21 replies to this topic

[Big Jim]

Did the Lotus 49B race with the ZF or Hewland transmission? If it had the Hewland, does anyone know where I can find a good photo or drawing of the installation?

[Tim Murray]

The 49B only ever used Hewland, initially the FG400 and then, from the end of 1968, the DG300.

[rgsuspsa]

The 49B only ever used Hewland, initially the FG400 and then, from the end of 1968, the DG300.

Note that the Lotus 49 debuted at the 1967 Dutch Grand Prix with a ZF gearbox in the cars of Graham Hill and Jim Clark.


Ron Sparks

[Tim Murray]

Yes indeed. The change to Hewland came with the introduction of the 49B.

[Wirra]

49T - Hill or Clark?

[Ray Bell]

It was the '67 French GP that convinced Chapman that the ZF had to go...

Both cars retired with broken gearboxes, IIRC, and the problem (again, IIRC) was that the suspension loads fed into the housing were too great.

As for the FG400 followed by the DG300, I'd think it was the other way round, wasn't it? The FG400 was pretty much standard use in F1 through the early to mid-seventies.

Let's see if I have this right... the DG300 is the same crownwheel and pinion as the FG400, but the FG400 has the lighter gears of the FT200. And in the later days they would replace gears after every practice and race.

[JtP1]

Surely the main reason for changing to the Hewland was that the gears were easily changed in situ. But the ZF required a time consuming stripdown and changing the gear ratios to suit the circuit was quite important with early peaky DFVs

[Ray Bell]

I don't think so...

Colin seemed to be a bit hung up on the ZF stuff, even though he had a lot to do with the early VW-based Hewlands.

[Tim Murray]

It was the '67 French GP that convinced Chapman that the ZF had to go...

Both cars retired with broken gearboxes, IIRC, and the problem (again, IIRC) was that the suspension loads fed into the housing were too great.

The French GP was only the 49’s third race. The problem was temporarily sorted by fitting massive cross-bolted side plates at the British GP while ZF redesigned the casing to solve the problem. The reason for the change to Hewland is as JtP1 said. Here’s what Doug wrote in Theme Lotus:

During their ZF years Team had taken a choice of complete transmissions with them to each race, changing whole assemblies rather than strip and reassemble a gearbox to change ratios ‘in the field’. With the DFV’s characteristics this was unworkable, and early in 1968 the easily-gutted omni-adjustable Hewland gearbox was to be adopted.

As for the FG400 followed by the DG300, I'd think it was the other way round, wasn't it? The FG400 was pretty much standard use in F1 through the early to mid-seventies.

I’ve been through the listings in Autosport. The gearbox types aren’t always listed, but Graham Hill certainly used the FG400 to win Monaco 1968, the 49B’s debut. The FG400 continued to be used on 49Bs during 1968 until Hill apparently used a DG300 to finish second in the USA, but was back to a FG400 for his Mexico win. As far as I can tell, the DG300 was used throughout 1969 and 1970 – Rindt used a DG300 for his 1970 Monaco win, and Fittipaldi had a DG300 when he finished fourth in Germany, the 49’s last finish in the points.

[xj13v12]

Surely the main reason for changing to the Hewland was that the gears were easily changed in situ. But the ZF required a time consuming stripdown and changing the gear ratios to suit the circuit was quite important with early peaky DFVs

Exactly right. Until then they carried complete transaxles and changed that rather than changing ratios.

[Big Jim]

Thanks everyone.
Most views of the rear of a 49B are obstructed by oil tanks and such. If anyone knows where I can find a good photo of the Hewland's installation on the 49B, it would be appreciated.

[Doug Nye]

During the first 49 season in 1967 the ZF casings flexed, affecting final-drive gear mesh and causing several very costly failures. The quick fix adopted involved bolting iron cheek plates to the casings. For all its elegance and perceived efficiency, the impracticality of the ZF in terms of timed-consuming and fiddly ratio-changing away from the factory, was now exacerbated by excessive weight. Talking to me about transmission choice Colin referred to Hewland's finest as "a bunch of old mangle gears"...but they worked.

DCN

[xj13v12]

During the first 49 season in 1967 the ZF casings flexed, affecting final-drive gear mesh and causing several very costly failures. The quick fix adopted involved bolting iron cheek plates to the casings. For all its elegance and perceived efficiency, the impracticality of the ZF in terms of timed-consuming and fiddly ratio-changing away from the factory, was now exacerbated by excessive weight. Talking to me about transmission choice Colin referred to Hewland's finest as "a bunch of old mangle gears"...but they worked.

