Series 2a 109 more top end

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flyingbanana

Member
Posts
92
Location
Southampton england
I'm trying to find ways to increase my road speed top end at moment it's about 46mph to slow to keep up
With traffic Due to my perkins diesel a trifle slow
1. Change diffs to 3.54:1 ? (Finding some early RR,defender,is there others ) ?
2. Possible change transfer box out of a disco 1.2 ratio possibly cheapest and easiest (can this be done) ?
3. Overdrive (cost) ?
4. Engine change and which is best option (time,cost)
Thanks Andy
 
flyingbanana said:
I'm trying to find ways to increase my road speed top end at moment it's about 46mph to slow to keep up
With traffic Due to my perkins diesel a trifle slow
1. Change diffs to 3.54:1 ? (Finding some early RR,defender,is there others ) ?
2. Possible change transfer box out of a disco 1.2 ratio possibly cheapest and easiest (can this be done) ?
3. Overdrive (cost) ?
4. Engine change and which is best option (time,cost)
Thanks Andy
Click to expand...
Overdrive works, but it raises low range a bit too much for some off road use, and the torque of the Perkins can damage them.

Ashcroft high range transfer box is a good strong option, raises high range, without raising low range. I liked mine.

Easiest option of all is not to worry about it unless something breaks, fit a good hefty towball, and most people won't drive into the back of you! :)
 
46 mph is an accident waiting to happen.

Diffs are the easiest way, few gaskest and some oil job done.

Does not have to be early diffs with the fillers, front diff alreayd has pan level bung so for rear a few people use later diffs and either weld on their own oil level, or just fill by removing a halfshaft.

Stuck early rr 3.5 diffs in my s2 with tdi years ago, been fine.

Also worth running 85/140 oil in the entire drivetrain to help with the power/torque from the engine.
 
Is yours a 4203? Mine will get my LWB with camper roof and roof rack up to 65 and cruise at 55-58. Between 58-60 the engine temp rises sharply. Even with all the gear and a loaded Sankey we can hold 50+.
We have:
3.54 diffs
Fairey OD
235/85 -16 A/T tyres - 31 3/4 OD
Its comes out at 2000 rpm at 60 in OD top. (30 mph / 1000rpm). I go into OD top at around 45 on the level which is a lovely smooth 1500 rpm
Its a pleasure to drive becuase its so low revving and we get 30 + mpg. The only really big downside is that 1st and reverse are really high. Its best to go into low range if a traffic jam is crawling up hill. With the S2A box reverse seems much higher than first so even in low range idle in reverse is a brisk walking pace. We are 99% on road but we've done some off road "courses" and its been fine. We've even been up the Brooklands test hill That hill is 1:8, then 1:5 and 1:4 on the last section and you can hear the Perkins never slows.
Start at 1:30 I think this is low range 2nd,
 
I'm getting a pair of diffs now my only issue is I need to put in oil filler holes in axel as the diffs don't have them, any help please where I can buy them has anyone done this info please if poss thanks Andy
 
Mine have the fillers in the diffs, pans are plain. Not sure whether this means they are early RR or the diff internals were swapped into the series case (if that's possible). Mine was modified quite a bit when the Perkins was fitted some time in early 80's so its hard to know what was used, I'm still discovering things. When I bought it there was no mention of 3.54 diffs, on the drive home I thought it was odd that I was going the same speed at trucks on the M25 at an indicated 42mph. Jacked a wheel up and counted the prop turns.to work out what was going on. The 4203 and the 3.54s are a good match.
 
flyingbanana said:
I'm getting a pair of diffs now my only issue is I need to put in oil filler holes in axel as the diffs don't have them, any help please where I can buy them has anyone done this info please if poss thanks Andy
Click to expand...

You would have to drill holes (at correct height) in the diff pans and weld short threaded tubes to the outer face of the pan over the holes.

The original plugs were tapered BSP threaded types, but any suitably sized thread would work.
 
Last edited:
Get sensible sized bolt, M14/M16 fit a plain nut, drill hole 14/16mm hole to suit bolt you are going to use in diff same height/postiion as front diff, push bolt though until nut touches casing, weld nut to casing, remove bolt and fit copper washer. refit bolt job done.
 
In my opinion it needs to be quite precisely spaced.

After normal road driving, my front differential drive pinion will leak a few drops of EP90 when I stop. This is with the oil level up to just above the bottom of the front diff pan plug threads.

This stops once enough has dripped out to get it just a couple of mm below the threads. It doesn't seem to lose any more oil after that and the level stays the same.

The rear diff that has a fill plug on the diff casing does the same thing. If filled to the "correct" level it drips out again until it gets slightly lower then stays at that level.
 
Webley1991 said:
In my opinion it needs to be quite precisely spaced.

After normal road driving, my front differential drive pinion will leak a few drops of EP90 when I stop. This is with the oil level up to just above the bottom of the front diff pan plug threads.

This stops once enough has dripped out to get it just a couple of mm below the threads. It doesn't seem to lose any more oil after that and the level stays the same.

The rear diff that has a fill plug on the diff casing does the same thing. If filled to the "correct" level it drips out again until it gets slightly lower then stays at that level.
Click to expand...

Spedi sleeve or a new flange will fix that.
Last flange I bought was 10 quid.
 
I have fitted new seals before, the flanges were also fine. The same thing still happened when the new seals were in place.
 
Webley1991 said:
I have fitted new seals before, the flanges were also fine. The same thing still happened when the new seals were in place.
Click to expand...

Then the flanges are worn even if they look fine, it is one of the few things that does not leak on my series!
I see dozens of pinion seals weekly, if they leak (pretty rare tbh on modern vehicles) its either the seal or flange worn.
If you are convinced they are good chuck a speedi sleeve on with a new seal and see how you get on.

Leather or rubber seals?
 
They are modern nitrile rubber seals on both diffs.

I can live with it as long as the oil level doesn't change. About 2mm below the plug threads seems to stay in there. Anything above that will leak out again until it drops to that level.
 
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