What is the maximum I can drop whilst staying on reduction boxes? I have read many threads stating 'one outer' is the safe limit. But what is the maximum I can drop without:

Getting adverse camber
Draining oil out of reduction boxes
Having to pry wheels out with a bar (don't mind letting tyres down)

I want to be able to increase rear tyre size over standard (to up the gearing) without getting to much rake when using only dropped spindles on the front.

I'd appreciate actual experience i.e." I dropped mine * outer and $ inner splines and this is me experience"

I lowered my reduction boxes to level out the bus when it just had the drop spindles on the front. I cant be sure but I think I went down 2 outer splines. It had loads of camber and the axles were running back down towards the gearbox!!. I had Empi 5 style alloys on at the time with loads off offset and had to let the tyres down to get the wheels off. Tyres on the back 185/65/15 it was ok gearing wise but I didnt really drive much over 60 mph. As for lack of oil I did about 3500 miles like that and when I took it all to bits to straight axle there was still oil in the reduction boxes.

Thanks for replying. Couple of Q's:

How much space did you have in the wheels well with that drop....enough for a bigger rear tyre? Do you have any pics of it like that?

Thanks,
Rory

Hi Rory,

About 10 years ago I had a 58, that was dropped 2 splines and had no problem other than when it had 14" wheels with 185/60 tyres on, it was low but the gearing was terrible.

Its not the best option for lowering a bus, but it works.

You can get away with a bigger tyre than 185/65, but you are going to struggle getting the wheels on and off.
I messed around with a bus I had in the yard and lowered it 2 spines with stock tyres on (like a 18/80/15). The only way I could fit the wheels is to take the drum off to give enough clearance to squeeze the tyre in.


Cheers,
Dom.

I would have thought if you are using steel wheels you could use a higher tyre profile and still get it to fit. The higher profile tyre you use though the lower you will need to go to get it level and will end up with massive camber.

Monkeydub wrote:
I want to be able to increase rear tyre size over standard (to up the gearing) without getting to much rake when using only dropped spindles on the front.

I'd appreciate actual experience i.e." I dropped mine * outer and $ inner splines and this is me experience"

Stock tyre sizes (close as poss with metric) are either a 195/80/15 or a 205/75/15. In 14" a 205/80/14 is closest.

These are the tallest profile tyres that you can buy anyway, so you will not be able to "up the gearing" any further by using different tyres. Unless you go with Crossplies then you can use a 6.70/15 and this will up the gearing over stock.

Best gearing you can hope for with modern radial tyres is stock factory gearing. It is possible to squeeze in a 215/75/15 in metric radial which will take the gearing over stock but this definitely would not be possible with a lowered bus.

If you planning on using stock 195/80/15 tyres then you will not be able to remove the rear wheels without jacking down the springplates even if you only lower the bus one outer spline on RGB`s. I have tried to do this on someones bus for them and they decided to go with lower profile tyres for it to work. They wanted the "look" and subsiquently put up with the high rpm`s and rubbish fuel economy. There is not too much of a problem with oil getting to the RGB`s with one outer spline.

Even with just one outer spline you will get positive camber and this does really chomp through tyres I`m afraid. The continual camber also wears out the bearings (which act as the wheel bearings) in the RGB`s quicker too and they start to howl after a while. If left, the howling bearings eventually collapse leading to a dead RGB.

Sweet Rides wrote:

Monkeydub wrote: Even with just one outer spline you will get positive camber and this does really chomp through tyres I`m afraid. The continual camber also wears out the bearings (which act as the wheel bearings) in the RGB`s quicker too and they start to howl after a while. If left, the howling bearings eventually collapse leading to a dead RGB.

But don't some buses have stock negative camber to allow for a load. So when these run empty they continually have the negative camber.
Mine is one spline lower and yes it gets through tyres quicker (Due to uneven wear) and does have positive camber, but the reduction boxes have been fine for just over 10 years. And i usually turn the tyres round on the rim when they are roughly half way through the tread depth.
I would have thought with just the one spline lower, you don't need to worry about the reduction boxes. I can't see the wear been much more than not having it lowered.

Thanks for the replies. I'm on 14" wheels at the mo, so will try a 1 outer spline drop and see how it goes. For future reference what's the easiest/cheapest way to go swing axle?

CCSICeman wrote:
But don't some buses have stock negative camber to allow for a load. So when these run empty they continually have the negative camber.
Mine is one spline lower and yes it gets through tyres quicker (Due to uneven wear) and does have positive camber, but the reduction boxes have been fine for just over 10 years. And i usually turn the tyres round on the rim when they are roughly half way through the tread depth.
I would have thought with just the one spline lower, you don't need to worry about the reduction boxes. I can't see the wear been much more than not having it lowered.

Negative camber - NO, only some unladen commercials (panels and pick ups) have a bit of negative camber due to lack of weight when unladen. It is assumed that they will be running laden to one degree or another so they will rarely drive with negative camber. In any case the tiny amount of negative camber early commercials run unladen is not at all proportionate like the positive camber achieved from running just one outer spline. to put it into perspective, I have NEVER seen any stock height bus wear its rear tyres unenely due to negative camber. Negative camber keeps the oil at the correct level in the RGB`s, whilst positve allows it to drain back into the centre section. This allows the top outer bearing to run dry a lot of the time.

