Syncro AVK 4th gear change?

[mviszek]

Hi All,

I am rebuilding the Syncro and I am planning to put there ADY 2,0 petrol engine 115 hp (from VW golf) which I rebuild for that purpose earlier this year. Now, I have AVK gearbox 38/7 with the 4th gear 0,78 (according to my research).

As I need to rebuild the gearbox I thought about changing the fourth gear. The reason for this is that I will be traveling (highways) with this Syncro and would like to have the comfortable engine working with say 120 kilometers speed (no need to go faster) on the highway.

What do you think makes sense to consider (0,76 or even lower?)? Should I consider 4th and 3rd change to make this working better?

I will appreciate very much any of your suggestions and or recommendation.

EDIT: I gonna use Yokohama Geolandar A/T (G015) 215/70 R16 100H, RPB

Regards,

Maciej

[Sodo]

Maybe .78 is OK for OEM size tires 185/80R14.
For 15 or 16 inch tires you will have to use 3rd gear often.
_________________


'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, SyncroShop pressure-oiled pinion-bearing & GT mainshaft, filtered, cooled gearbox.
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered original gearbox
....KTMs, GasGas, SPOT mtb

[mviszek]

@Sodo thanks for your advice, I have Yokohama Geolandar A/T (G015) 215/70 R16 100H, RPB , so 16".

[Sodo]

The 2.1L WBX makes maximum torque at 3,000 rpm.
Many inline 4-cylinder engines have more than the WBX at 5,000 rpm, but at 3,000 they have less torque.

I don't have an inline 4.
I don't know anything about the 2,0 but I will be surprised if an engine from a small car has (much) more torque at 3,000 RPM than the 2.1L WBX.

I have a Subaru EJ25 ( and 215/75R15, 27.8") and the OEM gearing .85 is good for this 173 HP engine, with 27.8" tires.
Lots of people who changed to taller gearing for the EJ25 and using larger wheels, describe needing 3rd gear often, for small inclines.
_________________


'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, SyncroShop pressure-oiled pinion-bearing & GT mainshaft, filtered, cooled gearbox.
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered original gearbox
....KTMs, GasGas, SPOT mtb

[crazyvwvanman]

The tranny in question has a 5.43 r&p ratio.

To the OP, with that size tire I wouldn't make 4th any taller.

Please say what model you have and how heavy the vehicle is loaded when you are driving it. A light empty van can use taller gears than a heavy model full of stuff.

I have a heavy Syncro Camper with 5.43 and .82 4th, along with 750 rev/mile tires similar to yours. With that gearing it has had inline 5 and an inline 4 gas engines. Neither engine wanted a taller 4th when loaded for camping trips. Yours is already a little taller than mine, overall.

Mark

[mviszek]

Thanks, Crazyvwvanman,

Actually mine is a Syncro Pop-up Camper and there are usually 2 people traveling with this Westy. We're not super heavy loaded but also we basically have always with us a basic camping gear. Car is equipped with the rear, swing away spare wheel rack and additional rear rack-shelf, both quite heavy plus ARB awning and some additional stuff.

So according to your previous post I shouldn't go any taller 4th gear?

many thanks,

Maciej