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selecting reverse with a quaife chain drive diff
gaz_gaz - 27/9/13 at 07:56 AM

Can any of you chaps advise on the correct nethod for selecting reverse using the following

http://quaife.co.uk/shop/products/qba7r

I have tried it engine off, and its very stiff. I'm not convinced there isn't a problem but I'd like to make sure before sending the car back.


minitici - 27/9/13 at 08:06 AM

They are quite stiff to pull the actuating lever and the teeth need to be pretty much in line for them to engage.
Maybe try creeping slightly whilst engaging the unit.
Failing that increase the leverage on the engagement system.

The seals and grease in the QBA7R can also make it difficult to pull the unit into reverse (certainly was an the one I had a play with).
The unit 'vents' via the sprocket bolt holes but once the bolts are in position you appear to be fighting creating a vacuum when the unit is put into reverse.


gaz_gaz - 27/9/13 at 08:13 AM

Thanks for that. Nice to hear it's not just me struggling with

It's a real pain in the arse. It managed to get stuck between Forward and Reverse the other day so the car wouldnt roll in either direction.
Had to gently rock it back and forth to free it up.
If the problems persist I think I'll be tempted to leave it in forward and remove the reverse mechanism.


minitici - 27/9/13 at 08:48 AM

The QBA7R is a big heavy lump of metal - can't help thinking that replacing it with a Lynx-AE geared electric reverse on the gearbox output and using a QDF7ZR differential would be a better and lighter solution on the SR4.
qba7R reverse diff
qba7R reverse diff

Repackaged QBA7R reversing differential unit

[Edited on 27/9/13 by minitici]


gaz_gaz - 27/9/13 at 09:15 AM

The opinions I've had back on the Radical forum seem to be following the same trend. "The reverse is there, but not really there to be used"
I tend to do days by myself so pushing the car isn't always that easy.

What would be involved in switching over to the diff you recommend?

Thanks for taking the time to respond so far.

[Edited on 27/9/13 by gaz_gaz]


minitici - 27/9/13 at 12:46 PM

http://secure2.cyberware.co.uk/~rad-shop/acatalog/pr6assemblywithoutreverse.html

Radical's non-reverse unit.

http://www.lynxae.co.uk/Products-Bikesports.htm

Lynx-Ae's electric reverse units

You would also require new sprockets as the non-reversing unit has a different centre hole and pcd.

[Edited on 27/9/13 by minitici]