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FAO Blackbird owners with reverse box: Rubber coupling issues


Klunk

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I'm in the middle of replacing the rubber coupling between the engine and the first propshaft and have noticed that the alignment between the engine and the propshaft is more than is desirable and putting undue strain on the coupling.

 

I have tried altering the engine position and tightening it all up but it just moves back. I also moved the reverse box as far as I can but to no avail.

 

To be honest, I'm not a fan of the engine mount set up but, as it's the standard set up, I'm keen to know if anybody else has experienced this problem and what, if anything, they have done to resolve it. Photos for reference would great as well, if possible. *smile*

Many thanks,

Giles

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Hi there, I've got standard blackbird set up. It's true that there is a slight misalignment in the system. I haven't found it a problem though . I presume you have the rubber doughnut Cush drive unit between engine output and first props haft with three bolts in each

It is a general motors unit , off a senator I think. It does deteriate with age but I've only changed mine once in four years. What problem are you having once it is all bolted up?

If you like you can contact me direct on blatmail .

Cheers Neil

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Thanks guys.

 

Charlie, at the moment I'm trying to understand if this problem is just mine or is generic hence my staying with standard for the moment. From what Neil says, it sounds generic so I will certainly look to improve it when time allows. I've tried shimming it to no real effect but you've just given me another idea *idea* *thumbup*

 

Neil, you're right, it's the rubber cush drive and it's off a 2.0 Vauxhall Omega or pretty much any BMW since the 1990's. On recommendation, I deliberately bought an OEM Febi made one as the quality is much better. The problem is the deflection of the cush drive when bolted up. Nova recommend about 1.5deg misalignment but mine's more like 4deg.. It doesn't sound like much, but when you have the cush drive bolted up with the reverse box end of the prop disconnected, the misalignment is quite alarming and it requires a fair bit of force to align the two again. The one I took off was cracked; not dangerously so, but it's not "right". I will post a photo of the misalignment later.

 

Regards,

Giles

 

 

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I had 4 degrees on my Busa cush drive. I only had it a while and changed it once. The second owner changed two or three in only a few miles. He drove it a lot harder and faster than I did. In the end he fitted a U.J in place of it and I think it was perfect after that.

 

Jason

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With a snapped cam chain the busa is out and I noticed my second Cush drive is showing signs of ware. To be fair its lasted a complete season of Sprints and Hills. The first that came from Nova lasted just 4 events.

 

This one was a BMW item. Alignment is spot on as I welded the reverse box mounts in place once all the props were fitted.

 

I guess it depends on the type of work it has to do. One seasons sprints and hills can not be more than 60 miles.

 

I will be removing the reverse box and installing the electric reverse solution.

 

My prop man reckons the UJ would be fine particularly as splines these days tend to come with a rubberised coating eliminating metal to metal harshness.

 

I am concerned a little about the main gear drive shaft though. It could just be worth the £35 to change it every year.

 

 

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Thanks Jason. I think a lot of it comes down to the quality of the part used. Some only have a small tolerance for flex, others more. Checking on their website the Febi one is good for 3deg so hopefully I be okay.

 

If I start chewing them up, I'll look into the other option *smile*

 

Regards,

Giles

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Simon, the car is going to be a mixture of road and track - depends how flush I am! However, I doubt it will get the abuse your car gets in a season, but it will probably do a lot more miles *smile*.

 

I know someone who chewed his way through a Nova cush on one track day. He replaced it with the Febi part and apparently all is well so far hence my purchase. Sounds like we have the same part. I think I will see how I get on and modify the mounts in the future.

 

Regarding the solid drive, you can get props that are like Metalastik bushes with the rubber between, bonding the 2 shafts together. Bailey Morris do them here.

 

Regards,

 

Giles

 

Edited by - Klunk on 25 Jun 2013 21:32:31

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Giles

 

When I replaced my prop Bailey Morris recommended I replace the nova racing rubber cushion with a a universal joint and put a through tube rubber coupling similar to the drawing you linked to. I have the electric reverse option and this means you can get the angle closer to zero. Do you need a reverse?

 

Nick

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Hi Nick,

I'd like to keep the reverse box if I can as I have steep drive and currently have to reverse the car into an awkward garage. If I move towards the alternative prop design (which I will if I keep chewing cush drives) then I might review the need for it as it's one less thing to go wrong! 😬

 

Interestingly, all the other bike engined kit car manufacturers (Westfield/MK/MNR) all appear to use the BM style double UJ front prop instead of the cush drive. *rolleyes* *smile*

 

Regards,

Giles

 

 

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