Gearbox to match rebuilt 1.6TD JX engine - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

Gearbox to match rebuilt 1.6TD JX engine by epowell on 17 Oct, 2017 01:47
HI Folks

This thread, I would like to submit as a sister-thread to my JX REBUILD thread over here: http://vwdiesel.net/forum/index.php/topic,37157.0.html

The point is this - currently my JX and tranny (DM I think) are both working fine - no issues at all - but are both certainly pretty tired... I have an extra JX block which I will rebuild - but the other main question I have has to do about what to best do about the gearbox.

The gearbox I have now in the van is probably a DM (early Vanagon diesel 4-speed with VERY short gearing) which is meant to be used with a CS (1.6NA) engine. To be honest, I really love this short gearing, but *on the highway* it's a joke... I do not drive fast or much on the highway, but I DO want the possibility to do that so my goal is to find a 5-speed.

PROGRESS SO FAR: I have been working on this issue for about a year now and in my searches I have found one used tranny here in Czech for less than $200. I think maybe the gearing can be good for me. The seller upgraded the engine to a 1.9TDI and felt that this 5-speed tranny was geared too short for his added power. But for me, I'm guessing that it would be fine with a less powerful engine. Keep in mind that I don't like driving fast and I rarely go on highways > but any sort of 5th gear I think would improve my situation vastly.

The seller really seems like a very intelligent, kind, and decent person and I have the feeling I can trust him - what he says about this 5-speed is this: He does not know the code number (but codes don't mean much anyway since the gears inside can be swapped). It was in his bus when he bought it, and he drove it for 2 years. The 5th gear synchonizer is not in good shape (difficult to get it out of 5th). He is recommending me to visit a Czech *GEARBOX GURU* who is supposedly an older trusted gearbox specialist who can be consulted - and hired... he predicts an overhaul could cost around $400. This gearbox was for a gas engine so it would need a different bell-housing I guess. He was driving with this gearbox on highways long-term at 80-90KM but faster would be too loud. His goal was 100KM long-term.

I didn't have a good search for about 9 months, so maybe now something else might appear in this country (or Poland/Germany??) but I have a feeling that this 5-speed might be the right thing for me.

- - -

I don't know for sure but my guess is that my current tranny has:
- 5.83 R&P
- 0.85 4th gear.

My guess is that this used 5-speed has:
- 5.5 R&P
- 0.82 5th gear

Maybe (probably) this 5-speed is meant for an NA diesel engine?

From my understanding the code *BH* is specifically designed for 1.6TD engines and has:
- 4.83 R&P
- 0.816 5th gear
....so finally this used 5-speed might feel a bit too short with my rebuilt JX?

- - -
- - -

One thing I have been seriously considering doing is to REBUILD this 5-speed tranny myself. Has anyone here done this kind of thing? I realized it is not commonly advised to do it - but how *out there* is it really to consider such an undertaking? I like the idea of really knowing for myself what I have in there and how it was done... otherwise gearboxes are such a mystery - and we never can know what can happen.

If I would rebuild this 5-speed myself I could swap in there the exact gearing I would want. I have a 12-ton press but realize that rebuilding would require buying some expensive tools and take a lot of time to study up on how to do it.

Thanks for your time and any suggestions.

Edward
#1 by libbydiesel on 17 Oct, 2017 09:50
If the 5-speed was from a gas engine, then it would have the 4.8 R+P. It would be a good match for the 1.6TD. A 5-speed with the 5.43 and .77 5th is also a good match to the 1.6TD with taller than stock tires fitted.

I have not yet done a rebuild on the vanagon trans, but have a couple I plan on doing. There are a couple good build threads on the Samba, this one in particular: https://www.thesamba.com/vw/forum/viewtopic.php?t=491932&postdays=0&postorder=asc&highlight=svx+gearing&start=120
#2 by epowell on 17 Oct, 2017 11:24
thanks....
...we can't be sure it originally came from a gas engine. All he said was that the his van (which came with that tranny) had a gas engine. Then he converted to TDI, and he needed to get a diesel bellhousing because the gas bellhousing is different. So we don't know for sure if that tranny was originally made for a gas engine > or, even if it was, if it has not been opened and manipulated.

Quite a weird game: this tranny business.

Maybe the thing to do is to buy 2 or 3 of them - open them all, and build one good one.

As I have talked about for a long time, I am tempted to make a trip down to Bosnia and survey the junkyards there. T3's are the national car down there and it is a cheap country - odds are that there are gearboxes in junkyards in every town.
#3 by epowell on 18 Oct, 2017 03:21
My decision for the moment (not my ulitimate goal, but rather logical next step) is to get one or two good working second hand back-up gearboxes of the same type as I have now (early diesel short geared boxes DM, DZ... etc). My first priority is reliability on long trips and to have backups for everything, and the ability to remove/install by myself.

Having a 5th gear would be nice, but it is far from essential. I will however put on some bigger tires to buy me a tad more 'gearing length' because as it is now I can easily afford to lose a little bit on the low gear 'peppiness'.

Changing to a 5 speed box would mean also changing shift linkage and nose mounts... Ultimately > long range goal > is to do this 'some day', but for now I am just going to keep it simple - and get peace of mind by hoarding a few early boxes for "bolt on" replacement if/when necessary.

Another issue is that with my K24 turbo, it will give even less immediate boost with a longer geared box - so hence another reason to achieve more gearing length via bigger tires rather than (for now) longer tranny gears.

Ultimately of course I would like to return my van to stock with a K14, and a 3H tranny... but that is for the future.
#4 by libbydiesel on 18 Oct, 2017 10:25
Having 5 speeds instead of 4 really improves drivability with the big box and a relatively low-powered engine. Instead of acquiring more 4-speed boxes, I would get two 5-speeds (at least one of which currently works) and the appropriate linkage. I would then do a quick swap of linkage and trans to the 5-speed. Then rebuild the other one at leisure getting the gearing how you want it after having the experience with driving the 5-speed.
#5 by epowell on 18 Oct, 2017 12:57
Quote from: libbydiesel on 18 Oct, 2017 10:25
Having 5 speeds instead of 4 really improves drivability with the big box and a relatively low-powered engine. Instead of acquiring more 4-speed boxes, I would get two 5-speeds (at least one of which currently works) and the appropriate linkage. I would then do a quick swap of linkage and trans to the 5-speed. Then rebuild the other one at leisure getting the gearing how you want it after having the experience with driving the 5-speed.

That's sound advice. I will do more tranny searching... a lot depends on what is available. .. but I like your suggestion. I was driving today, and noticing how insanely short my tranny is! It's fun... but leads to high revs all the time.