DCN

Yes, much as has been discussed in the thread 1960s race speeds. But something I am not sure of is if the alternative Collotti transaxle or Ferrari units did have quick change gears at that time? The Hewland remains a major component in use in many guises in historic racing and was a significant contributer to the entire process of maximising engine torque and power for different circuits, indeed for different corners or straights on every individual circuit.

[Ray Bell]

Originally posted by Doug Nye
.....For all its elegance and perceived efficiency, the impracticality of the ZF in terms of time-consuming and fiddly ratio-changing away from the factory, was now exacerbated by excessive weight.....

So what were the details of this ZF? I recall the units that were commonly used in sports cars, such as Matich used here initially... they had synchromesh, IIRC, and I can't see them as being unduly light. And the 5-litre sports cars of the day had plenty of torque and didn't seem to faze them at all.

Were these the ones that Team Lotus used? Or did they have a 'special' such as the Queerbox had been in earlier days, made exclusively for them?

For that matter, I recall that Clark missed out on a likely win at Monaco when he got jammed in two gears at once, was that a ZF or a Hewland? If the latter, it could have added up to Chapman's dislike for the Pommie product.

And were the ZFs used in the 49s possibly even a carryover from the 1.5 formula?

[Tim Murray]

For that matter, I recall that Clark missed out on a likely win at Monaco when he got jammed in two gears at once, was that a ZF or a Hewland? If the latter, it could have added up to Chapman's dislike for the Pommie product.

This was in the 1963 race and the gearbox was a ZF.

[JtP1]

This was in the 1963 race and the gearbox was a ZF.

With synchromesh, which seemed to be prefered by Jim Clark. I always wondered how after looking at most other boxes, how he overcame the inhibitors for double selection of the gears. Was one of them missed out while building the box?

Did Mike Hewland not work for Lotus at some point before setting up his gearbox company?

[Peter Morley]

So what were the details of this ZF? I recall the units that were commonly used in sports cars, such as Matich used here initially... they had synchromesh, IIRC, and I can't see them as being unduly light. And the 5-litre sports cars of the day had plenty of torque and didn't seem to faze them at all.

Were these the ones that Team Lotus used? Or did they have a 'special' such as the Queerbox had been in earlier days, made exclusively for them?

For that matter, I recall that Clark missed out on a likely win at Monaco when he got jammed in two gears at once, was that a ZF or a Hewland? If the latter, it could have added up to Chapman's dislike for the Pommie product.

And were the ZFs used in the 49s possibly even a carryover from the 1.5 formula?

The ZF box used in the Lotus 49 was a 5DS12, the box used in big sportscars was a 5DS25 and the 1½ liter box a 5DS10
Apart from the 49 the 5DS12 was used in the Lotus 62 and I think the 48 F2 cars.
I dont think anyone else used them - they were probably exclusive to Lotus.

I'm not sure about the two gears at once issue, the ZFs tended to fail because the sideplate moved too much which meant the crown wheel wasn't properly supported and destroyed itself against the pinion.
Colottis were good at selecting more than one gear at a time - in fact they still are, the one in the other Scirocco (e.g. Dean Butler's not mine) did that just after being rebuilt and caused a lot of damage to the gearbox.

Interestingly, apart from having synchromesh, the ZF has a mechanism that means you have to go through every gear one after the other, so you can't go from 4th to 2nd for example which slows down gearchanges.

[Ray Bell]

DSJ explained the 'two gears at once' thing...

He made mention of Clark in 'cruise mode' with the race well in hand, and this meant he wasn't throwing the lever into and out of gear as hard as normal, somehow this led to the double engagement.

[JtP1]

DSJ explained the 'two gears at once' thing...

He made mention of Clark in 'cruise mode' with the race well in hand, and this meant he wasn't throwing the lever into and out of gear as hard as normal, somehow this led to the double engagement.

which is usually impossible with the use of detent plungers. So did ZF not use them or someone miss them out building the box?

[Tim Murray]

Clark also had gearbox problems in practice for the next race at Spa. Ian Bamsey in Lotus 25 - A Technical Appraisal quotes DSJ as writing that 'assembly problems' plagued Clark's gearboxes at this stage, which he says were later resolved.

[David Lawson]

"Big Jim"

On page 135 in "Lotus 49, The Story of a Legend" by Michael Oliver there is a photograph of the Hewland gearbox (without the oil tank) when first fitted to a 49B at Invercargill.

I hope this helps.

David

[Big Jim]

Thanks David. I missed that one somehow.