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Hi guys
Gearbox has given up so looking for second hand one. Problem is not sure what to go for.
When the original 1.6 jx set up was replaced with a 1.9 TD the 5 speed gear box was also replaced with a 4 speed. The code on the box reads ABB which according to brickyard should be a petrol gearbox? Ideally I'd like to find one I can just slot on without having to muck about with, do are there a few different options? Could the ABH or ABS also do the job - do they have the same fittings etc
Many thanks for any help - currently stuck at parents in west Wales on what was meant to be a camping trip
polish van ben wrote:When the original 1.6 jx set up was replaced with a 1.9 TD the 5 speed gear box was also replaced with a 4 speed. The code on the box reads ABB which according to brickyard should be a petrol gearbox?
The only real difference between a "petrol gearbox" and a "diesel gearbox" are the ratios. Because petrol engines rev higher than diesel engines, a petrol box is geared lower. So, to get <say> 70mph at peak power revs, a petrol engine with 4500rpm peak power would need to be geared at 15.5mph/1000rpm, whilst a diesel engine with 3500rpm peak power would need to be geared at 20mph/1000rpm.
Seems that they've gone the wrong way, though - they've put a shorter-legged box in with the more powerful engine. Should go like wotsit off a shovel off the line, but be a right pain on the motorway. The norm would be to swap t'other way round with an engine upgrade - put a diesel box in with a more powerful petrol.
Thanks for all advise guys - just found a box advertised as a 4 speed diesel gearbox with abr code off an old jx - now according to brickyard list this code should be a 5 speed - is there any reason that I shouldn't be able to fit this box to my current set up even if it is a 5 speed?
And if I go what else might I need to make conversion?
Ok, have now found 4 speed gearbox in East Midlands - from guy called Peter at T25 East Midlands (I guess this guy must me familiar with this forum as he specialises in T25's?)
Prob is that he doesn't have engine code as its worn off, though said it is def a 4 speed from a TD and in working order
So question is should any 4 speed TD generally slot on easily enough - and would it be right for my engine - which is a TDI but with mechanical injectors?
Don't fancy forking out £300 plus courier for it all to be wrong
Sorry to be thick, but what should the final drive be for a TDi? They all seem to around the 4.87 mark
I'm sure I read somewhere that a TDi needs a lower ratio than regular TD - but don't know if this is the case or is true for TDi's with mechanical injectors fitted?
polish van ben wrote:Sorry to be thick, but what should the final drive be for a TDi? They all seem to around the 4.87 mark
You also want to check the actual gear ratios.
I'm sure I read somewhere that a TDi needs a lower ratio than regular TD - but don't know if this is the case or is true for TDi's with mechanical injectors fitted?
Lower ratio = "longer legs", so it can take better advantage of the extra power to give you a more relaxed cruise.
So - the ABR has following ratios - 1st 4,11/2nd 2,3/3rd 1,476/4th 1,023/5th 0,816 with a final drive of 5.5
First and second are the slightly higher ratio than the current ABB, 3rd is way higher and 4th is lower than 3rd, but 5th is a lower ratio than 4th on the ABB - final drive is 5.5 on the ABR, but 4.57 on the ABB
So would it still mean that the revs would be very high in 5th though the ratio is actually lower because the final drive is higher??
It looks like this ABR box is my best bet at the moment so would be good o know exactly what effect it may have on drive
One more question - do the air cooled boxes also fit water cooled engines?? There is a DK available which has the exact same ratios as the ABB
that ABB was a pretty good compromise for the TDi as it means lower revs throughout the range and is a later model with the 112bhp gears rather than a DT
same again would work, swap over the diesel bellhousing and input shaft from the old one
ABD is 4.86 petrol version, most common and works out the same in 4th as the TD 4 speed the ABH which along with the rest of the diesel boxes will be too low geared and cause the revs to be hight over 60mph
if crown and pinion in the ABB are ok then rebuild it, with a 0.82 fourth gear or a 0.78 if you can find one
Hi Aidan
Many thanks for reply - in the end I found a guy down the road who was willing to do a rebuild on it, as was having trouble finding a similar box. He hasn't done a T25 box before but has done others and seemed to know his stuff. He gets started on it next week.
I directed him towards the camper van culture vids on your website as a starting point - but are you available for advice and parts if necessary? He might need it....and will def need parts
He totally slated Just Kampers when I mentioned them, so know he has some sense about him!
