Recommended Diesel Gearing?

[BugChit]

Trying to pull all my thoughts together and est cost for my anticipated 1.9TD Build..

So it brings me to the Trans Gearing Question.

It is a 2WD Manual Van

If I was starting from scratch, which Trans gearing Package should I consider.. My tire size is approx. 25" tall.

I have a few 091 4 spds, that I can use as donors, just not sure what is the preferred R&P and Best 1st-4th gear selection.. One thing I do know is I'd prefer a .70 or .77 4th wish I could go even lower then .70 to get the best fuel mileage I could.

OK, all You Gear Heads... Your Thoughts
.

[?Waldo?]

Are you planning a 1.9TDI build or 1.9TD? The difference is very pertinent to gearing. The 1.9TDI engines do not like to rev as high as the 1.9TD (AAZ) engine whereas the 1.9TD (AAZ) does not have as much low-end torque.

[svenakela]

I would say, if you are going to use a stock tranny the AAP is the best choice whatever diesel you choose. I even had one in my standard 1.6TD before. very nice combination.

If you're willing to rebuild, it's a totally different story.

[crazyvwvanman]

We never got the AAP over here. Nothing even close

For 1.9TD use the stock waterboxer tranny, add larger tires

Mark

[BugChit]

[MarkWard]

For my TDI powered vanagon.

Stage 1 transmission from an aircooled Vanagon. Stock 4.57 ring and pinion. Stock gearing

Stage 2 215/65/16 tires. Good for a 200 rpm drop

Stage 3 Custom built transmission from later WBX vanagon with 4.14 ring and pinion, .77 4th gear.

Stage 4 Ended up too tall for long uphill grinds, had to add larger nozzles. Gearing ideal now.

The ALH TDi makes max torque at 2200 rpm stock and max hp at 3800 rpm. I can cruise easy at 70 mph at around 2900 rpm with the above setup. Fuel economy really suffers on the TDI above 2400 rpm. Plan accordingly. The nice thing about upgrading the ring and pinion is all the gears are improved.

[Jon_slider]

rsxsr is using a 27" tire with a 4.14 ring and pinion and a .77 4th. I agree with that combination, and would also suggest a 1.14 3rd.

> if possible i'd like to keep things low.

Then you will need to change ring and pinion like rsxsr, even if you don't match his tire size and stay with your 25" tire (what is the exact tire you are using, I would confirm that dimension)

So for your 25" tire I recommend a 4.14 ring and pinion, and change to a 1.14 3rd and a .77 4th.

You could later go to a 27" tire like rsxsr if you find the gearing too short with your tire size, but the gear spacing and ring and pinion would not need to be changed again, IF you use a 4.14 ring and pinion.

IF you were willing to go to a 28" tire, you would not need to change your 4.86 ring and pinion, and then I would recommend a 1.88 2nd, 1.08 3rd, .7 4th (however a 1.88 is very difficult to obtain)

Your choice of tire size, determines whether you need to change ring and pinion. And your choice of ring and pinion, determines what 3rd and 4th gear to use.

I think you are making a mistake trying to run a 25" tire on a TDi, and I think changing ring and pinion is an unnecessary expense, IF you can accept that a 28" tire is a better choice for a Diesel.
_________________
My Soapboxes: Inflation; Handling; Gearing; Decoupling; Swepco

[furrylittleotter]

With those tyres, the absolutely lowest Ring and pinion you can get and a stock Diesel 5 speed tranny.

[crazyvwvanman]

The 1.88 2nd was a rare Syncro gearing variation AFAIK. 1st and 2nd gears are machined into the mainshaft. The mainshaft of a 2wd is different than that of a Syncro. I don't think you can get even near to a 1.88 2nd in a 2wd tranny without screwing up 1st gear too tall.

Mark

[jimeg]

Going to install an AAZ in my Syncro. I would like run 195/75 - 16 tires. Do I need to re-gear my trans, or run a different tire size than this?
_________________
1986 Root Beer Syncro Tin Top....so many plans.

Here: http://www.thesamba.com/vw/forum/viewtopic.php?t=578490

[outwesty]

If you are going to chip tune and add injectors on the AHU I'd do a 1.14 3rd and a 0.70 4th and stock R&P....I run 215 70 16 tires and I think its about perfect. Just yesterday I did donner pass with the cruise on at 73 no problem. If you run any larger tires than that I would not do the .70 4th. At 3000 RPMS's I'm at 72 MPH.

[crazyvwvanman]

That is about a 755 rev/mile tire. I consider that about right for taller tires with a stock AAZ and stock US Syncro tranny. I have run that tire/gearing combo with AAZs for many years.

195/75/16 is not a very common size. I guess you are planning Nokians?

Mark

[jimeg]

[Jon_slider]

> Just want to get up the mountain passes as the speed limit.

no problem, as long as the speed limit is 58mph, which is what you will be doing at 3000rpm in 4th with a stock box and those tires.

You can always regear later if you dont like the stock gearing.

I believe hans j is currently running a stock tranny with a TDi, he goes offroad a lot, maybe touch base with him. I dont think he cares about going on the freeway.
_________________
My Soapboxes: Inflation; Handling; Gearing; Decoupling; Swepco

[crazyvwvanman]

If it is a fairly stock AAZ he won't be doing 58 up many mountain passes in 4th. Maybe if he put a 5.43 r&p.

Mark

[jimeg]

[jimeg]

[outwesty]

[quote=

Also. I don't think I intend to "chip" of tweak the engine much. Just want to get up the mountain passes as the speed limit. Don't need to be that quick, mostly efficient and long lasting. I still have some more to learn about this engine though. Waiting on a few more parts to arrive from the seller, then I can make a full assessment and plan.

Thanks![/quote]

Just to let you know a chip in most cases increases your MPG's while adding a significant amount of power. I'm getting ready to do a second AHU Tdi swap and can't imagine not chipping it....its too easy not to and only $300

[jimeg]

[Witless Joe]