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lt77 vs series box


wood-gee
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I'm curious to hear people opinions- I've got a series 3 with a 200 tdi and currently run a stock box with overdrive and disco wheels- I forget what size but it works out as 60mph at 2200rpm. The series box is overdue a rebuild for various reasons. I also have a recently reconditioned lt77 sitting in the shed.

I'm sitting on the fence between when it comes to it whether I rebuild the series box or fit the it77- I do a lot of motorway miles, so reducing gear whine is a motivation, as is tall gearing, and am happy to accept that fitting an lt77 would involve changing prop lengths, rear prop attention (88'') for uj angle and would likely modify for part time 4wd.

In peoples experience is the lt77 especially quieter than a series box? Is it worthwhile for the extra strength with a 200 tdi?

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Thought a few more points to add to that, I also run 3.54 diffs, the lt77 is out a disco (also recognise this would require rebuilding around different input shaft bellhousing and shifter), so would also have the advantage of giving me a more 'normal' low range

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LT77, no questions.

For years I've been saying I'll stick with the Series gearbox in my 88 - also 200 powered, never saw the need to change, it's a perfectly good box and isn't destroyed by the 200 on a weekly basis. I've also been saying for years that my project 109 will be getting the LT77 but retaining the Series transfer case. Reasons were that the LT77 is quieter - a lot quieter - and my 109 will become the daily driver and the 88 will go into a state of semi-retirement. I saw no need to go to an LT230 as the Series case is more than capable of putting up with a lot of abuse, and I didn't want the problems of the shorter front output housing also sitting further back, necessitating longer skinny props. Using the Series case meant it was further forward anyway. I then fitted LT77 and LT230 in our other 109 and I've changed my mind - completely! All 3 will now be getting the full LT77 and LT230 treatment.

One of the things that changed my mind was that for years I'd been told you couldn't fit the LT77 under a Series tunnel, and although I doubted it I couldn't prove it. The chance arose, I proofed it - it does fit! LT230 has been modified to operate off the old Series levers, and in time will also be converted to operate in 2WD/4WD mode.

I came to realise that if I did go with the LT77 and Series transfer case route, I'd end up with a hybrid - you'd not be able to fit an overdrive because of the special input gear arrangement, neither Fairey Series or GKN Defender would fit - and you'd also not be able to fit either version of PTO, except possibly the mega expensive extremely rare Series bottom PTO. By sticking to LT77 and LT230 I'll be able to fit a GKN overdrive if I wish, or a Defender PTO. I can even change the gears for a different ratio if I want - not possible with a Series transfer case.

You don't say whether it's an 88 or 109? You might struggle with a 1.2 disco LT230 in a 109, but the 88's love it. Some people have tried the 1.2 in 110's and been bitterly disappointed and gone back to 1.4's, other's seem to get on with the 1.2. It's strange and I can't figure out exactly why, it doesn't even seem to be a case of the heavier station wagons not liking it and the lighter rag tops being fine.

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That's really reassuring news, cheers for the input! I was hoping I'd here that noise wise- since putting the tdi in the gearbox noise is equal if not louder at motorway speed which so it'd be great to get that down to something a little more friendly! It is an 88'', I've no concerns about gearing to be honest - I previously had it with 3.54s diffs, overdrive and 7.50r16s and it still pulled gloriously, I think the disco box is a little lower gear than that. How come you chose to go with series levers over the defender ones- was this to maintain an original look? Did that take much massaging?

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One thing. Wright Offroad Soundproof kit.

With a full 88 setup you can get one that fits. With a full Defender setup - that is tunnel AND bulkhead, you can get one to fit. When I first put the LT77 in I used the Defender tunnel but I had to modify it slightly to fit the bulkhead - the defender one is obviously narrower than a series. Result is you can't get a soundproof kit because it's a hybrid, so back to Series setup it was, and it works very well.

Also, someone told me it couldn't be done....fatal mistake, never tell me something can't be done!

http://s1143.photobucket.com/user/109_photos1/library/LT77%20LT230%20conversion?sort=3&page=1

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Myself, Tuko, Ejparrott, & DiscoMikey have all fitted LT77's recently so you'll find several threads about how we each did it in the Special Builds section.

