sotal Posted September 16, 2006 Share Posted September 16, 2006 I've just been going through the Haynes Manual trying to work out which gearbox is best for ratios etc. I currently have a Suffix D Series 3 Gearbox. My father in law has 3 or 4 boxes lying around. My problems with the Suffix D box are: a - it's noisy b- the syncro on 3rd is very bad, and 4th isn't great c - there is a huge difference between 3rd and 4th c - is the bit we're trying to sort by choosing the best box. At the moment you have to over rev it in third to get decent performace in 4th. If you don't over rev it in third then in just lulls before getting going again in 4th. This is more noticeable on hills. The vehicle is a SWB 2.25 5 Bearing Diesel with 7.50x16 wheels on it. Is there a combination of transfer box and gearbox that is best?? Any suggestions would be great Quote Link to comment Share on other sites More sharing options...
bill van snorkle Posted September 17, 2006 Share Posted September 17, 2006 I've just been going through the Haynes Manual trying to work out which gearbox is best for ratios etc.I currently have a Suffix D Series 3 Gearbox. My father in law has 3 or 4 boxes lying around. My problems with the Suffix D box are: a - it's noisy b- the syncro on 3rd is very bad, and 4th isn't great c - there is a huge difference between 3rd and 4th c - is the bit we're trying to sort by choosing the best box. At the moment you have to over rev it in third to get decent performace in 4th. If you don't over rev it in third then in just lulls before getting going again in 4th. This is more noticeable on hills. The vehicle is a SWB 2.25 5 Bearing Diesel with 7.50x16 wheels on it. Is there a combination of transfer box and gearbox that is best?? Any suggestions would be great The suffix D box is the best of a very bad bunch that includes all series gearboxes(Except stage 1 V8's) It has undercut synchro teeth to address the common series 3 problem of jumping out of gear on a trailing throttle(coast) The ratio gap between 3rd and 4th is really no different to any of the series gearboxes from series 2A suffix C onwards. The only way you you could shorten the gap is to fit a series 1 or 2 gearbox, but then 1st gear ratio changes from 3.66:1 to 2.99:1. Then you would have to fit a suffix B transfercase gearset to restore your low range ratio or the truck would not be capable of pulling the skin off a banana.This is really not the way you should be heading. Just fit a set of leaf springs to 3rd and 4th synchro hub and some bearings and try to live with the gap. Bill. Quote Link to comment Share on other sites More sharing options...
LR90 Posted September 17, 2006 Share Posted September 17, 2006 I found the overdrive was handy on my 2.25 S2 as it could be used to give intermediate gears when towing. Quote Link to comment Share on other sites More sharing options...
simonb Posted September 17, 2006 Share Posted September 17, 2006 Your performance sounds typical of 2.25 diesel which is past its best.. don't blame the gearbox, its the engine which is down on power.. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 18, 2006 Share Posted September 18, 2006 2.25 5 Bearing Diesel with 7.50x16 wheels on it. There lies your problem - you have high gearing thanks to bigger tyres and an engine that, from the factory, put out about 3hp. The quickest & cheapest solution would be to fit a set of 205R16 tyres which would've been standard fit for an SWB. Then have a look at your engine options - 2.5D will pretty much drop in, 200TDi is a little bit of work for a very good engine (but the engine will likely cost you a few quid) and of course a V8 will kill your fuel economy but the gap between gears will seem so small you'll be wanting a 6-speed box to keep up Quote Link to comment Share on other sites More sharing options...
sotal Posted September 18, 2006 Author Share Posted September 18, 2006 I know what you mean about the tyres, but it had a set of 205's on when we got it, we added the 7.50's because we use it off-road. I would say the engne was still fairly powerful as it performs really well off-road, and cruises well at 65-70mph on the motorway. It also pulls well in every gear but it just seams a big jump between 3rd and 4th. I think the overdrive option is the best idea as it would give me a gear half way between 3rd and 4th and it would also give me a further gear for cruising at. I think my plan will be: 1 - swap the box out for another series box probably older 2 - then rebuild the suffix D box. 3 - put the D box back in and then add an overdrive box Quote Link to comment Share on other sites More sharing options...
Tonk Posted September 18, 2006 Share Posted September 18, 2006 AFAIK late ser3 swb came out the factory with 7.50's on as standard Quote Link to comment Share on other sites More sharing options...
PeterW Posted September 18, 2006 Share Posted September 18, 2006 I would say the engne was still fairly powerful as it performs really well off-road, and cruises well at 65-70mph on the motorway. It also pulls well in every gear but it just seams a big jump between 3rd and 4th. I would get your speedo checked... If you **can** get 70mph on the motorway, it sounds like you have had lower ratio diffs fitted also - IIRC you will top out a 2.25D with 7.50s on using a non-overdrive box before 70mph or before you go deaf from the engine noise... Cheers Pete Quote Link to comment Share on other sites More sharing options...
Jon White Posted September 18, 2006 Share Posted September 18, 2006 You wanna try it with 285/75's on it! They're even taller!!! Jon Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 18, 2006 Share Posted September 18, 2006 AFAIK late ser3 swb came out the factory with 7.50's on as standard No denying a Series should be able to pull 750's but if it can't I wouldn't expect the gearbox to be the problem. Quote Link to comment Share on other sites More sharing options...
