VW T4 Forum - VW T5 Forum banner

1 - 14 of 14 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter #1
Hi all. Really need some help / advice.

I've just had my 3rd gearbox replacement in 18 months & the only thing my mechanic thinks it could be is the wheels I ride on as both times 5th gear has been shredded when taken apart!

It's a year 2000 caravelle longnose.

I've got 245/45/18 on.

Do I change my lovely Borbets to a 15" option? Or just the profile to 235/40/18 to match the original rolling radius?

Anyone ever heard of this problem before?

Help!!
Cheers
 

·
Registered
Joined
·
6,655 Posts
I've been running 18s for the last 5 years on the 45 profile with no gearbox issues pal.....I'd suggest the problem lies elsewhere
 

·
Registered
Joined
·
794 Posts
Your tyres give you 4.5% more distance per rotation than stock 205/65/R15. So effectively you're slightly higher-geared than before, but the effect is pretty small and hardly enough to shred a gearbox.

On the other hand, have you had the engine uprated... that could be a bigger issue?
 

·
Registered
Joined
·
449 Posts
how can wheels damage a gearbox :confused:
never heard of it, heavy handed light footed gear changes maybe but wheels I:
 

·
Registered
Joined
·
6,655 Posts
Your tyres give you 4.5% more distance per rotation than stock 205/65/R15. So effectively yoe slightly higher-geared than be, but the effect is pretty small and hardly enough to shred a gearbox.

On the other hand, have you had the engine uprated... that could be a bigger issue?
I'm running 160bhp with 18" wheels....I had clutch issues to start with but after fitting an updated Sachs clutch ive had no more issues and non with the box
 

·
Registered
Joined
·
95 Posts
What clutch are you running? Dual mass or solid?
I've been told by a mechanic friend that VW fitted dmf's to stop the engines shaking the gearbox to pieces.
I don't know how true this is, but they must've fitted them for some reason....
 

·
Registered
Joined
·
6,154 Posts
What clutch are you running? Dual mass or solid?
I've been told by a mechanic friend that VW fitted dmf's to stop the engines shaking the gearbox to pieces.
I don't know how true this is, but they must've fitted them for some reason....
In layman's terms the DMF is a type of 'shock absorber'.

The mass of the conventional flywheel is simply split in two. One part continues to belong to the engine’s mass moment of inertia, while the other part now increases the mass moment of inertia of the transmission. The two decoupled masses are linked by a spring / damping system. One clutch disc, without a torsion damper, between the secondary mass and the transmission handles all the engaging and disengaging functions. .

A positive side effect is that the gears are easier to shift because of the low mass to be synchronized, and there is less synchronization wear. Well that is the theory anyway!

The reason for their introduction was to offer a higher level of comfort. The increased number of gears on modern cars (and hence more gear shifting), and the thinner oils used meant there was not as much vibration and noise being absorbed naturally. This was now going to be the job of the DMF.

Most gearboxes I have seen that have been 'shaken to pieces', have been the result of poor maintenance or poor operator use!
 

·
Registered
Joined
·
43 Posts
In layman's terms the DMF is a type of 'shock absorber'.

A positive side effect is that the gears are easier to shift because of the low mass to be synchronized, and there is less synchronization wear. Well that is the theory anyway!
Mass is the same because you shift with your clutch fully pressed - the synchros are not synchronizing the flywheel or any part of it.
 

·
Registered
Joined
·
794 Posts
If you had clutch issues it's because you're getting more torque out of the chipped engine. T:

But that means you can put more strain on the gearbox. :( Especially so if you use that extra torque to hang on to fifth gear instead of changing down when you hit a really steep hill.
 
1 - 14 of 14 Posts
Top