In my experience, and as a rough guide, One outer spline wears out the bearings at an approx rate of somewhere around 5 to 1. You would expect to get around 100000 miles out of a brand new set of RGB bearings properly maintained for that period. In a bus lowered one spline (with new bearings) you could expect to get approx 20000 miles to a set.

Once they howl - they`re dead. Once they howl the straight cut gears have enough movement to allow them to run slightly off true. The pressure caused by the slanted stub axle rapidly accelerates this process and causes one side of the gears to wear down. This menas they no longer mesh properly and this all adds to the noise levels.

If left howling and unchecked, eventually the bearings come out of the cages and chew up one or both of the gears inside the reduction box. Or due to the gears getting worn on one side thesmall points of the teeth can fracture off.
This is A) dangerous as the wheel will normally lock up without warning whilst driving and B) will mean complete replacement RGB gears AND bearings will need to be sourced. I have on occasion seen the casing get damaged to but this is not so common.

I have experienced a bus with two outer splines on RGB`s. The bearings lasted just shy of 5000 miles. The bearings were not new, but they made no noise before the bus was lowered.

I must just be lucky then, cos as I said its been lowered for 10 years and still running on reduction boxes when they were last checked this year they were fine.

I hope I'm not tempting fate saying that.

But the good think is all the bits are available for reduction boxes, people should just keep an eye on them and sort out any problems/ noises before its too late.

CCSICeman wrote:I must just be lucky then, cos as I said its been lowered for 10 years and still running on reduction boxes when they were last checked this year they were fine.

I hope I'm not tempting fate saying that.

But the good think is all the bits are available for reduction boxes, people should just keep an eye on them and sort out any problems/ noises before its too late.

As I said, on a fresh set of bearings you`ll get approx 20000 miles. Many buses only cover 500 - 1000 miles a year so the fact that yours has been like this for 10 years doesn`t necessarily mean it`s covered loads of miles like this

The bearings are all readily available new anyway And you normally get PLENTY of warning before they go anyway. If you change them out as soon as they start to howl then you`re unlikely to ever get any serious problems.

Ever thought of putting you bus back up to stock height? 1 spline lowering is not a lot so you don`t achieved a slammed look anyway. They drive SO SO much nicer stock, suspension is lovely and smooth and you can run higher profile tyres which will give you much better gearing/cruising speed

The big drawback to buses lowered on RGB`s is that is necessitates running low profile tyres on stock gearing. This Sucks. It means your doing way more RPM`s than you need to be at cruising speed which is obviously a strain on your engine and also gives rubbish fuel economy too Experiment by putting it up a spline at the back (no big job) and borrowing some 15" wheels with 195/80/15`s or 205/75/15" tyres and once you`ve driven with that gearing I don`t think you`ll go back

It won't go in the garage at stock height. In fact only just goes in now.

What revs would you expect, I've got 185 65 R15's on mine, not low profile.

At 50mph its 3000 rpm and at 65mph its just short of 4000rpm.

As for mileage i've done over 2000 this year so far and it will be 5000 by the end of the year.

Whilst were discussing reduction boxes, didn't VW make different gearing in reduction boxes for different markets.
Could you not change the gearing to increase top speed? Or do british vw's have the best available gearing in them for this.
I know they made a ratio of 1.68:1 for use in mountainous areas. Did they make a set for the Belgium market?

I`d Modify the garage

185/65/15`s are low profiles. Standard profile is 80. So 185/80/15`s are full profile 185 tyres. 185/80/15`s are still not as tall as the stock 640/15 crossplies. 195/80/15`s are a better match for stock to achieve standard gearing with a modern radial.

Unfortunately I don`t have a rev counter in my bus, so couldn`t tell you what rpm I get at given speeds, but with 65 profile tyres you`ll definitely be reving considerably harder than stock. (and using more fuel too )

No, there were not different RGB gearing options offered. Just standard and alpine and thats it. Alpine is VERY rarely found and is super low geared. The Small nut (pre 63) RGB`s are lower geared than the big nut (post 64) RGB`s. The gearing was raised to make use of the more powerful 1500 motor that was introduced at that time.

Although they didn`t offer any gearing options on the RGB`s (except alpine) VW did change the configuration of the gearing in the centre section a hell of lot over the years, using various differnt ratio combinations within the central cluster. Depending on what size fourth got put in would obviously have the effect of raising/lowering the crusing speed gearing.

Sweet Rides wrote:I`d Modify the garage

I'm working on it.
But the wife has a list of things that she wants first. and considering how much I spend on boys toys, I can't really blame her.

This is my panel wich is down 2 outer splines at the rear with notched springplates. Front has 4" beam and droped spindles.Ride is not too bad with the 195x65x15 rear tyres.(they fit tight but they DO fit).

I made sure the RGB's are FULL with oil too.