine speed by 335rpm at 60mph. I think I'd be content if I never went faster than 65mph on the highway, which puts me at 2600rpm. A 335 rpm jump might sound like too much, but not when you look at what the Rover engineers designed to.

Comparing the stock design (w/ auto) to 4.12 gears + my 30.5″ tires, I’d only be 230 rpm higher than design at 60 mph. And I'd only be 100 rpm higher when comparing to the 5-speed stock design. So that doesn’t seem too far out of bed for the 300Tdi, and might be exactly what I'm going for to gain a touch more performance in the hills while (fingers crossed) not lopping off too much of the top end. Will probably make the auto trans run a bit hotter, though, spinning 10% faster. Might have to run a transmission cooler?

All that said, still thinking about installing the gears to see how it feels, though it would be a lot of work to install them only to find out it was a horrible gear/tire combo and end up doing the swap twice. But then again, what better way to spend a day than under a truck lifting 50LB differentials while covered in grease and oil!

 

[NW40]

Oh, and if I size up to 235/85 (31.7") tires when I'm due for new rubber, that would drop my RPMs back down to 2312 rpm at 60 mph. Which is right in line with the stock design for a 5-speed!

Am I just convincing myself that these gears are going to be fine?

 

[XJLI]

If you never plan on going above 60, sure this sounds fine. I don't know about you but I drive 70 on the highway... any slower and I'd be getting run over.

 

[ZG]

Put it this way... For a couple weeks I had 30.5" tires on my D1 with 4.11s. I couldn't go above 60 comfortably.