Tonk Posted September 18, 2006 Share Posted September 18, 2006 No denying a Series should be able to pull 750's but if it can't I wouldn't expect the gearbox to be the problem. i never said it was i agree it would be down to the engine not havin enough grunt, sayin that the even though the 2.25 diesel engine is not the fastest engine in the world, they are quite capable of pushing that gearing if its healthy. Quote Link to comment Share on other sites More sharing options...
sotal Posted September 18, 2006 Author Share Posted September 18, 2006 I would get your speedo checked... If you **can** get 70mph on the motorway, it sounds like you have had lower ratio diffs fitted also - IIRC you will top out a 2.25D with 7.50s on using a non-overdrive box before 70mphor before you go deaf from the engine noise... Cheers Pete I've got the LWB clocks in and I've verified the speedo using GPS. It tops out at 67mph confirmed by my GPS unit, the noise isn't that bad in 4th - 3rd gear gets very noisy as I have to rev it quite a lot to build enough speed up for fourth to be in the right power band. I can change up to fourth earlier to avoid over reving it but then 4th takes longer to get going. At the end of the day the LWB landrovers all had 7.50x16's on as standard and as far as I know they had the same gearboxes - and if they didn't please let me know as I've got a few of them lying about! I don't want to go any faster than 70mph because the steering goes too light and wandary and the brakes would take about a week to slow down! Quote Link to comment Share on other sites More sharing options...
simonb Posted September 18, 2006 Share Posted September 18, 2006 I've got the LWB clocks in and I've verified the speedo using GPS. It tops out at 67mph confirmed by my GPS unit, the noise isn't that bad in 4th - 3rd gear gets very noisy as I have to rev it quite a lot to build enough speed up for fourth to be in the right power band. I can change up to fourth earlier to avoid over reving it but then 4th takes longer to get going.At the end of the day the LWB landrovers all had 7.50x16's on as standard and as far as I know they had the same gearboxes - and if they didn't please let me know as I've got a few of them lying about! I don't want to go any faster than 70mph because the steering goes too light and wandary and the brakes would take about a week to slow down! You won't get faster than 70mph with a 2.25 diesel as drag exceeds power. 67mph sounds about right. Your engine will be down on power hence, at max revs in 3rd you will be close to max power, when u change up to 4th, revs and hence power drop, and your engine is not healthy enough to maintain the speed in 4th. Personally I would check the pump timing and fit a new chain, get the injectors serviced and then worry about the gearbox. Quote Link to comment Share on other sites More sharing options...
sotal Posted September 18, 2006 Author Share Posted September 18, 2006 You won't get faster than 70mph with a 2.25 diesel as drag exceeds power. 67mph sounds about right. Your engine will be down on power hence, at max revs in 3rd you will be close to max power, when u change up to 4th, revs and hence power drop, and your engine is not healthy enough to maintain the speed in 4th. Personally I would check the pump timing and fit a new chain, get the injectors serviced and then worry about the gearbox. Yeah you might be right. The power just seems fine all the rest of the time. 4th does maintain the speed and does accelerate, but it's just a lot better if you over rev 3rd We put a set of recon injectors in, in March. The pump timing is slightly out as it is over-fuelling, but we were advised to leave it because it starts so well. Do you think the pump timing would help on it's own?? Quote Link to comment Share on other sites More sharing options...
simonb Posted September 19, 2006 Share Posted September 19, 2006 Yeah you might be right. The power just seems fine all the rest of the time.4th does maintain the speed and does accelerate, but it's just a lot better if you over rev 3rd We put a set of recon injectors in, in March. The pump timing is slightly out as it is over-fuelling, but we were advised to leave it because it starts so well. Do you think the pump timing would help on it's own?? If it starts and doesn't smoke i'd leave it. Unlike a Tdi there is less performance enhancement that can be achieved on a 2.25/2.5 by adjusting the pump. You can try it but don't expect to get much more performance. I think Land Rover quoted the offical top speed of a 2.25D as 69mph... 2.25 petrol should be slightly better as they have a few more hp, but at 70mph without an overdrive your ears will be bleeding from the racket especially with a diesel In a series your better off aiming for 60mph top speed, less engine wear and better mpg. Quote Link to comment Share on other sites More sharing options...
sotal Posted September 19, 2006 Author Share Posted September 19, 2006 I don't want to go any faster, as I said before the 67mph is scary enough!! All I wanted to do was improve the permance at the beginning of 4th gear Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 20, 2006 Share Posted September 20, 2006 Face facts - it's a 2.25D, they are world renowned for being slower than a glacier, unless you have good reason to suspect something is wrong with your engine just accept the fact that it's a 30-year-old vehicle with a 50-year-old design of engine that wasn't a skyrocket when it was invented. If you want a bit more go, fit a different engine - there are a hundred different engines that can be dropped into a LR pretty easily and will give better performance/economy. Weirdest one I've heard so far is an Audi A3 1.4 Diesel Quote Link to comment Share on other sites More sharing options...
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