In my case I went from a late suffix D series 3 box, Fairey overdrive, 3.54 diffs and 235/85R16's to Defender LT77S & 1.211 LT230 with the same diffs and tyres. That's in an 88".

Gearing is a touch lower than the previous arrangement but nicely so; 1st is quite a bit lower so pulling away on a steep hill is much easier, 5th is not far off 4th overdrive so it still cruises nicely past the Mercs & BMW's on the motorway. It's noticeably quieter, & much smoother. The only criticism I do have of my gearing is 30mph around town is right on the border of 3rd & 4th. The 1.22 transfer box might be better in that respect.

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Myself, Tuko, Ejparrott, & DiscoMikey have all fitted LT77's recently so you'll find several threads about how we each did it in the Special Builds section.

In my case I went from a late suffix D series 3 box, Fairey overdrive, 3.54 diffs and 235/85R16's to Defender LT77S & 1.211 LT230 with the same diffs and tyres. That's in an 88".

Gearing is a touch lower than the previous arrangement but nicely so; 1st is quite a bit lower so pulling away on a steep hill is much easier, 5th is not far off 4th overdrive so it still cruises nicely past the Mercs & BMW's on the motorway. It's noticeably quieter, & much smoother. The only criticism I do have of my gearing is 30mph around town is right on the border of 3rd & 4th. The 1.22 transfer box might be better in that respect.

Do you have a link to your thread for this? Interested to know what you did about the rear prop and if you off road it much, i.e. get full articulation.

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Do you have a link to your thread for this? Interested to know what you did about the rear prop and if you off road it much, i.e. get full articulation.

http://forums.lr4x4.com/index.php?showtopic=94591&hl=

Rear prop is the original Series prop shortened, front is a Disco rear shortened and re-phased.

The rear prop really isn't overly short, from the size thread in the tech archive I believe a Series 1 80" rear prop would have been the exact length I needed but it was quicker and cheaper to get the old one shortened.

2 weeks ago I spent a day at Whitecliff Quarry, I was able to do everything everyone else did and a few things others couldn't, I certainly didn't notice a lack of articulation and managed to misshape the tops of both rear wheel boxes on the axle twisters.

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The props was something I was curious about too so good to hear it wasn't too much of a faff. Have you had any issues with the increased angles or has it been fine? Also roughly what did it cost to get them shortened? (Apologies if this is mentioned in the threads-currently on phone so makes it trickier to trawl through them, but fully intend to at some stage)

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No issues with my propshafts but I have to admit that I've not tried it offroad yet. I bought my through North West Propshafts and I think I paid £160 each. BTW, my prop's are not shortened but rather new replacements with wide angle joints.

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I've only done The 109 so far, and the rear prop is just the standard Series 4-cylinder prop shortened by 4" and welded back together. Haven't figured the front yet but because it's got to be longer it'll probably be a skinny rangy one to a special length

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Cool, I was partly curious whether you'd used wide angle or normal so that answers that question. And that also gives me a good idea of prop cost . Does that mean you've kept with 'normal angle' props with no issues pollywog?

Yes I've stuck with bog standard prop yolks but I don't have any lift on my truck, it's running GME parabolics and Procomp shocks so get good articulation but at standard height.

Tuko is running on coils so has more call for the wide angle props, and with Ejparrot's longer wheel base he shouldn't have any issues. I think Mikey has Rocky Mountain springs on his 88" which give some lift so it would be interesting to know how he gets on with the standard yolks.

I've only done The 109 so far, and the rear prop is just the standard Series 4-cylinder prop shortened by 4" and welded back together. Haven't figured the front yet but because it's got to be longer it'll probably be a skinny rangy one to a special length

Do you have a part number for the skinny Rangie prop? Is it the same length as the Disco one? One thing I did note with the Disco prop is how little slip joint it has compared to the Series props but it doesn't seam to have been an issue for me so far...

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Nothing yet. I'll most likely end up getting prop tech to make me one special. For The 109 I don't need much slip, she'll not be offroading anyway. She's also on military chassis and running on the lower hole so she's got a 1.5" lift in effect. Standard springs in good nick. For the 88 and my 109 though I definitely do need a good length of slip joint. That most likely will be special job.

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